No aliens in NASA's debut UFO report — but big questions remain

A still from a U.S. Navy video reportedly showing an unidentified anomalous phenomena encountered in military airspace off America's east coast in 2015.
A still from a U.S. Navy video reportedly showing an unidentified anomalous phenomena encountered in military airspace off America's east coast in 2015. (Image credit: U.S. Navy/DOD)

NASA's UFO study team released its long-awaited first report today, and while its experts found no signs of extraterrestrial origins for reported sightings, the space agency is appointing a new chief to study the phenomenon.

NASA commissioned the independent panel of experts in 2022 in order to inform NASA and other government agencies how better data might be collected and analyzed in an attempt to understand UFOs, or unidentified anomalous phenomena (UAP), as they're now known (the term was adopted by the U.S. Department of Defense in order to encompass not only objects or events in the air that can't immediately be identified, but also those under water or in space or that travel between domains).

"The top takeaway from the study is that there is a lot more to learn," NASA Administrator Bill Nelson said Thursday (Sept. 14) while releasing the report. "The NASA independent study team did not find any evidence that UAP have an extraterrestrial origin, but we don't know what these UAP are."

To investigate further, NASA is appointing a director of UAP research to develop and oversee UAP research, Nelson announced.  "We will use NASA expertise to work with other agencies to investigate UAPs," he said.

Related: US government is hiding evidence of 'non-human intelligence', UFO whistleblower tells Congress

The cover of NASA's NASA unidentified anomalous phenomena independent study team report released Sept. 14, 2023. (Image credit: NASA)

NASA's UAP study team's first report does little to shine light on the UFO enigma, but offers recommendations on how NASA might be able to help move the topic forward. In its conclusion, the report argues that NASA can best contribute to the topic by leveraging its Earth observation satellites to help provide better data and evidence of UAP.

"At present, analysis of UAP data is hampered by poor sensor calibration, the lack of multiple measurements, the lack of sensor metadata, and the lack of baseline data," the report states. "Making a concerted effort to improve all aspects is vital, and NASA's expertise should be comprehensively leveraged as part of a robust and systematic data acquisition strategy within the whole-of-government framework."

NASA Administrator Bill Nelson attends a press conference at NASA headquarters on September 14, 2023 in Washington, DC. (Image credit: Win McNamee/Getty Images)

During a press briefing held Thursday (Sept. 14) at NASA headquarters in Washington, D.C., Nelson described the lack of data surrounding the topic, adding that because UFO sightings are often unpredictable and fleeting, they are difficult to study scientifically.

"Think about it: Most UAP sightings result in very limited data. That makes it even more difficult to draw scientific conclusions about the nature of UAP," Nelson said during the briefing. "And so this independent study team brought together some of the world's leading scientists, data, and artificial intelligence experts, and aerospace safety specialists, all with a specific charge for me, which is to tell how to apply the full focus of science and data to UAP."

Insets from NASA's UAP independent study team's report, detailing various UAP collected by U.S. government sensors and analyzed by the Pentagon's All-Domain Anomaly Resolution Office. (Image credit: NASA)

Other NASA leaders echoed this, noting that alleged UAP often remain unidentified solely due to the lack of clear data gathered on them. "UAP are one of our planet's greatest mysteries," said Nicola Fox, associate administrator for the agency's Science Mission Directorate. "While there are numerous eyewitness accounts and visuals associated with UAP, they're not consistent, they're not detailed, and they're not curated observations that can be used to make definitive scientific conclusions about the nature and the origin of UAP."

Meanwhile, Dan Evans, assistant deputy associate administrator for research at NASA's Science Mission Directorate, framed the agency's UAP study efforts in terms of airspace safety. "The presence of UAP raises serious concerns about the safety of our skies. And it's this nation's obligation to determine whether these phenomena pose any potential risks to airspace safety," Evans said. "Let's not forget that the first 'A' in NASA is aeronautics. So by understanding the nature of UAP, we can ensure that our skies remain a safe space for all."

To do this, the group's report recommends NASA should leverage the Federal Aviation Administration (FAA) and its own Aviation Safety Reporting System to help design identify data that could help shine a light on the UAP enigma. The document also recommends the use of artificial intelligence to help comb through massive data sets to identify possible anomalous phenomena.

The report also includes several images of alleged UAP, both those that have been identified and those that remain unexplained, including one that appears to show a metallic "orb-like" object flying without known methods of propulsion. "Due to limited data, the object remains unidentified," the report notes.

By approaching the topic with serious scientific scrutiny, the report argues, the agency could help remove the taboos and stigma associated with the study of UFOs, which has long been viewed as pseudoscientific. "NASA's very involvement in gathering future data will play an important role in reducing stigma associated with UAP reporting, which very likely leads to data attrition at present," the report states. "NASA's long-standing public trust, which is essential for communicating findings about these phenomena to citizens, is crucial for destigmatizing UAP reporting and scientific research."

UFOs, or UAP, have been a focus of U.S. government scrutiny over the last several years due to former intelligence community personnel and military servicemembers coming forward to share what they claim are encounters with unidentified objects or anomalous phenomena in the skies.

Several former U.S. military aviators have gone public in news media and cable television documentary series in recent years about their sightings of objects that appear to defy conventional understanding of aerodynamics and materials science, behaving in ways that are difficult to explain with known technologies.

A former Pentagon intelligence officer and U.S. Air Force veteran even testified to a congressional subcommittee in July 2023 that the American government has been hiding evidence of crashed UAP and evidence of biological "non-human intelligence."

No conclusive proof of these claims has been put forward, but several members of the United States Congress have nonetheless been vocal in their support of investigating them. Despite these claims, the head of the Pentagon's new UFO study organization, the All-Domain Anomaly Resolution Office (AARO), testified to the United States Senate Committee on Armed Services in April 2023 that his office has "no credible evidence thus far of extraterrestrial activity, off-world technology or objects that defy the known laws of physics."


Brett is a science and technology journalist who is curious about emerging concepts in spaceflight and aerospace, alternative launch concepts, anti-satellite technologies, and uncrewed systems. Brett's work has appeared on The War Zone at, Popular Science, the History Channel, Science Discovery, and more. Brett has English degrees from Clemson University and the University of North Carolina at Charlotte. In his free time, Brett is a working musician, a hobbyist electronics engineer and cosplayer, an avid LEGO fan, and enjoys hiking and camping throughout the Appalachian Mountains with his wife and two children. 

  • Mr T
    Interesting, they found no evidence of UFOs being alien in nature, but we know that humans can't make machines that perform like these clearly solid, metallic objects do. That doesn't leave many alternatives, if they are not human devices, and we are the only species on the planet that can make complex machines, that really only leaves one option.

    Of course, NASA is saying "they could be a natural phenomena" but all the evidence points against that. There have been thousands of witnesses to solid, physical machines that perform impossible manoeuvres, from pilots to military to whole towns of people, as well as several incidents where dozens to hundreds of school kids witnesses machines and even entities close-up (Ariel school, for example). Because science doesn't recognise anecdotal evidence, even when it is overwhelming, scientific investigations often come to a grinding halt with a "we don't know what they are" type result. Unless a craft lands and the pilots invite NASA scientists onboard, NASA will always reach a "We don't know what these are" result.
  • AntonSpirit12
    Well other theories have been suggested as well. One theory is that ufos are ultraterrestrial in origin. That theory says that other advanced life native to Earth exists/has existed and has more advanced technology than us. Avi Loeb I think even discussed this. There is also the interdimensional theory you can try looking into.
  • Hartmann352
    Asymptotic burnout and homeostatic awakening: a possible solution to the Fermi paradox?Michael L. Wong and Stuart Bartlett
    04 May 2022

    Previous studies show that city metrics having to do with growth, productivity and overall energy consumption scale superlinearly, attributing this to the social nature of cities. Superlinear scaling results in crises called ‘singularities’, where population and energy demand tend to infinity in a finite amount of time, which must be avoided by ever more frequent ‘resets’ or innovations that postpone the system's collapse. Here, we place the emergence of cities and planetary civilizations in the context of major evolutionary transitions. With this perspective, we hypothesize that once a planetary civilization transitions into a state that can be described as one virtually connected global city, it will face an ‘asymptotic burnout’, an ultimate crisis where the singularity-interval time scale becomes smaller than the time scale of innovation. If a civilization develops the capability to understand its own trajectory, it will have a window of time to affect a fundamental change to prioritize long-term homeostasis and well-being over unyielding growth—a consciously induced trajectory change or ‘homeostatic awakening’. We propose a new resolution to the Fermi paradox: civilizations either collapse from burnout or redirect themselves to prioritizing homeostasis, a state where cosmic expansion is no longer a goal, making them difficult to detect remotely.
    1. IntroductionLife as a feedback between flows of information and energyLife can be characterized as systems where fluxes of mass and energy lead to the production, transmission and utilization of functional information. This information is said to be ‘functional’ in that it allows the living system to survive over time through a combination of homeostatic mechanisms and autocatalytic behaviour (e.g. 1–3]). Hence, there is a tightly woven dynamic interplay between free energy and information in life: free energy allows information to be encoded, stored and used, and information channels external and internal flows of energy to promote the system's persistence.

    Similarly, evolution has been characterized by a series of innovations in the units undergoing selection, energy transduction and information processing. Szathmáry & Maynard-Smith 4] argued that the complexification of life over deep time can be attributed to a series of ‘major transitions’ in the characteristic units of selection acting within biological systems. Such transitions thus represent major shifts in the ways in which biological information is encoded and exploited. So too has human society been shaped and reshaped by innovations that accelerate and widen the spread of information—most notably the inventions of the printing press, telecommunication, computers and the internet. Throughout its evolutionary history, life has learned to exploit different free energy sources in its environment, from geochemical energy to sunlight to the potential energy stored by previous life in flesh and fossil fuels 5]. Within the past 100 years, human civilization has also unlocked nuclear energy and learned to transduce various ‘green’ energy sources (e.g. geothermal, wave motion and wind) into electric power.

    Advances in information processing and energy transduction reinforce one another autocatalytically: a greater ability to learn engenders exploration and innovation that opens new free energy resources; greater free energy resources allow for the transition to new information-processing paradigms. These evolutionary leaps sometimes involve the creation of new levels of biological organization and hence new units of selection, e.g. endosymbiosis, multi-cellularity and the formation of social colonies.
    Where do we fit in? The rise of human civilization and the dataomeWhen optimization processes form tight positive feedback loops, the rate of innovation and discovery (and the concomitant demand on energy resources) can quicken dramatically. We see this in the trajectory of human society since the emergence of the ‘dataome’. The dataome encompasses the external recording and processing of information (in e.g. books, architecture and computers) as well as the coevolution of those infological organisms atop of a collection of biological organisms, and it may represent the most recent major transition in information processing—one that we are not only witnessing but also partaking in today 6].

    The acceleration of the dataome was intimately tied to the Agricultural Revolution: an energy transition from hunter–gatherer societies to farming, enabled by innovations such as animal husbandry and pottery (e.g. 7,8]). Together, the energy excess afforded by agriculture and the growth of the dataome set the stage for the creation of cities—defined generally as permanent, dense settlements where individuals share resources, infrastructure and ideas—laying the foundation for human civilization as we know it.

    In some ways, a city is a superagent composed of individual human agents analogous to a multi-cellular organism that is a superagent composed of individual cellular agents. Both collectives support the differentiation of individual agents (often phrased as a ‘division of labour’), and in both cases, individual agents may come and go while the whole superagent retains its identity. However, there are some key differences between these two organizational structures of life that have been quantified in part thanks to advances in network and complexity science (e.g. 9]).
    Cities as a new universality class exhibiting unbounded growthRecently, cities have been studied as socio-biological phenomena that can be described quantitatively to reveal universal trends that reflect the underlying principles of their organization. Bettencourt et al. 10] showed that many properties of cities—GDP, patents, wages, disease and crime—are power law functions of population size with a superlinear scaling exponent β > 1, rendering increasing returns with increasing size. This places cities in a distinct universality class from biological metabolism, which scales as a function of size with a sublinear scaling exponent β < 1. Other aspects of cities—like number of gasoline stations, length of electrical cables and total road surface—do scale sublinearly; these are associated with material and energy flows and are therefore analogous to metabolism in biology.

    Sublinear scaling leads to economies of scale—enhanced efficiency of matter and energy processing, a necessary feature for selective favourability of increased organism size—and a decreasing pace of life with increasing size. Examples from biology include a slower metabolic rate in more massive animals, like elephants, than smaller ones, like mice 11].

    On the other hand, superlinear scaling results in an increasing pace of life with increasing size. A striking example is that the average walking speed is higher in larger cities 12]. So too with crime rates 13] and the spread of infectious diseases 14]. Importantly, the total energy consumption of cities scales superlinearly 10].
    The superlinear scaling of seemingly unrelated city properties is attributed to the socialnature of cities. Indeed, the observed values of this exponent for social characteristics (β∼ 1.2) can be estimated by how the number of effective contacts per capita increases with city size (10], electronic supplementary material). In other words, in cities, social interactions between agents create a dynamical network of information flow that is hypothesized to drive quantifiable changes in human behaviour that underlie the observed scaling laws 10].
    Because growth and wealth production scale superlinearly, cities are highly resilient dynamical entities. Throughout modern history, few cities have completely perished, despite two having had devastating atomic weapons used against them, and despite the coming and going of higher level power structures (e.g. empires, nation states and political parties) 15].

    Bettencourt et al. 10] developed a growth equation for cities, reproduced below:
    where dN/dt is the population growth rate, Y represents resources required by the population, R is the average resources it requires to maintain an individual and E is the average resources it requires to add a new individual to the population. Bettencourt et al. 10] generalized the equation further by allowing R, the maintenance energy per capita, to vary (see their electronic supplementary material for details), but the results are qualitatively the same.

    Their analysis showed that when β > 1, unbounded growth will occur, leading to infinite population (and hence infinite demand on resources) in a finite time. If such a ‘singularity’ is approached unchecked, the system will eventually exceed its energy supply and collapse (or significantly regress). However, Bettencourt et al. 10] suggested that singularities can be avoided by major qualitative changes, or ‘innovations’, that reset the initial conditions and parameters of the growth equation and set the city on a new trajectory. If the underlying dynamics remain, meaning β > 1 still holds true, then the city will be on a trajectory towards a new singularity later in time (figure 1). 1. The growth trajectory of a city with scaling coefficient β > 1 leads to singularities (dashed vertical lines) that must be avoided by innovative resets. The time scale between resets decreases as the population, N, increases. Adapted from Bettencourt et al. 10].
    The general growth equation of Bettencourt et al. 10] predicts that the time interval between resets, tcycle, decreases as the population grows where Ni(0) is the new initial condition after a new innovation occurs. In other words, the frequency of innovations must increase with time. This is consistent with the increasing frequency of population growth cycles and technological change.
    2. The asymptotic burnout hypothesisA virtually connected world as a global cityToday, the dataome is omnipresent in our daily lives: portable computers and smartphones bind people across the globe in a digital web of information. The internet—social media in particular—allows individuals who have never met physically to engage in faster, more frequent and more prolonged social interactions. Technology-driven globalization is not only metaphorically making the world smaller, it is quite literally sidestepping the physical limitations of human interactions and allowing people to exchange ideas and influence one another from previously impossible distances at previously impossible rates.

    Owing to how deeply intertwined the dataome and human biome has become, it is possible that we are in the midst of another major informational phase transition: one that pushes civilization into a state where the physical colocation of humans in cities is no longer the dominant constraint on human interaction. (Anecdotally, this is consistent with migration away from densely populated city centres to surrounding suburban regions during the COVID-19 pandemic, when work-from-home practices were adopted 16–18].) Liberated by the virtual interactions enabled by information technology, the world may behave as one global city, even if physical cities only cover a small fraction of the planetary surface.

    Because it is human interactions that appear to give rise to the superlinear scaling laws of cities, if civilization transitions into a state that can be described as one virtually connected globalized city, it is likely that such an organizational structure will exist in the same universality class as cities. In other words, we conjecture that a technologically connected civilization's productivity, growth and resource consumption would be characterized by scaling laws with a scaling exponent β > 1.

    As the dataome expands, the preponderance of information processing occurring at the societal level, rather than the individual level, grows. As advances in artificial intelligence are made, it is also possible that human–human interactions may become less important than human–technology, and eventually technology–technology interactions. While human–human interactions are constrained by time and cognitive capacity—the so-called ‘information saturation’ of human experience 19]—the ability for technological agents to interact with one another in an ever-growing digital planetary network could be boundless. What effect these near-future shifts may have on the scaling coefficient of a globalized city remains speculative, but we find it plausible that such transitions could result in an even larger β.
    2.2. Generalizing towards exo-civilizationsThe abstract nature of the driving force behind city productivity, growth and total energy consumption—namely, informational exchanges between individual agents—gives promise for the generalization of these principles to hypothetical civilizations elsewhere in the universe. We contend that such principles are likely to be invariant to changes in molecular composition of the lower level agents (e.g. different genetic or metabolic substrates). The emergence and evolution of life on other planets remains speculative at this time. However, it has been argued that certain major transitions—including the onset of life itself—are inevitable, irreversible and ‘reproducible’ (e.g. 20–22]).

    Such irreversibility is evident in the ‘core algorithms’ of life on Earth that we observe to stretch back, largely unaltered, in deep time 6]. Examples include the universality of a four-letter genetic code 23,24]; the universality of ATP synthase as a disequilibrium converting engine and ATP as an energy transfer molecule 25,26] and the widespread use of the RuBisCO enzyme in carbon fixation, the gateway for the vast majority of carbon assimilation on present-day Earth 27,28]. Once these innovations emerged, the advantages they confer ‘freeze’ them into the evolutionary threads of life (e.g. 29]), making it difficult for optimization processes such as Darwinian evolution (or hill-climbing on fitness landscapes) to lock in potentially superior alternatives later down the evolutionary line (e.g. 30,31]). While the material specifics of life on Earth may be historically contingent, the general principles of life should be universal. Life requires information storage (perhaps not with DNA), free energy transduction (perhaps not with ATP) and a way to assimilate environmental substrates into useful metabolic intermediates (perhaps not with RuBisCO)—but once life discovers how to perform these tasks, such abilities will be strongly selected for and hence persist through time.

    Similarly, we can consider higher order features of life—including endosymbiosis, multi-cellularity, language and the creation of a parallel living system in the dataome—to be features locked in by evolution. Although the exact timing of such innovations may be stochastic, once they do emerge, they are likely to persist because they become integrated into the positive feedback between information processing and energy transduction described in §1. Hence, we can consider exo-evolutionary trajectories that are similar to our own in that they are governed by the same physical constraints and information–energy feedbacks that have propelled biological evolution on Earth. On these alien worlds, perhaps societies composed of interacting agents will emerge and be subject to the same governing principles as human civilization, even if they do not share our particular material or historical details. At some point in their evolutionary path, societies will likely invent and intertwine themselves with dataomes of their own and may therefore self-organize into a globally connected state characterized by scaling laws with an exponent β > 1.
    2.3. Singularities at the civilization scaleIn the scenario laid out above, a global civilization will march towards a singularity where energy resources can no longer sustain the trajectory of unbounded growth. To reiterate, a singularity occurs for trajectories that are headed towards a state of infinite population and energy usage in a finite amount of time. While new energy resources may be discovered, briefly raising the ceiling for total energy consumption, new energy resources cannot sustain a superlinear system indefinitely due to the finite time scale associated with the singularity. Thus, in our view, the important question is not whether new energy resources can be found, but whether innovations (perhaps in energy efficiency or distribution) can reset the system's trajectory by altering the parameters in the growth equation (equation (1.1)). Thus, in this section, we centre our argument around relevant time scales.

    As with individual cities, the collapse or regression of planetary civilizations can be momentarily avoided by innovation-related resets that only delay the inevitable. The time scale between resets that must be achieved to maintain viability, tcycle, decreases over time; in other words, these adaptations must occur at an ever-increasing pace.

    Eventually, tcycle may become sufficiently short that it exceeds the civilization's time scale for innovation, tinnovate. Perhaps this occurs when tcycle ≪ tindividual's lifetime, or the system's learning time scale (driven, in humanity's case, by education). If just one cycle is missed, a regression to a weaker mode of activity will likely occur.

    For 2 > β > 1 (as is the case for modern cities, where β ∼ 1.2 for certain metrics), ∑tcycle is a divergent sum, so in theory, a civilization can stay viable forever so long as it meets every single singularity with a reset. However, harmful fluctuations—both external and internal—can threaten the system's stability.

    For instance, notable abandoned cities of the ancient world—Angkor, Babylon, Chichen Itza and Pompeii, to name a few—demonstrate that many major early cities succumbed to external fluctuations (e.g. volcanic, climatic or invasion), internal fluctuations (e.g. deforestation or overpopulation) or a combination of the two (e.g. 32–38]). Modern cities have also been abandoned for a variety of reasons: waning economic activity (e.g. California Gold Rush ‘boomtowns’ of the late 1840s and early 1850s), natural disasters (e.g. Craco, Italy, which was evacuated in 1963 after a landslide) and nuclear disaster (e.g. Pripyat, Ukraine, following the Chernnobyl disaster in 1986).

    As life grows in free energy-harnessing capability, the magnitude of its internal fluctuations also increases. Examples of energy expansion-related fluctuations include the flooding of the atmosphere with the toxic gas O2, due to the energy expansion of oxygenic phototrophy; anthropogenic climate change, driven by the energy expansion of fossil fuels; and the threat of nuclear winter, enabled by the energy expansion of nuclear fission. Informational expansions may also induce catastrophic fluctuations, such as an internet-induced ‘misinformation catastrophe’ in which agents lose their ability to distinguish truth from fiction because innovations in telling truth from lies do not keep pace with the rate at which misinformation becomes more sophisticated. While disease and physical crime may be less malignant in a virtualized global city, viral misinformation and cybercrimes may take their place. Finally, the emergence of any module that produces dissipation and autocatalysis without contributing to homeostasis and learning is a dangerous form of ‘sublyfe’ 3] that siphons useful resources away from the whole system; classic examples from biology include cancer and ‘cheaters’ in evolutionary game theory. The recent rise of blockchains and cryptocurrencies, which demand ever-increasing rates of computational resources but do not contribute much to overall stability, may exemplify harmful internal sublyfe fluctuations endemic to dataome–biome symbioses.

    Thus, with time, tcycle decreases while potentially harmful fluctuations become more likely to derail tinnovate. Once tcycle becomes short enough that internal fluctuations or external perturbations can cause tinnovate > tcycle with some non-negligible probability, collapse/regression may be inevitable.

    If civilization transitions into a new regime where β > 2, perhaps due to a shift where interactions between artificial agents dominate the flow of information, then ∑tcycle is a convergent sum (i.e. tcycle gets shorter and shorter, such that the cumulative sum converges to an upper bound). In other words, the time scale between innovations vanishes (tcycle → 0) in a finite amount of time, and there will be a hard cutoff to the longevity of such a civilization.

    In any scenario, it seems that a civilization in which social exchanges between agents form a dynamical network that results in superlinear scaling will eventually reach a point of collapse due to the ever more frequent singularities it faces. We call this concept ‘asymptotic burnout’ and define tburnout to be the time scale between the emergence of the dataome and collapse. If collapse were to happen today, and we take the emergence of human language to be the beginning of the dataome (e.g. 39,40]), then humanity's tburnout would be on the order of 105 years. If instead we use the emergence of the first cities or the emergence of written language as our starting point (e.g. 41,42]), tburnout would be on the order of 103–104 years.
    3. The homeostatic awakening hypothesisWhen burnout occurs, it will necessarily destroy the superagent's modus operandi (the ‘way of life’ that drives β > 1), but lineages of agents will likely persist, perhaps to self-organize again into cities given enough time. Even if the agents comprising a technological society do not survive long after burnout, it is doubtful that a global civilization's collapse will render its planet completely lifeless, even in the most extreme cases (e.g. nuclear winter). In this scenario, another agent may emerge to establish a new dataome, form the next wave of organized civilization and put itself on a trajectory of unbounded growth, cycles of innovation and eventual burnout.

    Can this cycle (indeed, metacycle) of collapse be avoided? At some point prior to tburnout, the civilization may be able to use its information-processing resources to construct a model of reality that reveals the trajectory that it is on. We define tawakening as the time scale between the emergence of the dataome and this realization. We consider the study by Bettencourt et al. 10], as well as related works, to be part of our own ‘homeostatic awakening’. Hence, for the case of humanity, Δtwindow = tburnout – tawakeningis positive. This Δtwindow is the ‘window’ that a civilization has to purposefully affect some kind of fundamental, systemic change that alters its modus operandi away from unbounded growth that results in an arbitrarily large demand on energy in a finite amount of time. Note that there is no a priori reason why Δtwindow must be positive. In many cases, tburnout may occur before tawakening.

    As life on Earth has increased in scale and complexity, its ‘cognitive horizon’—defined as the spatial and temporal extent of its predictive abilities and goal-driven behaviour—has increased as well 43]. The cognitive horizon of human civilization is unprecedentedly vast. We can predict the future of physical systems from the subatomic to the cosmological scale, including the behaviour of complex systems, such as humanity itself. It is this predictive power that leads to what we call an awakening—the realization that humanity has been unconsciously optimizing its autocatalytic feedbacks, resulting in the unbounded proliferation and energy exploitation that eventually gave rise to the superlinear scaling laws of cities.

    In the one example of life that we have, the cognitive horizon required to understand civilization growth seems to be a product of civilization itself. That is, the mathematical and scientific formalisms that are capable of describing complex systems, as in Bettencourt et al. 10], did not emerge at the level of bacteria, biofilms, ant colonies, forests, whale pods or paleolithic hominids; they emerged as a result of the informational transactions allowed when the architecture of human society transitions into cities. This raises the possibility that Δtwindow is, in general, short compared to, say, evolutionary or geologic time scales.

    In evolutionary histories where Δtwindow is positive, a civilization has the chance to discover how to enact the changes it must make to rearrange its own internal dynamics to consciously prioritize homeostasis. This likely requires a cognitive step beyond simply recognizing the problem of being on a trajectory of unbounded growth. Hence, we define another Δt: Δtaccomplishment = treorient – tawakening, where treorient is the time between the emergence of the dataome and the discovery of how to reorient civilization towards homeostasis. The ratio Δtwindow/Δtaccomplishment dictates whether a civilization achieves long-term survival (figure 2). 2. Three scenarios for the evolution of a civilization on a burnout trajectory. Top: Δtwindow < 0. In this scenario, the civilization does not realize its trajectory before it suffers from burnout. Middle: Δtwindow > 0, but Δtwindow/Δtaccomplishment < 1. In this scenario, the civilization realizes it is on a trajectory but is unable to accomplish a reorientation towards homeostasis before burnout. Bottom: Δtwindow > 0, and Δtwindow/Δtaccomplishment > 1. In this scenario, the civilization is able to both understand that it is on a burnout trajectory and is able to reorient towards prioritizing homeostasis.Download figureOpen in new tabDownload PowerPoint
    A redirection would require a rewriting of the fabric of global civilization so that unbounded growth is no longer the priority—or at least no longer the outcome. Because humanity has yet to discover what it must do in order to alter its fate, we are unsure of the cognitive horizon required to reach treorient. Many questions must be answered before treorient can be achieved, including: What, besides growth, would we optimize? Does open-ended evolution and novelty discovery require unbounded growth? Can we, as a species, convince ourselves that maximizing a different metric will not only guarantee our persistence, but also improve our overall well-being? Will the dataome play a crucial role in arriving at the solution?

    One example of a society actively choosing a non-growth trajectory is the small kingdom of Bhutan, located between India and China. Owing in large part to its pursuit of Buddhist philosophical ideals, Bhutan's government pursues a policy of maximizing ‘Gross National Happiness’ instead of gross domestic product. The achievement of this objective is quantified using an index designed to assess the well-being of Bhutan's population. The ‘four pillars of gross national happiness’ are the following:
    (i)sustainable and equitable socio-economic development(ii)environmental conservation(iii)preservation and promotion of culture(iv)good governance.
    By placing preservation and conservation front and centre, Bhutan is pioneering a potential path in which material and economic metrics are not necessarily maximized, but other goals such as human and environmental health and the pursuit of knowledge are instead emphasized. Bhutan may of course be an isolated special case that does not in fact demonstrate a society actively choosing an ‘awakened’ path. This country deliberately chose a different objective function to other nations—but whether this has relevance to avoiding burnout is another question. On the one hand, this choice was motivated by sustainability to a large extent, a key part of avoiding exponential growth catastrophes. On the other hand, Bhutan as a country is unlikely to reach any kind of technological singularity in the near-future (burnout risk is relatively low at present).

    History contains examples of ‘mini-awakenings’—humans recognizing their own trajectory towards a crisis and consciously learning to adapt, mitigate harmful fluctuations and prioritize homeostasis over unyielding growth. Here, we highlight three:
    (i)The mitigation of ozone depletion, caused as an unintentional byproduct of the emission of chlorofluorocarbons, in the second half of the twentieth century. Through legal actions, substances that were found to be harmful to the Earth's ozone layer were banned from use. Today, the trend has reversed and the ozone hole has diminished in size.(ii)The deescalation of weapons of mass destruction following the Cold War. During the height of the Cold War, the globe's nuclear arsenal exceeded 70 000 warheads, and numerous flashpoints threatened world stability against all-out nuclear warfare. While humanity has not yet removed the threat of nuclear annihilation, today it is somewhat diminished, and the global tally of nuclear warheads stands at less than 14 000 44].(iii)The international moratorium on whaling, enacted in 1982. While far from perfect, this moratorium had a fundamental positive impact on the plight of marine mammals. Although whaling was also declining for other reasons, the international recognition of the extinction trajectory caused by whaling in the late twentieth century helped redirect the path to one of conservation and respect. For example, Humpback whale numbers have rebounded significantly since the IWC moratorium and may eventually recover to pre-whaling levels.
    Previous evolutionary transitions may also offer a source of optimism. In multi-cellular organisms, neighbouring cells can ‘normalize’ aberrant cells, such as cancerous cells, by altering bioelectric gradients (e.g. 45–47]). Through the regulatory mechanisms of cell-to-cell communication, cells cooperate towards organ-level and organism-level homeostasis, no longer distinguishing between themselves as individual cells but as part of a larger ‘self’ 48–50]. If technological social connectivity is used wisely, perhaps humanity can notice the pain of the world more directly, learn to treat the planet better and wake up to the fact that, on our current trajectory, we're mutually harming ourselves both individually and collectively.

    Bettencourt et al. 10] showed that when individual organisms self-organize into cities, life transcends into a different universality class than individual organisms. Self-awareness-driven reprioritization towards homeostasis may be the next transcendence that life takes (or must take) after civilization as we know it 51].
    4. Burnout and awakening in the context of the Fermi paradoxThe Fermi paradox asks: in a universe that seems amenable to abiogenesis and the evolution of life leading to technological civilizations, why haven't we seen definitive evidence of extraterrestrial civilizations? We contend that this question presents itself as a ‘paradox’ because there is an implicit assumption that the trajectory of progress can be extrapolated from the past, i.e. that the future is a linear extension of past and current trends. Specifically, civilizations are projected to attain greater energy harnessing capabilities and greater knowledge of the universe until they spread in an unbounded colonialist manner across the galaxy.
    The Kardashev scale is one example of this mode of thinking. This measure of the ‘advancedness’ of civilizations is based on the concept of energy expansions: a Type I civilization uses all of the energy available at the planetary scale; a Type II civilization uses all of the energy available at the planetary system scale and a Type III civilization uses all of the energy available at the galactic scale. It has been argued that once a Type II civilization becomes interstellar, it should spread across the galaxy in a relatively short amount of time 52–55]. Hence, the lack of evidence of extraterrestrial visitors is widely considered to be consistent with the belief that a Type III civilization does not currently exist in the Milky Way. Additionally, extragalactic observations suggest that Type III civilizations are rare 56], although this absence may stem from an inability to observe in the appropriate way.

    Two important aspects of biology are missing from Kardashev-like frameworks: (i) evolution is not always gradual and linear, but is impacted by major transitions and ‘punctuated equilibria’ and (ii) the dynamics of city-like living systems in which information flows and energy flows result in superlinear scaling and singularity crises.

    Perhaps Type III civilizations on the Kardashev scale are in an unreachable part of biotechnological state space because most civilizations face burnout at the planetary/sub-planetary scale. When burnout approaches, if Δtwindow < 0, the civilization will necessarily collapse or regress until it iterates into a new cycle. If Δtwindow > 0, the civilization has a chance to consciously transcend into prioritizing homeostasis; otherwise, it will collapse or regress. Hence, there may be very few or no plausible trajectories through biotechnological state space that connect humanity's present state and the region occupied by hypothetical Type III civilizations (figure 3). 3. Perhaps hypothetical Type III civilizations are in an inaccessible region of biotechnological–population size state space, where civilization trajectories are bounded by a ‘burnout horizon’, and long-lived civilizations have consciously reoriented their trajectories away from growth in population size and length scales to explore other dimensions of biotechnological state space. Note that we do not rule out the possibility of some kind of channel that might allow a transition to the Type III region.Download figureOpen in new tabDownload PowerPointWhether homeostatic transcendence happens in all or a minute fraction of all cases is irrelevant to the observables consistent with the Fermi paradox. If collapse or reorientation are the only likely options, then whatever their yields are, a civilization's growth will cease—either because cosmic expansion is no longer viable or because it is no longer an imperative. This argument may provide a theoretical foundation for the ‘sustainabilty solution’ to the Fermi paradox 57].

    Other ‘solutions’ to the Fermi paradox involve ‘bottlenecks’ that are probability-based. In the language of the Drake equation 58], this takes the form of equating one of the biotechnical factors to a very low probability. The solution we propose here is of a different kind: it is an inevitable barrier, emergent from the dynamics of energy and information flows within a living system, that civilizations will either meet or learn to redirect themselves around. (Note that if the burnout–awakening hypothesis is borne out, this does not preclude the possibility of other ‘great filters’ as well).

    The lifetime of ‘technologically advanced’ civilization, L, is considered to be one of, if not the most, uncertain variables in the Drake equation. If the burnout–awakening hypothesis does indeed describe the fate of civilizations across the cosmos, then L may have a bimodal distribution. The civilizations that encounter burnout will be extremely short lived; the civilizations that consciously choose homeostasis will be significantly longer lived (figure 4). 4. An example bimodal distribution of the lifetime L of civilizations. The relative sizes of each mode is dependent on how many civilizations are able to transcend into homeostatic awakening and avoid burnout.Download figureOpen in new tabDownload PowerPoint
    Jill Tarter, formerly fromSETI (2021 personal communication) has suggested, provocatively, that it might be the detection of other extraterrestrial civilizations that spurs a civilization into the long-lived mode. This suggestion is not incompatible with our idea. Discoveries about the universe, in general, inform our collective psyche. The discovery of alien life, and especially alien intelligence, may play an important role in affecting the monumental changes necessary to complete a planetary civilization's reorientation towards homeostasis.

    Perhaps the formation of city-like entities (with β > 1) is not a universal feature of life in the universe, but some unique quirk of life on Earth. Astrobiologists often caution against using the specific characteristics of Earthly life to guide our search for life elsewhere, because such details might be single instantiations of, rather than fundamental to, what life is. For example, Kempes & Krakauer argue that replication is just one form of persistence, which is the more universal aspect of life. In a biosphere where self-replication of individuals is not the paradigm, evolution would proceed much differently, potentially resulting in different growth equations and macroscopic scaling laws. The idea of cities as an organizational structure of life may not even make sense in such a scenario.