Scientists have long assumed our universe would continue on for trillions of years, but a new study presents a much shorter life span for the cosmos: Our universe might last only another 33 billion years.

That's just a cosmic blink before everything collapses in on itself ‪—‬ a process dubbed the "Big Crunch," where expansion reverses, causing all matter and space-time to collapse back into an extremely dense state similar to the conditions of the Big Bang. While long considered a discarded possibility for the fate of the universe, because of accelerating cosmic expansion, this new research has reopened the surprising — and slightly unsettling — option.

The journey to this dramatic conclusion started with our quest to map the cosmos, where we've focused on dark energy, the mysterious force that's pushing the universe apart at an accelerating rate. Recent data from the Dark Energy Survey (DES) and the Dark Energy Spectroscopic Instrument (DESI) mapped hundreds of millions of galaxies to probe this expansion. These crucial tools suggest, with extremely high confidence that the dark energy "equation of state" — its pressure-to-energy density relationship, which dictates its effect on expansion — isn't simply a static number. Instead, its influence appears to be changing over time.

This strange dynamic opens the door for alternative explanations for what dark energy might be made of . This has led to the axion dark energy (aDE) model, which proposes that dark energy comprises both an axion field, which would be an ultra-light form of dark matter that sloshes around the universe, plus a cosmological constant, or fixed background expansion baked into the structure of space-time.

In the new paper, which was uploaded to the preprint server arXiv, the researchers applied this hybrid model to DES measurements. They discovered that this combination likely can explain the DES and DESI results, but with a twist: In the far future of the universe, the interplay of the axion field and the cosmological constant actually actively pulls the universe back together, leading to that ultimate Big Crunch.

By taking the model that best matched observations and running the simulation forward in time, researchers calculated a precise moment of cosmic demise: 33.3 billion years from now. This dramatically shorter future contrasts sharply with the trillion-year lifespan often traditionally considered. Instead of cosmic expansion stretching the universe out like a lonely, eternal highway, we get a cosmic U-turn that takes us back to the start of our journey.

This is fresh territory, and while evidence compels us, science always comes with caveats. The DES and DESI observations suggesting the cosmological constant isn't static are intriguing, but it still needs verification. This model depends on many variables, and several different combinations of them could still explain observations, though a negative cosmological constant ‪—‬ and a resulting Big Crunch ‪—‬ remains the most likely in their analysis.

More data is needed to rigorously test this model. The cosmos is a complicated beast; our understanding continually evolves. As we pursue increasing data streams, we piece together the greatest story ever told — but that story might end sooner than we expected.

This snapshot is just a small part of one of the most comprehensive and spectacular views yet of the universe — a web-like structure formed by millions of galaxies, stretching back to near the dawn of time.

Each tiny point in the image represents a galaxy mapped by the Dark Energy Spectroscopic Instrument (DESI). The galaxies aren't randomly distributed; instead, they form in filaments and clusters known as the cosmic web. Between these luminous strands of galaxies are vast empty regions known as voids, where few stars or galaxies exist.

The image is from the largest high-resolution 3D map of the universe ever created. DESI, which is mounted on the Nicholas U. Mayall 4-meter Telescope at Kitt Peak National Observatory in Arizona, uses 5,000 robotic fiber-optic sensors to capture light from distant celestial objects.

The five-year survey was supposed to gather data on 34 million galaxies and quasars (the bright cores of distant young galaxies). In practice, it detected over 47 million, along with more than 20 million nearby stars in the Milky Way. A visualization published alongside DESI's map shows how it has grown over those five years.

Some of the light captured in this image took billions of years to reach Kitt Peak, so it allows scientists to look back in time to reconstruct how the universe evolved. The result is a three-dimensional view that not only shows where galaxies are but also how they have moved and clustered over time.

Beyond its visual impact, the image plays a crucial role in probing mysterious dark energy, the name physicists have given to a force that appears to be driving the universe's accelerated expansion. It makes up roughly 70% of the universe, and its nature and distribution are among the biggest questions in physics.

By comparing the distribution of galaxies across different epochs, researchers can track how dark energy has influenced the structure of the universe over the past 11 billion years. Early DESI data has already hinted that dark energy may evolve through cosmic history ‪—‬ a breakthrough that would fundamentally reshape scientists' understanding of the universe and its ultimate fate.

The image is the result of a massive international collaboration. More than 900 researchers from over 70 institutions contributed to the project, which was led by Lawrence Berkeley National Laboratory and funded by the U.S. Department of Energy Office of Science.

DESI will continue observing the sky through 2028, expanding its map by about 20%. Future observations will target fainter and more distant galaxies, as well as harder-to-observe regions near the Milky Way (where stars get in the way) and in the southern sky (which requires the telescope to peer through more of Earth's atmosphere). The first results from the full dataset are anticipated in 2027.

See more Space Photos of the Week

Astronomers have produced one of the most accurate, comprehensive cosmic maps ever made, revealing a brilliant "sea of light" that permeated the early universe.

Unlike other universal maps, this 3D representation is composed of light emitted by a single element: hydrogen, the simplest and most abundant element in the universe, which emits large quantities of a specific wavelength of light when it becomes excited by energy from nearby stars.

By measuring this light across a vast patch of sky, astronomers got a glimpse of what the universe looked like 9 billion to 11 billion years ago, during an epoch of vigorous star formation.

The new research, described in a paper published March 3 in The Astrophysical Journal, is part of the Hobby-Eberly Telescope Dark Energy Experiment (HETDEX), a sky survey that aims to illuminate how dark energy and gravity shape the universe. The researchers can now compare their simulations with this new data, gathered with the Hobby-Eberly Telescope at the McDonald Observatory in Texas, to assess how cosmological models differ from observations.

An exciting way to see the baby universe

When hydrogen atoms are bombarded by stellar radiation, they become excited and emit Lyman-alpha light, a specific wavelength in the ultraviolet part of the electromagnetic spectrum.

Massive, bright galaxies are easier to detect, but fainter galactic structures and the immense interstellar gas clouds that form stars and galaxies have remained largely undetected — until now.

To reveal the sea of light that permeated the fledgling cosmos, the researchers used a technique called line-intensity mapping, which focuses on the telltale wavelengths, or signature spectral emissions, given off by different elements. Astronomers can therefore use line mapping to chart the concentration and distribution of those specific elements throughout the cosmos, forming a map of the luminous galaxies and glowing gas clouds lit up by excited hydrogen atoms.

Cosmology is about zooming out

When studying individual galaxies, stars or other discrete celestial objects, astronomers analyze their characteristics by zooming in. Cosmology, however, requires zooming out. Accordingly, the HETDEX survey doesn't observe individual galaxies but rather the combined light from every object in a designated region of the sky. As a result, astronomers can gather integrated data from a multitude of galaxies and intergalactic gas clouds simultaneously.

"Imagine you're in a plane looking down," study co-author Julian Muñoz, a theoretical cosmologist at The University of Texas at Austin, said in a statement. "The 'traditional' way to do galaxy surveys is like mapping the brightest cities only: you learn where the big population centers are, but you miss everyone that lives in the suburbs and small towns. Intensity mapping is like viewing the same scene through a smudged plane window: you get a blurrier picture, but you capture all the light and not just the brightest spots."

In the quest to understand dark energy and chart more than 1 million bright galaxies, HETDEX "has gathered more than 600 million spectra over an area equivalent to more than 2,000 full moons, creating an unprecedented dataset," the researchers said in a different statement.

A golden age of cosmic mapping

The mapping method made possible by HETDEX offers another way to examine cosmology’s driving forces and how mass is distributed throughout the universe.

"These new 3D maps allow us to study how galaxies cluster together," study co-author Karl Gebhardt, a professor of astrophysics at The University of Texas at Austin, told Live Science via email. "The culprit that causes galaxies to come together is gravity. So by studying the clustering properties, we are understanding the properties of gravity and how much mass exists," Gebhardt explained.

Seeing galactic structures as a collective is invaluable for measuring large-scale density fluctuations across the cosmos to explore the influence of dark energy, the mysterious entity that appears to be accelerating the universe's expansion.

Unsurprisingly, detecting the signals from ancient galaxies is hard, "but excluding the faint signal from everything else — faint galaxies in the foreground, noise from the detector, artifacts produced by the analysis techniques, scattered light sources like the moon, weak absorption/emission lines from the Earth's atmosphere, is even harder," study co-author Robin Ciardullo, a professor of astronomy and astrophysics at Penn State and the observing manager of HETDEX, told Live Science via email.

The next step is to improve noise-reduction techniques and separate the desired signals from the numerous astronomical and Earthly contaminants. The researchers can then use fainter sources and lower-mass objects as tracers of cosmic evolution to more robustly constrain gravity models.

"The Hobby-Eberly is a pioneering telescope," Muñoz said. "And with new, complementary instruments coming online, we’re entering a golden age for mapping the cosmos."

A six-year survey covering 669 million galaxies has revealed insight into dark energy, the mysterious phenomenon driving the universe's accelerating expansion.

The landmark survey paints a complicated picture about our understanding of the universe, showing that two leading theories of cosmology are both equally good fits for the new cosmic expansion observations. However, both theories still fall short in explaining why matter clusters in the universe the way it does, hinting that there’s more work yet to be done.

The analysis of the Dark Energy Survey (DES) combines four types of data collected by the Victor M. Blanco Telescope in Chile, covering about an eighth of the sky. The research zeroes in on the universe's past and present expansion, tightening constraints on models of that expansion about twice as much as previous studies had.

"These results from the Dark Energy Survey shine new light on our understanding of the Universe and its expansion," Regina Rameika, associate director of the U.S. Department of Energy's Office of High Energy Physics, said in a statement. "They demonstrate how long-term investment in research and combining multiple types of analysis can provide insight into some of the Universe's biggest mysteries."

Expanding our knowledge

Dark energy is thought to make up about 70% of the total energy in the universe, but astronomers still know very little about its true nature. Scientists proposed the concept to explain observations that suggest the universe is expanding at an ever-accelerating rate. The DES is one of several collaborations developed to study the phenomenon in more detail.

In a new paper posted to the preprint server arXiv Jan. 21, DES scientists used four kinds of markers to probe the universe's expansion: baryonic acoustic oscillations, or fluctuations in the density of normal matter throughout the universe; Type Ia supernovas, stellar explosions that can help scientists gauge the distance of cosmic objects; galaxy clusters; and weak gravitational lensing, which occurs when a galaxy cluster warps space-time, distorting the apparent shapes of objects behind it. A series of 18 supporting papers dig into the findings in detail.

Altogether, the data and analysis are consistent with previous studies of dark energy, though the new work places tighter constraints on models of how the universe behaves. The data mostly align with the standard model of cosmology, in which the density of dark energy is constant. The data also fit with a related model in which the dark energy density varies over time, but it didn't align any better than it did with the standard model.

"It is an incredible feeling to see these results based on all the data, and with all four probes that DES had planned," study co-author Yuanyuan Zhang, an astronomer at the National Science Foundation's NOIRLab, which manages the telescope, said in the statement. "This was something I would have only dared to dream about when DES started collecting data, and now the dream has come true."

Despite the relatively good fit between the data and the standard model, some questions remain. The pattern of galaxy clustering still doesn't line up exactly with predictions from the standard model, but it's not different enough to conclude that the standard model is wrong, the team added.

Still, DES researchers will continue testing this and other models of dark energy in conjunction with the Vera C. Rubin Observatory in Chile to further refine our understanding of the mysterious phenomenon.

"Rubin's unprecedented survey of the southern sky will enable new tests of gravity and shed light on dark energy," Chris Davis, NSF program director for NOIRLab, said in the statement.

Recent observations have revealed that our understanding of the cosmos is flawed, but it may be because the universe is "stickier" than we assumed, new research proposes.

In a paper that was published on the arXiv preprint server but has not been peer-reviewed, Muhammad Ghulam Khuwajah Khan, a researcher at the Indian Institute of Technology, suggests that space may possess a property called bulk viscosity.

Viscosity is a measure of how much a fluid resists flowing or changing shape — like the difference between pouring water versus honey. In this case, we are talking about the bulk viscosity of the vacuum itself, a ghostly resistance that occurs when space expands.

A constant problem

Traditionally, scientists have used a simple model to describe the universe. In this model, known as Lambda-CDM, dark energy — the mysterious force responsible for the accelerating expansion of the universe — is a steady, unchanging background known as the cosmological constant.

However, data from the Dark Energy Spectroscopic Instrument (DESI), which is mounted on the Mayall Telescope at Kitt Peak National Observatory in Arizona, released last year hinted that something may be fundamentally wrong with our understanding of dark energy. The new observations showed a slight mismatch between our standard theories and the actual, observed rate at which galaxies are zipping away from us.

To explain this discrepancy, Khan has proposed a model involving spatial "phonons." In solid-state physics, phonons are essentially the collective vibrations of atoms in a crystal. But Khan applied this idea to the fabric of space itself. He suggested that these longitudinal vibrations, which would act as sound waves of the vacuum, could be responsible for a viscous effect that slowed the expansion of the cosmos just enough to match what we see in the sky.

By treating the universe as a viscous fluid, this model introduces a drag on cosmic expansion. As space stretches, these spatial phonons slosh around, creating a pressure that opposes the outward push. In fact, the study shows that this simple, data-based model fits the DESI data with great precision, potentially solving some of the headaches caused by the standard cosmological constant.

But we should tread lightly — this is merely a guess. Viscous dark energy would be a foundational shift in how we view the vacuum of space, and the hard data from DESI are still being analyzed by the scientific community. We aren't yet sure if this viscosity is a fundamental property of nature or just a sluggish artifact of our current measurements.

So, where do we go from here? The next decade of data from missions like the Euclid space telescope and continued monitoring by DESI will be the ultimate test. We need more observations to see if these ghostly vibrations are truly ruling the cosmos, or if space is as smooth as we once believed.

A new paper has predicted that the universe's expected lifespan is drastically shorter than once thought — and that the cosmos will start to die in just 10 billion years.

This is only one possible theory, however, and nobody really knows when the universe will end.

There are two leading theories for how the universe may die: the "Big Freeze" theory, which suggests that the cosmos will continue to expand until all the stars have lost their energy and cooled to absolute zero; and the "Big Crunch" theory, which suggests that the universe's expansion is only temporary and that, after a certain point, it will begin to contract and eventually collapse in a reverse Big Bang. Scientists struggle to agree on which is more likely because recent observations have revealed uncertainties over how fast the universe is expanding — dubbed a cosmological crisis.

One way of resolving this crisis is to uncover the true value of the cosmological constant, a theoretical "magic number" that can be used to calculate cosmic expansion. But to do this, we first need to uncover the elusive identity of dark energy — the mysterious force or substance that seems to be driving the universe's expansion.

To that end, in a new paper uploaded June 30 to the preprint server arXiv that has not yet been peer-reviewed, researchers looked at recent findings from the Dark Energy Survey (DES) and the Dark Energy Spectroscopic Instrument (DESI), which hint that dark energy is made up of axions.

Axions are hypothetical ultralight particles that rarely interact with matter. If they exist, then it means that the cosmological constant has a negative value, which will lead to a Big Crunch, the researchers argued. And their calculations indicate that this would happen sooner than expected.

Related: 10 wild theories about the universe

Using their new model for the Big Crunch, the researchers estimate that the total lifespan of the universe is around 33 billion years. Given that the universe is currently believed to be around 13.8 billion years old, this means that the cosmos has already completed over one-third of its total life.

If the new timeline is correct, the universe will stop expanding in around 10 billion years and begin to rapidly contract much faster than other models have previously predicted, Live Science's sister site Space.com recently reported. Other models suggest that the Big Crunch may not happen for hundreds of billions of years.

The true identity of dark energy remains a mystery, however, meaning that the new model is purely theoretical.

Other possible timelines

This is not the first study to suggest that the Big Crunch may start to happen sooner than expected. In 2022, researchers proposed that the universe could stop expanding in as little as 100 million years.

But if the universe instead ends in a Big Freeze, which was the scenario favored by Albert Einstein, then its death will likely come much later.

Recent research has suggested that the soonest the Big Freeze may come to pass is in around 1 quinvigintillion (1 followed by 78 zeroes) or 1,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000 years.

Other theories suggest that cosmic expansion may be capable of suddenly reversing multiple times, which further complicates potential timeframes for either scenario. Stephen Hawking's work on black holes also suggested that everything in the universe could evaporate before either scenario plays out.

Some experts have additionally suggested that our universe could be one of many reincarnations in an endless cycle of Big Bangs, or Big Bounces. These would essentially make the cosmos immortal. Others have proposed that the universe is a simulation or hologram, which raises the question of whether it is even "real" at all.

The only thing that most researchers can agree on is that it could take a very, very long time to find out who is right.

Astronomers have found what they claim is fresh evidence that Earth and our Milky Way galaxy are suspended inside a gigantic void that's skewing our observations of the cosmos.

The radical proposal, made by analyzing echoes of the Big Bang, suggests that our galaxy may be floating in a 2 billion-light-year region that's 20% less dense than average.

If the results hold up, they could help astronomers find the true age of our universe and offer a solution to one of the stickiest conundrums in cosmology — the discrepancy, known as the Hubble tension, that the distant universe expanded more slowly in the past than the nearby universe does today.

The findings would also prompt a major rewrite of existing cosmological models. The researchers shared their findings July 9 at the Royal Astronomical Society's National Astronomy Meeting in Durham, England.

Hubble trouble

Over the past decade, cosmology has been embroiled in a growing crisis as observations — first made by the Hubble Space Telescope and later by the James Webb Space Telescope — suggested that the universe is expanding at different rates depending on where astronomers look.

Currently, there are two gold-standard methods for figuring out this expansion rate, called the Hubble constant. The first involves poring over tiny fluctuations in the cosmic microwave background, an ancient relic of the universe's first light produced just 380,000 years after the Big Bang. This method enabled astronomers to infer an expansion rate of roughly 67 kilometers per second per megaparsec (km/s/Mpc), which closely matches predictions made by the standard model of cosmology.

Related: 'Our model of cosmology might be broken': New study reveals the universe is expanding too fast for physics to explain

But the second method — measuring closer distances with pulsating stars called Cepheid variables — returned a puzzlingly high value for the Hubble constant of 73.2 km/s/Mpc.

This discrepancy may not seem like much, but it's enough to completely contradict the predictions made by the standard model of cosmology. Astronomers have suggested many major and minor rewrites to this model to explain the tension, including tossing out dark energy and dark matter altogether.

But this anomaly could be specific to our cosmic backyard, the astronomers behind the new research suggest.

"A potential solution to this inconsistency is that our Galaxy is close to the centre of a large, local void," lead author Indranil Banik, an astronomer at the University of Portsmouth in the U.K., said in a statement. "It would cause matter to be pulled by gravity towards the higher density exterior of the void, leading to the void becoming emptier with time."

That would make local expansion inside the void faster than it is in denser, more distant regions of the cosmos, he added.

Filling the void

The notion that our part of the universe could be less dense than others first took shape in the 1990s, when researchers found fewer galaxies in our local universe than they expected compared with the surrounding universe.

Further research backed up these observations, indicating that our galaxy may be in the center of a region known as the local hole or KBC void, named after the initials of the study's astronomers. Nonetheless, some astronomers question whether the apparently underdense space could be filled with objects that don't emit light.

To investigate the evidence further, Banik and his colleagues collected 20 years' of data from observations of nearby baryon acoustic oscillations (BAOs) — pressure waves created during the Big Bang that froze in place and expanded alongside the universe, governing the distribution of galaxies we see today.

"These sound waves traveled for only a short while before becoming frozen in place once the universe cooled enough for neutral atoms to form," Banik explained. "They act as a standard ruler, whose angular size we can use to chart the cosmic expansion history."

According to the researchers' BAO measurements, it's 100 times more likely that we live in a cosmic void than a region of average density.

The next step for Banik and colleagues will be to compare their void model to other models to see which best fits the history of the universe's expansion. They will also need to explore tweaks to the standard model of cosmology, including throwing out the assumption that matter is evenly distributed throughout the universe.

The implications would be vast — not just for our understanding of how the universe behaves but for our own place in it. Modern astronomy has consistently revealed that our personal view of the cosmos is unexceptional. However, if we do live in the middle of a void, we could be more unique in our isolation than first thought.

Update: The first image reveal from the groundbreaking Vera C. Rubin Observatory will stream live in less than an hour! You can watch the live debut right here at 11 a.m. EDT today (Monday, June. 23) or on the Observatory's YouTube page.

The Observatory has already offered a stunning sneak peak of the new images this morning, sharing three images of distant galaxies and nebulas. Check them out at the link above to get ready for the full debut, streaming below.

How to tune in

If you want to watch from home, a news conference will be streaming on YouTube in English and Spanish at 11:00 a.m. EDT today (Monday, June 23). The link to watch is posted on the observatory's website, and is also embedded above.

If you'd prefer to bask in the awe of the cosmos with friends, you may be able to attend a watch party near you — or even host one of your own. Groups will gather across the globe in planetariums and universities to admire the highly detailed images and videos as they are released. The observatory has shared links to a map of all registered watch parties, as well as a link to sign up to become a host.

During the news conference, the observatory team will introduce the Rubin Observatory before showcasing the new images and discussing their significance. Watch parties may also hear from local scientists and special guests. Be sure to check out the details of a watch party before you attend to learn about any extra programming.

The Rubin Observatory

The observatory, perched high on a mountain in the Chilean Andes, will peer at interstellar comets and dangerous asteroids, as well as larger objects, like twisting galaxies and exploding supernovas.

Related: 'People thought this couldn't be done': Scientists observe light of 'cosmic dawn' with a telescope on Earth for the first time ever

Inside Rubin lies the world's largest digital camera and six of the largest optical filters ever produced. Together, they allow researchers to observe different facets of the universe in many wavelengths of light and remarkably high detail.

The camera will take a new high-resolution photo of the sky around every 40 seconds. The images will then be transmitted via fiber optic cables to a supercomputer in California, which will analyze the photos. When stitched together, the images can act as a time-lapse video of space, one that is planned to span 10 years.

Using its groundbreaking instruments, the observatory is expected to contribute to current understanding of widely debated phenomena, including dark energy and dark matter — two components that are thought to make up a vast majority of the universe, but remain poorly understood.

The new images could be the first of many that vastly improve our understanding of the cosmos. Whether you join a watch party or tune in from the comfort of your couch, these photos are not to be missed.

Editor's note: This article was updated Monday (June 23) to include a link to sneak peak images from the Observatory

Scientists have a pretty good idea of how our universe began: According to the Big Bang theory, an infinitely small, dense point rapidly expanded 13.8 billion years ago, and the universe has been experiencing accelerating expansion ever since. However, trying to imagine where our universe might go next, or even how and when it might eventually end, is still fiercely debated.

"In physics, we can only trust our ideas and theories when we gather the data that test them and confirm them," Nemanja Kaloper, a professor of physics at the University of California, Davis, told Live Science in an email. "[But] in cosmology that is notoriously difficult since the experiments are passive — we cannot recreate the universe to see how things go and improve the data sets at will."

So, exactly when will the universe end? That depends on which theory you find the most convincing. Two of the top leading theories are called the Big Freeze and the Big Crunch.

Related: Could a black hole devour the universe?

The Big Freeze

For Henry Tye, a professor emeritus of physics at Cornell University, the most likely scenario is the "Big Freeze."

"This is what is already happening right now," Tye said. "The universe's expansion will become faster and continue for 100 billion years, a trillion years or forever. There's no end point."

One cosmological model that explains this expansion is the idea that our universe is expanding toward an area called "de Sitter space," which is a part of space with intrinsic positive energy that may be helping push the universe outward. This means that the universe wouldn't necessarily end, but it wouldn't stay the same, either. As the name implies, the Big Freeze would dilute energy in the universe by so much that any form of activity — such as the burning of stars or the churning of black holes — would come to an end. This is what physicists call the "heat death of the universe."

The Big Crunch

However, it's also possible that this positive de Sitter space could one day decay into negative energy, which would reverse the direction of the universe.

"That would [mean] the Universe expands for a bit before reaching a max and then turns around," Antonio Padilla, a professor of physics at the University of Nottingham in the U.K., told Live Science in an email. "Such a universe would end in a crunch."

This "Big Crunch" would essentially reverse the expansion of the Big Bang and erase our universe. The spooky thing about this scenario, Tye said, is that it might already be happening in pockets throughout the universe, but it would be largely undetectable because evidence of those areas of space would be erased.

Some recent models have predicted that a Big Crunch, driven by dark energy — the mysterious force driving the accelerated expansion of the universe — could begin as soon as 100 billion years from now. In particular, this timeline was determined by studying a theoretical model of a type of dynamical dark matter called "quintessence." Conversely, in a paper Padilla contributed to in 2021, he found that the universe has at least another trillion years left — which he said was on the shorter end of estimates. This determination was made using the ideas of string theory, which imagines particles as tiny 1-dimensional strings instead of points.

Even then, the universe might not be ready to stop existing completely. Some scientists believe that a Big Crunch may just be part of a larger cycle of expansion and contraction that took place in the early universe called a Big Bounce. In this idea, the universe would "start" with rapid expansion (i.e. a Big Bang) and expand for a while before eventually collapsing again into the conditions necessary for another Big Bang.

As for which theory is correct, it's hard to say with total certainty, Padilla said.

"Predicting the far future is hard," he said. "My view is that observations can only take us so far here because of the very nature of what we are dealing with."

Even if none of these theories is correct, there may still be an expiration date on when all the regular matter in the universe — stars, galaxies, and even remnants of dead stars, such as black holes — will simply cease to be. Due to a type of spontaneous radiation predicted by Stephen Hawking, everything in the universe could slowly evaporate to nothing, a 2025 study published in the Journal of Cosmology and Astroparticle Physics suggests. The proposed timespan for this total evaporation is 1 quinvigintillion years — that's 1 followed by 78 zeros, or 10⁷⁸.

According to Tye, there is no one piece of evidence that could fully prove a theory about the universe's fate. Instead, cosmologists must improve existing models of our universe and extrapolate them infinitely. Gaining a better understanding of complicated topics like dark energy and string theory is one way scientists can better predict where our universe is going.

Physicists claim they may have found a long-awaited explanation for dark energy, the mysterious force that's driving the accelerated expansion of the universe, a new preprint study hints.

Their calculations suggest that, at the smallest scales, space-time behaves in a profoundly quantum way, differing drastically from the smooth, continuous structure we experience in everyday life. According to their findings, the coordinates of space-time do not "commute" — meaning the order in which they appear in equations affects the outcome. This is similar to how a particle's position and velocity behave in quantum mechanics.

One of the most striking consequences of this quantum space-time, as predicted by string theory, is that it naturally leads to cosmic acceleration. Moreover, the researchers found that the rate at which this acceleration decreases over time aligns remarkably well with the latest observations from the Dark Energy Spectroscopic Instrument (DESI).

"Viewed through the lens of our work, you could think of the DESI result as the first observational evidence supporting string theory and perhaps the first observable consequences of string theory and quantum gravity," study co-author Michael Kavic, a professor at SUNY Old Westbury, told Live Science via email.

The mystery of the universe's expansion

In 1998, two independent teams — the Supernova Cosmology Project and the High-Z Supernova Search Team — discovered that the universe's expansion was not slowing down, as previously thought, but was instead accelerating. They reached this conclusion by studying distant supernovas, which appeared dimmer than expected. This acceleration implied the presence of a mysterious entity permeating space, later dubbed dark energy.

Related: 'The universe has thrown us a curveball': Largest-ever map of space reveals we might have gotten dark energy totally wrong

However, the origin of dark energy has remained elusive. A popular hypothesis suggests it arises from quantum fluctuations in the vacuum, similar to those seen in the electromagnetic field. Yet, when physicists attempted to compute the expansion rate based on this idea, they arrived at a value that was 120 orders of magnitude too large — a staggering discrepancy.

Recent DESI observations further complicated the picture. According to the Standard Model of elementary particles, if dark energy were simply a vacuum energy, its density should remain constant over time. However, DESI data indicate that the acceleration rate is not fixed but that it decreases over time — something the Standard Model does not predict.

Solving the mystery with string theory

To address these inconsistencies, the researchers turned to string theory, one of the leading candidates for a quantum theory of gravity. Unlike the Standard Model, which treats elementary particles as point-like, string theory proposes that they are actually tiny, vibrating, one-dimensional objects called strings. These strings, depending on their modes of vibration, give rise to different particles — including the graviton, the hypothetical quantum carrier of gravity.

In a new paper that was posted in the preprint database arXiv but has not been peer-reviewed, physicists Sunhaeng Hur, Djordje Minic, Tatsu Takeuchi (Virginia Tech), Vishnu Jejjala (University of the Witwatersrand), and Michael Kavic applied string theory to analyze space-time at the quantum level.

By replacing the Standard Model's description of particles with the framework from string theory, the researchers found that space-time itself is inherently quantum and noncommutative, meaning the order in which coordinates appear in equations matters.

This radical departure from classical physics allowed them to derive the properties of dark energy not just from experimental data, but directly from a fundamental physical theory. Their model not only yielded a dark energy density that closely matches observational data but also correctly predicted that this energy should decrease over time, aligning with DESI's findings.

One of the most striking aspects of their result is that the value of dark energy depends on two vastly different length scales: the Planck length, the fundamental scale of quantum gravity, which is about 10⁻³³ centimeters; and the size of the universe, which is billions of light-years across. Such a connection between the smallest and largest scales in the cosmos is highly unusual in physics and suggests that dark energy is deeply tied to the quantum nature of space-time itself.

"This hints at a deeper connection between quantum gravity and the dynamical properties of nature that had been supposed to be constant," Kavic said. "It may turn out that a fundamental misapprehension we carry with us is that the basic defining properties of our universe are static when in fact they are not."

Experimental tests and future prospects

Although the team's explanation of the universe's accelerated expansion is a significant theoretical breakthrough, independent experimental tests are needed to confirm their model. The researchers have proposed concrete ways to test their ideas.

One line of evidence "involves detecting complicated quantum interference patterns, which is impossible in standard quantum physics but should occur in quantum gravity," Minic added.

Interference occurs when waves, such as light or matter waves, overlap and either amplify or cancel each other out, creating characteristic patterns. In conventional quantum mechanics, interference follows well-understood rules, typically involving two or more possible quantum paths. However, higher-order interference—predicted by some quantum gravity models—suggests more complex interactions that go beyond these standard patterns. Detecting such effects in the lab would be a groundbreaking test of quantum gravity.

"These are tabletop experiments that could be performed in the near future — within three to four years."

"There are many implications of our approach to quantum gravity," said Djordje Minic, a physicist at Virginia Tech and co-author of the paper, in an email. One line of evidence "involves detecting complicated quantum interference patterns, which is impossible in standard quantum physics but should occur in quantum gravity," Minic added.

Interference occurs when waves, such as light or matter waves, overlap and either amplify or cancel each other out, creating characteristic patterns. In conventional quantum mechanics, interference follows well-understood rules. However, some quantum gravity models suggest more complex interactions that go beyond these standard patterns. Detecting such effects in the lab would be a groundbreaking test of quantum gravity.

"These are tabletop experiments that could be performed in the near future — within three to four years."

In the meantime, the researchers are not waiting for experimental confirmations. They are continuing to refine their understanding of quantum space-time, as well as exploring additional avenues for testing their theory.

If confirmed, their findings would mark a major breakthrough not only in explaining dark energy but also in providing the first tangible evidence for string theory — a long-sought goal in fundamental physics.

The European Space Agency (ESA) has just released the first batch of data from the groundbreaking Euclid space telescope, which was built to study the mysteries of dark matter and dark energy throughout the universe.

The survey data, released March 19, includes initial scans of three regions that Euclid will observe regularly, as well as detailed classifications of more than 380,000 galaxies — a mere 0.4% of the galaxies scientists expect to catalog over the mission's planned six-year lifespan.

"With the release of the first data from Euclid's survey, we are unlocking a treasure trove of information for scientists to dive into and tackle some of the most intriguing questions in modern science," Carole Mundell, ESA's director of science, said in a statement.

Euclid, which launched in July 2023 and began collecting data in February 2024, aims to map the large-scale structure of the universe. Understanding this structure through the shapes, sizes and distribution of galaxies could help scientists determine the nature of dark matter and dark energy — two mysterious phenomena that together make up an estimated 95% of the universe but do not interact with light and so cannot be studied directly.

"The full potential of Euclid to learn more about dark matter and dark energy from the large-scale structure of the cosmic web will be reached only when it has completed its entire survey," Clotilde Laigle, a Euclid Consortium scientist at Institut d'Astrophysique de Paris, said in the statement. "Yet the volume of this first data release already offers us a unique first glance at the large-scale organization of galaxies, which we can use to learn more about galaxy formation over time."

Related: 'The universe has thrown us a curveball': Largest-ever map of space reveals we might have gotten dark energy totally wrong

The March 19 release includes a single scan of each of the deep-field regions, three areas of the sky that Euclid will revisit multiple times to observe far into the universe. In these initial images, the telescope captured 26 million galaxies, the most distant of which are 10.5 billion light-years away. (A light-year is the distance light can travel in one year — roughly 5.9 trillion miles or 9.5 trillion kilometers.)

"We will observe each deep field between 30 and 52 times over Euclid's six year mission, each time improving the resolution of how we see those areas, and the number of objects we manage to observe," Valeria Pettorino, Euclid project scientist at ESA, said in the statement. "Just think of the discoveries that await us."

Over the course of its planned mission, Euclid will likely capture images of 1.5 billion galaxies, sending about 100 gigabytes of data back to Earth each day. To process this tsunami of information, Euclid scientists are turning to artificial intelligence (AI). Last year, nearly 10,000 volunteers with citizen science project Galaxy Zoo helped train the "ZooBot" AI algorithm to recognize various features of galaxies, such as spiral arms, in early Euclid images.

"We're looking at galaxies from inside to out, from how their internal structures govern their evolution to how the external environment shapes their transformation over time," Laigle said in the statement. "Euclid is a goldmine of data and its impact will be far-reaching, from galaxy evolution to the bigger-picture cosmology goals of the mission."

Dark energy may have switched directions sometime in the distant past — and this violent transition may explain why cosmological observations aren't adding up, researchers propose in a new paper.

The modern picture of the evolution of the universe is known as ΛCDM (or lambda-CDM), for dark energy (represented by the Greek letter Λ) and cold dark matter. Dark energy is the mysterious force driving the accelerating expansion of the universe, and cold dark matter refers to the mysterious, invisible substance that provides most of the mass of almost every single galaxy.

This model has explained a wide variety of observations, such as the behavior of galaxies and clusters, the growth of large-scale structures, and the appearance of the cosmic microwave background. But in recent years, two troubling tensions have popped up.

One such problem, known as the Hubble tension, is a difference in measuring the present-day expansion rate of the universe, a number known as the Hubble constant. Probes of the distant, early universe seem to be giving estimates significantly lower than probes of the nearby, late universe do.

Related: After 2 years in space, the James Webb telescope has broken cosmology. Can it be fixed?

Related to this issue is the second problem, known as the sigma-8 tension. This is a measure of how clumpy matter is in the universe, and once again, different probes are yielding different results.

A cosmic slowdown

Something in the ΛCDM model has to be wrong, but we're not sure what. One hypothesis is that dark energy might be more dynamic than we originally thought. In the usual ΛCDM picture, dark energy is a cosmological constant. It stays the same through cosmic history.

But in a recent model that's been gaining interest, dark energy changes. And not by a little; it undergoes a complete phase transition, from decelerating the universe to accelerating the universe.

Now, adding a twist to that theory, a research team has explored the possibility that the phase change is even more dramatic. In a paper posted to the preprint server arXiv in February but not yet peer-reviewed, dark energy doesn't just switch signs; it also changes strength, so that it powers an acceleration differently than it powers a deceleration.

Then, the researchers tested their model against a wide variety of observations and datasets. These included the Planck space observatory's measurements of the cosmic microwave background, the oldest light we can see in the universe; a measurement of a phenomenon called the baryon acoustic oscillation, a pattern in the arrangement of galaxies at very large scales; the Pantheon dataset of supernova distance measures; and a weak lensing map that provides details accounting for the effects of dark matter.

They found that the new model alleviated some of the Hubble and sigma-8 tensions, and thus they contend that this approach might be a promising way forward.

That said, the researchers noted that this model isn't exactly grounded in known physics. It's just a toy, a way to explore the physical consequences of a model without knowing the underlying physics. But because it seems like a promising direction, this approach could motivate theorists to come up with mechanisms to explain how dark energy might switch like this.

No matter what, it appears that the universe — especially dark energy — is more complicated than we assumed.

The Euclid space telescope has captured a stunning and rare "Einstein ring" magnifying light from the depths of the universe.

The image shows a faint halo surrounding the nearby galaxy NGC 6505, created as the galaxy warps and magnifies light from an even more distant galaxy behind it.

This type of magnification is called gravitational lensing and was first predicted by Albert Einstein in 1915. The powerful magnification means that the resulting image shows us light from an unnamed and undiscovered galaxy 4.42 billion light-years into the universe's past — even though NGC 6505 is only 590 million light-years away, in Earth's "cosmic backyard." The researchers published their findings Feb. 10 in the journal Astronomy and Astrophysics.

"An Einstein ring is an example of strong gravitational lensing," study lead author Conor O'Riordan, a researcher at the Max Planck Institute for Astrophysics in Germany, said in a statement. "All strong lenses are special, because they're so rare, and they're incredibly useful scientifically. This one is particularly special, because it's so close to Earth and the alignment makes it very beautiful."

Magnifying the stars

Einstein's theory of general relativity describes the way massive objects warp the fabric of the universe, called space-time. Gravity, Einstein discovered, isn't produced by an unseen force but by space-time curving and distorting in the presence of matter and energy.

Related: Mysterious 'Green Monster' lurking in James Webb photo of supernova remnant is finally explained

This curved space, in turn, sets the rules for how energy and matter move. Even though light travels in a straight line, light traveling through a highly curved region of space-time, such as the region around a massive galaxy, also travels in a curve — bending around the galaxy and splaying out into a halo.

The new image was retrieved from data collected by the Euclid space telescope during its early testing phase in September 2023. Launched on July 1, 2023, Euclid was designed to compile wide-lens images to help scientists hunt for two of the universe's most mysterious components: dark matter and dark energy.Researchers think dark matter and dark energy together make up about 95% of the universe, but they do not interact with light so can't be detected directly.

Instead, scientists study these mysterious components by observing the way they interact with the visible universe around them: Dark matter can be seen by observing its gravitational warping effects on galaxies; and dark energy can be spotted in the force propelling the universe's runaway expansion.

Astronomers have identified hundreds of Einstein rings. But these phenomena aren't sought after just because they make pretty pictures. Because the rings magnify light, scientists can reconstruct this light into its original, pre-bent, form, which can enhance the details astronomers are able to spot in very distant galaxies.

Also, because the extent to which light bends depends on the strength of the gravitational field of the object that bends it, Einstein rings can act as a cosmic scale for gauging the masses of galaxies and black holes, including how much dark matter they contain.

"I find it very intriguing that this ring was observed within a well-known galaxy, which was first discovered in 1884," study co-author Valeria Pettorino, a project scientist working on Euclid, said in the statement. "The galaxy has been known to astronomers for a very long time. And yet this ring was never observed before. This demonstrates how powerful Euclid is, finding new things even in places we thought we knew well. This discovery is very encouraging for the future of the Euclid mission and demonstrates its fantastic capabilities."

Euclid is partway through its six-year mission to catalog a third of the entire night sky by capturing thousands of wide-angle images. All told, Euclid will capture light from more than a billion galaxies that are up to 10 billion years old, according to the European Space Agency.

Once this is done, astronomers will use Euclid's images to create two maps: one of the gravitational lensing of galaxies that should reveal concentrations of dark matter, and the other of shock waves called baryon acoustic oscillations that can trace dark energy.

Dark energy, the mysterious force that's driving the accelerating expansion of the universe, may not actually exist, scientists say. Their research has brought into question one of the cornerstones of modern cosmology.

In a new study, published Dec. 19, 2024 in the journal Monthly Notices of the Royal Astronomical Society, the researchers analyzed data from the Pantheon+ survey — the most comprehensive dataset of type Ia supernovae, whose consistent brightness allows astronomers to measure distances across the universe with incredible precision. Their analysis suggests that what we perceive as acceleration might be an illusion caused by the large-scale structure of the cosmos.

Studying the universe with type Ia supernovae

Type Ia supernovae, the explosive deaths of white dwarf stars, have long served as one of cosmology's most powerful tools. These stellar events occur when a white dwarf accretes enough material from a companion star to trigger a thermonuclear explosion. Because type 1a supernovae produce consistent peak brightness, measuring their brightness when observed from Earth can reveal how far away they are.

"Type Ia supernovae are extremely valuable in astronomy since they act as standardizable candles with which we can measure vast distances in the Universe," study co-author Zachary Lane, a researcher at the University of Canterbury in New Zealand, told Live Science in an email.

By combining this distance information with the redshift of the supernovae — the stretching of light to redder wavelengths due to the universe's expansion — scientists have mapped the universe's growth over time. Decades ago, researchers used this method to show that the universe's expansion was accelerating, a discovery that led to the hypothesis of dark energy — a mysterious, unseen force thought to permeate space and drive this acceleration.

Pantheon+ dataset

The Pantheon+ dataset is the most extensive and precise collection of type Ia supernovae ever assembled. Spanning decades of observations from both ground-based and space telescopes, it contains data on 1,500 supernovae across space-time.

"At the time of this study, the Pantheon+ Type Ia Supernovae spectroscopic dataset was the largest and most pristine collection of purely Type Ia supernovae," Lane said.

The dataset's precision and size make it a goldmine for testing cosmological models. Its detailed records of brightness and redshift offer unparalleled insights into how the universe has evolved, providing a critical testing ground for alternative theories to the standard cosmological model.

Challenging dark energy

While the idea of dark energy explains much of the observed acceleration in the universe, it has always carried an air of mystery. Dark energy has never been directly detected, nor has its origin been explained theoretically, prompting some scientists to explore other explanations.

The new study takes aim at a key assumption of the standard model: that the universe is homogeneous and isotropic on large scales, meaning it looks the same in every direction and from every vantage point.

This assumption underpins the need for dark energy to explain the universe's expansion. However, Lane and his colleagues tested an alternative idea called the timescape model, which suggests that the apparent acceleration could be a byproduct of cosmic structures like voids — vast, near-empty regions of space between galaxy clusters.

"The standard model of cosmology is built on the assumption that the Universe is uniform and featureless on large scales and that cosmic structures do not significantly impact the evolution of the Universe," Lane said. "Timescape abandons these assumptions and finds that the apparent acceleration of the Universe is the result of feedback between cosmic structures."

Because of their sparse matter and gravity, voids expand faster than denser parts of the universe, such as galaxy clusters. According to the timescape model, the dominance of these voids in the cosmic landscape could explain the observed acceleration without the need for dark energy.

Evidence in favor of timescape

The team analyzed the Pantheon+ dataset and found that their results align remarkably well with the timescape model — and in some cases even outperformed the standard cosmological model.

"When considering every supernova, including those very close to us in the Milky Way, which could be influenced by local structures, we find very strong preference in favor of the Timescape model," Lane said. When supernovae in the nearby universe were excluded to account for local differences, the evidence remained supportive, echoing findings from the Dark Energy Survey (DES).

These results pose a direct challenge to the necessity of dark energy. "Consistently finding moderate or stronger evidence for a cosmological model without dark energy using one of the most historically significant observational methods is an exciting prospect to be explored for the future of cosmology," Lane said.

The road ahead

While the findings are compelling, Lane stressed that further research is needed to solidify the case for timescape. "While other factors need to be considered for this to be more established within the cosmology community, it proves a promising initial test," he said.

In the future, the team plans to combine the Pantheon+ dataset with data from the Dark Energy Survey and baryon acoustic oscillations — patterns in the distribution of galaxies that can be used as another cosmic ruler. The astronomers are also conducting simulations of how voids expand under the framework of general relativity and exploring how these effects apply to galaxy formation and evolution.

"Our research group is exploring several extensions to our current work, aiming to challenge foundational aspects of cosmology," Lane said. "A strong competing framework will still enhance the future of cosmology and our current understanding of the challenges facing the field."

New observations made by the James Webb Space Telescope (JWST) have further cemented one of the most bizarre observations in all of physics — that the universe expanded at different speeds across varying stages of its lifetime.

The conundrum, referred to as the Hubble tension, has fueled a debate among astronomers that could alter or even upend the field altogether.

In 2019, measurements by the Hubble Space Telescope confirmed the problem was real. Then in 2023 and 2024, even more precise measurements from JWST appeared to confirm the discrepancy.

Now, further measurements have used the largest sample of JWST data collected over its first two years in space to further cement the problem. The new physics that could answer the mystery remains unclear but, as the researchers outline in a paper published Dec. 9 in the The Astrophysical Journal, the tension is not going anywhere.

"The more work we do the more it is apparent that the cause is something much more interesting than a telescope flaw. Rather it appears to be a feature in the universe," lead study author and Nobel laureate Adam Riess, professor of physics and astronomy at Johns Hopkins University, told Live Science. "[The] next steps are many. More data on many fronts and new ideas are needed."

Related: After 2 years in space, the James Webb telescope has broken cosmology. Can it be fixed?

There are two gold-standard methods for figuring out the Hubble constant, the value that quantifies the speed of the universe's expansion. The first is taken by measuring tiny fluctuations in the cosmic microwave background — an ancient snapshot of the universe's first light produced just 380,000 years after the Big Bang.

After mapping out this microwave hiss using the European Space Agency's Planck satellite, cosmologists inferred a Hubble constant of roughly 46,200 mph per million light-years, or roughly 67 kilometers per second per megaparsec (km/s/Mpc). This, alongside other measurements of the early universe, aligned with theoretical predictions.

The second method operates at closer distances and in the universe's later life using pulsating stars called Cepheid variables. Cepheid stars are slowly dying, and their outer layers of helium gas grow and shrink as they absorb and release the star's radiation, making them periodically flicker like distant signal lamps.

As Cepheids get brighter, they pulsate more slowly, enabling astronomers to measure the stars' intrinsic brightness. By comparing this brightness to their observed brightness, astronomers can chain Cepheids into a "cosmic distance ladder" to peer ever deeper into the universe's past.

With this ladder in place, and after anchoring the Cepheids' brightnesses to explosions from Type Ia supernovae, astronomers can find a precise number for the universe's expansion speed from how the flickering stars' light has been stretched out, or redshifted. The Hubble constant returned by this method is around 73 km/s/Mpc: a value far outside of the error range of the Planck measurements.

Related: 'It could be profound': How astronomer Wendy Freedman is trying to fix the universe

Astronomers have offered various explanations for the cause of this disagreement, with some attempting to tease out the possibility of systematic error within the results. Meanwhile, Riess and his team have been cementing the tension with increasingly precise and wider-encompassing studies.

This new study is yet another link in this chain. Covering roughly a third of the sample size of the 2019 Hubble study, the new analysis used JWST to measure the sample's Cepheid distances to within 2% accuracy — a big improvement on Hubble's precision of 8-9%.

Cross-checking these results with other distance-measuring stars such as carbon rich stars and bright red giants returned a value of 72.6 km/s/Mpc, making it nearly identical to Hubble's original measurement.

Exactly what could be causing the strange mismatch is unclear ("I wish I knew," Riess told Live Science). But speculation is rife among astronomers.

One possibility is "something missing in our understanding of the early universe, such as a new component of matter — early dark energy [the mysterious phenomenon driving cosmic expansion] — that gave the universe an unexpected kick after the big bang," Marc Kamionkowski, a cosmologist at Johns Hopkins University who helped calculate the Hubble constant and who was not involved in the study, said in a statement. "And there are other ideas, like funny dark matter properties, exotic particles, changing electron mass, or primordial magnetic fields that may do the trick. Theorists have license to get pretty creative."

Astronomers have analyzed the largest map of the universe — and found that Einstein was right yet again about gravity, according to a series of new studies.

The analysis, which looked at nearly 6 million galaxies and quasars spanning 11 billion years of cosmic time, found that even at colossal scales the force of gravity behaves as predicted by Albert Einstein's theory of general relativity.

The result validates cosmologists' leading theory of the universe and appears to limit alternative theories of gravity, the researchers said. Where the results leave room for new explanations to strange discrepancies in the model, such as the universe's divergent expansion rates at different stages of its life, remains unclear. The researchers published their findings today (Nov. 19) in several papers on the preprint server arXiv and will present them in January at a meeting of the American Astronomical Society in National Harbor, Maryland.

"General relativity has been very well tested at the scale of solar systems, but we also needed to test that our assumption works at much larger scales," Pauline Zarrouk, a cosmologist at the French National Centre for Scientific Research (CNRS) who co-led the analysis, said in a statement. "Studying the rate at which galaxies formed lets us directly test our theories and, so far, we're lining up with what general relativity predicts at cosmological scales."

Cosmologists have long debated the behavior of gravity at large distances. The predominant theory, called the lambda cold dark matter model, builds out from Einstein's theory to offer the most comprehensive view of a wide range of astronomical phenomena.

Related: Researchers spot rare 'triple-ring' galaxy that defies explanation

But doubts about some elements within the model, such as dark matter and dark energy — two mysterious entities that do not interact with light but account for a majority of the mass and energy in the universe — along with the model's inability to predict some observations, have led rival factions to champion alternative explanations.

One of these is modified Newtonian dynamics (MOND), which proposes that for gravitational pulls 10 trillion times smaller than those felt on Earth's surface, such as the tugs between distant galaxies, Newton's laws (which general relativity builds upon) break down and must be replaced by other equations.

To search for clues on how gravity behaves at large scales, the researchers turned to data from the first year of the Dark Energy Spectroscopic Instrument (DESI) mounted on the Nicholas U. Mayall 4-meter Telescope in Arizona, which pinpoints the monthly positions of millions of galaxies to study how the universe expanded up to the present day.

The scientists conducted a "full-shape analysis" that made a precise measurement of the growth of galactic structures over time. It revealed that, while dark energy could be evolving over time, the universe's structure closely matches predictions made by Einstein's theory.

"This is the first time that DESI has looked at the growth of cosmic structure," Dragan Huterer, a professor of theoretical cosmology and astrophysics at the University of Michigan and the co-lead of DESI's group interpreting the cosmological data, said in the statement. "We're showing a tremendous new ability to probe modified gravity and improve constraints on models of dark energy. And it's only the tip of the iceberg."

It's too early to say exactly what this means for our overall view of the cosmos, but the next two years of DESI's collected data is set to be released in spring 2025. The experiment, which is now in its fourth of five years, will collect data from around 40 million galaxies and quasars by the time it ends. If the answers are out there, we may not have to wait too long to find them.

Scientists have just come up with another potential explanation for why we have never found signs of extraterrestrial life in the cosmos — we may be living in the wrong universe.

A new theoretical model based on the famous Drake equation suggests that alien life is more likely to emerge in specific parallel universes that could potentially exist alongside ours in a never-ending multiverse. If this is the case, it means we do not live in the "optimal universe" for detecting extraterrestrial civilizations.

The Drake equation was a theoretical formula written by American astrophysicist Frank Drake in 1961 to help tackle the dichotomy between the high probability that extraterrestrial intelligence exists and the fact that we have no evidence for such aliens — a problem known as the Fermi Paradox. The Drake equation estimates the chances of detecting extraterrestrial life in the Milky Way. It primarily hinges on the number of stars in our galaxy, because aliens would likely need a star to spawn an exoplanet they could call home and provide the energy needed to spark their emergence and evolution, despite some theories to the contrary.

But in a new study, published Wednesday (Nov. 13) in the journal Monthly Notices of the Royal Astronomical Society, researchers took this idea and extrapolated it on a multiversal scale by calculating how differences in the density of dark energy — the mysterious force driving the expansion of the universe — may affect how many stars can form in different parallel universes.

The model revealed that the optimal density of dark energy in a universe would enable up to 27% of non-dark matter to turn into stars. But in our universe, the fraction of such matter that turns into stars is 23%, meaning there are fewer stars and, as a result, fewer places for aliens to emerge, according to a statement by researchers.

Related: 32 strange places scientists are looking for aliens

The new findings are completely hypothetical and assume that a multiverse exists, which is a theory that is far from being proved. However, "it will be exciting to employ the model to explore the emergence of life across different universes and see whether some fundamental questions we ask ourselves about our own universe must be reinterpreted," study co-author Lucas Lombriser, a cosmologist at the University of Geneva in Switzerland, said in another statement.

Dark energy is a currently-unidentifiable substance or force that works against gravity, causing space-time to expand rather than collapse in on itself. Astronomers think that dark energy exists because the universe's expansion is accelerating, but they have no clear idea what it is.

The amount of this mysterious energy in different parallel universes would influence the universes' respective star formation by impacting the rate of their cosmic expansion: If a universe has less dark energy than ours, it could expand more slowly, which would decrease star formation by enabling gravity to collapse large-scale structures, such as stellar clusters, galaxies or galactic superclusters. But if a universe has more dark energy than ours, it could increase star formation by dispersing matter more widely and enabling more large, star-forming structures to take shape.

However, too much dark energy would cause a universe to expand so quickly that it would reduce the amount of star formation by scattering matter too widely. As a result, the new model calculated the optimal density of dark energy that would maximize the rate of star formation, which turns out to be slightly higher than the density we observe in our own universe. That means intelligent beings in other universes may have better luck finding each other than we’ve had searching for aliens in ours.

The researchers also suspect that across the multiverse, the optimum dark energy density would be more common than other possible configurations of the mysterious force, such as the density of our universe's dark energy.

"We may not live in the most likely of universes," study lead author Daniele Sorini, a cosmologist at Durham university in England, said in the second statement.

Astronomers may have found tantalizing evidence that dark energy — the mysterious energy driving the accelerating expansion of our universe — could be connected with black holes.

Dark energy makes up roughly 70% of our universe, and is thought to have emerged in the aftermath of the Big Bang, 13.8 billion years ago, to drive the growth of the cosmos.

But exactly where the mysterious force came from remains unclear. In recent years, some astronomers proposed a radical theory that, rather than being diffusely spread throughout all space, dark energy could emerge from the hearts of gigantic black holes. Others, however, discounted the proposal as outlandish.

Now, a new study claims to have found the first hints of a connection between the two seemingly unrelated phenomena: a match between the increasing density of dark energy and the growing mass of black holes as the universe aged. The researchers published their findings Oct. 28 in the Journal of Cosmology and Astroparticle Physics.

Related: James Webb telescope confirms there is something seriously wrong with our understanding of the universe

"If you ask yourself the question, 'Where in the later universe do we see gravity as strong as it was at the beginning of the universe?' the answer is at the center of black holes," study co-author Gregory Tarlé, professor of physics at the University of Michigan, said in a statement. "It's possible that what happened during inflation runs in reverse, the matter of a massive star becomes dark energy again during gravitational collapse — like a little Big Bang played in reverse."

To search for clues that dark energy may be connected to black holes, the researchers used the Dark Energy Spectroscopic Instrument (DESI) mounted on the Nicholas U. Mayall 4-meter Telescope in Arizona, which pinpoints the monthly positions of millions of galaxies to study how the universe expanded up to the present day. This enables astronomers to infer the density of dark energy throughout the universe's life from the speed at which the cosmos stretches outward.

By comparing this proxy data for dark energy to black hole growth at different stages of the universe's life, the researchers made an intriguing observation.

"The two phenomena were consistent with each other — as new black holes were made in the deaths of massive stars, the amount of dark energy in the universe increased in the right way," co-author Duncan Farrah, an associate professor of physics at the University of Hawaii, said in the statement. "This makes it more plausible that black holes are the source of dark energy."

If the hypothesis is borne out, it could help to solve a growing conundrum in cosmology. For years, astronomers have found that the universe appears to be expanding at different speeds depending on where they look — a problem they call the Hubble tension. Some of the measurements confirm our best current understanding of the universe, while others threaten to break it.

Nonetheless, despite the interesting connection, the astronomers say that many more observations, by DESI and other experiments, are needed before any firm conclusions can be reached.

"Fundamentally, whether black holes are dark energy, coupled to the universe they inhabit, has ceased to be just a theoretical question," Tarlé said. "This is an experimental question now."

The first piece of what will one day be the largest-ever 3D map of the universe has been revealed, and it's crammed with 14 million galaxies.

The snapshot was taken by the European Space Agency's (ESA) Euclid space telescope. Launched on July 1, 2023, Euclid was designed to compile wide-lens images to help scientists hunt for two of the universe's most mysterious components: dark matter and dark energy.

The stunning new image is a mosaic of 208 gigapixels, representing just a fraction of a percent of the sky. By capturing hundreds of images like this one, the space telescope will eventually catalog one-third of the entire night sky and image more than a billion galaxies that are up to 10 billion years old, according to ESA.

"This stunning image is the first piece of a map that in six years will reveal more than one third of the sky," Valeria Pettorino, a Euclid project scientist at ESA, said in a statement. "This is just 1% of the map, and yet it is full of a variety of sources that will help scientists discover new ways to describe the Universe."

Related: Mysterious 'Green Monster' lurking in James Webb photo of supernova remnant is finally explained

The released image is a mosaic of 260 observations collected across two weeks between March and April 2024. It represents a 132-square-degree sweep of the southern sky that is more than 500 times the area of the full moon.

The map, which contains 100 million sources of light, is just one small piece in the cosmic jigsaw puzzle being assembled by Euclid. Upon completion, it will enable scientists to probe the mysteries of dark matter and dark energy.

Researchers think dark matter and dark energy together make up about 95% of the universe. But they do not interact with light, so they can't be detected directly.

Instead, scientists study the mysterious components by observing the way they interact with the visible universe around them: Dark matter can be seen by observing its gravitational warping effects on galaxies, and dark energy is evident in the force propelling the universe's runaway expansion.

So far, 12% of Euclid's mission has been completed. Further releases, including a preview of Euclid's Deep Field areas, are planned for release in March 2025, and the mission's first year of cosmology data will appear in 2026.

Researchers have found that a hypothetical form of dark energy may lead to a grim fate for the universe: a "long freeze" where everything just…slows down.

In this scenario, the universe would expand to a finite size, but everything would grow so cold that all activity would essentially cease.

Dark energy is the mysterious force responsible for accelerating the expansion of the universe. It was discovered in the 1990s, but despite over two decades of research, it still remains the central mystery of modern cosmology. Over the years, scientists have presented some fascinating research into what it is and how it works.

One idea is known as holographic dark energy. In this scenario, gravity — and space itself — is an illusion. Our universe is really only two-dimensional, and exotic quantum forces on that surface give rise to the appearance of gravity and the structure of 3D space.

A consequence of this theory is a natural accelerated expansion of the universe, which we identify as dark energy.

Related: Our universe is merging with 'baby universes', causing it to expand, new theoretical study suggests

While many researchers have studied holographic dark energy models and ways to test it, a pair of astrophysicists examined the long-term fate of the universe if it is indeed ruled by holographic dark energy. They published their results Sept. 30 to the preprint database arXiv. (It has not been peer-reviewed.)

Dark energy takes up roughly 70% of the energy density of the entire cosmos. As the universe expands, the density of both regular and dark matter drops, while more and more dark energy manifests. To study the ultimate long-term fate of the universe, the researchers ignored matter and focused solely on the evolution of holographic dark energy.

They found that, as expected, holographic dark energy will continue to expand the universe. But, over time, its influence will slowly peter out and slow acceleration. The universe's expansion rate will steadily decrease until the cosmos reaches a nearly static value, essentially locking it to a final size.

But as the universe's expansion slows down, the density of holographic dark energy dwindles along with it. And since the density of matter also shrinks as the universe expands, the universe grinds to a halt. The researchers dub this scenario "the long freeze," in contrast to other commonly known fates of the universe like the "Big Freeze" (the accelerated expansion continues unabated) and the "Big Crunch" (something causes the universe to contract back toward the Big Bang).

The long freeze isn't a rosy scenario. While the universe's expansion will eventually stop, there won’t be any new sources of energy for all the matter inside of it. This means that eventually all the stars will wink out and decay, and all the subatomic particles will drift away from each other in the cold.

Unfortunately, even in their most exotic theories, cosmologists can't come up with a way to give the universe a happy ending.

The James Webb Space Telescope (JWST) is the largest and most powerful space telescope built to date. Since it was launched in December 2021 it has provided groundbreaking insights. These include discovering the earliest and most distant known galaxies, which existed just 300 million years after the Big Bang.

Distant objects are also very ancient because it takes a long time for the light from these objects to reach telescopes. JWST has now found a number of these very early galaxies. We're effectively looking back in time at these objects, seeing them as they looked shortly after the birth of the universe.

These observations from JWST agree with our current understanding of cosmology — the scientific discipline that aims to explain the universe — and of galaxy formation. But they also reveal aspects we didn't expect. Many of these early galaxies shine much more brightly than we would expect given that they existed just a short time after the Big Bang.

Brighter galaxies are thought to have more stars and more mass. It was thought that much more time was needed for this level of star formation to take place. These galaxies also have actively growing black holes at their centres — a sign that these objects matured quickly after the Big Bang. So how can we explain these surprising findings? Do they break our ideas of cosmology or require a change to the age of the universe?

Scientists have been able to study these early galaxies by combining JWST's detailed images with its powerful capabilities for spectroscopy. Spectroscopy is a method for interpreting the electromagnetic radiation that's emitted or absorbed by objects in space. This in turn can tell you about the properties of an object.

Our understanding of cosmology and galaxy formation rests on a few fundamental ideas. One of these is the cosmological principle, which states that, on a large scale, the universe is homogeneous (the same everywhere) and isotropic (the same in all directions). Combined with Einstein's theory of general relativity, this principle allows us to connect the evolution of the universe —- how it expands or contracts —- to its energy and mass content.

Related: The James Webb telescope has brought cosmology to a tipping point. Will it soon reveal new physics?

The standard cosmological model, known as the "Hot Big Bang" theory, includes three main components, or ingredients. One is the ordinary matter that we can see with our eyes in galaxies, stars and planets. A second ingredient is cold dark matter (CDM), slow-moving matter particles that do not emit, absorb or reflect light.

The third component is what's known the cosmological constant (Λ, or lambda). This is linked to something called dark energy and is a way of explaining the fact that the expansion of the universe is accelerating. Together, these components form what is called the ΛCDM model of cosmology.

Dark energy makes up about 68% of the total energy content of today's universe.

Despite not being directly observable with scientific instruments, dark matter is thought to make up most of the matter in the cosmos and comprises about 27% of the universe's total mass and energy content.

While dark matter and dark energy remain mysterious, the ΛCDM model of cosmology is supported by a wide range of detailed observations. These include the measurement of the universe's expansion, the cosmic microwave background, or CMB (the "afterglow" of the Big Bang) and the development of galaxies and their large-scale distribution — for example, the way that galaxies cluster together.

The ΛCDM model lays the groundwork for our understanding of how galaxies form and evolve. For example, the CMB, which was emitted about 380,000 years after the Big Bang, provides a snapshot of early fluctuations in density that occurred in the early universe. These fluctuations, particularly in dark matter, eventually developed into the structures we observe today, such as galaxies and stars.

How stars form

Galaxy formation consists of complex processes influenced by numerous different physical phenomena. Some of these mechanisms are not fully understood, such as what processes govern how gas in galaxies cools and condenses to form stars.

The effects of supernovae, stellar winds and black holes that emit significant amounts of energy (sometimes called active galactic nuclei, or AGN) can all heat or expel gas from galaxies. This in turn can boost or curtail star formation and therefore influence the growth of galaxies.

The efficiency and scale of these "feedback processes", as well as their cumulative impact over time, are poorly understood. They are a significant source of uncertainty in mathematical models, or simulations, of galaxy formation.

Significant advances in complex numerical simulations of galaxy formation have been made over the past ten years. Insights and hints can still be gained from simpler simulations and models that relate star formation to the evolution of dark matter halos. These halos are massive, invisible structures made from dark matter that effectively anchor galaxies within them.

One of the simpler models of galaxy formation assumes that the rate at which stars form in a galaxy is directly tied to gas flowing into those galaxies. This model also proposes that the star formation rate in a galaxy is proportional to the rate at which dark matter halos grow. It assumes a fixed efficiency at converting gas into stars, regardless of cosmic time.

This "constant star formation efficiency" model is consistent with star formation increasing dramatically in the first billion years after the Big Bang. The rapid growth of dark matter halos during this period would have provided the necessary conditions for galaxies to form stars efficiently. Despite its simplicity, this model has successfully predicted a wide range of real observations, including the overall rate of star formation across cosmic time.

Secrets of the first galaxies

JWST has ushered in a new era of discovery. With its advanced instruments, the space telescope can capture both detailed images and high resolution spectra — charts showing the intensity of electromagnetic radiation emitted or absorbed by objects in the sky. For JWST, these spectra are in the near infrared region of the electromagnetic spectrum. Studying this region is crucial for observing early galaxies whose optical light has turned into near infrared (or "redshifted") as the universe has expanded.

Redshift describes how the wavelengths of light from galaxies become stretched as they travel. The more distant a galaxy is, the greater its redshift.

Over the past two years, JWST has identified and characterized galaxies at redshifts with values of between ten and 15. These galaxies, which formed around 200-500 million years after the Big Bang, are relatively small for galaxies (about 100 parsecs, or 3 quadrillion kilometres, across). They each consist of around 100 million stars, and form new stars at a rate of about one sun-like star per year.

While this does not sound very impressive, it implies that these systems double their content of stars within only 100 million years. For comparison, our own Milky Way galaxy takes about 25 billion years to double its stellar mass.

Early galaxy formation

The surprising findings from JWST of bright galaxies at high redshifts, or distances, could imply that these galaxies matured faster than expected after the Big Bang. This is important because it would challenge existing models of galaxy formation. The constant star-formation efficiency model described above, while effective at explaining much of what we see, struggles to account for the large number of bright and distant galaxies observed with a redshift of more than ten with a redshift of more than ten.

To address this, scientists are exploring various possibilities. These include changes to their theories of how efficiently gas is converted into stars over time. They are also reconsidering the relative importance of the feedback processes — how phenomena such as supernovae and black holes also help regulate star formation.

Some theories suggest that star formation in the early universe may have been more intense or "bursty" than previously thought, leading to the rapid growth of these early galaxies and their apparent brightness.

Others propose that different factors, such as lower amounts of galactic dust, a top-heavy distribution of star masses, or contributions from phenomena such as active black holes, could be responsible for the unexpected brightness of these early galaxies.

These explanations invoke changes to galaxy formation physics in order to explain JWST's findings. But scientists have also been considering modifications to broad cosmological theories. For example, the abundance of early, bright galaxies could be partly explained by a change to something called the matter power spectrum. This is a way to describe density differences in the universe.

One possible mechanism for achieving this change in the matter power spectrum is a theoretical phenomenon called "early dark energy". This is the idea that a new cosmological energy source with similarities to dark energy may have existed at early times, at a redshift of 3,000. This is before the CMB was emitted and just 380,000 years after the Big Bang.

This early dark energy would have decayed rapidly after the stage of the universe's evolution known as recombination. Intriguingly, early dark energy could also alleviate the Hubble tension — a discrepancy between different estimates of the universe's age.

One paper published in 2023 suggested that the galaxy findings from JWST required scientists to stretch the age of the universe by several billion years.

However, other phenomena could account for the bright galaxies. Before JWST's observations are used to invoke changes to broad ideas of cosmology, a more detailed understanding of the physical processes in galaxies is essential.

The current record holder for the most distant galaxy — identified by JWST — is called JADES-GS-z14-0. The data gathered so far indicate that these galaxies have a large diversity of different properties.

3D visualisation of galaxies observed by the JWST, including JADES-GS-z14-0.

Some galaxies show signs of hosting black holes that are emitting energy, while others seem to be consistent with hosting young, dust-free populations of stars. Because these galaxies are faint and observing them is expensive (it takes exposure times of many hours), only 20 galaxies for which the redshift is more than ten have been observed with spectroscopy to date, and it will take years to build a statistical sample.

A different angle of attack could be observations of galaxies at later cosmic times, when the universe was 1 billion to 2 billion years old (redshifts of between three and nine). JWST's capabilities give researchers access to crucial indicators from stars and gas in these objects that can be used to constrain the overall history of galaxy formation.

Breaking the universe?

In the first year of JWST's operation, it was claimed that some of the earliest galaxies had extremely high stellar masses (the masses of stars contained within them) and a change in cosmology was needed to accommodate bright galaxies that existed in the very early universe. They were even dubbed "universe-breaker" galaxies.

Soon after, it was clear that these galaxies do not break the universe, but their properties can be explained by a range of different phenomena. Better observational data showed that the distances to some of the objects were overestimated (which led to an overestimation of their stellar masses).

The emission of light from these galaxies can be powered by sources other than stars, such as accreting black holes. Assumptions in models or simulations can also lead to biases in the total mass of stars in these galaxies.

As JWST continues its mission, it will help scientists refine their models and answer some of the most fundamental questions about our cosmic origins. It should unlock even more secrets about the universe's earliest days, including the puzzle of these bright, distant galaxies.

This edited article is republished from The Conversation under a Creative Commons license. Read the original article.

What it is: The Rosette Nebula

Where it is: 5,000 light-years away, in the constellation Monoceros, the unicorn.

When it was shared: Oct. 1, 2024

Why it's so special: The Rosette Nebula is a big deal. At about 130 light-years across, it's roughly five times the size of the Orion Nebula — the closest star-forming region to Earth — and about four times farther away, according to the National Science Foundation's NOIRLab. It contains a lot of gas and dust. If that sounds dull, think again — just look at this spectacular image from the Dark Energy Camera (DECam) in Chile.

Those sparkling colors are caused by the ultraviolet radiation produced by the nebula's massive stars. That radiation ionizes (electrically charges) the surrounding hydrogen gas. In this image of the nebula, you can see shades of yellow and gold (ionized oxygen), red (ionized hydrogen) and pink (ionized silicon).

Related: 38 jaw-dropping James Webb Space Telescope images

At the center of the 377-megapixel image is NGC 2244, a bluish cluster of young, massive stars that has sculpted and illuminated a large cavity within the surrounding gas. NGC 2244 is about 2 million years old — an infant, in cosmic terms — and formed after the nebula's gases coalesced into clumps brought together by their mutual gravity. They give the Rosette Nebula its glowing "eye."

If you look closely at the central void, you'll see "elephant trunks," or pillars of dust that mark the transition from the ionized hydrogen near the hot, young stars to the cooler hydrogen beyond. They're in trunk-like shapes because, as the shell-like void expands beyond the star cluster, the clumps of cooler gas resist.

We're seeing this "cosmic rose" at just the right time — within about 10 million years, the radiation from the hot, young stars of the cluster will have dissipated the nebula.

The image — also available as a zoomable version — was published to mark the fifth anniversary of NOIRLab, the U.S. national center for ground-based, nighttime optical and infrared astronomy. It was taken using the 570-megapixel DECam, which is mounted on the Víctor M. Blanco 4-meter Telescope at the Cerro Tololo Inter-American Observatory in the southern Atacama Desert in Chile.

For more sublime space images, check out our Space Photo of the Week archives.

The James Webb Space Telescope (JWST) has discovered yet another troubling sign that there's something very wrong with our model of the universe.

Depending on which part of the universe astronomers measure, the cosmos seems to be growing at different rates — a problem scientists call the Hubble tension. Measurements taken from the distant, early universe show that the expansion rate, called the Hubble constant, closely matches our best current model of the universe, while those taken nearer to Earth threaten to break it.

Now, a new study using the gravitationally-warped light of a 10.2 billion light-year distant supernova has revealed that the mystery could be here to stay. The researchers released their findings in a series of papers in The Astrophysical Journal. The Hubble tension calculations have also been accepted for publication in the journal, and are posted in a paper on the pre-print database arXiv.

"Our team's results are impactful: The Hubble constant value matches other measurements in the local universe, and is somewhat in tension with values obtained when the universe was young," co-author Brenda Frye, an associate professor of astronomy at the University of Arizona said in a statement.

Related: 'It could be profound': How astronomer Wendy Freedman is trying to fix the universe

Currently, there are two gold-standard methods for figuring out the Hubble constant. The first involves poring over tiny fluctuations in the cosmic microwave background, an ancient relic of the universe's first light produced just 380,000 years after the Big Bang. This method enabled astronomers to infer an expansion rate of roughly 67 kilometers per second per megaparsec (km/s/Mpc), which closely matches predictions made by the standard model of cosmology.

But the second method, measuring closer distances with pulsating stars called Cepheid variables, contradicts this — returning a puzzlingly high value of 73.2 km/s/Mpc. This discrepancy superficially may not seem like much, but it's enough to completely contradict the predictions made by the standard model. According to the model, a mysterious entity known as dark energy is supposed to be driving the universe’s expansion at a constant rate, but the new findings throw a wrench in this understanding.

In the new studies, astronomers pointed JWST's near-infrared camera (NIRCam) at the galaxy cluster PLCK G165.7+67.0, also known as G16, which is located 3.6 billion light-years from Earth. There, they spotted three distinct points of light that came from a single type IA supernova whose light had been both magnified and bent, or gravitationally lensed, by a galaxy in front of it.

Type Ia supernovae occur when the material from one star falls onto the embering husk of a dead star, known as a white dwarf, leading to a gigantic thermonuclear explosion. These explosions are thought to always happen at the same brightness, making them "standard candles" from which astronomers can measure far-off distances and calculate the Hubble constant.

Follow-up observations made with the ground-based Multiple Mirror Telescope and Large Binocular Telescope, both in Arizona, confirmed the dots' point of origin.

By studying the time delays between the dots and plugging them, alongside the supernova's distance, into various models of gravitational lensing, the researchers produced a Hubble constant value of 75.4 km/s/Mpc, plus 8.1 or minus 5.5 — flatly contradicting the standard model once more.

The calculation is unlikely to be the final word on the tension, with other research groups pursuing their own lines of investigation into the cosmic conundrum. For their part, the researchers behind the new studies say that they will continue to gather vital clues from other exploding stars found around the galaxy.

For the past few years, a series of controversies have rocked the well-established field of cosmology. In a nutshell, the predictions of the standard model of the universe appear to be at odds with some recent observations.

There are heated debates about whether these observations are biased, or whether the cosmological model, which predicts the structure and evolution of the entire universe, may need a rethink. Some even claim that cosmology is in crisis. Right now, we do not know which side will win. But excitingly, we are on the brink of finding that out.

To be fair, controversies are just the normal course of the scientific method. And over many years, the standard cosmological model has had its share of them. This model suggests the universe is made up of 68.3% "dark energy" (an unknown substance that causes the universe's expansion to accelerate), 26.8% dark matter (an unknown form of matter) and 4.9% ordinary atoms, very precisely measured from the cosmic microwave background — the afterglow of radiation from the Big Bang.

It explains very successfully multitudes of data across both large and small scales of the universe. For example, it can explain things like the distribution of galaxies around us and the amount of helium and deuterium made in the universe's first few minutes. Perhaps most importantly, it can also perfectly explain the cosmic microwave background.

This has led to it gaining the reputation as the "concordance model". But a perfect storm of inconsistent measurements — or "tensions" as they're known as in cosmology — are now questioning the validity of this longstanding model.

Related: Is the James Webb Space Telescope really 'breaking' cosmology?

Uncomfortable tensions

The standard model makes particular assumptions about the nature of dark energy and dark matter. But despite decades of intense observation, we still seem no closer to working out what dark matter and dark energy are made of.

The litmus test is the so-called Hubble tension. This relates to the Hubble constant, which is the rate of expansion of the universe at the present time. When measured in our nearby, local universe, from the distance to pulsating stars in nearby galaxies, called Cepheids, its value is 73 km/s/Mega parsec (Mpc is a unit of measure for distances in intergalactic space). However, when predicted theoretically, the value is 67.4 km/s/Mpc. The difference may not be large (only 8%), but it is statistically significant.

The Hubble tension became known about a decade ago. Back then, it was thought that the observations may have been biased. For example, the Cepheids, although very bright and easy to see, were crowded together with other stars, which could have made them appear even brighter. This could have made the Hubble constant higher by a few percent compared to the model prediction, thus artificially creating a tension.

With the advent of the James Webb Space Telescope (JWST), which can separate the stars individually, it was hoped that we would have an answer to this tension.

Frustratingly, this hasn't yet happened. Astronomers now use two other types of stars besides the Cepheids (known as the Tip of the Red Giant Branch stars (TRGB) and the J-region Asymptotic Giant Branch (JAGB) stars). But while one group has reported values from the JAGB and TRGB stars that are tantalisingly close to the value expected from the cosmological model, another group has claimed that they are still seeing inconsistencies in their observations. Meanwhile, the Cepheids measurements continue to show a Hubble tension.

It's important to note that although these measurements are very precise, they may still be biased by some effects uniquely associated with each type of measurement. This will affect the accuracy of the observations, in a different way for each type of stars. A precise but inaccurate measurement is like trying to have a conversation with a person who is always missing the point. To solve disagreements between conflicting data, we need measurements that are both precise and accurate.

The good news is that the Hubble tension is now a rapidly developing story. Perhaps we will have the answer to it within the next year or so. Improving the accuracy of data, for example by including stars from more far away galaxies, will help sort this out. Similarly, measurements of ripples in spacetime known as gravitational waves will also be able to help us pin down the constant.

This may all vindicate the standard model. Or it may hint that there's something missing from it. Perhaps the nature of dark matter or the way that gravity behaves on specific scales is different to what we believe now. But before discounting the model, one has to marvel at its unmatched precision. It only misses the mark by at most a few percent, while extrapolating over 13 billion years of evolution.

To put it into perspective, even the clockwork motions of planets in the Solar System can only be computed reliably for less than 1 billion years, after which they become unpredictable. The standard cosmological model is an extraordinary machine.

The Hubble tension is not the only trouble for cosmology. Another one, known as the "S8 tension", is also causing trouble, albeit not on the same scale. Here the model has a smoothness problem, by predicting that matter in the universe should be more clustered together than we actually observe — by about 10%. There are various ways to measure the "clumpiness" of matter, for example by analysing the distortions in the light from galaxies, produced by the assumed dark matter intervening along the line of sight.

Currently, there seems to be a consensus in the community that the uncertainties in the observations have to be teased out before ruling out the cosmological model. One possible way to alleviate this tension is to better understand the role of gaseous winds in galaxies, which can push out some of the matter, making it smoother.

Understanding how clumpiness measurements on small scales relate to those on larger scales would help. Observations might also suggest there is a need to change how we model dark matter. For example, if instead of being made entirely of cold, slow moving particles, as the standard model assumes, dark matter could be mixed up with some hot, fast-moving particles. This could slow down the growth of clumpiness at late cosmic times, which would ease the S8 tension.

JWST has highlighted other challenges to the standard model. One of them is that early galaxies appear to be much more massive that expected. Some galaxies may weigh as much as the Milky Way today, even though they formed less than 1 billion years after the Big Bang, suggesting they should be less massive.

However, the implications against the cosmological model are less clear in this case, as there may be other possible explanations for these surprising results. Key to solving this problem is to improve the measurement of stellar masses in galaxies. Rather than measuring them directly, which is not possible, we infer these masses from the light emitted by galaxies.

This step involves some simplifying assumptions, which could translate in overestimating the mass. Recently, it has also been argued that some of the light attributed to stars in these galaxies is generated by powerful black holes. This would imply that these galaxies may not be as massive after all.

Alternative theories

So, where do we stand now? While some tensions may soon be explained by more and better observations, it is not yet clear whether there will be a resolution to all of the challenges battering the cosmological model.

There has been no shortage of theoretical ideas of how to fix the model though — perhaps too many, in the range of a few hundred and counting. That's a perplexing task for any theorist who may wish to explore them all.

The possibilities are many. Perhaps we need to change our assumptions of the nature of dark energy. Perhaps it is a parameter that varies with time, which some recent measurements have suggested. Or maybe we need to add more dark energy to the model to boost the expansion of the universe at early times, or, on the contrary, at late times. Modifying how gravity behaves on large scales of the universe (differently than done in the models called Modified Newtonian Dynamics, or MOND) may also be an option.

So far, however, none of these alternatives can explain the vast array of observations that the standard model can. Even more worrisome, some of them may help with one tension but worsen others.

The door is now open to all sorts of ideas that challenge even the most basic tenets of cosmology. For example, we may need to abandon the assumption that the universe is "homogeneous and isotropic" on very large scales, meaning it looks the same in all directions to all observers and suggesting there are no special points in the universe. Others propose changes to the theory of general relativity.

Some even imagine a trickster universe, which participates with us in the act of observation, or which changes its appearance depending on whether we look at it or not — something we know happens in the quantum world of atoms and particles.

In time, many of these ideas will likely be relegated to the cabinet of curiosities of theorists. But in the meantime, they provide a fertile ground for testing the "new physics".

This is a good thing. The answer to these tensions will no doubt come from more data. In the next few years, a powerful combination of observations from experiments such as JWST, the Dark Energy Spectroscopic Instrument (DESI), the Vera Rubin Observatory and Euclid, among many others, will help us find the long-sought answers.

Tipping point

On one side, more accurate data and a better understanding of the systematic uncertainties in the measurements could return us to the reassuring comfort of the standard model. Out of its past troubles, the model may emerge not only vindicated, but also strengthened, and cosmology will be a science that is both precise and accurate.

But if the balance tips the other way, we will be ushered into uncharted territory, where new physics will have to be discovered. This could lead to a major paradigm shift in cosmology, akin to the discovery of the accelerated expansion of the universe in the late 1990s. But on this path we may have to reckon, once and for all, with the nature of dark energy and dark matter, two of the big unsolved mysteries of the universe.

This edited article is republished from The Conversation under a Creative Commons license. Read the original article.

Astrophysicists have used artificial intelligence (AI) to precisely estimate five of the universe's six "settings" with unprecedented precision. The system could one day help researchers crack the mystery of the Hubble tension.

Scientists use six cosmological parameters to describe the large-scale makeup of our universe. These describe the density of its ordinary matter, or baryons; the density of dark matter and dark energy; and the conditions immediately following the Big Bang — including the universe's opacity and clumpiness.

Getting precise estimates of these numbers is important for understanding how our universe began and how it will evolve. But traditional methods typically only estimate these parameters by looking at the way galaxies are spread out over large scales. 

By applying AI to the problem, the researchers were able to extract numbers for the parameters across smaller scales, yielding a result for our universe's matter clumping that had less than half the uncertainty of previous results. The scientists published their findings Aug. 21 in the journal Nature Astronomy.

"Each of these [telescope] surveys costs hundreds of millions to billions of dollars," study co-author Shirley Ho, a group leader at the Flatiron Institute's Center for Computational Astrophysics (CCA) in New York City, said in a statement. "The main reason these surveys exist is because we want to understand these cosmological parameters better. So if you think about it in a very practical sense, these parameters are worth tens of millions of dollars each. You want the best analysis you can to extract as much knowledge out of these surveys as possible and push the boundaries of our understanding of the universe."

The researchers trained their AI system on 2,000 models of box-shaped universes, each with different cosmological settings and muddied data to reflect the limitations in real-life observations. This enabled their model to spot patterns in how galaxies looked based upon the alterations made to each universe's settings.

Related: James Webb telescope confirms there is something seriously wrong with our understanding of the universe

Then, the researchers presented the AI with 109,636 real galaxies measured by the Baryon Oscillation Spectroscopic Survey. The system produced estimates for the cosmological parameters that were as precise as a traditional survey using four times as many galaxies.

Past efforts to estimate the parameters "haven't been able to go down to small scales," study lead author ChangHoon Hahn, an associate researcher at Princeton University, said in the statement. "For a couple of years now, we've known that there's additional information there; we just didn't have a good way of extracting it."

The researchers have proposed a number of applications for their method, possibly the most exciting of which will be to study the Hubble tension. For years, scientists have been locked in a fierce debate over the tension — a problem which arises from mismatched estimates showing the universe expanding at different rates depending on where in space astronomers look.

By feeding data from new cosmic surveys coming online in the next few years into their model, the researchers hope to arrive at an understanding of whether the tension can be resolved, or if it demands a completely new model of the universe.

"If we measure the quantities very precisely and can firmly say that there is a tension, that could reveal new physics about dark energy and the expansion of the universe," Hahn said.

Microscopic wormholes may be driving the accelerated expansion of the universe, scientists say. These tiny wormholes are constantly being born from the vacuum of space due to subtle quantum effects.

If confirmed through experiments and observations, the wormholes could become a valuable source of information on quantum gravity — a theoretical unification of the fundamental forces of the universe, often considered to be the Holy Grail of theoretical physics.

Numerous astronomical observations show that our universe is expanding at an ever-increasing rate. However, Einstein's general theory of relativity states that if the universe contains only the species of particles and radiation we know, such behavior of the fabric of space is impossible.

To reconcile the observations of universe expansion with this theory, scientists have proposed that space is filled with an enigmatic entity that can't be detected in ground or space-based experiments.

This mysterious substance, called dark energy, interacts very weakly with other types of matter and fields, so, there is currently no reliable information about its structure or origin.

In a recent study published April 5 in the journal Physical Review D, researchers proposed a bold new candidate for dark energy: subatomic-size wormholes — or tiny tunnels connecting disparate points in space.

Related: Wormholes might bend light like black holes do — and that could be the key to finding them

According to the authors, these wormholes are constantly being born and destroyed in the vacuum of space due to quantum effects. This is similar to how particles are produced near the event horizons of black holes, leading to Hawking radiation; or how electron-positron pairs are generated by a strong electric field — a phenomenon known as the Schwinger effect.

However, the creation of these wormholes is somewhat different from those other phenomena because their mathematical description requires quantum effects in gravity to be accounted for — a task that's much more complicated and poorly understood.

These difficulties in calculating quantum gravitational phenomena prevented the authors from accurately deriving the wormhole birth rate. However, using an approach known as Euclidean quantum gravity, they showed that if about 10 billion wormholes are spontaneously created per cubic centimeter per second, the energy they generate would be sufficient to explain the currently observed rate of the universe's expansion.

"Although our result was derived on the grounds of Euclidean quantum gravity… it is likely that our modification may hold for other quantum gravity theories as well," study co-author Stylianos Tsilioukas, a doctoral student at the University of Thessaly and National Observatory of Athens, told Live Science via email.

Moreover, the team's analysis showed that their model of dark energy is even better observationally than the most widely accepted theory, known as the Standard Cosmological Model, which posits that dark energy has a time-independent energy density.

"According to our proposal dark energy can change as time flows," Tsilioukas said. "This is a major advantage because recent observations suggest that the rate of expansion of the universe is different in recent times than it was in the early universe."

However, no matter how successful the researchers' model is at explaining the general properties of dark energy, the validity of any physical theory must be tested with experimental data. And for now, the theory remains untestable.

In the future, the ever-increasing accuracy of space experiments and observations should enable astronomers to deduce the universe expansion rate in more detail, as well as to measure other observable manifestations of dark energy. This could enable researchers to test whether this newly proposed model of dark energy is correct.

In the meantime, the authors plan to further improve their theoretical analysis. "We are working right now on a model which calculates the rate of wormhole formation. " Tsilioukas said. "The research seems promising and we hope to publish the results very soon."

The James Webb Space Telescope (JWST) has spotted the earliest galaxy ever seen, and its unusually bright light is coming from a bizarre frenzy of star formation.

Named JADES-GS-z14-0, the galaxy formed at least 290 million years after the Big Bang, and contains stars that have been bursting into life since an estimated 200 million years after our universe began. 

Spotted by JWST's Near InfraRed Spectrograph (NIRSpec) instrument, the mysterious origins and rapid development of the stars has opened up some fundamental questions about how our universe came to be. The researchers published their findings July 29 in the journal Nature.

"The discovery by JWST of an abundance of luminous galaxies in the very early Universe suggests that galaxies developed rapidly, in apparent tension with many standard models," the researchers wrote in the study. "Galaxy formation models will need to address the existence of such large and luminous galaxies so early in cosmic history."

Astronomers aren't certain when the very first globules of stars began to clump into the galaxies we see today, but cosmologists previously estimated that the process began slowly within the first few hundred million years after the Big Bang.

Related: James Webb telescope confirms there is something seriously wrong with our understanding of the universe

Current theories suggest that halos of dark matter (a mysterious and invisible substance believed to make up 85% of the total matter in the universe) combined with gas to form the first seedlings of galaxies. One billion to 2 billion years into the universe's life, these early protogalaxies reached adolescence, forming into dwarf galaxies that began devouring one another to grow into ones like our own.

But discoveries made by the JWST confounded this view. In February 2023, a group of astronomers analyzing data from the telescope discovered a group of six gargantuan galaxies — aged between 500 to 700 million years after the Big Bang — that were so massive they were in tension with 99% of cosmological models.

The light from JADES-GS-z14-0 is similarly puzzling. In the new research, the light detected by NIRSpec finds its origins in an enormous halo of young stars surrounding the galaxy's core, which have been burning for at least 90 million years before the point of its observation. The galaxy is also crammed with unusually high quantities of dust and oxygen, which suggests its history of star birth and death may be even longer.

Interestingly, the researchers wrote, this finding shows that ultra-bright galaxies in the early universe are not just the product of active black holes greedily gobbling up matter, as is often assumed to be the case. The new observations show that runaway star formation is also a viable explanation for the surprising brightness of these ancient galaxies.

So how did galaxies like JADES-GS-z14-0 produce so many stars, so quickly? Answers to this cosmic mystery remain elusive, but it's unlikely they will break our current understanding of cosmology. Instead, astronomers are toying with explanations that include the earlier-than-anticipated appearance of giant black holes; supernova feedback; or even dark energy to understand why these ancient stars were able to form so rapidly.

Not long after the James Webb Space Telescope (JWST) began its science operations, astronomers announced that they had discovered galaxies in the early universe that were far too large, bright and full of stars for their age. While headlines around the world claimed that these galaxies were "breaking" our understanding of the Big Bang, the truth is much more nuanced — and much more interesting.

The Big Bang theory is our general picture of the history of the universe, starting in its deep past, when the cosmos was much smaller, hotter and denser than it is today. This model, initially developed in the early 20th century, has survived a battery of observational tests and is extremely good at explaining a variety of cosmological observations, including the redshifting of light from distant galaxies, the appearance of leftover radiation in the form of the cosmic microwave background, the abundances of light elements, and the evolution of galaxies and larger structures.

While the Big Bang theory can't say for certain which galaxies will appear where, it can talk about probabilities. For example, cosmologists can say roughly how many small galaxies, how many medium galaxies and how many large galaxies should appear in a given volume at a certain age of the universe. But until JWST, we did not have direct observational access to the earliest stages of galactic evolution — something the telescope was explicitly designed to study.

In 2022, astronomers announced that they had found extremely distant galaxies that were surprisingly, weirdly large. They had measured the redshift of the galaxies to be over 16, implying that these galaxies existed just 200 million to 250 million years after the Big Bang. Yet they were gigantic and appeared to be fully formed, with spiral arms and everything.

Related: 'The early universe is nothing like we expected': James Webb telescope reveals 'new understanding' of how galaxies formed at cosmic dawn

These galaxies seemed far outside the expectations of the Big Bang theory; they were like finding teenagers in a kindergarten classroom. So what was going on?

Bending cosmology

Cue the brazen headlines proclaiming the death of the Big Bang theory. But those stories left out a crucial detail: Astronomers estimated the redshift of those galaxies through a technique known as photometry, which is incredibly uncertain. A full evaluation of the ability of those galaxies to "break" cosmology would have to wait for a more precise measurement of their redshift, and hence their age.

When those more precise measurements finally came a few months later, those galaxies turned from record-shattering to just … normal galaxies. For example, one galaxy's redshift was revised from over 16 to just 4.9, moving its age from 240 million years after the Big Bang to well over a billion years. That's more than enough time for the normal Big Bang theory to explain their sizes and shapes.

But along with those less-exciting revisions came some new confirmed redshifts of other galaxies, including JADES-GS-z14-0, the current most distant known galaxy, with a redshift of 14.32. This galaxy was alive and well when the cosmos was just 290 million years old.

Astronomers fully expected galaxies to exist 290 million years after the Big Bang; that's why they built JWST. And as galaxies go, JADES-GS-z14-0 is certainly a juvenile — it's only 1,600 light-years across, compared with the Milky Way's 100,000 light-years. But interestingly, the galaxy is rather bright and full of stars — not enough to outright break cosmology, but enough to open up some questions about the origins and development of the first galaxies to appear in the universe.

Building cosmology

It's quite possible that the Big Bang theory is wrong; scientists must maintain the mental discipline to admit the possibility. But with such a wealth of evidence behind it, the Big Bang is unlikely to be unseated from a single observation. And it's worth reiterating that JWST is doing exactly what we designed and built it to do: answer some major lingering questions about how the first stars and galaxies appeared.

It's entirely possible that cosmologists will be able to explain the appearance of galaxies like JADES-GS-z14-0 within the framework of the Big Bang without having to make any major revisions. For example, large black holes may have appeared before these galaxies did, and their superpowered gravitational attraction may have triggered bright bursts of star formation. Or perhaps supernova feedback and other mechanisms caused the first galaxies to be richer with stars than present-day galaxies, making those early galaxies appear mighty despite their small size.

Or maybe our initial observations are biased toward these small-but-bright outliers and further campaigns will reveal larger populations of more mundane galaxies, thus reducing the tension with galaxy formation models.

And lastly, perhaps we need to add some new ingredient to the universe, like allowing for dark energy to evolve with time, to produce these kinds of galaxies at such early times.

This is exciting enough on its own, without the need to upend the Big Bang as we know it. There are more than enough mysteries and hidden corners within the universe to keep astronomers up at night wondering about the possibilities — and up in the morning to keep working on how to solve them.

Originally posted on Space.com.

Astronomers are about to begin making a time lapse of the night sky using the largest digital camera ever constructed.

Designed to reveal any new or moving point of light as well as the structure of the universe, the new $473 million Vera C. Rubin Observatory in Chile will take so many images, so fast, that it will effectively produce an astronomical movie that allows scientists to see the universe in real time. While still not yet fully operational, the Observatory's first batch of sneak peek images has already left scientists staggered.

Formerly known as the Large Synoptic Survey Telescope, the Rubin Observatory is expected to give astronomers the data they need to unravel some of the deepest mysteries of how the universe works. The observatory is named after the trailblazing astronomer Vera C. Rubin, who found evidence for dark matter, the mysterious substance that binds galaxies together.

The observatory is set to undertake a 10-year time lapse of the universe. Here's everything you need to know about the Vera C. Rubin Observatory and its groundbreaking mission.

What is the Vera C. Rubin Observatory, and why is it unique?

The Vera C. Rubin Observatory will be like no other telescope on Earth. The extremely wide-field telescope will initiate the decade-long Legacy Survey of Space and Time (LSST), a hugely ambitious project to image the entire Southern Hemisphere night sky every three to four nights.

While many modern telescopes are built for close-ups, the observatory's Simonyi Survey Telescope, which boasts a 27.6-foot-wide (8.4 meters) primary mirror, has a field of view about the same as the diameter of seven full moons.

The Rubin Observatory has been under construction since 2014 at an altitude of 8,900 feet (2,700 m) on the peak of Cerro Pachón in Chile. It is expected to be fully operational by late 2025.

Related: 6 incredible objects hidden in Vera C. Rubin Observatory's mind-boggling first image

First images

The Vera C. Rubin Observatory revealed its first images to the world on June 23, 2025. Meant to showcase the Observatory's immense field of view, one of the images shows more than 10 million galaxies located in and around the Virgo Cluster, about 55 million light-years from Earth. Many of these galaxies have never been studied before, Observatory researchers said at a news conference.

The Observatory also released stunning, zoomed-in views of the colorful Trifid and Lagoon nebulas, as well as a snapshot of space revealing roughly 2,100 newly discovered asteroids.

As of July 2025, the Observatory still isn't fully operational, and many, many more staggering views of the cosmos are yet to come.

What kinds of instruments does the Rubin Observatory use?

The Rubin Observatory is fitted with the world's largest camera dedicated to astronomy and astrophysics. The $168 LSSTCam has a 2-foot-wide (0.6 m) focal plane with 189 individual 16-megapixel charge coupled device sensors, resulting in a remarkable 3,200-megapixel image. It also has six of the largest optical filters ever produced to see the universe in different wavelengths of light, according to the telescope's official website.

Just as impressive is the mount, which will slew to a new position in just five seconds, allowing the camera to take a high-resolution image every 39 seconds. Fiber optics will carry each image to a supercomputer in California within two minutes for analysis. If there's anything new or changed in the image compared with a reference image, astronomers will be alerted.

What will the Rubin Observatory look for?

The telescope's data will be used for two purposes. The first is planetary defense. Its images are expected to reveal about 90% of all potentially hazardous asteroids, which are defined as asteroids larger than 640 feet (140 m) in diameter that could come within 4.65 million miles (7.48 million kilometers) of Earth. This includes dangerous and elusive asteroids normally hidden in the sun's glare.

In addition, the observatory should identify as-yet-unseen interstellar comets, free-floating stars and rogue planets. One of the biggest solar system objects it could reveal is Planet Nine, a hypothetical world that may lurk at the outer reaches of our solar system. Experts say that within a year of going live, the giant telescope may have produced enough data to find the elusive world — or rule it out forever.

However, in the longer term, it will also reveal many thousands — or even millions — of supernovas, as well as galaxies and their structures, which could prove crucial to our understanding of dark energy and dark matter.

When will the Rubin Observatory start operations?

The Observatory released its first images in June 2025, but science operations are still a ways off. They're expected to start late in 2025 or early 2026, according to the Rubin website.

Editor's note: This article was updated on July 11, 2025, to include the Rubin Observatory's first images.

A first-of-its-kind NASA mission aims to put a new "star" in the sky by the end of the decade to help solve a wide range of the universe's biggest mysteries, scientists have announced. 

The Landolt NASA Space Mission aims to send an artificial star satellite into orbit around Earth by "early 2029," Peter Plavchan, an astronomer at George Mason University in Virginia and the Landolt mission's principal investigator, told Live Science in an email. 

The satellite will be "about the size of a proverbial breadbox" and will be equipped with eight lasers that will enable it to mimic almost any type of star or supernova from across the cosmos when viewed by ground-based telescopes, Plavchan added. This will help astronomers improve how they study the real versions of these objects.

The fake star will be placed exactly 22,236 miles (35,785 kilometers) above Earth's surface, according to a statement by researchers. This will put the satellite in a geosynchronous orbit around our planet, meaning its speed will match Earth's spin so it will appear to be fixed in place in the night sky. For the first year of the mission, researchers plan for this fixed point to be somewhere above the U.S., Plavcham said. 

But that doesn't mean everyone will be able to see the new star in the night sky. "It will be more than 100 times too faint to see with the human eye but will be easy to see for moderate-sized telescopes equipped with digital cameras," Plavchan said.

The new mission is named after the late Arlo Landolt, who helped to create extensive stellar brightness catalogs. NASA officially gave the mission a green light in February, Plavchan said, but it was only announced to the public on June 10. 

The project will likely have a team of around 30 people and is estimated to cost around $19.5 million, Plavcham said.

Related: Space photo of the week: Astronomers make an 'artificial star' over Hawaii

The main goal of Landolt is to help astronomers calculate the absolute flux calibration of distant stars. This is the measurement of the rate of light particles, or photons, being emitted by stars, which is currently hard to determine accurately. This is partly because atmospheric interference alters the light observed by ground-based telescopes, but also because there are no real reference points for absolute flux calibration, apart from the sun. 

Because researchers can control the photon output of their artificial satellite, the fake star will provide a reliable reference point for telescopes to compare against real stars. This should hopefully help astronomers to determine the absolute flux capacity of a star to around 0.25% of its true value, which is around 10 times more accurate than current estimates.

Four ground-based telescopes have been earmarked to focus on the artificial star: George Mason University's 0.8-meter (2.6 feet) telescope, the UH88 telescope at the Mauna Kea Observatories in Hawaii, the Hale Telescope at Palomar Observatory in California and the upcoming Vera C.Rubin Observatory, which is currently under construction in Chile and is due to begin scanning the sky next year.

It is rare for a space mission to involve surface and orbital technologies linking together in this way, Plavcham said. "This is the first modern example of what is considered a hybrid mission that requires the use of facilities both on the ground and in space working together to make measurements."

Researchers believe that being able to measure the brightness and distance of stars more accurately will yield enormous benefits for multiple fields of astronomy. For example, it could help detect more exoplanets around alien stars, while also determining how old a star is and how others like it have evolved over time.

Another major goal of the Landolt mission is to aid researchers in studying dark energy and accurately determining the rate of the universe's expansion, which is currently one of cosmology's biggest problems.

The early universe contained far fewer miniature black holes than previously thought, making the origins of our cosmos's missing matter an even greater mystery, a new study has suggested.

Miniature, or primordial, black holes (PBHs) are black holes thought to have formed in the first fractions of a second after the Big Bang. According to leading theories, these dime-sized singularities popped into existence from rapidly collapsing regions of thick, hot gas.

The pockets of infinitely dense space-time are how many physicists explain the universe's dark matter, a mysterious entity that, despite being completely invisible, makes the universe much heavier than can be explained by the matter we see. 

But even though the hypothesis is popular, it has one big problem: we've yet to directly observe any primordial black holes. Now, a new study has offered a possible explanation as to why they didn't form, throwing open cosmology's dark matter problem to wider speculation. 

According to the research, the modern universe could have taken shape with far fewer primordial black holes than previous models estimated. The researchers published their findings May 29 in the journal Physical Review Letters.

Related: 1st detection of 'hiccupping' black hole leads to surprising discovery of 2nd black hole orbiting around it

"Many researchers feel they [primordial black holes] are a strong candidate for dark matter, but there would need to be plenty of them to satisfy that theory," lead author Jason Kristiano, a graduate student in theoretical physics at the University of Tokyo, said in a statement. "They are interesting for other reasons too, as since the recent innovation of gravitational wave astronomy, there have been discoveries of binary black hole mergers, which can be explained if PBHs exist in large numbers. But despite these strong reasons for their expected abundance, we have not seen any directly, and now we have a model which should explain why this is the case."

 A hole in the picture  

The universe began 13.8 billion years ago with the Big Bang, causing the young cosmos to explode outward due to an invisible force known as dark energy. 

As the universe grew, ordinary matter, which interacts with light, congealed around clumps of invisible dark matter to create the first galaxies, connected together by a vast cosmic web. Nowadays, cosmologists think that ordinary matter, dark matter and dark energy make up about 5%, 25% and 70% of the universe’s composition, respectively.

Initially, the universe was opaque, a plasma broth that no light could traverse without being snared by electromagnetic fields produced by moving charges. Yet after 380,000 years of cooling and expansion, the plasma eventually recombined into neutral matter, giving off microwave static that became the universe's first light, the cosmic microwave background (CMB).

Cosmologists have been searching for these early black holes by studying this first baby picture of the universe. Yet, so far, none have been found.

Some physicists think there's a possibility they haven't discovered the vast numbers of primordial black holes necessary to account for dark matter simply because they've yet to learn how to detect them.

But by applying a model built on an advanced form of quantum mechanics called quantum field theory to the problem, the researchers behind the new study arrived at a different conclusion — we can't find any primordial black holes because most of them simply aren't there.

Primordial black holes are believed to have emerged from the collapse of short but strong gravitational waves rippling across the universe. By applying their model to these waves, the researchers found that it could take much less of these waves to combine than other theories estimate in order to shape larger structures across the universe. And the fewer the waves necessary to recreate the picture, the fewer primordial black holes.

"It is widely believed that the collapse of short but strong wavelengths in the early universe is what creates primordial black holes," said Kristiano. "Our study suggests there should be far fewer PBHs than would be needed if they are indeed a strong candidate for dark matter or gravitational wave events."

To confirm their theory, the researchers will look to future, hyper-sensitive gravitational wave detectors such as the Laser Interferometer Space Antenna (LISA) project, which is due to be sent into space on an Ariane 3 rocket in 2035.

The European Space Agency’s (ESA) Euclid space telescope's first five science images of our cosmos have been revealed, and they're absolutely stunning.

The images — taken during just 24 hours of observation — show twinkling galaxy clusters, colorful wisps of gas clouds and one of the largest-known spiral galaxies in unprecedented levels of detail. 

By capturing thousands of images like these for the next six years, the space telescope will catalog a third of the entire night sky and image more than a billion galaxies that are up to 10 billion years old, according to ESA.

"This space telescope intends to tackle the biggest open questions in cosmology," Valeria Pettorino,  a Euclid project scientist, said in a statement. "And these early observations clearly demonstrate that Euclid is more than up to the task."

Launched into orbit on July 1, 2023, Euclid was designed to compile wide-lens images to help scientists hunt for two of the universe's most mysterious components: dark matter and dark energy.

Related: Mysterious 'Green Monster' lurking in James Webb photo of supernova remnant is finally explained

Researchers think dark matter and dark energy together make up about 95% of the universe, but they do not interact with light so can't be detected directly. Instead, scientists study these mysterious components by observing the way they interact with the visible universe around them: Dark matter can be seen by observing its gravitational warping effects on galaxies; and dark energy in the force propelling the universe's runaway expansion.

By collecting images across its enormous field of view, Euclid will help scientists to detect the telltale clues of warped matter by creating two maps — one of the gravitational lensing of galaxies that could reveal dark matter, and the other of matter shock waves called baryon acoustic oscillations that can measure dark energy.

But besides having immense scientific value, Euclid's images are also stunning. Here's our guide to the five released on Thursday (May 23).

Abell 2390 and Abell 2764

Euclid's first image is of the galaxy cluster Abell 2390, a gigantic grouping of 50,000 galaxies located inside the Pegasus constellation 2.7 billion light-years from Earth. The image features  "intracluster light" from stars ripped out of their parent galaxies and beaming as lone lanterns in interstellar space. By measuring the warping of light around immense galaxies such as this, Euclid can help reveal the quantity and distribution of invisible dark matter across the universe.

Another image, of the galaxy cluster Abell 2764 that's located 1 billion light-years from Earth in the Phoenix constellation, shows hundreds of galaxies held within a halo of dark matter, with some galaxies spiraling around each other.

Messier 78

This stunning image of the star nursery Messier 78, located 1,300 light-years away within the constellation Orion, shows stars forming between vibrant tendrils of gas and dust. More than 300,000 new objects were revealed by Euclid's powerful infrared eye in this image, including baby stars and ejected rogue planets.

NGC 6744

This image shows the massive spiral galaxy NGC 6744, situated 30 million light-years away within the Local Group — the super-group of more than 20 tight-knit galaxies to which the Milky Way belongs. Euclid's image captured a previously undetected dwarf galaxy orbiting its larger neighbor. By studying this region, scientists hope to understand how stars form within galaxies and discover the role that spiral structures play in this process. 

The Dorado Group

The final image showcases the Dorado Group, a collection of galaxies 62 million light-years away in the constellation Dorado. These sparring galaxies are locked in a complex dance, at the end of which they will collide with each other and merge. 

The five images are part of Euclid's early release observations, and they will be joined by many more images in the coming years. 

"They give just a hint of what Euclid can do," Pettorino said. "We are looking forward to six more years of data to come!"

A variation on the theory of quantum gravity — the unification of quantum mechanics and Einstein's general relativity — could help solve one of the biggest puzzles in cosmology, new research suggests.

For nearly a century, scientists have known that the universe is expanding. But in recent decades, physicists have found that different types of measurements of the expansion rate — called the Hubble parameter — produce puzzling inconsistencies.

To resolve this paradox, a new study suggests incorporating quantum effects into one prominent theory used to determine the expansion rate.

"We tried to resolve and explain the mismatch between the values of the Hubble parameter from two different prominent types of observations," study co-author P.K. Suresh, a professor of physics at the University of Hyderabad in India, told Live Science via email.

An expanding problem

The universe's expansion was first identified by Edwin Hubble in 1929. His observations with the largest telescope of that time revealed that galaxies farther from us appear to move away at faster speeds. Although Hubble initially overestimated the expansion rate, subsequent measurements have refined our understanding, establishing the current Hubble parameter as highly reliable.

Later in the 20th century, astrophysicists introduced a novel technique to gauge the expansion rate by examining the cosmic microwave background, the pervasive "afterglow" of the Big Bang.

However, a serious problem arose with these two types of measurements. Specifically, the newer method produced a Hubble parameter value almost 10% lower than the one deduced from the astronomical observations of distant cosmic objects. Such discrepancies between different measurements, called the Hubble tension, signal potential flaws in our understanding of the universe's evolution.

Related: Newfound 'glitch' in Einstein's relativity could rewrite the rules of the universe, study suggests

In a study published in the journal Classical and Quantum Gravity, Suresh and his colleague from the University of Hyderabad, B. Anupama, proposed a solution to align these disparate results. They underscored that physicists infer the Hubble parameter indirectly, employing our universe's evolutionary model based on Einstein's theory of general relativity.

The team argued for revising this theory to incorporate quantum effects. These effects, intrinsic to fundamental interactions, encompass random field fluctuations and the spontaneous creation of particles from the vacuum of space.

Despite scientists' ability to integrate quantum effects into theories of other fields, quantum gravity remains elusive, making detailed calculations extremely difficult or even impossible. To make matters worse, experimental studies of these effects require reaching temperatures or energies many orders of magnitude higher than those achievable in a lab.

Acknowledging these challenges, Suresh and Anupama focused on broad quantum-gravity effects common to many proposed theories.

"Our equation doesn't need to account for everything, but that does not prevent us from testing quantum gravity or its effects experimentally," Suresh said.

Their theoretical exploration revealed that accounting for quantum effects when describing the gravitational interactions in the earliest stage of the universe's expansion, called cosmic inflation, could indeed alter the theory's predictions regarding the properties of the microwave background at present, making the two types of Hubble parameter measurements consistent.

Of course, final conclusions can be drawn only when a full-fledged theory of quantum gravity is known, but even the preliminary findings are encouraging. Moreover, the link between the cosmic microwave background and quantum gravitational effects opens the way to experimentally studying these effects in the near future, the team said.

"Quantum gravity is supposed to play a role in the dynamics of the early universe; thus its effect can be observed through measurements of the properties of the cosmic microwave background," Suresh said.

"Some of the future missions devoted to studying this electromagnetic background are highly probable and promising to test quantum gravity. … It provides a promising suggestion to resolve and validate the inflationary models of cosmology in conjunction with quantum gravity."

Additionally, the authors posit that quantum gravitational phenomena in the early universe might have shaped the properties of gravitational waves emitted during that period. Detecting these waves with future gravitational-wave observatories could further illuminate quantum gravitational characteristics.

"Gravitational waves from various astrophysical sources have only been observed so far, but gravitational waves from the early universe have not yet been detected," Suresh said. "Hopefully, our work will help in identifying the correct inflationary model and detecting the primordial gravitational waves with quantum gravity features."

A strange "cosmic glitch" in gravity could explain the universe's weird behavior on the largest scales, researchers suggest. 

First formulated by Albert Einstein in 1915, the theory of general relativity remains our best and most accurate understanding of how gravity works on medium to large scales. 

Yet, zoom out even farther to view enormous groups of gravitationally bound galaxies interacting, and some inconsistencies appear to emerge. This suggests that gravity, which is theorized to be a constant across all times and scales, could actually become slightly weaker at cosmic distances. 

In a study published March 20 in the Journal of Cosmology and Astroparticle Physics, researchers described this discrepancy as a "cosmic glitch," and they say their proposed fix for it could help us understand some of the universe's most enduring mysteries.

"[It's] like making a puzzle on the surface of a sphere, then laying the pieces on a flat table and trying to fit them together," study co-author Niayesh Afshordi, a professor of astrophysics at the University of Waterloo in Ontario, told Live Science. "At some point, the pieces on the table will not quite fit each other, because you are using the wrong framework.

Related: James Webb telescope confirms there is something seriously wrong with our understanding of the universe 

"The glitch is the smoking gun for a fundamental violation of Einstein's equivalence principle (or Lorentz symmetry), which could point to radically different pictures for quantum gravity, the Big Bang, or black holes," Afshordi added.

Cosmos for concern 

Einstein's theory of general relativity is remarkably good at describing the universe above quantum scales, and it has even predicted other aspects of our cosmos, including black holes, the gravitational lensing of light, gravitational waves, and the Big Bang.

Yet some discrepancies between theory and reality remain. First, attempts to scale down general relativity to describe how gravity operates on quantum scales transform its usually robust equations into incomprehensible nonsense. 

Second, completing our current model of the universe required the introduction of two mysterious additions, known as dark matter and dark energy. Believed to make up most of the contents of the universe, these entities have never been directly detected and fail to explain why our cosmos is expanding at different speeds depending on where we look. 

In response to these problems, the authors of the new paper came up with a simple suggestion: a tweak to Einstein's theory at different distance scales.

"The modification is very simple: We assume the universal constant of gravitation is different on cosmological scales, compared to smaller (like solar system or galactic) scales," Afshordi said. "We call this a cosmic glitch."

Afshordi said this tweak makes changes to patterns found in the cosmic microwave background — the leftover radiation produced 380,000 years after the Big Bang — and in the universe's structure and expansion. These adjustments are subtle, but the implication that the laws of gravity change over distance scales could be profound.

"We find evidence for the glitch: cosmic gravity is about 1% weaker than galactic/solar-system gravity," he added. 

The researchers said the glitch's existence could be confirmed by next-generation galaxy surveys, including those performed with the European Space Agency's Euclid space telescope, the Dark Energy Spectroscopic Instrument and the Simons Observatory. They say that these instruments should make measurements of the glitch four times more precise than is currently possible and, therefore, confirm or rule out their theory.

However, some scientists say a simple modification of Einstein's relativity might not be enough. In fact, it's possible that the discrepancies revealed by astronomical observations are hints that our understanding of the universe needs a complete rewrite.

"It's not that surprising that this new model is a slightly better fit to the data, but maybe that is telling us something," said Scott Dodelson, a professor of physics and the chair of the physics department at Carnegie Mellon University, who was not involved in the study.

"If so, it means we understand even less than we thought we did," he told Live Science. "My hunch is that instead of adding more new stuff, we need a new paradigm. But no one has come up with anything that makes any sense yet."

What it is: CG 4, a "cometary globule" often called "God's Hand"

Where it is: Gum Nebula, 1,300 light-years away in the constellation Puppis (the "poop deck")

When it was shared: May 6, 2024

Why it's so special: CG 4 is a fairly typical cloud of gas and dust where stars are being born, but its strange shape has earned it two odd names. Described as a "cometary globule" because of its faint tail's resemblance to a comet, it's also called "God's Hand" for its likeness to a massive outstretched arm reaching across the cosmos. 

In this new image from the Dark Energy Camera (DECam) on the Blanco Telescope in Chile, CG 4's dusty head and long tail resemble a mouth about to eat a side-on galaxy called ESO 257-19. It's a chance alignment because the galaxy is over 100 million light-years beyond. A zoomable close-up image shows CG 4's head and tail and two young stars being born. 

How cometary globules form is a mystery. Some astronomers theorize that they're shaped by stellar winds from massive hot stars nearby. Others suggest that these structures may be spherical nebulas that deform after being impacted by a nearby supernova — a star that exploded.

Related: James Webb telescope reveals fiery 'mane' of the Horsehead Nebula in spectacular new images

CG 4 could itself be the expanding remains of a supernova from about a million years ago. Cometary globules are not rare in the Milky Way, but the Gum Nebula is home to at least 32, according to the National Science Foundation's NOIRLab. The Gum Nebula is an emission nebula — a cloud of hot gas energized by a nearby star. 

Although the Gum Nebula is a large structure, it's very faint. Scientists used DECam's special Hydrogen-alpha filter to image CG 4. Hydrogen becomes ionized when struck by radiation from stars, enabling DECam to image a faint red glow within CG 4's head and around its outer rim. 

Managed by NOIRLab, DECam is a 570-megapixel camera with 74 sensors. It sits on the Víctor M. Blanco Telescope, a 4-meter telescope at the Cerro Tololo Inter-American Observatory on Cerro Pachon in Chile.

Could the cosmos be dominated by particles that move faster than the speed of light? This model of the universe agrees surprisingly well with observations, a pair of physicists has discovered.

In a new paper that has yet to be peer-reviewed, the physicists propose that our universe is dominated by tachyons — a hypothetical kind of particle that always moves faster than light. Tachyons almost certainly don't exist; going faster than light violates everything we know about the causal flow of time from past to future. But the hypothetical particles are still interesting to physicists because of the small chance that even our most closely held notions, like causality, might be wrong.

The researchers suggest that tachyons might be the true identity of dark matter, the mysterious form of matter that makes up most of the mass of almost every single galaxy in the universe, outweighing normal matter 5 to 1. Astronomers and physicists alike currently do not know what dark matter is made of, so they are free to cook up all manner of ideas —– because, after all, sometimes a far-out idea is right, and even if it's wrong, it can help us on the path to a better understanding.

The researchers calculate that an expanding universe filled with tachyons can initially slow down in its expansion before reaccelerating. Our universe is currently in an accelerating phase, driven by a phenomenon known as dark energy, so this tachyon cosmological model can potentially explain both dark energy and dark matter at the same time.

Related: There may be a 'dark mirror' universe within ours where atoms failed to form, new study suggests

To test this idea, the physicists applied their model to observations of Type Ia supernovae, a kind of stellar explosion that allows cosmologists to build a relationship between distance and the expansion rate of the universe. It was through Type Ia supernovae that astronomers in the late 1990s first discovered that the universe's expansion rate is accelerating.

The physicists found that a tachyon cosmological model was just as good at explaining the supernova data as the standard cosmological model involving dark matter and dark energy. That itself is a surprise, given how unorthodox this idea is.

However, that's only the beginning. We now have access to a wealth of data about the large-scale universe, like the cosmic microwave background (remnant radiation released just after the Big Bang) and the arrangement of galaxies at the very largest scales. The next step is to continue testing this idea against those additional observations.

The tachyon cosmological model is unlikely to pass those rigorous experimental tests, given the unlikely nature of tachyons. But continuing to push in new, even unorthodox, directions is important in cosmology; we never know when we might get a breakthrough. Scientists have been attempting to understand dark matter for 50 years and dark energy for a quarter century, without any conclusive results. The solutions to these conundrums are likely to come from unexpected directions.

The team's research was published to the preprint database arXiv in March.

It has been over two decades since the discovery of dark energy.

Scientists have therefore had more than 20 years to decode the secrets of this invisible substance that appears to be pulling the universe apart. Yet, they still know close to nothing about it. Dark energy, in fact, may not even be a substance. It could be a force or even an intrinsic property of space itself.

For instance, the standard model of cosmology — our leading theory of cosmic evolution — does suggest dark energy is unwavering across the universe and throughout time, making it a fundamental property of space. If constant, the mysterious dark energy that makes up a whopping 70 percent of the universe would push away all stars and galaxies. However, the biggest survey of the universe's cosmic history could indicate that dark energy, also known as a hypothetical "anti-gravity" force, may evolve with time rather than remain constant, hinting at a less lonely future for residents of the universe.

If this early result holds with future observations, cosmologists may have to, at the very least, explore systematic uncertainties in the prevailing Lambda CDM (LCDM) model, a mathematical model of the universe in which lambda represents dark energy. They may also need to start sifting through dozens of other models of our universe to find the true best fit. Still, the evidence is tentative — it does not reach what's known as the "5-sigma threshold," which determines whether a signal can be celebrated as an official discovery. So, continuously emerging interpretations about dark energy's evolution could change with more data scheduled to come within the next few years.

"If this is true, this just turns cosmology upside down," said Dillon Brout of Boston University, who measures the acceleration of the universe with supernovas. Such a discovery would be a "paradigm shift in our thinking of what our best understanding of our universe is."

Related: James Webb telescope confirms there is something seriously wrong with our understanding of the universe

Streetlights of the universe

Perched atop the Nicholas U. Mayall 4-meter telescope at Arizona's Kitt Peak National Observatory, the Dark Energy Spectroscopic Instrument, or DESI, pinpoints positions of a million galaxies each month. Through these observations, cosmologists can measure the universe's expansion rate as it increased over the past 11 billion years. These faraway galaxies, which can be likened to the "streetlights of the universe," are thus helping cosmologists study the universe-permeating enigma of dark energy.

And, on April 4, the DESI collaboration shared the largest-ever 3D map of the universe. It includes high-precision measurements of the universe's expansion rate over the past 11 billion years as well. In its first year of operations alone, DESI has proven to be twice as powerful at measuring the expansion history of the early universe as its predecessor, the Sloan Digital Sky Survey, which took more than a decade to build a similar 3D map.

This "is the next generation of data we've been waiting a long time for, so it's really nice to see it having arrived," said Brout, who is not involved with the DESI collaboration.

In addition to countless galaxies clustered together like knotted threads, DESI's new 3D map spotlights a faint pattern in the early universe known as Baryon Acoustic Oscillations, or BAO. These subtle, 3D wrinkles had flown through matter that existed during the first 380,000 years of our universe's history, freezing with time and turning into relics of an infant cosmos. By mapping the sizes of those frozen BAOs, researchers managed to estimate the distances to galaxies and infer how fast the universe was expanding at various points in time.

Because light from typical galaxies is too faint to see, as those galaxies sit very far away from us and the light they emit is relatively low-intensity, the DESI collaboration also studied over 400,000 intensely bright objects called quasars. As light from these objects glides through interstellar space, it gets absorbed by clouds of gas and dust, helping cosmologists map pockets of dense matter in a similar way to mapping galaxies.

"It lets us look out further to when the universe was very young," Andreu Font-Ribera, a scientist at the Institute for High Energy Physics in Spain and a member of the DESI collaboration, said in a statement. "It's a really hard measurement to do, and very cool to see it succeed."

'If this is real, we're in uncharted territory'

The preliminary conclusion that dark energy could be evolving with time comes from an early analysis of DESI data combined with data from other cosmological data. The researchers found a varying dark energy model agreed better with the data compared to the standard model. To be clear, no single dataset by itself convincingly reveals the time-evolving nature of dark energy, but the signal becomes slightly stronger when all datasets are combined.

"It is not a strong enough preference that I would say Lambda CDM is wrong," Kyle Dawson, the co-spokesperson for DESI at the University of Utah, told Space.com. "We've actually never found deviations from that model before with any real meaning."

From the early analysis, however, it appears dark energy is transitioning from being a strong driver of acceleration of our universe to tapering off to some degree, said Dawson.

"If this is real, we're in uncharted territory," said Brout. The DESI collaboration used the second simplest model of our universe after Lambda CDM, which is unremarkable except for its ability to help cosmologists check for deviations from the standard model. If future observations in the pipeline indeed find dark energy is evolving with time, dozens of other models too would become viable, and cosmologists would have to start testing all of them individually, said Brout.

"If it's not Lambda CDM, who knows?"

Originally posted on Space.com.

This billowing mass of dust filaments and gas tendrils stretching across 100 light-years of space like delicate lace is the Vela supernova remnant — scattered ashes of a star that exploded about 11,000 years ago.

The image was acquired by the Dark Energy Camera (DECam), which is mounted on the Victor M. Blanco 4-Meter Telescope at the Cerro Tololo Inter-American Observatory in Chile. DECam was originally designed to conduct a survey of distant galaxies to measure the strength of dark energy as it accelerates the universe's expansion and draws those galaxies away from us. On the completion of that survey, however, DECam has been used in more general fashion. It is one of the most powerful wide-field instruments ever built, and this image of the Vela supernova remnant is proof of its capabilities. It's in fact the largest image ever released by the camera at 1.3 gigapixel (1.3 billion pixels) in size. For comparison, a top-of-the-line smartphone might have a 48 megapixel (48 million pixel) camera.

The image has to be large to capture all that detail across such a large swath of sky. As mentioned, the Vela supernova remnant is a nebula that is about 100 light-years across. Because it's about 800 light-years away from us, it means the Vela supernova remnant spans an area on the celestial sphere 20 times larger than the angular diameter of the full moon (which is 31 arcminutes, or half a degree across in the sky).

The Vela supernova remnant itself is of crucial astronomical importance. It gives us a good look at the late stages of the development of such a remnant, and offers insight into how material blown out by the supernova gradually disperses into the interstellar medium, which is the thin mist of gas that fills the space between stars. The shockwave from the ancient stellar explosion that formed the Vela supernova remnant is still expanding into space, where it is colliding with the interstellar medium and compressing it, creating the delicate filaments we can see in the image. Absorption lines from elements like calcium, carbon, copper, germanium, krypton, magnesium, nickel, oxygen and silicon — many of them ionized and doubly ionized — have been detected in the supernova debris as well. These are heavy elements forged either by fusion processes within the star before it exploded, or by the ferocious energies unleashed by the explosion itself.

A supernova doesn't just spew a star's guts into deep space; it also leaves behind the dead star's core, now compacted under gravity into an ultra-dense object just 10 or 12 kilometers (about 6 to 8 miles) across. This is called a neutron star.

Such an object is usually born spinning many times per second, flashing radio beams from its poles like a cosmic lighthouse. We call such objects "pulsars," and indeed one lurks at the heart of the Vela supernova remnant that radio telescopes have clocked spinning at a dizzying rate of 11 rotations per second.

The Vela pulsar is one of the closest pulsars to us, and is blowing what's called a "pulsar wind nebula," which is a smaller nebula inside the larger supernova remnant formed of charged particles emanating from the pulsar and impacting circumstellar material ejected by the obliterated star as well as the wider interstellar medium. In a way, the remnant and the pulsar wind nebula are like a nebula within a nebula, a-la cosmic Matryoshka doll. Given that it is formed of energetic particles, a pulsar wind nebula tends to be more detectable in X-rays and gamma rays.

Even the constellation that the Vela supernova remnant lies within has an interesting history. The constellation is Vela, the Sails, but once upon a time this area of sky was part of a much larger constellation called Argo Navis, which is the name of the Greek mythological ship that took Jason and the Argonauts in search of the Golden Fleece. This southern constellation was so huge as to be unwieldy, so in 1755 French astronomer Nicolas Louis de Lacaille split the Argo Navis into three smaller constellations: Carina the Keel, Puppis the Poop Deck (or stern) and Vela, the Sails.

Those three constellations still exist to this day, but judging by DECam's image, perhaps in the end the Argonauts — we astronomers — did indeed find our Golden Fleece in the shape of the Vela Supernova Remnant.

Originally posted on Space.com.

The ever-accelerating expansion of the universe may be driven by a mysterious form of matter called "unparticles," which do not obey the Standard Model of particle physics, a new theoretical paper suggests.

Scientists widely acknowledge that the universe is expanding, though the cause of that expansion remains elusive. One of the most popular proposed explanations is a mysterious entity called dark energy in the form of a cosmological constant, which leads to expansion at a rate independent of the age of the universe and the temperature of matter and radiation. However, recent astronomical observations challenge this hypothesis, prompting physicists to explore alternatives to what dark energy could be.

Now, in a new paper, researchers analyzed the idea that dark energy is instead made of a theoretical form of matter called unparticles. They found that this theory aligns better with observations than the prevalent standard cosmological model, which assumes a cosmological constant.

"Observationally, discrepancies arise in the values of the universe's expansion rate and the growth of large-scale structures [galaxies and galactic clusters] between measurements," study co-author Utkarsh Kumar, a cosmologist at Ariel University, told Live Science in an email. "Various observations, including Cosmic Microwave Background measurements, dimming of supernovae and many others, contribute to this tension."

Related: There may be a 'dark mirror' universe within ours where atoms failed to form, new study suggests

Quantities such as the Hubble constant, which determines the rate of expansion, and the so-called S8, which contains information about the formation of large-scale structures, are not measured directly. Instead, they are calculated from observations of the cosmic microwave background (leftover radiation from the Big Bang) and distant stars and galaxies, using mathematical  theories. However, different theories yield different values of these parameters from the same data, posing a huge tension in cosmology.

To address this problem, the authors of the new study, published in December 2023 in the Journal of Cosmology and Astroparticle Physics, suggest that the expansion of the universe is driven not by a cosmological constant but by unparticles, which had previously been considered in the context of particle physics.

"The idea of unparticles was introduced by [theoretical physicist Howard] Georgi over a decade ago," lead study author Ido Ben-Dayan, also of Ariel University, told Live Science in an email. "In fundamental physics, we usually discuss fields, like the electric field, where particles are excitations of that field. In the electric field case, these are the photons," or packets of light. In almost all cases, Ben-Dayan added, particles are excitations with a well-defined mass and momentum.

However, "unparticles are the result of a set of fields that their excitations do not have a well-defined momentum and mass," Ben-Dayan said. "Thus, at the macroscopic level, they behave as a fluid. A special outcome of this property is that their equation of state, describing the ratio between the pressure they exert and their energy density, depends on temperature."

This equation of state strongly resembles the equation for the cosmological constant. Moreover, the very weak interaction of unparticles with “regular” matter, which is predicted by all theoretical models of the substance, makes it an excellent candidate for dark energy.

Unparticles untangled

In their work, Ben-Dayan and Kumar used the unparticle hypothesis instead of the cosmological constant and combined it with observational data collected from many experiments. They found that, unlike the values calculated using the standard cosmological model, the values of the Hubble constant and the S8 parameter deduced from these experiments were consistent with each other when they used the unparticle theory.

"Moreover, their model reduced the discrepancy between the measurements of the Hubble constant and S8, thus restoring the agreement between the different measurements, Kumar said. 

For now, there is no empirical evidence to back up this theory.  However, the authors are confident that, in the next decade or so, the accuracy of astronomical measurements will improve enough to determine whether the unparticle theory is correct.

"Our model is tested by constantly improving cosmological observations," Ben-Dayan said. "If it is correct, future Cosmic Microwave Background experiments should [confirm it]."

Experiments to measure the nature of dark energy are currently being developed, but will require telescopes to "probe further back in time" than they currently do, Ben-Dayan added.

Moreover, the physicists plan to increase the accuracy of their calculations and look for possible manifestations of unparticles in more familiar experiments with elementary particles in accelerators, which could be affected by the presence of unparticles.

"We plan to consider interactions between unparticles and the Standard Model of elementary particles," Kumar said. "This can further test our model. We will further study some extensions of our model and their cosmological consequences."

The Space Telescope Science Institute has announced which astronomy proposals have been selected to be given time with the James Webb Space Telescope over the next two years.

On Thursday (Feb. 29), the organization outlined 253 General Observers (GO) programs that will use humanity's most powerful and sensitive space telescope for a collective 5,500 hours between July 2024 and June 2025. This range is known as Cycle 3 of JWST operations.

Cycle 3 will build upon the previous two years of scientific advancements made by this $10 billion dollar telescope, which began beaming back data in 2022.

Some of the JWST's third-year targets include potential exomoons, or moons that surround exoplanets, exoplanets themselves in conjunction with their atmospheres, supermassive black holes and even distant galaxies that existed during the dawn of time. The JWST will also study large-scale structures in the cosmos to reveal details about the accelerating expansion of the universe and dark energy, the mysterious force that drives such movement.

Related: After 2 years in space, the James Webb telescope has broken cosmology. Can it be fixed?

The hunt is on for exomoons

One of the teams lucky enough to get time with the JWST during Cycle 3 will be searching for moons outside the solar system. These are known as extra-solar moons, or simply, "exomoons."

David Kipping, an assistant professor of astronomy at Columbia University, is part of the team that hopes to find moons around the exoplanet Kepler-167e in particular. This gas giant is around the size and mass of Jupiter and is located 1,115 light-years from Earth.

"We're thrilled to get one of our proposals accepted!" Kipping told Space.com. "Our exomoon search around Kepler-167e was accepted, and it's the best target we've ever had for moon hunting."

Thus far, exomoons have proved an elusive subject for astronomers because they are hunted using the same light-blocking technique employed to spot exoplanets around stars. However, this technique is difficult enough when looking for large worlds beyond Earth — searching for little exomoons with it is immensely challenging. Not only would exomoons block far less light than the exoplanets they orbit would, but they'd also need to be in the right position at the right time.

An exomoon that's detectable would have to be orbiting its planet precisely as that planets crosses, or "transits," the face of its parent star to obscure some light when viewed from our vantage point in the cosmos. That obstruction would be detected by scientists' equipment, which would allow them to reverse-calculate that an exoplanet (or potentially exomoon) gave rise to it.

Kipping is hoping that, by focusing on Kepler-167e with the JWST's Near Infrared Imager and Slitless Spectrograph (NIRISS), he and his team can make the first undisputed detection of an exomoon. "This is hopefully just the beginning of the exomoon revolution. New worlds that will surely hold some remarkable secrets," Kipping said.

Of course, the JWST's Cycle 3 GO projects also include a wealth of investigations focusing on exoplanets themselves and not just their potential moons. This includes a few that wish to determine whether some exoplanets have the conditions needed to support life as we know it.

Among those exoplanet habitability projects is one called "Constraining the atmosphere of the terrestrial exoplanet TOI-4481b." This will use the JWST's Mid-Infrared Instrument (MIRI) for 16 hours to determine if a roughly Jupiter-mass exoplanet, which orbits a star around half as massive as the sun that sits some 39 light-years away, has been able to hang on to its atmosphere.

The result could serve as a first step in understanding the habitability of rocky planets and establishing whether M-type stars, also known as red dwarfs, have terrestrial planets with significant atmospheres. This is important in the search for life beyond Earth because red dwarfs are the most common stars in the Milky Way.

Seeking out supermassive black holes

Astronomers widely believe the majority of our universe's large galaxies have supermassive black holes in their hearts with masses as great as millions, or even billions, of suns. Some of these supermassive black holes are actively swallowing gas and dust that surrounds them in disks of matter called accretion disks.

These monster black holes' gravitational influences are thought to heat the material in those accretion disks, causing them to emit bright radiation across the electromagnetic spectrum and create regions called Active Galactic Nuclei (AGN). Additionally, any matter that isn't swallowed by the black hole can be channeled to its poles, where it is blasted out as jets of particles traveling at speeds approaching light. When that happens, the phenomenon is a called a quasar.

The violent conditions of these events make AGNs and quasars the brightest objects in the universe, often luminous enough to outshine the combined light of every star in the galaxies around them. Our theoretical understanding of supermassive black holes has burgeoned since the Event Horizon Telescope (EHT) revealed the first image of a black hole, the supermassive black hole at the heart of the galaxy Messier 87 (M87), in 2019.

And the JWST's Cycle 3 missions will further contribute to this knowledge.

The JWST Cycle 3 supermassive black hole observation programs include the investigation of quasars in the early universe and the nature of the first black holes. Scientists hope to understand how those black holes may have influenced the growth of galaxies over billions of years.

The JWST's observations of supermassive black holes in the early universe could also reveal how these cosmic titans grew to the tremendous masses scientists observe — before the universe was even 1 billion years old. Such a question can be answered by using MIRI to investigate if a giant molecular cloud that existed around 13.2 billion years ago could have directly collapsed, birthing a "heavy black hole seed" that would account for a rapid growth mechanism.

Xavier Calmet is a researcher at the University of Sussex who investigates the intersection between black holes and quantum mechanics. He told Space.com he is particularly excited to see the JWST focusing on supermassive black holes and AGNS.

"The JWST Cycle 3 projects are very exciting," Calmet explained. "Given my own research interests, I am particularly eager to see what we will learn about black holes."

The James Webb Space Telescope goes big

One of the primary roles of the JWST is investigating objects in the early universe. The powerful space telescope has this capacity because the expansion of the universe stretches wavelengths of light from distant objects as this light travels toward us, moving the wavelengths toward the "red end" of the electromagnetic spectrum.

The longer that light has traveled to reach us, the more redshifted the light has become. This means light that has been traveling for around 12 billion years is extremely redshifted, all the way into the infrared region of the electromagnetic spectrum and outside the visible range we can see with the unaided eye. Effectively, infrared light is invisible to us. The JWST, however, is capable of observing this infrared light and thus helps to investigate the first stars and earliest galaxies, something it will continue to do in 2025 with several Cycle 3 GO projects.

Luz Angela Garcia is a cosmologist at the Universidad ECCI in Columbia who focuses on how dark energy expands the cosmos at an accelerating rate, which in turn helps with investigations regarding the universe's evolution. She is particularly enthusiastic about GO projects that will look at an era of cosmic evolution called the epoch of reionization, which occurred around 500 million years after the Big Bang.

During this period, neutral atoms of hydrogen populating the cosmos were ionized by radiation that stripped away their electrons and left them as ionized hydrogen, or hydrogen ions. Studying high-redshift galaxies can reveal more about this crucial stage in cosmic evolution, including how the first galaxies acted as the source of this ionizing radiation.

"Some of the proposals that catch my interest are 'Understanding galaxy formation at cosmic dawn,' 'Galactic Winds in the Early Universe' and 'Dead or alive? Unveiling the nature of massive galaxies in the early Universe,'" Garcia told Space.com. "All of these accepted projects seek to identify and characterize galaxies that are the drivers of the epoch of reionization.

"Most of these proposals focus on studying the properties of the first galaxies in the universe — very high-redshift systems that need spectroscopic confirmation."

This is just the tip of the celestial iceberg when it comes to the range of topics Cycle 3 GO projects will cover. Between 2024 and 2025, astronomers will also train telescopes on distant stars to better understand stellar physics and populations, as well as examine the gas that exists between stars that can become the building blocks of the next generation of stars and planets. Though the JWST was designed with the study of distant objects in mind, Cycle 3 will also see the observatory used to study bodies within our own solar system. These will include hunting for the source of gas plumes coming from Saturn's moon Enceladus, investigating the dynamics of the Uranus' rings and characterizing icy objects that exist in the Kuiper Belt at the very edge of the solar system.

Looking beyond JWST Cycle 3, the call for Cycle 4 GO proposals will go out on August 1, 2024, with a deadline set for Oct. 16 this year. The Cycle 4 Telescope Allocation Committee (TAC) review will run between Feb. 3 and Feb.12, 2025, with selections revealed around March 5 next year. JWST Cycle 4 GO programs will then begin making observations of the cosmos on July 1, 2025.

A full list of accepted Cycle 3 JWST programs is available on the STScI website. 

Originally posted on Space.com.

Our universe is expanding at an ever-accelerating rate — a phenomenon that all theories of cosmology agree upon but none can fully explain. Now, a new theoretical study offers an intriguing solution: Perhaps our universe is expanding because it keeps colliding with and absorbing "baby" parallel universes.

Studies of the cosmic microwave background, the afterglow of the Big Bang, have revealed that our universe is experiencing accelerated expansion. For this observation to fit with  the main theory of cosmic evolution — called the Standard Cosmological Model — physicists assume that the universe is filled with an enigmatic substance dubbed dark energy that drives the expansion.

But this elusive form of energy does not manifest itself in any other way, leading many astrophysicists to question its existence and explore the possibility of an alternative cause for the universe's expansion.

In a new study published Dec. 12, 2023 in the Journal of Cosmology and Astroparticle Physics, scientists proposed the idea that the expansion of the universe may be driven instead by constantly merging with other universes.

"The main finding of our work is that the accelerated expansion of our universe, caused by the mysterious dark energy, might have a simple intuitive explanation, the merging with so-called baby universes, and that a model for this might fit the data better than the standard cosmological model," lead study author Jan Ambjørn, a physicist at the Copenhagen University told LiveScience in an email.

Swallowing cosmic 'babies'

While the idea of multiple universes interacting with ours isn't new, this study develops a mathematical model to explore the hypothetical impact of this on the evolution of our universe. The researchers' calculations showed that merging with other universes should increase the volume of our universe, which could be perceived by our instruments as an expansion of the universe.

The scientists also computed the rate of expansion of the universe using their theory, and their calculations more closely fit with observations of the universe than the traditional Standard Cosmological Model, the researchers said.

Related: After 2 years in space, the James Webb telescope has broken cosmology. Can it be fixed?

The authors' theory also addresses  the problem of cosmological inflation — the mysterious super-rapid expansion that occurred in the early moments of the universe.

Physicists have previously proposed that this expansion was caused by "the inflaton" — a hypothetical field that drove ultra-rapid expansion in the first milliseconds after the Big Bang. But in the new study, the authors suggest this super-rapid early expansion could have been caused by our young universe being absorbed by a larger universe.

"The fact that the Universe has expanded … in a very short time, invites the suggestion that this expansion was caused by a collision with a larger universe, [that is] it was really our Universe which was absorbed in another 'parent' universe," the researchers wrote in their paper. "Since we have presently no detailed description of the absorption process, it is difficult to judge if such a scenario could take place in a way that would actually solve the problems inflation was designed to solve, but one interesting aspect of such a scenario is that there is no need for an inflaton field."

The scientists suggested that, after being absorbed, our newly enlarged universe then continued to collide with other “baby universes”  and incorporate them as well.

Although the authors' theory enables us to solve some important problems of modern cosmology, only observational data can validate their hypothesis. Many experiments are currently being carried out to study the properties of the microwave background, so scientists may be able to answer these fundamental questions in the near future.

"Our late time expansion of the Universe is different from the standard cosmological predictions and we believe that observations from the Euclid telescope and the James Webb telescope will settle which model is best describing the present time expansion of our Universe," Yoshiyuki Watabiki, a physicist at the Tokyo Institute of Technology, told Live Science.

A survey of more than 25 million galaxies has found a strange contradiction in how astronomers measure the universe's clumpiness, and it could threaten the standard model of cosmology, which describes how the universe formed and evolved.

The discrepancy, found by measuring the warping of light by the powerful gravitational fields of distant galaxies, suggests that the cosmos is less packed-together than previously predicted.

If the measurement is accurate, it will join the Hubble tension as yet another significant challenge to our preconceptions of how the cosmos evolved — one that could give way to new physics or even an entirely different model of the universe. The researchers published their findings Dec. 11 in the journal Physical Review D.

Related: After 2 years in space, the James Webb telescope has broken cosmology. Can it be fixed?

"We're still being fairly cautious here," Michael Strauss, chair of Princeton University's Department of Astrophysical Sciences and one of the leaders of the team that made the discovery, said in a statement. "We're not saying that we've just discovered that modern cosmology is all wrong. The statistics show that there's only a one in 20 chance that it's just due to chance, which is compelling but not completely definitive. But as we in the astronomy community come to the same conclusion over multiple experiments, as we keep on doing these measurements, perhaps we're finding that it's real."

According to the standard model of cosmology, after the Big Bang the young cosmos was a roiling plasma broth that began to rapidly expand due to an invisible force known as dark energy. As the universe grew, ordinary matter, which interacts with light, congealed around clumps of invisible dark matter to create the first galaxies, connected together by a vast cosmic web. Nowadays, cosmologists think that ordinary matter, dark matter and dark energy make up about 5%, 25% and 70% of the universe, respectively.

Yet there are growing problems with this picture. To test their models, astronomers often compare the past to the present universe. Their past measurements are drawn from the cosmic microwave background (CMB), the static fizz of the universe's first light that left its source (recombining atoms) 380,000 years after the Big Bang. 

Yet the Hubble constant — a value that tracks the expansion rate of the universe — predicted from the CMB disagreed with the calculations derived from celestial objects in the contemporary cosmos. This discrepancy has led to a crisis in cosmology known as the Hubble tension.

The new discrepancy about the lumpiness of the universe centers around a number called S8, which measures how much matter clusters, or clumps together, across the universe. After using the Planck satellite to study the cosmic microwave background (CMB), astronomers previously plugged the data into the standard model of cosmology and got a predicted value for S8 of 0.83. 

This clashes with a new measurement of S8 using Japan's Subaru Telescope, which studied how much light is warped by the presence of matter in galaxies. Researchers took its results and produced a smaller value for S8 of 0.77. The new result was replicated by two other collaborations mapping the universe's matter with gravitational lensing — the Dark Energy Survey and the Kilo-Degree Survey — making an individual anomalous result unlikely.

"We're confirming a growing sense in the community that there is a real discrepancy between the measurement of clumping in the early universe (measured from the CMB) and that from the era of galaxies, 'only' 9 billion years ago," Arun Kannawadi, an associate research scholar at Princeton University who was involved in the analysis, said in the statement.

Though the problem points to yet another large hole in our understanding of the universe, cosmologists don't have great ways to fill it yet. It's possible that cosmologists are wrong about the amount of dark matter in the universe, or how it clumps together. Maybe dark energy changed over the course of the universe's life — an explanation that would resolve both the S8 and the Hubble tension with a tweak to the standard model of cosmology.

Or perhaps, most excitingly of all, it could mean that the standard model is broken and needs a total replacement. For scientists to know for certain, they will make more precise measurements from even more powerful telescopes. Two such contenders are the Vera C. Rubin Observatory in Chile and the Nancy Grace Roman Space Telescope, which are due to come online in 2025 and 2027, respectively.

Something is awry in our expanding cosmos.

Nearly a century ago, the astronomer Edwin Hubble discovered the balloon-like inflation of the universe and the accelerating rush of all galaxies away from each other. Following that expansion backward in time led to our current best understanding of how everything began — the Big Bang.

But over the past decade, an alarming hole has been growing in this picture: Depending on where astronomers look, the rate of the universe's expansion (a value called the Hubble constant) varies significantly.

Related: 'It could be profound': How astronomer Wendy Freedman is trying to fix the universe

Now, on the second anniversary of its launch, the James Webb Space Telescope (JWST) has cemented the discrepancy with stunningly precise new observations that threaten to upend the standard model of cosmology.

The new physics needed to modify or even replace the 40-year-old theory is now a topic of debate.

"It's a disagreement that has to make us wonder if we really do understand the composition of the universe and the physics of the universe," Adam Riess, a professor of astronomy at Johns Hopkins University who led the team that made the new JWST measurements, told Live Science. Reiss, Saul Perlmutter and Brian P. Schmidt won the 2011 Nobel Prize in physics for their 1998 discovery of dark energy, the mysterious force behind the universe's accelerating expansion.

Starting with a bang

On this much cosmologists can agree: It started with a bang.

Then in an instant, the young cosmos was formed: an expanding, roiling plasma broth of matter and antimatter particles that popped into existence, only to annihilate each other upon contact.

Left to their own devices, the matter and antimatter inside this plasma mire should have consumed each other entirely. But scientists believe that some unknown imbalance enabled more matter than antimatter to be produced, saving the universe from immediate self-destruction.

Gravity compressed the plasma pockets, squeezing and heating the matter so that sound waves traveling just over half the speed of light, called baryon acoustic oscillations, rippled across their surface.

Meanwhile, the high energy density of the early universe's crowded contents stretched space-time, pulling a small fraction of this matter safely from the fray.

As the universe inflated like a balloon, the standard story goes, ordinary matter (which interacts with light) congealed around clumps of invisible dark matter to create the first galaxies, connected together by a vast cosmic web.

Related: James Webb telescope detects the earliest strand in the 'cosmic web' ever seen

Initially as the universe's contents spread out, its energy density and therefore its expansion rate decreased. But then, roughly 5 billion years ago, galaxies began to recede once more at an ever-faster rate.

The cause, according to this picture, was another invisible and mysterious entity known as dark energy.

The simplest and most popular explanation for dark energy is that it is a cosmological constant — an inflationary energy that is the same everywhere and at every moment; woven into the stretching fabric of space-time. Einstein named it lambda in his theory of general relativity.

As our cosmos grew, its overall matter density dropped while the dark energy density remained the same, gradually making the latter the biggest contributor to its overall expansion.

Added together the energy densities of ordinary matter, dark matter, dark energy and energy from light set the upper speed limit of the universe's expansion. They are also key ingredients in the Lambda cold dark matter (Lambda-CDM) model of cosmology, which maps the growth of the cosmos and predicts its end — with matter eventually spread so thin it experiences a heat death called the Big Freeze.

Many of the model's predictions have been proven to be highly accurate, but here's where the problems begin: despite much searching, astronomers have no clue what dark matter or dark energy are.

"Most people agree that the universe's present composition is 5% ordinary, atomic matter; 25% cold, dark matter; and 70% dark energy," Ofer Lahav, a professor of astronomy at University College London who is involved in galaxy surveys of dark energy, told Live Science. "The embarrassing fact is, we don't understand the last two of them."

But an even greater threat to Lambda-CDM has materialized: Depending on what method astrophysicists use, the universe appears to be growing at different rates — a disparity known as the Hubble tension. And methods that peer into the early universe show it expanding significantly faster than Lambda-CDM predicts. Those methods have been vetted and verified by countless observations.

"So the only reason that I can understand, at this point, for them to disagree is that the model that we have between them is perhaps missing something," Riess said.

Climbing the cosmic ladder

Measuring the universe's expansion takes a little bit more than a radar gun.

The first method to measure this growth looks at the so-called cosmic microwave background (CMB), a relic of the universe's first light produced just 380,000 years after the Big Bang. The imprint can be seen across the entire sky, and it was mapped to find a Hubble constant with less than 1% uncertainty by the European Space Agency's (ESA) Planck satellite between 2009 and 2013.

In this cosmic "baby picture," the universe is almost entirely uniform, but hotter and colder patches where matter is more or less dense reveal where baryon acoustic oscillations made it clump. As the universe exploded outward, this soap-bubble structure ballooned into the cosmic web — a network of crisscrossing strands along whose intersections galaxies would be born.

Related: $100,000 Breakthrough physics prize awarded to 3 scientists who study the large scale structure of the universe

By studying these ripples with the Planck satellite, cosmologists inferred the amounts of regular matter and dark matter and a value for the cosmological constant, or dark energy. Plugging these into the Lambda-CDM model spat out a Hubble constant of roughly 46,200 mph per million light-years, or roughly 67 kilometers per second per megaparsec. (A megaparsec is 3.26 million light-years.)

Let's pause on this number for a moment: if a galaxy is at a distance of one megaparsec away from us, that means it will retreat from us (and us from it) at 67 kilometers per second. At twenty megaparsecs this recession grows to 1,340 kilometers per second, and continues to grow exponentially there onward. If a galaxy is any further than 4,475 megaparsecs away, it will recede from us faster than the speed of light.

A second method to find this expansion rate uses pulsating stars called Cepheid variables — dying stars with helium-gas outer layers that grow and shrink as they absorb and release the star's radiation, making them periodically flicker like distant signal lamps.

In 1912, astronomer Henrietta Swan Leavitt found that the brighter a Cepheid was, the slower it would flicker, enabling astronomers to measure a star's absolute brightness, and therefore gauge its distance.

It was a landmark discovery that transformed Cepheids into abundant "standard candles" to measure the universe's immense scale. By stringing observations of pulsating Cepheids together, astronomers can construct cosmic distance ladders, with each rung taking them a step back into the past.

"It's one of the most accurate means that astronomers have today for measuring distances," Wendy Freedman, an astrophysicist at the University of Chicago, told Live Science.

To build a distance ladder, astronomers construct the first rung by choosing nearby Cepheids and cross-checking their distance based on pulsating light to that found by geometry. The next rungs are added using Cepheid readings alone.

Then, astronomers look at the distances of the stars and supernovas on each rung and compare how much their light has been redshifted (stretched out to longer, redder wavelengths) as the universe expands.

This gives a precise measurement of the Hubble constant. In 2019, the method was used by Riess and his collaborators, who trained the Hubble Space Telescope on one of the Milky Way's closest neighbors, the Large Magellanic Cloud.

Their result was explosive: an impossibly high expansion rate of 74 km/s/Mpc when compared to the Planck measurement.

Yet Hubble lacked the necessary precision for the crowded regions of space the team was studying, causing some distant Cepheids to blur into neighboring stars. Dissenting cosmologists had some room left to argue that the result, however shocking, could have come from a measurement error.

Related: Hubble Telescope captures a galaxy's 'forbidden' light in stunning new image

So when JWST launched in December 2021, it was poised to either resolve the discrepancy or cement it. At 21.3 feet (6.5 m) wide, JWST's mirror is almost three times the size of Hubble's, which is just 7.9 feet (2.4 m) wide. Not only can JWST detect objects 100 times fainter than Hubble can, but it is also far more sensitive in the infrared spectrum, enabling it to see in a broader range of wavelengths.

By comparing Cepheids measured by JWST in the galaxy NGC 4258 with bright Type Ia supernovas (another standard candle because they all burst at the same absolute luminosity) in remote galaxies, Riess and his colleagues arrived at a nearly identical result: 73 km/s/Mpc.

Other measurements — including one made by Freedman with the Hubble Space telescope on the rapid brightening of the most luminous "tip of the branch" red giant stars, and another with light bent by the gravity of massive galaxies — came back with respective results of 69.6 and 66.6 km/s/Mpc. A separate result using the bending of light also gave a value of 73 km/s/Mpc. Cosmologists were left reeling.

"The CMB temperature is measured at the level of 1% precision, and the Cepheid distance ladder measurement is getting close to 1%," Ryan Keeley, a cosmologist at the University of California, Merced who has been working to explain the Hubble tension, told Live Science. "So a difference of 7 kilometers per second, even though it's not very much, is very, very unlikely to be a random chance. There is something definite to explain."

Cosmology in crisis

The new result leaves the answer wide open, splitting cosmologists into factions chasing staggeringly different solutions. Following the Hubble Space telescope result, an official attempt to resolve the issue at a 2019 conference at the Kavli Institute for Theoretical Physics (KITP) in California only caused more frustration.

"We wouldn't call it a tension or problem, but rather a crisis," David Gross, former director of the KITP and a Nobel laureate, said at the conference.

How things can be fixed is unclear. Riess is pursuing a tweak to the Lambda-CDM model that assumes dark energy (the lambda) isn't constant but instead evolves across the life of the cosmos according to unknown physics.

However Keeley's research, published Sept. 15 in the journal Physical Review Letters, contradicts this. He and his colleagues found that the expansion rates matched the predictions of Lambda-CDM all the way back to the CMB. So, if the model needs fixing anywhere, it's most likely in the very early universe, Keeley said.

It could be possible to add some extra dark energy before the emergence of the cosmic microwave background, Keeley said, giving some additional oomph to the universe’s expansion that needn't make it break from the standard model.

Another group of astronomers is convinced that the tension, alongside the observation that the Milky Way resides inside an underdense supervoid, means that Lambda-CDM and dark matter must be thrown out altogether.

What should replace it, according to Pavel Kroupa, a professor of astrophysics at the University of Bonn, is a theory called Modified Newtonian Dynamics (MOND).

The theory proposes that for gravitational pulls ten trillion times smaller than those felt on Earth's surface (such as the tugs felt between distant galaxies) Newton's laws break down and must be replaced by other equations.

Other astronomers say that their own calculations nix the MOND claims, yet Kroupa insists that cosmologists looking to tweak the standard cosmological model are "basically adding additional complications to an already very messy and complicated theory."

"What I am experiencing and witnessing is an essential breakdown of science," Kroupa said.

Lahav is agnostic. It's possible Lambda-CDM just needs a tweak, he said, or maybe dark matter and dark energy are the modern-day equivalent of epicycles, the small circles ancient Greek astronomers used to model planets orbiting Earth. "The orbits of planets were described very accurately by epicycles," Lahav said. "It was a good model! It fitted the data."

But once astronomers placed the sun in the center of the solar system in newer models, epicycles eventually became irrelevant, he added.

"If we want to go philosophical, maybe that's what's going on," Lahav said. "But maybe also there is dark matter and dark energy and it's just not been discovered yet."

Cosmologists are looking for answers in a number of places. Upcoming CMB experiments, such as the CMB-S4 project at the South Pole and the Simons Observatory in Chile, are searching for clues in ultraprecise measurements of the early universe's radiation. Others will look to the dark matter maps produced by ESA's Euclid space telescope or to the future dark energy survey conducted by the Dark Energy Spectroscopic Instrument.

Although it now may seem less likely, it's also still possible the Hubble tension could be resolved by figuring out some unseen systematic flaw hiding inside current measurements.

For Freedman, such a solution, or possibly further riddles, will come from the JWST. Her team is using the telescope’s powerful eye to make ultradetailed measurements of Cepheid variables; tip-of-the-red-giant-branch stars; and a type of carbon star called JAGB stars all at once distance.

"We'll see how well they agree and that will give us a sense of an overall systematic answer," Freedman said.

Freedman has looked only at stars in one galaxy so far but is already seeing a difference from the Hubble space telescope measurements.

"I'm really excited because I think we're going to have something really interesting to say," Freedman said. "I'm just completely open. I don't know where this is going to fall."

The first images from the Euclid space telescope have been revealed, and they are stunning.

The European Space Agency (ESA) telescope, which launched on July 1 on a SpaceX Falcon 9 rocket, is designed to explore the composition and evolution of the "dark universe"  —  the collective name given to dark matter and dark energy.

This is one of the most pressing issues in modern cosmology: Together, dark matter and dark energy comprise around 95% of the "stuff" in the universe, yet scientists can't see them and have very little idea what they actually are. Dark matter and dark energy also play a significant role in the evolution and structure of the visible 5% of the universe  —  such as stars, planets, galaxies and even our bodies.

"Dark matter pulls galaxies together and causes them to spin more rapidly than visible matter alone can account for; dark energy is driving the accelerated expansion of the universe," Carole Mundell, ESA's director of science, said in a statement. "Euclid will, for the first time, allow cosmologists to study these competing dark mysteries together."

"Euclid will make a leap in our understanding of the cosmos as a whole, and these exquisite Euclid images show that the mission is ready to help answer one of the greatest mysteries of modern physics," Mundell added.

Related: Dark energy could lead to a second (and third, and fourth) Big Bang, new research suggests

These first images show that Euclid, located at a gravitationally stable point between Earth and the sun about 1 million miles (1.5 million kilometers) from our planet, is off to an excellent start.

The Perseus galaxy cluster

The first image released from the Euclid telescope features 1,000 galaxies that are part of the Perseus cluster, located around 240 million light-years from Earth. In the background of the image are a further 100,000 galaxies located at even greater distances.

Many of these galaxies have never been seen before, and some are so far away that their light has traveled for around 10 billion years to reach us.

This is the first time so many Perseus galaxies have been spotted in great detail and in the same image. Mapping the distribution and shape of these galaxies could help scientists determine the role of dark matter in sculpting that part of the universe.

The "hidden" spiral galaxy IC 342

The next Euclid image features the spiral galaxy IC 342, also known as the "Hidden Galaxy" or Caldwell 5.

IC 342, located around 10.8 million light-years away, is tough to spot because it is hidden behind stars, gas and dust in the plane of the Milky Way. Using its near-infrared instrument, Euclid peered through these obstructions to reveal previously unseen details of IC 342's steller occupants.

The irregular galaxy NGC 6822

As Euclid looks deeper into the cosmos and further back in the history of the universe, neat spiral galaxies like our own and IC 342 should become less common, and instead irregular, blob-like galaxies should appear more often.

Euclid's third recently released image shows just such an irregular galaxy, NGC 6822 — but this blobby galaxy is located just 1.6 million light years from Earth.

The globular cluster NGC 6397

In another stunning image from the space telescope, a globular cluster — a tightly gravitationally bound collection of hundreds or even thousands of stars — is captured in breathtaking detail.

This particular globular cluster, NGC 6397, is located around 7,800 light-years from Earth, making it the second-closest globular cluster to our planet. Euclid will shed new light on globular clusters, as it is the only current telescope able to observe every star in such a collection in fine detail. This could help scientists map the distribution of dark matter through the Milky Way as the development of these clusters is molded by the gravitational influence of dark matter.

The Horsehead Nebula

In perhaps the most colorful image from Euclid's first set of observations, the Horsehead Nebula is shown in vibrant detail. Also known as Barnard 33, the nebula is a stellar nursery of hot, young stars located in the Orion Nebula — which at between 1,500 and 1,350 light-years away is the closest star-forming region to Earth.

Alongside its work studying the dark universe, Euclid will search regions like this for Jupiter-mass planets, young "failed star" brown dwarfs and infant stars.

"We have never seen astronomical images like this before, containing so much detail," René Laureijs, ESA's Euclid project scientist, said in the statement. "They are even more beautiful and sharp than we could have hoped for, showing us many previously unseen features in well-known areas of the nearby universe. Now we are ready to observe billions of galaxies and study their evolution over cosmic time."

Over the next six years, Euclid will investigate the dark universe by creating a map of the large-scale structure of the universe, observing billions of galaxies out to a distance of around 10 billion light-years and across over a third of the sky over Earth. This should reveal the changing structure of the universe through cosmic history, enabling scientists to determine the role dark matter and dark energy have played in this process.

Hopefully, the best is yet to come for Euclid as it helps to unravel some of the most pressing mysteries in physics and helps us see the cosmos in new detail.

We see countless stars and galaxies sparkling in the universe today, but how much matter is actually there? The question is simple enough — its answer, however, is turning out to be quite a head-scratcher. 

This dilemma exists largely because current cosmological observations simply disagree on how matter is distributed in the present-day universe.

Of some help could be a new computer simulation that traces how all elements of the universe — ordinary matter, dark matter and dark energy — evolve according to the laws of physics. The breathtaking visuals virtually show galaxies, and clusters of galaxies, manifesting in the universe, fed by the so-called cosmic web. This web is the largest structure in the universe, built with filaments made up of both normal matter, or baryonic matter, and dark matter.

Unlike previous simulations that only considered dark matter, the new work, carried out by a project called FLAMINGO (short for Full-hydro Large-scale structure simulations with All-sky Mapping for the Interpretation of Next Generation Observations), tracks ordinary matter too.

"Although the dark matter dominates gravity, the contribution of ordinary matter can no longer be neglected," Joop Schaye, a professor at Leiden University in the Netherlands and a co-author of the three new studies on the FLAMINGO project, said in a statement.

As for how much matter the universe really contains, astronomers say computer simulations like this one are not just great cosmic eye candy but also important probes to help pin down the cause of a major discrepancy in cosmology called the "S8 tension." That's the debate over how matter in the cosmos is distributed.

What is the S8 tension?

When investigating the universe, astronomers sometimes work with what's known as the S8 parameter. This parameter basically characterizes how "lumpy," or strongly clustered, all the matter in our universe is, and can be measured precisely with what are known as low-redshift observations. Astronomers use redshift to measure how far an object is from Earth, and low-redshift studies like "weak gravitational lensing surveys" can illuminate processes unfolding in the distant, and therefore older, universe. 

But S8's value can also be predicted using the standard model of cosmology; scientists can essentially tune the model to match known properties of the cosmic microwave background (CMB), which is the radiation leftover from the Big Bang, and calculate the lumpiness of matter from there. 

So, here's the thing. 

Those CMB experiments find a higher S8 value than the weak gravitational lensing surveys. And cosmologists don't know why — they call this discrepancy the S8 tension.

In fact, S8 tension is a brewing crisis in cosmology slightly different from its famous cousin: Hubble tension, which refers to the inconsistencies scientists face in pinning down the rate of expansion of the universe.

The reason it's a big deal that the team's new simulation doesn't offer an answer to S8 tension is, unlike previous simulations that only considered the effects of dark matter on an evolving universe, the latest work takes into account the effects of ordinary matter too. In contrast to dark matter, ordinary matter is governed by gravity as well as pressure from gas across the universe. For example, galactic winds driven by supernova explosions and actively accreting supermassive black holes are crucial processes that redistribute ordinary matter by blowing its particles out into intergalactic space.

However, even the new work's consideration of ordinary matter as well as some of the most extreme galactic winds was not sufficient to explain the weak clumping of matter observed in the present-day universe.

"Here I am at a loss," Schaye told Space.com. "An exciting possibility is that the tension is pointing to shortcomings in the standard model of cosmology, or even the standard model of physics."

Exotic physics or a flawed model?

So, where did this S8 tension originate?

"We don't know, which is what makes this so exciting," Ian McCarthy, a theoretical astrophysicist at Liverpool John Moores University in the U.K. and the co-author of three new studies, told Space.com.

Computer simulations, however, like those carried out by FLAMINGO could be bringing us a step closer. They may help reveal the cause of S8 tension because a grand, virtual map of the cosmos might assist with identifying possible errors in our current measurements. For example, astronomers are slowly ruling out more mundane explanations for the issue, such as the fact it could be due to general uncertainties in observations of large-scale structures or related to a problem with the CMB itself. 

In reality, the team speculates, perhaps the effects of normal matter are a lot stronger than in current simulations. That too seems unlikely though, as simulations agree very well with observed properties of galaxies and galaxy clusters.

"All of these possibilities are extremely exciting and have important implications for fundamental physics and cosmology," said McCarthy. The most exciting possibility, however, "is the Standard Model is incorrect in some way."

For example, dark matter could have exotic self-interacting properties not considered in the standard model — the S8 tension may be signaling a breakdown of our theory of gravity on the largest scales, McCarthy said.

Nonetheless, while the latest simulations track effects of normal matter and subatomic particles known as neutrinos — both of which are found to be important to make accurate predictions of how galaxies evolve across eons — they did not resolve the S8 tension.

Here's the ultimate head-scratcher: At low-redshifts, the universe is significantly less lumpy than predicted by the standard model. But measurements that probe structures of the universe between the CMB and low-redshift measurements are "fully consistent with standard model predictions," McCarthy said. "It seems the universe behaved as expected for a significant fraction of cosmic history, but that something changed later on in cosmic history."

Maybe the key to resolving the S8 tension lies in the answer to what, exactly, drove that change.

This research is described in three papers published in the journal Monthly Notices of the Royal Astronomical Society.

Originally posted on Space.com.

Astronomers have long assumed that two black holes that circle close to each other are always destined to become one in a cataclysmic merger that spans eons.

That needn't always be the case, new research finds.

In a new study, physicists found that it is theoretically possible for two black holes to remain at a fixed distance from each other, thanks to their mutual gravitational pull being perfectly counterbalanced by the speed at which the universe is expanding.

"Viewed from a distance, a pair of black holes whose attraction is offset by cosmic expansion would look like a single black hole," study co-author Óscar Dias, a physicist at the University of Southampton in the U.K., said in a statement. "It might be hard to detect whether it is a single black hole or a pair of them."

Related: Newly discovered black hole 'speed limit' hints at new laws of physics

The team reported their findings Sept. 25 in the journal Physical Review Letters. They demonstrate that two black holes could be delicately balanced, despite conventional theories predicting otherwise, by pointing out "a logical inconsistency in the proof of one theorem and a limiting assumption in another," Toby Wiseman, a professor of theoretical physics at Imperial College London who was not involved with the new work, said in a different statement.

One of the key assumptions in those theorems is that the region around black hole pairs is empty. However, according to the standard model of cosmology — our current best description of the universe — dark energy causes the universe to expand at an accelerated rate. This dark energy is sometimes considered equivalent to the puzzling cosmological constant in the theory of general relativity.

In the new study, Días and colleagues show that two black holes can be positioned such that their mutual gravitational attraction is offset by acceleration due to the cosmological constant. "If these black holes are set up in precisely the correct way, they sit in an unstable equilibrium, akin to a pen balanced on its pointed end," Wiseman said. "Any disturbance will ruin this perfect balance."

Physicists say that wobbly balance could be made more stable when black holes are rotating. For instance, the gravitational attraction of two such identical black holes rotating in opposite directions could be balanced by their spins, although this possibility is yet to be proved.

The study only considered a pair of static black holes, so follow-up studies should address how stable spinning black holes could be.

"Our theory is proven for a pair of static black holes, but we believe it could be applied to spinning ones too," said study co-author Jorge Santos, a professor of theoretical physics at the University of Cambridge in England. "Also, it seems plausible that our solution could hold true for three or even four black holes, opening up a whole range of possibilities."

The European Space Agency's (ESA) dark universe detective, the Euclid spacecraft, is on track after locating its guiding stars, which it lost as a result of cosmic misidentification.

The satellite can now begin investigating dark matter and dark energy, which are some of the greatest mysteries in cosmology. Dark matter accounts for 85% of the matter in the universe but is effectively invisible, and dark energy causes the cosmos to expand at an ever-increasing rate.

Euclid launched to investigate these cosmological mysteries, sometimes collectively known as the dark universe, on July 1 and took a four-week journey to Lagrange point 2, a gravitationally stable point in the Earth-sun system. Although Euclid reached its destination safely, its operators noticed a problem after the spacecraft took its first incredible images of the cosmos: Euclid's Fine Guidance Sensor was having trouble finding its guiding stars, which Euclid uses for navigation. 

The cause of this issue was cosmic rays  —  charged particles that the sun emits during periods of high solar activity. The cosmic rays were impacting the Fine Guidance Sensor, creating signals that Euclid was incorrectly identifying as stars. In addition, stray light from the sun and solar X-rays were interfering with the spacecraft. As a result, artifacts caused by this interference occasionally outnumbered the real stars being spotted by Euclid, meaning the spacecraft couldn't resolve the star patterns it needed to navigate. 

A striking example of the effect of this hiccup on Euclid's operations is an image of a distant star field that shows strange loops and lassos, reminiscent of a child's doodles (shown above). Although beautiful, these doodles aren't helpful in the search for the subtle patterns in distant galaxies and star clusters that could reveal clues about dark energy and dark matter.

Ironing out Euclid's teething troubles

These types of glitches are often experienced during the initial phase of a spacecraft's operations, known as the commissioning phase. Teams at ESA mission control have been working around the clock to better equip the craft for its space-based environment.

The mission team created a software patch that was first applied to an electric model of Euclid here on Earth before being tested on the real thing at Lagrange point 2, which is   around 1 million miles (1.5 million kilometers) from home, ESA officials said in a statement. After being updated and undergoing 10 days of testing in orbit, the Fine Guidance Sensor is working as intended, and Euclid's guide stars have once again been located.

"Our industrial partners  —  Thales Alenia Space and Leonardo  —  went back to the drawing board and revised the way the Fine Guidance Sensor identifies stars," Micha Schmidt, Euclid spacecraft operations manager, said in the statement. "After a major effort and in record time, we were provided with new on-board software to be installed on the spacecraft. We carefully tested the software update step by step under real flight conditions, with realistic input from the Science Operations Centre for observation targets."

Euclid is now ready to restart its all-important performance verification phase,  which was interrupted in August ,  during which final testing will be performed.

"The performance verification phase that was interrupted in August has now fully restarted, and all the observations are carried out correctly," Giuseppe Racca, Euclid project manager, said in the statement. "This phase will last until late November, but we are confident that the mission performance will prove to be outstanding and the regular scientific survey observations can start thereafter."

This is the last step before Euclid can start investigating the dark universe. Euclid will do this by examining around a third of the sky over Earth and by looking back over 10 billion years of cosmic history, mapping 3D models of galaxies to see how the 13.8 billion-year-old universe has taken shape and what role dark matter has played in this evolution. Euclid will also look at large-scale galactic disturbance to see the influence of dark energy as it pushes galaxies apart faster and faster.

"Now comes the exciting phase of testing Euclid in science-like conditions, and we are looking forward to its first images showcasing how this mission will revolutionize our understanding of the dark universe," Carole Mundell, ESA's director of science, said in the statement.

Originally posted on Space.com.

Dark energy is the name given to a mysterious force accelerating the universe's expansion. NASA estimates that dark energy makes up 68% of the universe, but while physicists can tell dark energy is real, they don't know much about it. 

At Live Science, our expert writers and editors explain the latest findings from researchers studying this strange force. Whether it’s  why dark energy could lead to a second (and third, and fourth) Big Bang, how the largest dark energy map could reveal the fate of the universe or if the expansion of the universe could be a mirage, you’ll find  the latest dark energy news, features and articles right here.  

Update: This article was updated on May 23, 2024, with new information and images about Euclid's first science observations.

The European Space Agency's (ESA) Euclid space telescope successfully blasted off from Cape Canaveral, Florida, on July 1, 2023 and shared its first scientific observations on May 23, 2024.  The groundbreaking space telescope will hunt for clues about two of the universe's greatest mysteries: dark matter and dark energy.

Despite making up an estimated 95% of the universe, dark matter and dark energy cannot be detected directly. Instead, scientists observe them in the gravitational warping effects seen in many galaxies across the universe.  Euclid's enormous field of view will significantly expand this search for warped space-time.

Here's everything you need to know about Euclid and its search for the universe's most mysterious components.

What is Euclid?

Named after the ancient Greek mathematician who's considered the "father of geometry," Euclid is a space telescope that is 14.7 feet (4.5 meters) tall and 10.2 feet (3.1 m) in diameter. The telescope is mounted with just two instruments: a near-infrared camera that will measure the distance and brightness of galaxies, and a visible-light camera that will study their shapes.

Taken on their own, Euclid's cameras are common among space telescopes. What makes Euclid groundbreaking is these instruments' field of view, with a third of the entire night sky and over a billion galaxies expected to be cataloged by the time the telescope has finished its planned six years of scanning. The telescope should be able to peer up to 10 billion years into the past — slightly less than the James Webb Space Telescope, which has looked back more than 13 billion years.

Related: 35 jaw-dropping James Webb Space Telescope images

First science observations

On May 23, 2024, ESA shared five images taken during Euclid's first 24 hours of science operations.

The stunning images include the most detailed-ever look at the Messier 78 star-forming region (above), located 1,300 light-years away within the constellation Orion. The vibrant image reveals more than 300,000 previously unknown objects in the region, including newborn stars, and mysterious "runaway" rogue planets ejected from their star systems.

The first crop of science observations also include detailed views of the massive spiral galaxy NGC 6744, the chaotic Dorado Group of colliding galaxies, and the gargantuan galaxy clusters Abell 2390 and Abell 2764. A map of Euclid's first 10 tagets, including its debut science images and five test images, can be seen below.

Euclid's debut images

On July 31, 2023, ESA shared the first images taken by Euclid to test the satellite's two main science instruments.

An image taken with Euclid's Near-Infrared Spectrometer and Photometer (NISP) revealed a dazzling starscape of billions of stars and galaxies. Before reaching the instrument's detector, light from the distant objects passed through a filter that splits the light of every star and galaxy according to wavelength, allowing astronomers to determine what each object is made of and, in turn, how far it is from Earth.

The researchers also tested Euclid's VISible instrument (VIS), to capture the cosmos in visible light (the same type of light that we can see with our unaided eyes). This dense starscape took Euclid 566 seconds to collect, according to ESA. Both test images are largely unprocessed, and only offer a hint at what Euclid will be capable of delivering when fully operational.

What will Euclid study?

Once Euclid's data has been collected, scientists will use it to create two maps of the universe. The first will detail the spread of dark matter across our universe by gravitational lensing, in which matter bends light from a distant source through curved paths in space-time, thus magnifying it.

The second will use so-called baryon acoustic oscillations, gigantic matter shock waves created when the universe was hot and now frozen in time, as cosmic tree rings to study the universe's accelerating growth and its suspected cause: dark energy.

What is dark matter?

Dark matter is a mysterious and somewhat contradictory type of matter. It makes up an overwhelming 85% of the universe's matter; yet, because it doesn't directly interact with light, it is completely invisible.

So how do we know dark matter is there? While dark matter itself is invisible, the gravitational interactions it has with its surroundings are not — making its presence apparent in its extreme gravitational warping of galaxies, or in how it accelerates stars to otherwise inexplicable speeds as they orbit galactic centers.

The composition of dark matter isn't known. Some theories suggest that hypothetical particles called weakly interacting massive particles (WIMPs), each weighing 10 to 100 times the mass of a proton, could be ideal candidates to fill the theoretical gaps. Others have proposed that a minuscule particle less than a billionth the size of an electron — called an axion — could be the substance's primary candidate.

What is dark energy?

Aside from a similar name, dark energy has little to do with dark matter. Dark energy is the name given to the enigmatic phenomenon of the universe's accelerating, runaway expansion — something that shouldn't be happening given the quantity of our universe's matter and the subsequent strength of its gravity. The answer cosmologists have offered is that some mysterious force in the fabric of the universe must be pushing everything outward.

NASA has estimated that 68% of the universe is composed of dark energy; 27% is dark matter, and visible matter makes up just 5%.

Scientists could soon test Einstein's theory of general relativity by measuring the distortion of time. 

According to new research published June 22 in the journal Nature Astronomy, the newly proposed method turns the edge of space and time into a vast cosmic lab to investigate if general relativity can account for dark matter — a mysterious, invisible form of matter that can only be inferred by its gravitational influence on the universe's visible matter and energy — as well as the accelerating expansion of the universe due to dark energy. The method is ready to be tested on future surveys of the deep universe, according to the study authors.

Related: The expansion of the universe could be a mirage, new theoretical study suggests

General relativity states that gravity is the result of mass warping the fabric of space and time, which Einstein lumped into a four-dimensional entity called space-time. According to relativity, time passes more slowly close to a massive object than it does in a mass-less vacuum. This change in the passing of time is called time distortion.

Since its introduction in 1915, general relativity has been tested extensively and has become our best description of gravity on tremendous scales. But scientists aren't yet sure if it can explain invisible dark matter and dark energy, which together account for around 95% of the energy and matter in the universe.

"Time distortion predicted by general relativity has already been measured very precisely at small distances," Camille Bonvin, lead study author and an associate professor at the University of Geneva, told Live Science via email. "It has been measured for planes flying around the Earth, for stars in our galaxy, and also for clusters of galaxies. We propose a method to measure the distortion of time at very large distances."

The method suggests testing time distortion by measuring redshift, the change in the frequency of light an object emits as it moves away from us. Bonvin said the difference here is that this technique measures redshift caused as light attempts to climb out of a gravitational well, a "dent" in space-time created by a massive object. 

"This climb changes the frequency of the light because time passes at different rates inside and outside of the gravitational well," she said. "As a consequence, the color of the light is changed; it is shifted to red. … By measuring gravitational redshift, we obtain a measurement of the distortion of time."

Time to test general relativity

Time distortion suggests that time is not absolute in our universe but rather passes at varying rates depending on gravitational fields.This idea is not exclusive to general relativity.

"Time distortion exists in all modern theories of gravity," Bonvin said. "However, the amplitude of the time distortion  —  how much the presence of a massive object slows down time —  varies from theory to theory."

In general relativity, the distortions of time and space are predicted to be the same; in other theories of gravity, this is not always the case. That means that by measuring the distortion of time and comparing it to the distortion of space, physicists can test the validity of general relativity.

The team's new method could also test another leading theory of the cosmos: Euler's formula, which astronomers use to calculate the movement of galaxies. Specifically, the team's proposed measurement of time distortion could prove whether dark matter obeys Euler's equation, as prior studies of time distortion have presumed.

"We have never observed a particle of dark matter directly. We have only felt its presence gravitationally," Bonvin said. "As a consequence, we don't know if dark matter obeys the Euler equation. It may very well be that dark matter is affected by additional forces or interactions in our universe besides gravity. If this is the case, then dark matter will not obey the Euler equation."

The team's method could be employed by future missions, including the European Space Agency's Euclid telescope, which is set to launch in July, and the Dark Energy Spectroscopic Instrument, which is three years into its five-year survey of the universe.

"It will be possible to measure the distortion of time with the data delivered by these surveys," Bonvin said. "This is very interesting because, for the first time, we will be able to compare the distortion of time with that of space, to test if general relativity is valid, and we will also be able to compare the distortion of time with the velocity of galaxies, to see if Euler's equation is valid. With one new measurement, we will be able to test two fundamental laws."