Astronomers detect millions of signals from an intelligent civilization: Us

The powerful 330-foot (100 meters) radio telescope at Green Bank, West Virginia.
The powerful 330-foot (100 meters) radio telescope at Green Bank, West Virginia. (Image credit: mike zorger via Getty Images)

The Universe seems like a lonely place.

We know - we're proof of it - that intelligent civilizations (yes, civilizations) are possible. Finding signs of other civilizations in the Milky Way galaxy is not such a simple matter, but we do have tools at our disposal. Based on our own technological capabilities, we can extrapolate what signals alien technology might emit, and search for those.

These signs are called technosignatures, and our efforts in the search for extraterrestrial intelligence (SETI) revolve around them, particularly in radio wavelengths.

"One of the great advantages of the search for technosignatures at radio wavelengths is that we are sensitive to signals emitted from thousands of light years away, and it does not take that much power," astronomer Jean-Luc Margot of the University of California Los Angeles told ScienceAlert.

"For instance, our search can detect the Arecibo Planetary Radar at distances of over 400 light years. And it can detect a transmitter that is only 1,000 times more powerful than Arecibo - a trivial improvement for an advanced civilization - all the way to the centre of the galaxy. The volume of the galaxy that can be sampled with a radio search for technosignatures is immense."

Margot and his team recently conducted a search for technosignatures using the Green Bank Telescope, a powerful radio telescope in West Virginia.

In April of 2018 and 2019, for a total observing time of four hours, they homed in on 31 Sun-like stars around the galactic plane, detecting a total of 26,631,913 candidate technosignatures.

A closer analysis of the data revealed that every single one of those candidate technosignatures was generated right here on Earth.

But the methods used to process those data are a significant step forward in identifying possible alien technosignatures, teasing them out from the background humming and pinging of anthropogenic radio noise - what we call radio-frequency interference, or RFI. Navigation technology, satellite technology, mobile phones, microwave ovens, aircraft, communications; we're constantly bathing our surroundings in radio-frequency radiation.

"RFI could potentially obscure an extraterrestrial signal," Margot said. "RFI makes our job more difficult because we detect tens of millions of signals per hour of telescope time, and we need to make a determination about every single signal: is it anthropogenic or is it extraterrestrial?

"It would be a lot easier if we detected only a few signals. Fortunately, our algorithms allow us to automatically classify over 99.8 percent of the signals."

The team made several improvements to their data processing pipeline, refining the sensitivity and signal detection rate, as well as the filter used to automatically classify RFI signals in the data, and thus rule them out as alien technosignatures.

As Margot noted, these filters correctly flagged 26,588,893 (99.84 percent) of the signals as anthropogenic RFI. When you're dealing with numbers that large, that still leaves a lot of data to process; in this case, it was 43,020 signals.

The majority of these remaining signals fell within the range of known RFI, and were classified accordingly. That left 4,539 signals as the most promising alien technosignature candidates. These had to be carefully visually inspected - and every single one was also ultimately determined to be anthropogenic in origin.

"If a signal is detected in multiple directions on the sky, we can be extremely confident that it's anthropogenic," Margot said. "An extraterrestrial signal from an emitter at interstellar distances would be detected in only one direction."

The result isn't unexpected. A search earlier this year of a much larger stellar sample, 10 million stars, also turned up no signs of alien technology. But that wasn't really the point; or at least, not the only point.

Firstly, Margot uses SETI data processing as a tool for training students at UCLA.

"We conduct the search as part of a SETI course that I have taught at UCLA annually since 2016. This course appears to be unique in the US and perhaps worldwide," he explained.

"Students collect terabytes of data from known or suspected planetary systems, write a data-processing pipeline collaboratively, search for technosignatures in the data, and publish the results. It is most satisfying to witness the students acquire important skills .. all in the context of this important search."

The team's refined pipeline also revealed some issues with previous attempts to process SETI data; more specifically, attempts to quantify how many transmitting civilisations there might be in the Milky Way galaxy. Their results show that these estimates may be too low by up to a factor of 15, partially because the data-processing pipelines "fail to detect some of the signals that they are designed to detect," Margot noted.

"We implemented a signal injection and recovery analysis tool that allows us to quantify the efficiency of data-processing pipelines. This efficiency must be taken into account when attempting to place bounds on the number of transmitting civilisations."

There are some limitations to the team's pipeline. Where two signals intersect, the algorithm only picks up the one with the highest signal-to-noise ratio; faint signals against a high level of background noise can be missed, too. This means that regions of high signal density can result in a reduction of the signal recovery rate.

Overcoming these limitations could be the focus of future work. But it's work worth doing. RFI isn't just a problem for SETI but for all radio astronomers, so much so that some measurements can no longer be made from Earth. Hence scientists are eyeing the far side of the Moon for a radio telescope. The Moon acts as a natural buffer against anthropogenic radio interference.

And, of course, there's the possibility - slight, but non-zero - that we might detect something.

"The search may answer one of the most profound scientific questions of our time: Are we alone?" Margot told ScienceAlert.

"All life on Earth is related to a common ancestor, and the discovery of other forms of life will revolutionise our understanding of living systems. On a more philosophical level, it will transform our perception of humanity's place in the cosmos."

The research has been accepted into The Astronomical Journal, and is available on arXiv.

This article was originally published by ScienceAlert. Read the original article here.

Michelle Starr

Michelle Starr is a senior journalist at ScienceAlert, with over 15 years of experience in the science and technology sectors. Prior to joining the ScienceAlert team in 2017, she worked for seven years at CNET, where she created the role of Science Editor. Her work has appeared in "The Best Australian Science Writing" anthologies, and in 2014, she was awarded the Best Consumer Technology Journalist in the Optus IT Journalism Awards. She absolutely adores orcas, corvids and octopuses, and would be quite content to welcome any one of them as the new overlords of Earth.

  • Snorrie
    I don't understand the possible benefits of looking for "Space Aliens" that most likely would be hundreds/thousands of light years distant. E.G.: Even with a simple "hello" message both the sender and receiver would be long dead due to tranmission time. Aside from scientific methodologies, perhaps looking for E.T. is not cost justified? Wouldn't an effort to better understand the evolution of H. Sapiens on Earth in the physical, environmental, cultural and psychological matrix that we live in be more efficacious to our species well being?
  • Hildy
    While an alien Aricebo equivalent might detect our Aricebo's one shot in the dark signal, it would be far more useful to know how far away their SETI could detect our strongest continuously broadcast signals which, I believe are clear channel AM radio stations.

    Broadcast signals might make sense for a planet but not for a solar system, much less a galactic empire. They just waste too much power versus directed signals.
  • Hayseed
    The chances of detecting passive signals are slim. The best way to get someone's attention, if your sure you want to do to transmit a one frequency signal that is offset from the natural spectrum of starlight. And blinking or intermittent. Check all spectrum archives for a small offset light signal. Check all X-ray spectrum archives as well.

    Even though communication is probable, knowing that intelligent life is out there will change this world and science very quickly.
  • Hildy
    I think the chances of a "we are here" narrow cast signal being directed in Earth's vicinity are close to nonexistent because space is big. The LGM signal turned out to be a pulsar (a type of object unknown at the time) and the WOW signal, while still not definitely explained, does not appeal to contain information. Other than those we've found nothing.

    OTOH, we, and possibly alien worlds, broadcast a whole spectrum of radio emissions. I presume that if we built an Aricebo equivalent on, say, Ceres, it would be able to detect some of these.

    My question is, if there was an Aricebo equivalent in, say, the Proxima Centauri system, would it be able to detect them? If so, how much further out could a stellar system be and still have a chance of detecting them.
  • dizzo
    Did you know Cosmic Radio Signals can be polarized at 91mhz (fm radio);

    160mhz (vhf radio ); 610 mhz ( on channel 78 uhf-tv) by keying a cb

    microphone over a radio receiver set on these radio channels with your home


    These are known cosmic radio sources from outer space,25mhz natural

    source, 91 mhz unknown source from the Constellation Sagittarius , 160mhz

    unknown source, 440 mhz, 1440 mhz and many others from Annual Review

    of Astrophysics and Astronomy 1966 editor Leo Goldberg.

    Facts : A lot of the static snow that you recieve is your non cable

    uhf tv; is cosmic radio signals......many elements naturally emit

    radio pulses where excited; You can polarize these signals with CB radio

    Microphone by keying the transmitting CB microphone over the speaker of a

    receiving radio set at 91 mhz..(91fm)..160 mhz..(160 vhf radio)..and

    transmit the spacey sound you hear to a receiving TV set at channel

    78 UHF tv.....then you will see a ATT type of symbol..and see the

    oscillations and fluctuations of the cosmic radio signal that has

    been just polarized and hear strange 1960s Star Trek spacey sounds, ( I think

    scientist playon around with 195s electronic equipment radio and TV made

    some odd findings, like the ATT symbol ( world with stripes ) the CBS electron

    gun inspired the 1950s CBS eye logo, and those 1960 Star Trek sound

    effects...the odds are in our favor.we are receiving artificially generated radio

    signals...I think 91 mhz FM radio and 160 mhz VHF radio is artificially

    generated...remember the old national weather radio station was at 162 mhz

    VHF radio.
  • adam
    There is an initial question to ask related to the possibility of SETI finding alien life that is not asked - how many alien beings have technology we cannot detect because its superior or inferior to ours.

    It seems likely that life developed at different times

    It seems likely our technology would be primative to any space travelling beings.

    Next their may be aliens who are our peers in many ways -
    ie not space travellers - but have developed technologies we cannot detect that do a similar job to our radio waves etc

    This would seem to rule out a big chunk of possible SETI contacts as being either too advanced to find or too primative or not on our wave lengths and so being undetectable.

    I guess the other underlying question is who are you looking for and why ?

    Also do aliens already know we are here and are they hiding from us ?

    The article is interesting it starts

    "The Universe seems like a lonely place.

    We know - we're proof of it - that intelligent civilizations (yes, civilizations) are possible. Finding signs of other civilizations in the Milky Way galaxy is not such a simple matter, but we do have tools at our disposal. Based on our own technological capabilities, we can extrapolate what signals alien technology might emit, and search for those.

    These signs are called technosignatures, and our efforts in the search for extraterrestrial intelligence (SETI) revolve around them, particularly in radio wavelengths."

    However there may be other ways of living and being outside our current society and understanding

    We consider ourselves advanced but we could be very primative.

    Each human age or epoch has somewhat considered itself to know all

    We leave some "primative" humans on earth issolated on their islands or in the jungle because of the damage we could do and have done to others from our contact and consider ourselves advanced for doing so.

    Could other beings be doing the same to us ?

    Many of us are unwilling to talk to other humans we consider strange.

    Alternatively our governments could be hiding their existing knowledge of alien life and technology from us, and SETI could just be a smoke screen to "show" nothing has been found

    Such a strategy would be no great surprise if it were true. Governments hide much lesser secrets and continue to do so.

    So what evidence exists to say aliens are more advanced and are hiding from us making SETIs role questionable?

    The universe is about14 billion years old.

    Some advanced life probaly exists that may be a billion years old.

    Imagine what knowldge could have been gained over say just 1 billion years of existence -
    meaning that such Beings could be able to travel and communicate at speeds or ways we can only vaguely if at all comprehend.

    Perhaps they could split their consciousness in some way so as to watch their own arrival at a destination and so deliberately avoid contacting us.

    In any event why would someone who could fold time and space to arrive instantly, or travel at warp speed, talk to most or any of us? We would be like children or less than children

    Quantum entanglement highlights how space and time may make no difference to communication and may even indicate the possibility of foreknowledge of an event.

    Quantum entanglement shows it is possible that information can travel faster than the speed of light. However we are not yet clever enough to work out how to get there and use it
    There is also some evidence of a higher consciousness - for example random number generators can be used to indentify and predict that an unknown major event is about to happen. This indicates something is either malfuntioning in multiple unconnected locations or some foreknowledge exists.

    It has also been shown that after a major event has happened, the event continues to effect the random number generator and it continues for an extended time to "malfunction"
    So SETI may be looking for a needle in a field of haystacks that have needles it cannot see.

    There could be other dimensions of existence that we cannot yet see or meaningfully detect let alone communicate with or understand

    Travel and communication could be instant for some life forms and time and space as we understand it may not exist. So distance may be meaningless for such beings making SETI research very limited to only our alien peers who have developed similar technologies

    Just because we dont understand or cannot comprehend does not mean its not possible

    200 years ago people did not dream of jet travel, nuclear power or that exploring space was possible, let alone being able to communicate instantly over 1000s of miles or doing so meaningfully with other life forms here on earth.

    We still cannot talk to the animals, whales birds or plants on earth so why would advanced life that can reach earth in a few days, months or years or even instantly talk to us or reply to SETI signals ?

    See the article below

    hevf1011 said:
    I wrote an essay several years ago titled “SETI’s Mission Impossible.” I argue that the complexity of any extraterrestrial life form that could evolve to the point that it could produce radio signals which could be detected by radio telescopes on Earth is virtually impossible. Using human beings as a proxy, I challenged the famous Drake Equation used to estimate the likelihood of civilizations on other planets with capabilities similar to ours – that is to the point where they could send out radio waves. As opposed to the Drake Equation’s seven variables, I identified 57, but used only 40, which are assumed to be sequential and thereby calculated as a factorial. The end result for succession of 40 conditions in order for life like ours to exist on another planet would be 40!, which is 8.16^47. That is to say, the chances of another alien civilization like ours is a little under one in 8.16 trillion, trillion, trillion, trillion. So, clearly, the Search for Extraterrestrial Intelligence is all but impossible.

    For those who might be interested in this essay, see
  • Snorrie
    These comments reveal a wealth of diverse knowledge and insights that folks have. It is very informative to read them. Sadly, it seems to me that the laws of economics, physics, biology and chemistry as we currently understand them predestine H. Sapiens to be the only form of "compatible intelligent life" within a radius of 46bly of Earth. However, the searching and space programs do yield benefits direct applicable to our current existence which is a sufficient reason to prudently and economically continue.
  • adam
    Here is another interesting perspective on alien life

    Some alien life may have wiped itself out already and those that didnt may be billions of years old and come from nearer the center of the Universe
    Also an article on possible space travel via superhighways.

    Given this has only recently been detected there seems a good chance of other more complex energy fields that we have not detected or even understand that would allow faster space travel that is outside any current field of public knowledge