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What If SETI Finds Something, Then What?

Beyond its immediate cultural and philosophical implications, the reception of a signal from another civilization will call for analysis across all academic disciplines as we try to make sense of it. Herewith a proposal for an Interstellar Communication Relay, both data repository and distribution system designed to apply worldwide resources to the problem. Author Brian McConnell is an American computer engineer who has written three technical books, two about SETI (the search for extraterrestrial intelligence), and one about electric propulsion systems for spacecraft. The latter, A Design for a Reusable Water-Based Spacecraft Known as the Spacecoach (Springer, 2015) has been the subject of extensive discussion on Centauri Dreams (see, for example, Brian’s A Stagecoach to the Stars, and Alex Tolley’s Spaceward Ho!). Brian has also published numerous peer reviewed scientific papers and book chapters related to SETI, and is an expert on interstellar communication systems and on translation technology. His new paper on the matter is just out.

by Brian McConnell

SETI organizations understandably focus most of their efforts on the initial step of detecting and vetting candidate signals. This work mostly involves astronomers and signal processing experts, and as such involves a fairly small group of subject matter experts.

But what if SETI succeeds in discovering an information bearing signal from another civilization? The process of analyzing and comprehending the information encoded in an extraterrestrial signal will involve a much broader community. Anyone with a computer and a hypothesis to test will be able to participate in this effort. I would wager that the most important insights will come from people who are not presently involved in SETI research. What will that process look like?

The first step following the detection of an extraterrestrial signal will be to determine if the signal is modulated to transmit information. Let’s consider the case of a pulsed laser signal that optical SETI (OSETI) instruments look for. This type of signal consists of a laser that emits very bright but very short pulses on nanosecond time scales. By transmitting very short pulses, the laser can outshine its background star while it is active, and without requiring excessive amounts of energy. OSETI detectors work by counting individual photons as they arrive. Photons from the background star will be randomly distributed over time, while the pulsed signal’s photos will arrive in tight clusters.

This type of signal can be modulated to transmit information in several ways. The duration of each pulse can be altered, as can the time interval between pulses. The transmitter can also transmit on several different wavelengths (colors) to further increase the data rate of the combined signal.

Image: Pulse interval modulation varies the delay between individual pulses.

This type of modulation will be easy to see with currently deployed OSETI detectors, so it is possible that in the case of an OSETI detection, we would also be able to extract data from the signal right away.

How much information can be encoded in an OSETI signal that is also designed to be easy to detect? We can calculate the transmission rate as follows.

Let’s work an example as follows. The signal has 20 distinct color channels and chirps on average about ten times per second. Each pulse can have a duration of 1, 2, 3 or 4 nanoseconds, and so it encodes two bits of information in the pulse width. The interval between pulses can have 256 unique values, and so it encodes 8 bits of information in the pulse interval. Plugging these numbers into the equation, we get 2,000 bits per second. While this is glacially slow compared to high speed internet connections, this works out to 172 megabits of data per day, or 21.6 megabytes per day. At this rate, the sender could transmit several thousand high resolution images per year.

The Interstellar Communication Relay, described in a recently published paper in the International Journal of Astrobiology, is a system that will be deployed in the event of a detection of an information bearing signal. It is modeled off the Deep Space Network, although it will be much less expensive to build and operate, as it will use virtualized / cloud based computing and data transfer services. The ICR will enable millions of amateur and professional researchers worldwide to obtain data extracted from an ET signal, and to participate in the analysis and comprehension effort that will follow the initial detection.

What type of information might we encounter in an alien transmission? This is anyone’s guess, and that is why it will be important to have a broad range of people and expertise represented in the message analysis and comprehension effort. Anything that can be represented in a digital format could potentially be included in a transmission.

Let’s consider images. A civilization that is capable of interstellar communication will, by definition, be proficient at astronomy and photography. Images are trivially easy to encode in a digital communication channel. Images are an interesting medium because they are easy to encode, and can represent objects and scenes on microscopic to cosmological scales. Certain types of images, such as planetary images, will be especially easy to recognize, and can be used to calibrate the decoding process on the receiver’s end.

The bitstream below is an example of what an undecoded image might look like in a raw binary stream. The receiver only needs to guess the number of pixels per row to see the image in its correct aspect ratio. This image is encoded with nine bits per pixel, with the nine bits arranged in 3×3 cells, so the undecoded image appears in its correct aspect ratio. Even before the image is decoded, it is obvious that it depicts a spheroid object against a black background, which is what a planetary image will look like,

The receiver only needs to work through a small number of parameters to decode the image successfully, and once they have learned the transmitter’s preferred encoding scheme(s), they will be able to decode arbitrarily complex images. Because planetary images have well understood properties, the receiver can also use these to calibrate the decoding algorithm, for example to implement non-linear brightness encodings.

Image: The bitstream above decoded as a grayscale (monochrome) image. Credit: NASA / Apollo 17.

What about color? Color is a physical property that will be well understood by any astronomically literate civilization. The sender can assist the receiver in decoding photographs with multiple color channels by sending photographs of mutually observable objects such as nebulae.

Image: The Cat’s Eye nebula, imaged in red, green and blue color channels.

Image: Combining these color channels yields the following image. A receiver can work out which color channels were used in an image by combining them and comparing the output against images they have taken of the same object.

Images are a good example of observables. Observables, such as images and audio, are straightforward to encode digitally. Communicating qualia, internal experiences, may be quite difficult or impossible due to the lack of shared senses and experiences, but it will be possible to communicate quite a bit through observables which, in and of themselves, may be quite interesting. Photographs from another inhabited world would surely captivate scientists and the general public.

Computer programs or algorithms are another type of information to be on the watch for. Computer programs will be useful in interstellar communication for a number of reasons. The sender can describe an interpreted programming language using a small collection of math and logic symbols. While this foundation can be quite simple, with about a dozen elemental symbols, the programs written in this language can be arbitrarily complex and possibly even intelligent.

An algorithmic communication system will have a number of advantages over static content. The programs can interact with their receivers in real-time, and thus eliminate the long delays associated with two-way communication across interstellar distances. Algorithms can also make the communication link itself more reliable, for example by implementing robust forward error correction and compression algorithms that both boost the information carrying capacity of the link, and allow transmission errors to be detected and corrected without requesting retransmission of data.

Take images as an example. Lossy compression algorithms, similar to the JPEG format, can reduce the amount of information needed to encode an image by a factor of 10:1 or more. Order of magnitude improvements like this will favor the use of algorithmic systems compared to static, uncompressed data.

These are just a couple of examples of the types of information we should be on the watch for, but the range of possible information types we may encounter is much greater than that. That’s why it will be important to draw in people representing many different areas of expertise to evaluate and understand the information conveyed by an ET signal.

The paper is McConnell, “The interstellar communication relay,” International Journal of Astrobiology 26 August 2020 (abstract).


Comments on this entry are closed.

  • Mike Serfas August 31, 2020, 12:15

    What’s really going to bake your noodle is if you can track the transmission to 40,000 light years away … and the Cat’s Eye nebula is depicted from our perspective.

    It seems cheaper to encode light frequencies in a header as numerical multiples of the fundamental transmission frequency. They can assume we’d figure out their numbers, given some low-bandwidth basic exercises, and they don’t have to count on us looking at the same nebula in the same frequencies from the same angle.

    • Brian McConnell August 31, 2020, 18:53

      The best approach is to provide multiple paths to comprehension. In the case of images, they could also include a solar spectrum and add a marker to point to the wavelength for a given color channel. But that is just one part of image encoding. You also need to provide clues about non-linear brightness (gamma curves). This is why I like the idea of sending pictures of mutually observable objects. Then the receive can cross check their decoding process against pictures they have taken of the same object. If I were designing a transmission, I would think about multiple ways to hint at the correct solution.

  • Michael Fidler August 31, 2020, 12:32

    What about AI, we are already having issues in planetary imaging using an AI system called Topaz AI that can bring detail in images but can also cause artifacts and false data. This is because the AI does not have enough training but for interstellar messaging the opposite may be true and the database may be huge. This would give the receiving end little data needed to decipher the message while leaving ET’s such as us without the database to decipher it.

  • DCM August 31, 2020, 12:48

    Then just silently listen and look.

  • Andrei August 31, 2020, 14:13

    The idea of sending a program that will provide real time 2 way communication is one touched upon in Science fiction. It is the behind the scenes reason for the the events described in W. Gibsons Neuromancer. If such a set of program instructions is received it should be carefully handled though, the risk of a Troyan horse should be very carefully considered.
    There’s other things to keep a lookout for though, I amused myself of thinking this might be an example of alien art or a feat made by a super civ, of course it is not but KIC 2856960 is indeed midboggling.
    “KIC 2856960: The impossible triple star”
    Authors: T. R. Marsh D. J. Armstrong & P. J. Carter

  • Geoffrey Hillend August 31, 2020, 15:33

    I like the idea of images used for interstellar communication. A optical first contact might be simple like the images on plaque of the Pioneer spacecraft because there is no ambiguity and no need for high resolution. It is logical to assume intelligent ET’s who wanted to communicate optically with us or planet in another star system would keep things simple since that is the way we would do it.

    Also language and letters can be used which is easy to decipher since all languages have nouns which always are the same or repeat in words and the way language is constructed since the other parts of speech are universal.

    • H. Floyd August 31, 2020, 17:59

      First ETI contact through images is a fascinating possibility. It could communicate as much about the sender’s neurological context as about the image content itself.

      On that topic: you might enjoy the novel Axiom’s End, published this year. Similar themes to the film Arrival, except Lindsay Ellis takes a more sophisticated stab at the unanticipated risks posed by intelligent interspecies communication.

    • Brian McConnell September 1, 2020, 19:08

      It’s important to note that many different media types could be included in a digitized message. A sender who is trying to establish communication with a naive receiver would be smart to send a multipart message that includes a variety of content types. That said, images are a good place to start since they will be a lingua franca for astronomically literate civilizations (even if vision is not a species preferred sense, they will need to understand light and photography to be proficient at astronomy).

  • Alex Tolley August 31, 2020, 16:37

    I think that we should think more about the purpose of such signaling and therefore what technologies and content would be used and transmitted.

    Unless ETI has a lurker in our system that must report back to the homeworld at FTL velocity, then the ETI will have no current knowledge of its targets. For an ET 1000 light years away, at best it can see our civilization [s] around 1000 CE. If 10,000 lightyears way, there will be effectively no human civilization at all. If the ETI wants to attract our attention, it would make most sense to use very slow modulation of its signal to attarct attention by any low-tech civilization. This might be a laser or other method to modulate its stellar output in the direction of the target. The modulation would be obviously artificial, perhaps pulses depicting some number sequence that can be readily detected by eye and repeated in some way. There may or may not be a signal embedded in the pulses, but the aim is to draw attention to the source so that at some point, a high-tech civilization can attempt to decode the signal embedded in simple attention grabbing one.

    Given that the ETI has some information that its targets can decode more complex signals, why would it use signaling that can be detected by our current, rather transient, level of technology? Why not use simpler technology? If they use even more sophisticated technology, we (as a target) would be unable to extract any signal. A lurket parked nearby might have a better opportunity to assess our technology level based on our emissions, but then its approach and aims might be rather different.

    There is an implicit assumption that ETI usees in color as we do. The RGB coding matches our color perception. We know that other animals on Earth either have fewer different color receptors, and some have more. They may also see in different wavelengths, for example insects see more UV than we do. As ETI cannot know what, if any, color perception we have, why would they embed color in the signal at all?

    Images, whether hi-definition as in the planet example, or much more abstract, do seem to be what we would argue is universal. However, some mathematicians have preferred abstract mathematics as a way to communicate. While I love the idea of transmitting computer algorithms, this strikes me as much more difficult to encode unambiguously, and hence decode. This is rather like the scenario of Stanislaw Lem’s His Master’s Voice. The more one moves away from universals, the more there must be an overlap in cognitive modes to enable understanding. While the late John McCarthy believed ETI minds would be convergent with ours, IMO it was more a belief based on some dubious ideas about convergent evolution on Earth than any strong argument.

    Lastly, the SETI endeavor maintains the assumption that ETI has to remain on its homeworld, or at the very least, will transmit from within a star system. This is even more apparent with the targeting of exoplanets with planets in the HZ. IMO, this is another trap in thinking based on our beliefs about the possibilities of interstellar travel. If the anti-METI people are correct in their thinking, this might be the last thing that a civilization would do. If they did not want to stay silent, they would want to transmit from a location distant from their system, just in case. Cixin Liu made quite a good argument for a predatory situation in his Remembrance of Earth’s Past trilogy.

    Given the issue of lightspeed communication lags, it strikes me that placing a probe[s] with AGI level capabilities in a system with worlds in the HZ and with evidence of life might be the most economical option. The probe could remain dormant for the eons of time where there was no technological life. It could readily detect stray emissions from early technology, and activate at some point. It could then try to initiate a conversation without the lag issues. All that this probe would need is a technology that could withstand the rigors of time between later replacements. If FTL communication is possible, then the probe could act as a conduit to the homeworld, bypassing the need of the target world to develop the technology needed. The target world could even just show physical pictures to the probe which could send them home, and in turn display images to the locals.
    A probe that could travel at just 1% of c, whether with FTL communication capabilty or AGI would rapidly prove more effective than communication with em radiation over interstellar distances.

  • Al Jackson August 31, 2020, 17:53

    Murray Leinster seems to have given it the name.


  • Thomas W Hair August 31, 2020, 22:07

    Given the age of the Universe and its evolution over time if THEY exist at all, then THEY could be billions of years old. This implies that if THEY are not solipsistic, then THEY know we are here. THEY could scan the whole galaxy if THEY wished. Therefore if THEY truly exist, then searching for them is moot even if there are many different THEY. It would only take one of the THEY to abrogate this silence we perceive for us to be contacted. PS sorry for the all caps thing, just making a simple observation/opinion in a highly speculative field of great endeavor.

    • Alex Tolley September 1, 2020, 11:40

      Even a billions of years old civilization, if located in a small part of the galaxy, far from us, and still subject to light velocity, may not know about us at all. Their knowledge of Earth would be many millennia old, even if they had surface, documentary detailed, knowledge of Earth and its species. H. sapiens would be just another tool using animal, with the sole unique feature of using fire.

      They might just be content to watch and monitor. They might even start to send some sort of transmissions on the chance we had developed some sort of receiving capability. If so, I maintain that the simplest thing to do is just draw attention with a signal that is readily observable with the human eye. Some millennia later, they would then know if we had noticed, and then send something more complex, but always with the assumption that Earth technology was no more advanced that they had observed.

      If this civilization is so old, and it is avoiding other civilizations, then it would remain in observation mode only, fearing any transmission could alert another advanced civilization.

      Robin notes that we may just intercept a communication transmission by chance. Others have suggested leaks from power transmissions, or starship exhausts. Unless the galaxy is a very busy place, using technologies we currently have or can envisage, the probability of such a detection is very low, akin to being in a remote place on Earth and hoping to detect a stray transmission from an airliner. Not zero, but vanishingly low.

      If we are as ants with our nest near a freeway or greefield mall development, far better to try to understand that the artifacts are non-natural, rather than hope for meaningful chemical communication and getting confused by polluting chemicals in the air and soil.

      The Haldane quote is relevant, yet we still insist of doing SETI as if the aliens are Adamski’s benevolent, humanoid Venusians, or many religions humanoid gods or angels.

      • Thomas W Hair September 1, 2020, 22:25

        Greats comments Alex, as always. My only response is that you and I can envision a very large monitoring device placed above the galactic plane able to monitor nearly everything within our galaxy with great precision given enough time and technological advancement…say an optical/infrared/uv telescope with the diameter of our moon. Billions of years of intelligence is a tough nut for us to wrap our heads around and using five thousands years of human history as a guide to knowing THEY seems strange to me. I agree with DCM, just look and listen because THEY might not know for sure we are here, but THEY might suspect with some probability (unfathomable to us) that we might arrive on scene within a predictable time frame based upon their current view.

        As for the light time delay, THEY can probably run probabilistic models so precise on 50,000 year old observations of Earth that said computations would be incomprehensible to us. I would think THEY would have a pretty well-defined confidence interval on the possibility that intelligence would eventually arise on our planet based upon their detailed observations.

    • randomengineer September 3, 2020, 19:27

      So what happens if the issue here is that the great S curve of intelligent life has it that the practical max of species intellect is the level of tech used by the Klingons? Not the theoretical max, the practical one. We’d have a handful of galactic regions hosting warp drive and such, and maybe one or two of these had their eye on the sagittarius arm some 30 kya, but found nothing interesting. Everything else seems bound by S curves; why would this not apply to intellect?

      Alternately, it could be that the universe is full of ET and due to dunning-kruger we can’t know, and we can’t know that we can’t know. Think of this as the Rumsfeld-verse.

      • Ron S. September 4, 2020, 16:24

        It is incorrect to assume a strong correlation between intellect and technological/scientific progress, and you also need to precisely define “intellect”. Let’s assume intellect (of some description) plateaus. If progress requires super-geniuses they will still come along though at a slower pace. If not, progress may be slower but can be at least partially compensated by number of participants and resources.

        Even if that is insufficient, all you need is to achieve the construction of AI and it will do the job instead, either itself or by improving itself or designing more advanced AI that can do the job.

        Rather than any ceiling in intellectual capacity it would be very difficult to avoid continuous improvement. How it would manifest is more difficult to predict.

        I have no idea why you think D-K syndrome is relevant.

        • randomengineer September 4, 2020, 23:11

          There plenty of adherents to the notion that we hear nothing — the great silence — because we’re not worthy or clever enough (feel free to substitute other descriptors); we lack the requisite tech and/or smarts. We’re isolated.

          Now if you’re right and it’s abundantly clear that supergenius level IQ is attained sooner or later via AI then this surely shouldn’t escape ET. There would be no reason to isolate us because it’s not going to matter. A species acquires intelligence enough to control fire and invent metallurgy, and at that point it’s a matter of time — not if, but when. Wild earthlings isolated because we’re dangerous or … [pick reason] doesn’t seem to jibe with the notion that technological species develop AI. There would be no reason for ET detecting us and assuming we can’t ever detect them.

          Meanwhile, I was suggesting D-K could apply to us because Prof Hair’s proposition that his “THEY” would be so far ahead of us that we can’t (and won’t) be able to know it. D-K at its core is little more than saying the ignorant can’t know they’re ignorant.

          • Ron S. September 5, 2020, 8:44

            I don’t disagree with you on the ignorance comment (i.e. lack of knowledge and even inability to know what one doesn’t know) as it relates to ETI. However D-K is misjudgment about one’s own competence in a field in part due to poor knowledge of the field. The word “ignorance” should not be applied with too broad a brush. That said, some with strong opinions on SETI do exhibit signs of D-K syndrome.

  • Robin Datta September 1, 2020, 0:11

    A received EM signal, if incidental from an alien radar or propulsion system would still be informative enough to reset the Fermi paradox. Even a communication signal may be no more helpful than “Return to base” or “Returning to base”.

    Then again it could be a news bulletin to a ship or a colony, or a status report from one of them to home. A nearby lurker probe may communicate locally, signal home, or both. And then there have been musings about The Black Cloud.

    Maybe someone has the altruism to beam an atlas or photo gallery to us. With a aspect to structures that might only be apparent at a few thousand light years’ remove from us. And perhaps an encyclopedia. Along with a Trojan Horse?

    Those who are doung SIGINT for a living should be tasked with the analysis of any such phenomena to exclude Trojans before its general release.

    “The Universe is not only queerer than we suppose, but queerer than we can suppose”. J. B. S. Haldane, in Possible Worlds and Other Papers (1927), p. 286.

    • Michael Fidler September 2, 2020, 1:47

      Interesting that you mention SIGINT since the military black programs are years ahead of the Star Trek mentality of some SETI researchers. The Delta Heavy sitting on the launch pad as we speak is a SIGINT updated satellite. The military and contractors for these projects must have volumes of information on non earth signals all under national security secrets act. This is why the U.S. government does not fund SETI, because they already spend 10s of billions of dollars on it each year…

      • Michael Fidler September 2, 2020, 9:07

        Three good articles…

        Want to Talk to Aliens? Try Changing the Technological Channel Beyond Radio.

        Finding cosmic civilizations might require a more innovative approach than listening for radio transmissions.
        By Adam Mann on September 2, 2020


        A breakthrough in the search for extraterrestrial intelligence.

        Posted by Deborah Byrd in HUMAN WORLD | SPACE | September 2, 2020
        The researchers called their new analytical technique “a milestone in SETI.” One researcher commented: “We now know that fewer than one in 1,600 stars closer than about 330 light years host transmitters just a few times more powerful than the strongest radar we have here on Earth.”


        Extending the Breakthrough Listen nearby star survey to other
        stellar objects in the field.
        We extend the source sample recently observed by the breakthrough Listen Initiative by including additional stars (with parallaxes measured by Gaia) that also reside within the FWHM of the GBT and Parkes radio telescope target fields. These stars have estimated distances as listed in the extensions of the Gaia DR2 catalogue. Enlarging the sample from 1327 to 288315 stellar objects permits us to achieve substantially better Continuous Waveform
        Transmitter Rate Figures of Merit (CWTFM) than any previous analysis, and allows us to place the tightest limits yet on the prevalence of nearby high-duty-cycle extraterrestrial transmitters.
        The results suggest . 0.0660+0.0004 −0.0003% of stellar systems within 50 pc host such transmitters (assuming an EIRP & 1013 W) and . 0.039+0.004 −0.008% within 200 pc (assuming an EIRP &
        2.5×1014 W). We further extend our analysis to much greater distances, though we caution that the detection of narrow-band signals beyond a few hundred pc may be affected by interstellar
        scintillation. The extended sample also permits us to place new constraints on the prevalence of extraterrestrial transmitters by stellar type and spectral class. Our results suggest targeted
        analyses of SETI radio data can benefit from taking into account the fact that in addition to the target at the field centre, many other cosmic objects reside within the primary beam response
        of a parabolic radio telescope. These include foreground and background galactic stars, but also extragalactic systems. With distances measured by Gaia, these additional sources can be
        used to place improved limits on the prevalence of extraterrestrial transmitters, and extend the analysis to a wide range of cosmic objects.


        “Enlarging the sample from 1327 to 288315 stellar objects permits us to achieve substantially better Continuous Waveform
        Transmitter Rate Figures of Merit (CWTFM) than any previous analysis, and allows us to place the tightest limits yet on the prevalence of nearby high-duty-cycle extraterrestrial transmitters.”

      • ljk September 2, 2020, 9:41

        A definite possibility, but the problem is the military tends to ignore anything that is not part of their objective, which is to monitor terrestrial signals. I doubt that attitude has changed since the Cold War.

        This is exactly what happened with the discovery of pulsars. They were actually detected in 1964 by a member of the USAF:


        To quote:

        Schisler returned to Clear with the coordinates of other radio sources that he thought he might be able to detect with the radar. Throughout the late summer and early autumn, he began a meticulous log of anything he could spot on the scope. Because the radar was designed to pick up man-made pulses bouncing off incoming missiles rather than steady signals, Schisler believes most of the things he saw were pulsars. By his own count, he spotted about a dozen sources.

        “My commanders didn’t know what the hell I was doing,” he recalls.


        For his part, Schisler says he never quite understood what he was looking at until he heard of Hewish and Bell Burnell’s discovery on a short-wave radio. When he learned that they had discovered a pulsating radio star, Schisler says, the significance of his own work became clear. But he says he didn’t dare speak about the log until nearly half a century later, when the old early-warning system at Clear was finally decommissioned. He says that he feels he deserves no credit for his work, but he still regrets that he was unable to share what he had seen.

        “I wish we had had a way to communicate with the scientific community,” he says.

  • Richard Burke-Ward September 1, 2020, 5:44

    I agree with what Alex Tolley says. I think searching for ETI artefacts within the bounds of our own solar system is neglected at our peril.

    But this is just one symptom of a deeper malaise in SETI, which is the unavoidable problem of anthropomorphism. Most radio- and O-SETI practitioners will admit that the reason for their particular searches is not that it is the ‘best’ way to detect ETI, but that it is one of the few methods at our disposal. It’s potentially the equivalent of looking for a needle in a haystack by sound because ears are all we have to search with.

    In the case of this particular article, it is of course possible that ETI will have some sort of vision: the selection effect here lies in the fact that in order to transmit to other stars, they must be aware that those stars exist – and that implies (though it doesn’t guarantee) that they have some ability to perceive at least some electromagnetic frequencies, because that is one of very few ways that information can be carried over interstellar distances. So, all those ETI that evolved from some alien analogue of naked mole rats or cave fish or bats may be out there, but they are unlikely to transmit to us. Having said that, even if they have an electromagnetic sense, how easy would we find it to decode an image of astronomical objects as seen in gamma frequencies? It’s possible, but it might take a long time before the eureka moment…

    The idea of using ‘simplified’ images like the Pioneer plaque is problematic too. There are levels of coding embedded in that image which most people don’t think about – cultural assumptions about seeing things in silhouette, what a line-drawing indicates, and so on. The plaque is full of our (western) society’s history of representing 3 dimensions on a 2 dimensional surface. There are plenty of folk in the forests of Irian Jaya or in the Amazon forests who would be utterly non-pluses even by the human outlines; they just wouldn’t be able to decode it into a representation of people. And they’re *human*!

    Another problem is political. There will be counters, organisations, cults, media channel, etc who resolutely do not want any message decoded. How do we deal with them? How do we deal with the fact that if the signal originates from a location lying broadly on Earth’s ecliptic, and if it is longer than about 12 hours, then no single country is likely to have the whole message because the Earth rotates? It’s a reasonable assumption that an ETI might contain insights that offer an strategic advantage to countries or organisations that have a monopoly on its content. So, we should expect sabotage, espionage, whispering campaigns, disinformation, civil protest, the forging and dismantling of unusual international alliances aimed at creating whole versions of the message…

    The premise of this article is that any decoding effort should draw on expertise from a wide variety of source. Yes, and yes again. In terms of understanding a message whose structure and meaning is profoundly alien (IMHO, deeply unlikely to be an image with the kind of encoding schemes the article envisions, or even if it is, then it’s unlikely to be an image whose content is easy to parse into our understanding of what constitutes a separable object or entity), then the more the merrier. And this can happen after message is detected.

    Much more urgent, I think, is to forge an international agreement on how the message is assembled from nationally-held fragments by the international community, and who runs the decoding effort, and where. There are huge political issues here which the world’s politicians have failed to address – perhaps for fear of losing popularity by talking about ‘little green men’. There are people working to develop such plans – but without widespread international political backing, they are meaningless.

    I would love for humanity to detect an extraterrestrial civilisation or artefact. It has profound philosophical consequences, and may just help expand our minds beyond the limits of our petty local concerns – something we desperately need as a species. However, the very existence of such a signal has the potential to destabilise our fragile no-longer-fit-for-purpose political structures, revealing in a very concrete and destructive way our inability to recognise that we all share the same small planet and that there is less genetic difference in the entire human race than in a single troupe of chimps.

    • randomengineer September 3, 2020, 19:07

      Hold on a sec, you’re sort of on the verge of claiming that a super intelligent ET couldn’t see FRB’s or pulsars because of non native need for such organs?

      The reason for use of radio and optical isn’t limited to what we can easily mess with, but that it is all part of the electromagnetic spectrum. We don’t see in UV natively but we can certainly create that which optimises that bandwidth. We can construct instruments like LIGO that “see” gravity. One would presume that any sort of intelligence would be able to master electromagnetic (and other) frequencies; it’s all physics.

      If we can see the galaxy cleanly via electromagnetism, why wouldn’t any other species?

      • Richard Burke-Ward September 4, 2020, 5:14

        That’s not quite what I’m saying. It’s clearly true that any ETI that might send signals into interstellar space is likely to be aware of the electromagnetic spectrum (but note that this says nothing about any ETI don’t send such signals). The issue is how they *interpret* any data they acquire from electromagnetic sources. There are countless biological and cultural filters involved in the human process of perception, consolidation and communication of the original electromagnetic data we receive from our eyes – and we have carried all those filters with us into the way we perceive and communicate information from other parts of the EM spectrum. My point is that there is a huge and non-logical leap implied in the (very human) assumption that if a particular ETI is capable of receiving and processing electromagnetic information we must therefore have enough in common to be able to ‘read’ a communication from them. This is just a fallacy, as is evidenced by the fact that we think of things like the Pioneer plaque as being ‘simple’; It’s anything *but* simple. Try it as an experiment – give an etching of the plaque to a blind person for them to feel, tell them it is a representation designed for someone with an electromagnetic sense. That person may understand what electromagnetism is – they may even use it in their day to day job, they could be a radio astronomer, whatever – but will they ‘understand’ the plaque? Not a chance. Chances are, they won’t even be able to figure out that there are two human forms represented on it. And this is *human-to-human* communication! Communication with ETI is likely to be many orders of magnitude harder, even if they share the same understanding of physic as us.

  • ljk September 1, 2020, 14:28


    Reworking the SETI Paradox: METI’s Place on the Continuum of Astrobiological Signaling

    T. Cortellesi

    The Search for Extraterrestrial Intelligence (SETI) has heretofore been a largely passive exercise, reliant on the pursuit of technosignatures. Still, there are those that advocate a more active approach. Messaging Extraterrestrial Intelligence (METI) has had a controversial history within the larger SETI project; it is claimed that the risks involved outweigh any potential benefits. These arguments are ultimately not compelling, result in absurd policy recommendations, and rest on a faulty appreciation of the nature of technosignatures, whose detectability implies intent to signal.

    Present technology is advancing quickly such that we will soon have great observational reach, to the point of reliably detecting such technosignatures and biosignatures: a capability that can be matched or exceeded elsewhere.

    To escape the SETI Paradox properly defined, at least one technological civilization must choose not to suppress its own continuum of astrobiological signals, of which METI is merely the most effective endmember. Passive SETI’s low likelihood of success in the short-term is a serious obstacle to sustainable funding, alongside a ‘giggle factor’ enhanced by a pernicious fear of contact.

    The scientific community must integrate an active approach to better ensure both the continuity and eventual success of the SETI project.

    Comments: 15 pages, accepted JBIS 7 July 2020

    Subjects: Popular Physics (physics.pop-ph); Earth and Planetary Astrophysics (astro-ph.EP)

    Journal reference: JBIS Vol. 73 No. 07 (July 2020) 260-267

    Cite as: arXiv:2006.01167 [physics.pop-ph]
    (or arXiv:2006.01167v3 [physics.pop-ph] for this version)

    Bibliographic data

    [Enable Bibex (What is Bibex?)]

    Submission history

    From: Thomas Cortellesi [view email]

    [v1] Mon, 1 Jun 2020 18:01:59 UTC (316 KB)
    [v2] Sat, 4 Jul 2020 14:17:51 UTC (321 KB)
    [v3] Mon, 27 Jul 2020 14:36:05 UTC (411 KB)


    • Robin Datta September 1, 2020, 20:25

      METI might be comparable to experimenting with insect or other pheromones using a rather limited repertoire of EM frequencies to signal, with SWAGs as to the responses likely to be elicited, and without definitive knowledge of the existence of a recipient or of their capabilities to detect the signal. A lot of faith and expectation of good fortune would be de rigueur.

    • DCM September 2, 2020, 4:55

      Don’t assume detectability implies intent to signal. Our radio and television broadcasts beginning a century ago were purely local [Earth] news and entertainment, not intentional signals to aliens. There were attempts to contact possible Martians and Venusians but the assumption was they strongly resembled us and that wasn’t our basic overall reason for broadcasting.
      We’re actually operating on assumptions and mental projections, not even well based hypotheses. We simply don’t know anything about possible aliens.
      Look and listen only for now.

      • ljk September 2, 2020, 9:34

        You and many others can say “look and listen for now,” but with 7.8 billion humans on a planet where the proper technology is becoming more available, that advice is like a sieve trying to stop sand.

        This also assumes that all other intelligent technological species out there are somehow well behaved in ways we are not, that there won’t be any members of their kind sending messages into the galaxy to provoke a response.

        Rather than spending time and resources policing everyone on Earth with a radio and dish antenna (or laser) in a futile effort, it would be better to prepare ourselves for the eventualities of living in a Universe that is very probably not ours alone.

        • Alex Tolley September 2, 2020, 11:17

          While absence of evidence does not logically mean evidence of absence, it does not preclude that outcome either.

        • DCM September 2, 2020, 11:37

          Exactly. We simply don’t know what alien life might be like, especially complicated intelligent life.
          We need to be developing out neighborhood and building O’Neill type space habitats.
          Possibly we’re just lucky there’s nobody else within our immediate reach, allowing us to do just that without interference.

          • ljk September 2, 2020, 13:26

            I actually agree with this strategy, but keep in mind the Universe is not obligated to wait until we are ready, whenever or however that is.

            It keeps throwing viruses, hurricanes, and earthquakes at us all the time without warning. ETI will probably be the same, as I have little faith in them having a version of the Prime Directive.

  • Alex Tolley September 2, 2020, 11:14

    This also assumes that all other intelligent technological species out there are somehow well behaved in ways we are not, that there won’t be any members of their kind sending messages into the galaxy to provoke a response.

    … living in a Universe that is very probably not ours alone.

    But then you run into the Fermi Question again. All these “rogue” broadcasters would have to be using technologies we don’t have and cannot yet listen in to for this scenario to be the case as well as the apparently lack of detection so far.

    • ljk September 2, 2020, 13:33

      Until recent years, SETI was sporadic and limited in its range and equipment types, so we could have easily missed a lot of signals, intentional and otherwise. Even now it is not like we are covering the skies 24/7 with a wide variety of instruments.

      And I don’t know if this has changed, but I recall Frank Drake saying not too long ago that they have collected tons of data but did not have either the funding or personnel to sift through it all.

      This is why I do not get too worked up when it is said we should have detected a signal by now. SETI has been amateur hour for most of its history at best.

      You can see the history of SETI searches for yourself here:


      • Brian McConnell September 4, 2020, 18:11

        Jason Wright, who does a lot of Dysonian SETI research, quantified the parameter space to be searched and how much we have covered to date. The search space is roughly the equivalent of a large bath tub relative to the oceans. So even modern SETI searches are limited in how much of the sky they can monitor at any time, data recording capacity, etc.

        • Alex Tolley September 5, 2020, 0:56

          The analogy has been used a lot, but it may not be the correct one. For example, you don’t need to trawl the ocean to catch fish, you just need to leave a gillnet in the ocean and the fish swimming by will get caught in in.

          Similarly, to detect animals on Earth, you don’t have to do more than watch carefully and they will come within range.

          The Fermi Question is relevant too. The evidence of aliens should be everywhere, yet there seems no evidence of them. Without checking each cubic meter of water in a lake, we can put out a few nets or traps and if nothing is caught, assume that there is nothing to be caught. Designing ever more complex nets and traps will unlikely change that result.

          If ETI is out there, the civilization should be fairly ubiquitous. If we cannot detect them with the nets, err em frequencies we are using, either we need a very different communication mode, or we might consider that they are not there at all. Trying to cover all the possibly em spectrum for all teh sky for a long period of time is a brute force, rather than smart way of looking for ET.

          SETI is a bit like cryptozoology. People used to look for such animals with various expeditions. Loch Ness is well observed in an attempt to find “Nessie”. But it turned out the smart way to look for such a beast was to sample the waters of the Loch and analyze the DNA fragments that have been exuded or sloughed off. The analysis found the species known to be in and around teh Loch, but no hint of anything exotic. That pretty much put a nail in Nessie’s coffin and no doubt has diminished the income of a number of the Loch’s locals.

          Recently, hidden cameras placed on animal trails in forests have caught a number of rare species. This proved a far cheaper approach than setting traps and other labor intensive approaches that came up empty.

          What these smarter methods might be for ETI IDK, but there has got to be better approaches than listening to small patches of the sky with radio telescopes and other em based methods. It is possible full sky surveys might turn up evidence of ETI, but if so, I suspect it will be a seredipitous discovery while looking art some other phenomenon that requires this approach. Like detecting an aircraft indirectly by the vortices it sheds.

          • Ron S. September 5, 2020, 9:02

            “SETI is a bit like cryptozoology.”

            This is sadly often true. I see it in the attempt to fit poor or ambiguous data to a predetermined conclusion. A blurry photograph is Nessie or a sasquatch. An unexplained burst of EM signal is ETI communication. A dimly detected space object is an alien artifact. Poorly resolved images in a small telescope are canals.

            Of course that may indeed be a picture of Nessie, but it almost certainly isn’t. Jumping to conclusions is too tempting for some. A you say, better data is needed. We do not need a larger catalog of blurry images.

  • James Essig September 2, 2020, 15:17

    I just finished reading an article in this September’s issue of Astronomy magazine.

    The article I read was a fascinating presentation on how we will find extraterrestrial life. Accordingly, the life might include any life in the following three categories: 1) Carbon based life like ours; 2) life not much unlike our but based on other chemistries beside carbon based DNA and RNA; and 3) life that we cannot currently imagine or understand.

    After reading the article, I pondered how we humans typically divide our ontology from a philosophical perspective in a three-fold manner: 1) vegetative life; 2) sensitive life; and 3) intellective life. Theories of a soul commonly use the following distinctions of its faculties as intellect, will, sensitive life, and memory.

    Psychodynamic theories make the following 3-fold division of our psyche;; 1) consciousness; 2) sub-conscious; 3) unconscious; and perhaps 4) ultra-unconscious or alternatively, the ID, ego, and superego.

    ETI life likely if discovered will have different religious and cultural preferences along with species specific averaged psychodynamic traits.

  • FrankH September 2, 2020, 15:55

    I think any SETI signal will be from a machine/non-organic AI. If we do get a SETI signal from an organic civilization, I wouldn’t be surprised (but a bit saddened…) if it’s an ad for reproductive pseudopod enhancement.

    • Ron S. September 2, 2020, 21:28

      Why sad? The ad would tell us quite a lot about their biology, technology and culture.

    • ljk September 3, 2020, 10:00

      As I learned in my anthropology classes back in the day, scientists learn a lot more truth from a culture’s trash heaps than they do from the official records.

    • Gary Wilson September 3, 2020, 14:30

      Ads for reproductive pseudopod enhancement would be better than those for the latest laser canon and personal nuclear fusion weapons in the megaton range.

  • Martin Alfredsson September 2, 2020, 18:51

    Why would an ETI send pictures of their homeworld to us?
    Why would they send us anything?

    Its all so anthrosphic, we think we would do it so we assume they would. The chance of a civilisation near enough and near enough to our level of development is astronomicaly small and we just assume that even if one is there they have this urge to contact us.

    Yes, we look at other sentient beings on our world but we are incapable to communicate with dolphins and have a hard time even with chimps. Our urge to communicate with chimps or dolphins is something that a few scolars may be interested in. Most people dont care and funding is almost nonexistant.

    By all means, look for tech, look for remenents of communication not directed at us but dont assume they (ETI) would care for us.

  • Michael Fidler September 3, 2020, 8:54

    I have figured the whole thing out!!! The Aliens are watching us with keen interest because we are developing all sorts of new ideas and technology. They know that as soon as they make contact with us we will stop imagining ideas that they have not thought of and just want all their technology. Like every culture in mans history we will become like zombies just waiting for the next tidbit of information from them. We will become lazy good for nothing slaves to their technology!!! So there you have it, the answer to Fermi’s Paradox… ;-}

    • DCM September 3, 2020, 12:23

      Too much speculation without real knowledge, not enough immediate action with what we can achieve here and now.

    • Michael Fidler September 4, 2020, 10:25

      Now that I made this great discovery, there may be another much more controversial reason no one has contacted us. What if the earth is one of the few locations in our galaxy that has had a virgin birth of life. Now do not laugh and no I do not mean anything religious but what if other civilizations had seeded the galaxy billions of years ago. Now if we were in their situation would it not be very important not to interfere with a planet that has developed life via natural processes? The galaxy may be full of civilizations that developed because of seeding / ET panspermia but finding a planet that naturally had life on it would be like finding a rare gem. So we may be the rarest of life in our galaxy and interfering with a protected planet may have dire consequences…

  • Alex Tolley September 3, 2020, 12:58


    Cixin Liu’s “The 3-Body Problem” is to be developed by Netflix into a tv series.

    A different take on First Contact with its historical scope, could make this a treat if developed well.

  • Gary Wilson September 3, 2020, 14:35

    I don’t think we’ll find ETI by scanning for EM signals. I think it will be a drill down process starting with finding exoplanets in habitable zones with biosignatures (requiring hundreds of years to find), then followup studies with even bigger detectors to look for signs of system wide sentient activity (further hundreds of years) followed by a massive decision about whether or not to send a directed signal and what information to encode in it. I wouldn’t be surprised if the types of ETI we can find and finally recognize are hundreds of light years away. Be prepared to take your life extension medication and then be very, very patient :).

    • ljk September 4, 2020, 10:36

      We may have better luck if we stop assuming the kinds of ETI that we early 21st Century humans can detect will be sitting on the planets they may have evolved from.

      Rather, we should be looking in places like the cold outer regions of the Milky Way galaxy and objects with infrared signatures but no optical counterparts. Or in the vicinity of black holes. For starters.


  • AlexTru September 4, 2020, 4:17

    Very anthropomorphic speculations that are disconnected from reality.
    Optic Image transfer, tricolor approach, 8-bit data size etc… it is so human related and even more related to our modern main stream technology. Arguments used by author – result and sequence of the Earth life evolution paths, and most probable will never repeat in any place of the Universe. ETI, if exists will be very different from homo sapience.
    I am sure that scientific approach requires at first some artificial signal detection, if detected – it can (or cannot) be analyzed and we can try to extract information from alien signal.
    We cannot “dictate” ETI how (and what) they should modulate, code and how send the signals.
    If there are ET civilization, I can bet , none (excluding our own) will match described in discussed article pattern.
    Summary author is describing ways how one homo sapience from the planet Earth can communicate with other homo sapience from the planet Earth, may be this ideas can even allow interstellar communication (not sure).
    Because we do not have any information about ETI (our potential distant correspondent ) every crazy, Sci-Fi or fairy-tales ideas are equal on this stage… There is no any reason to limit our imagination by our modern technology level.

  • David M Ocame September 4, 2020, 10:30

    I think we are getting way ahead of ourselves when trying to build in 2 way comms for SETI. The distances are so vast, there is virtually no possibility of 2 way communications. …and, we don’t have subspace comms, so please don’t offer that as a solution.

    • Alex Tolley September 4, 2020, 18:36

      You are assuming as the SETI folks do, that the ETIs are stuck in their home system. However, if they have sent probes out to potential systems, those probes could communicate with us in near real-time. This would make far more sense. A civilization far older than ours should have little difficulty doing this in the galaxy. If would can do this within the next millennium, why not any older civilization? (Assuming of course that c remains a universal constraint)

      • AlexTru September 5, 2020, 3:28

        If ETI have sent probe that can communicate with us, we can suppose for sure that ETI did not related to SETI structure, so ETI probe detection does not need SETI facility, i.e. SETI is useless in this (probe) scenario too.

        • Alex Tolley September 5, 2020, 15:58

          I am not so sure about that. SETI was involved in listening for signals from ‘Oumuamua. I agree that we need different search strategies to look for lurkers and probes. Active SETI using radar, or even METI might be used to try to detect a probe or provoke a response. (The anti-METI people would also be likely to be cautious about that too.) What such a search should determine is how to start, how to detect camouflaged probes, what approaches would offer the best chances of determining if a probe[s] exists without brute force looking everwhere, the same failing strategy pursued by SETI that fuels its [designed?] never-ending program.

          • AlexTru September 6, 2020, 3:57

            We cannot know what could be probable ETI probe , so the best strategy to find one – is intensive exploration by every possible methods.
            Exploration – it is what scientist do everyday, there is no need to invent special organization like SETI, that uses very doubtful anthropomorphic approach.
            There is one fact, from anthropomorphic point of view:
            electromagnetic waves (I mean out knowledge and technology that we know about EM waves today) – are bad method (probably useless) for interstellar communication , but whole SETI efforts that are based on strong anthropomorphic approach completely ignoring this fact and choose bad communication method as corner stone in fruitless searches.
            In same time EM waves can help us to explore the Universe, if we will invest efforts in better astronomic instruments, that probably could allow us to get direct optical and/or radio imaging of distant words, direct imaging doe not require anthropomorphic ETI (or even any ETI) existence and help on opposite side. We do not need to wait the moment when clever ETI will send us image, I am sure in close future we can do that without assistance.
            Sadly SETI efforts are not dedicated for direct imaging, so useless.
            SETI waits till some unknown ETI (unknown also ETI ability to see, hear, sense like homo sapiens) will send image (or message) of unknown format, on unknown frequency, from unknown direction…

  • Michael Fidler September 6, 2020, 8:41

    There is a much simpler way, listen to earth for non human made signals! After all, if there is intelligent life out there where would they be doing their research on earth? Of course on Earth!!! Remember; Delta Heavy sitting on the launch pad as we speak is a SIGINT updated satellite! Just think MIB!

  • Michael Fidler September 8, 2020, 7:14

    So this is our symbol now out to 81 light years!


    So should we be looking for a return pattern based on this?

    Funny, but I remember the Chiefs head being much larger???

    • AlexTru September 9, 2020, 4:37

      Your notes, are good sign why anthropomorphic approach it is the wrong way.
      TV test table you give as example looks totally different on other countries and continents.
      And my childhood memory brings different pictures…
      What could be ETI “tv test table” none knows, most probably any at all.

  • Michael Fidler September 8, 2020, 7:23

    Should be receiving a reply back from Trappist 1 about now.

    Maybe they think we are just an evolved dinosaur or Feathered Serpent!