≡ Menu

San Marino: Assessing Active SETI’s Risk

Our recent discussions of active SETI, otherwise known as METI (Messaging to Extraterrestrial Intelligence), highlighted many of the key issues involved while demonstrating just how controversial the topic has become. But is there a way to look at METI experiments more objectively?

The San Marino Scale has been widely suggested as a method for assessing the risks we incur with deliberate transmissions from the Earth to other stars. Introduced by Iván Almár in 2005, the Scale is a work in progress that draws on the model of the Richter Scale, which quantifies the severity of earthquakes. The IAA SETI Permanent Study Group continues to work on it, hoping to measure “…the potential exposure of employing electromagnetic communications technology to announce Earth’s presence to our cosmic companions, or replying to a successful SETI detection.” More on the background of the Scale here.

San Marino Scale

Hungarian theorist Tibor Pacher has been calling my attention to the San Marino Scale for some time, and recently provided the link to a paper by Almár and Paul Shuch that looks at past METI transmissions. Note that this is a simple ordinal scale ranging from a risk factor of 1 (insignificant) and climbing to 10 (extraordinary). Almár and Shuch apply it to several widely known experiments, looking at them in terms of duration, directionality, information content and transmitter power, before assigning them a value on the scale.

The experiments are these:

  • Evpatoria Planetary Radar Telescope: The source of three METI attempts, beginning with the Cosmic Call transmissions of 1999 and 2003, and including the so-called Teen Age Message to the Stars in 2001. The Evpatoria experiments targeted specific stars; their signal amplitude exceeded that of the quiet sun (see below) by about four orders of magnitude. Almár and Shuch assign them a San Marino Scale value of 7, which ranks as ‘high’ in significance.
  • Arecibo Message: This was the first METI attempt ever made, sent in November of 1974 and targeting M13, a star cluster some 25,000 light years from Earth. By the paper’s calculations, the Arecibo message outshone the Sun by a factor of 105. The authors assign it a San Marino score of 8, ranking it as ‘far-reaching’ on the scale.
  • Planetary Radar: This one is quite interesting. Planetary radars like that at Arecibo are routinely used (when funding is present!) to study near-Earth objects like asteroids and comets. Such transmissions are not intended as communications signals, but Alexander Zaitsev at Evpatoria has examined their potential for detectability over interstellar distances, and Almár and Shuch consider them inadvertent but de facto METI signals. Here we have a powerful signal but little information content, registering at a 6 on the San Marino Scale for ‘noteworthy.’
  • Finally, and perhaps still more curious, is Allen Tough’s continuing work with the Invitation to ETI Initiative. Here we have no targeted interstellar transmissions but an attempt to reach out via the Internet. Thus even with the most powerful uplink signals to satellites, we are many orders of magnitude below the solar flux, so the intensity of the message can be discarded. On the other hand, the information content at the Invitation site is high, creating a combined San Marino score of 4, or ‘moderate.’ The Invitation strategy assumes an ETI civilization advanced enough to monitor terrestrial networks, and thus the presence of an ETI probe nearby.

A key in all such grading is the character of the information content in a message and the intensity of the transmitted signal. Almár and Shuch examine the latter in relation to the solar flux. Modeling a ‘quiet sun’ baseline (i.e., conditions of minimum solar noise), the researchers compare the outgoing signal to that flux. Obviously, the actual flux varies significantly, but the method is carefully chosen. From the paper:

By quantifying our transmissions relative to minimum solar flux, we are perhaps overstating the SNR [signal to noise ratio] which a given terrestrial transmission might impart on extraterrestrial receivers. This approach ensures that our resulting Intensity term, which contributes to the overall San Marino Scale value, is a best-case number as far as signal detectability is concerned. Since it is the potential negative consequences of transmission which we seek to quantify, we believe this conservative approach, which may slightly overstate signal impact, is appropriate to the function the San Marino Scale was intended to serve.

How useful are the San Marino Scale’s gradations? Are the distinctions between METI experiments helpful as we look to future possibilities? I’m glad to see an attempt being made to quantify the risks involved, but the Scale seems to be only a beginning given the complexity of the issues involved. And I agree with Tibor Pacher, who said this in a recent comment here:

I think it would be useful to devote some really interdisciplinary effort to investigate the role of such a measure like the San Marino Scale. Informatics, social sciences, law, etc. could say a lot about this; so I hope that people knowledgeable in these fields will pick up the issue.

‘Interdisciplinary’ is the key word for a topic with potential ramifications for our entire species. More details in the paper, which is Shuch and Almár, “Quantifying Past Transmissions Using the San Marino Scale,” available online. See also the same authors’ “The San Marino Scale: A New Analytical Tool for Assessing Transmission Risk,” Acta Astronautica 60 (January 2007), pp. 57-59, available here.

Comments on this entry are closed.

  • Rob January 2, 2008, 9:55

    After reading the linked PDF, it sounds to me like a lot of “see we’re concerned, now just let us keep doing as we please” semantics. Quantifying ten levels of “almost dead” when you’re hemorrhaging in a shark tank doesn’t accomplish much towards the outcome of your predicament if you’re already IN the tank.

    It would behoove use to consider a higher level of technology for the detecting civilization when assessing risk. By this I mean let the ‘think tank’ conjure up the biggest, wildest device possible for detecting faint radio signals (or communicating with your invasion forces a few light years off), and presume someone out there has built it.

    There would not be much danger from detection by other civilizations with technology levels comparable to our own.

  • Starfleet commander January 2, 2008, 12:21

    Not to worry folks – it’s all taken care of :-)

    But seriously; I’ve been following these threads and very interesting and stimulating discussion.

    However, I would say that the risk asessment concerning Active SETI should concentrate on analysing every possible way we/earth could be harmed by alerting potential alien civilisations.

    A risk asessment based on what their motives might be is much more difficult. If we are to do so we have to take into account the murderous dominant behaviour of human history – its the only example we have and hence I dont think the resultant conclusions about risk could only be anything other than negative. Our larger brains not only allowed us to cultivate/store food but it also helped us learn how to murder on an industrial scale. We still do it today. This is a fact we cannot deny and I dont think it makes us any greater or worse from a universal standard or perspective. We are very much the progeny of natural forces and those same natural forces appear to be consistent throughout the universe.

    So are we not better off asessing how far in advance these Aliens may be and what that means about their capabilties to inflict harm on us x ly in distance? The why or why not does’nt come into a clean risk management job of this nature. One has to assume they will act according to the laws of nature whether through competitive attitude or paranoia through their knowledge of the violent nature of the universe.

    Hoping they will be altruistic really is the height of folly and proves our existence has become far too comfortable.

  • Starfleet commander January 2, 2008, 12:27

    Just to add:

    Lighting up the earth like a big flashing bulb for all the galaxy to see may the stupidest thing we ever do. It could also explain Fermis paradox.

    I think we need to shut up, watch and listen for a lot longer.

  • Colin Weaver January 2, 2008, 20:31

    I believe there are a few significant issues, some social, some scientific, which should caution us against initiating attempts to communicate with ETIs, at least until we are a lot closer to resolving the Fermi paradox.

    1. It is arrogant in the extreme, for a small group of scientists to take upon themselves the responsibility of representing all 6 billion of humankind. Nobody has ever asked the citizens of the world whether they agree to their presence being broadcast far and wide. Regardless of whether contact with ETIs is completely benign or a profound discontinuity in our history, it is a step which should not be made unilaterally by a small group without the consent of a majority of our global civilization.

    2. We cannot know anything about the intent or cultural imperatives of an alien intelligence. They are, by definition, utterly unlike us. At this stage, bar the wild speculations of science fiction, we cannot begin to reason about what their driving principles would be. Indeed we don’t even know if we would recognize them as intelligence, or whether they would recognize us in return.

    3. Although the analogy is likely to break down due to point 2. above, our own history shows that in any contact between a more advanced race and a less advanced race, the less advanced comes off very badly indeed. If we extend this analogy to cover our interactions with the other near-intelligent species of earth – the great apes and cetaceans, the picture is even more one sided. Now imagine US in cast in the role of the less advanced race. Even if the intentions of the ETI are completely benign, we cannot know how it will play out.

    For these reasons, in my opinion we need to tread very carefully indeed, both with active ETI attempts and with pollution of the electromagnetic spectrum that advertises our presence. Until we know why the sky seems to be devoid of intelligent signals, we MUST not advertise our presence with the only such signal within hundreds or thousands of light years.

    Brisbane, Australia

  • tacitus January 2, 2008, 21:26

    So what if everyone in the Galaxy has the same attitude? Are we all cowering in fear, afraid to make our presence known for fear of encountering a hostile force? If so, it would be an extremely sad and unfortunate state of affairs, and one it would be almost impossible to overcome. If no one is willing to make the first move, then all civilizations would remain forever isolated and insular.

  • Administrator January 2, 2008, 21:52

    I’m very much with Colin Weaver on this, not with the thought that silence may always be necessary, but rather that it is necessary until we know a great deal more about what is out there. But let’s return to the San Marino Scale for a moment. Are there ways it can help to clarify the issues raised by active SETI? I find it interesting as a launching point for further discussion, preferably with a broad community that is cross-disciplinary, and I suspect that as a work in progress, it will undergo modifications as we get more such input. Meanwhile, the fact that we are apparently sending inadvertent signals via our planetary radars — not the targeted messages but the necessary examinations of near-Earth objects — makes the issue more pressing. We can’t do without those radar defenses because we have to know where the potential Earth-crossing asteroids are. That makes understanding how significant their signals might be, and how observable, a serious issue.

  • andy January 2, 2008, 22:24

    Tacitus: given the literal translation of your username, that’s an interesting position to take… :-p

  • wim January 3, 2008, 2:00

    METI has already been in full force since radio was invented. With radio waves reaching out to 80 lightyears, an alien race, especially if it is more advanced technologically than we conventionally perceive, has the high possibility of already detecting our transmissions. From these transmissions an alien race can come to overarching conclusions about our culture, temperament, values from our transmitted entertainment, military communications, news, etc. Sadly, many of these transmissions, especially the more recent, will include our “entertainment” which has included graphic violence as a major theme and the degradation of society will be one of the things which will be noted. Watching Fred Astaire for entertainment is different than watching Freddy Kruger or even Jack Bauer. EM waves already in play could detrimentally taint the perspective of any exocivilisation about what makes humanity what it is. Luckily these transmissions are more recent, therefore not as far reaching space. But if we are serious about METI and seriously think that people from space with a culture and moral compass exist, we should be much more responsible not merely in officially setting up a METI programme but in all transmission content. Because if I was an alien and have been listening to our noisy planet’s broadcasts, I’d avoid it and never have anything to do with “humans.”

  • David January 3, 2008, 5:30

    One of the basic relationships between species is that of predator and prey. If a hypothetical, intelligent species who were prey developed technology, it would make sense that one of the first uses for that technology would be to change things so that they no longer remained prey. By technology I mean things as basic as arrows and clubs.

    If said intelligent species started out as predators, it does not make sense for them to change that so that they became prey to another species. The result is that any any intelligent, technological civilization humans make contact with is very likely to either have always been a predator or have used their technology to become one. So assuming that such a technological civilization was now altruistic, it would be a good bet that that was not always the case.

  • Ronald January 3, 2008, 6:07

    As I also mentioned in the thread on ‘Active SETI and the Public’: first things first;
    we do not even have a good or complete characterization of nearby planetary systems, nor do we know any terrestrial planets yet, let alone having detected and analyzed any biosignatures of those planets.

    Any ETI related work may be quite premature, and METI even arrogantly so.

  • david January 3, 2008, 7:45

    So what if everyone in the Galaxy has the same attitude? Are we all cowering in fear, afraid to make our presence known for fear of encountering a hostile force?

    If there are a large number of ETIs out there then the odds that they would all cower in fear is unlikely. Where are those who announce themselves?

    For them to cower in fear suggests that they, like us, are not aliens to violence.

    One of the common methods tyranny uses to unite a group of people is ‘fear of the other’. I am pretty sure that if we were to gain undeniable proof of alien intelligence that a number of groups here on earth would use that knowledge to generate fear in order to keep their populations in check. In a few centuries we might very well be one of the species that some ETI might reasonably cower from.

    Nations would use that fear the same way the US/USSR hyped fear about each other during the cold war.

    Religious groups could claim only humans have souls and that ETIs are the spawn of the devil.

    Sadly we humans are more than capable of killing each other when ideology demands it. Why should we assume that we are less willing to kill ETIs once our technology allows us to? Why shouldn’t we assume that at least some of them are as willing to kill as we are, or even more so? If there are a thousand ETIs out there it would only take one aggressive one to eliminate us, even if the other 999 are all pacifists.

  • Starfleet commander January 3, 2008, 8:06


    “So what if everyone in the Galaxy has the same attitude? Are we all cowering in fear, afraid to make our presence known for fear of encountering a hostile force? If so, it would be an extremely sad and unfortunate state of affairs, and one it would be almost impossible to overcome. If no one is willing to make the first move, then all civilizations would remain forever isolated and insular.”

    Beats being dead because we were so naive as to think other civilisations share our delusional sense of altruism. Also, no-one is saying let’s never commit to Active SETI. Most urging caution want to wait until we have better detection methods so we can get a good look at what is around our local neighborhood. Nothing wrong or “cowering” about taking time to do local reconnasaince before we start shouting out like a baby hatchling.

    Personally i think we need to have some idea about how we would defend ourselves against known risks. These risks should be evaluated during a risk assesment of what their capabilities might be like.

    Active SETI without us taking any precautions is really dumb for a supposedly successful and smart sentient species.

    I feel the same way about asteroid impacts but thats another discussion.

  • ljk January 3, 2008, 9:32

    If we are beaming radar into space to analyze various
    space bodies (plus military radar doing the same for its
    own purposes), we should assume that other civilizations
    with our capabilities and better are doing the same. Of
    course since the beams are aimed at objects in the
    respective solar systems and not at specific stars, the
    odds of detecting them are slim, but it only takes one
    that happens to be lined up just right to make the

  • Administrator January 3, 2008, 9:50

    Larry, yes, the odds on detection would be long indeed. But it’s indeed possible that some non-repeating phenomena like the famous ‘Wow’ signal could be explained by something of this sort, a local signal generated for scientific or military purposes that happened to line up on that particular occasion. Hard to build a SETI program around such, but an indication that even a civilization not intent on broadcasting its presence may make itself inadvertently known. The San Marino Scale at least tries to give us some idea of the significance of this.

  • Christopher L. Bennett January 3, 2008, 10:38

    It seems to me there’s a bit of a paradox in the viewpoint of this blog. On the one hand, it strongly advocates developing a means of travel to Alpha Centauri. On the other hand, it advises caution about making our existence known to ETIs. But wouldn’t any propulsion system powerful enough to send a ship across interstellar distances within a human lifetime put out a pretty massive and detectable energy signature? And wouldn’t a signature proving that we’re actually going to the stars be even more, err, inflammatory to these hypothetical dangerous aliens than mere communication signals would be? If their aggression is motivated by caution or intolerance of rivals, they’d see us as more of a threat (especially since any really high-velocity space drive is potentially a weapon of mass destruction), and if it’s motivated by acquisition, they’d see us as a more advanced and desirable world to conquer.

    So how do you reconcile these points of view? If it’s worthwhile to embrace the challenge and risk of travelling to new worlds, how is it not worthwhile to embrace the challenge and risk of trying to communicate with them?

    (By the way, I just bought the CENTAURI DREAMS book. Looking forward to reading it.)

  • Edg Duveyoung January 3, 2008, 10:41

    Musing here.

    We don’t even know where all the chunks of rock are in our own solar system, let alone know how many planets are within, say, 100 light years from Earth. In the next ten years or so, we’ll have a pretty good idea of what is near by and who could possibly be able to “get here” before we are advanced enough to defend ourselves or at least finally tap into the Cosmic Discourse somehow. 100 years from now, our physics, engineering and astronomy might be able to give us the confidence to either do METI, but until then it’s a toss of the dice, methinks.

    Then again, how many years from now will it be before we know all the brown dwarfs in our 200 light year wide neighborhood? 100 years might not be enough time for our technology to advance enough to detect them — and they could be hollowed-out-space-ship-worlds traveling at a leisurely pace and sending out probes etc. We must be prepared for the marauding brown dwarfians, right?

    But consider that everything affects everything. At some subtle level — maybe far more subtle than today’s physics can imagine — our Earth may be as “obviously there” as a frog is to us when we see a spreading ring of ripples across a pond. What ripples do we make? We cannot know at this time.

    Of course, if faster than light travel is possible, Fermi looms much larger, cuz, they’d be here already if there was anything here they wanted.

    Once ET’s technology reaches that Star Trek level where fusion and fission are done in high school labs, what is there for any ETI to want from us? Gold, plutonium, water? Nope. Nothing physical that’s for sure. Beauty? That’s everywhere. Domination of lesser evolved species? Maybe but that’s scant psychological profit that could be given by the ton by holodecks, robots, and other “virtual” entertainments.

    500 years from now, probably we will be able to transform any orb in our system into a living world. What with space so huge, so filled with material, filled with radiance — why would ETs come here unless it was for some much higher purpose than mere “profit?” Some religious purpose might be a motivation, but to expect ET to come here to give us sermons is like like thinking the Pope will be trying to evangelize to a local ant colony.

    The Borg concept does have its appeal for imagining a threat from space, but where are they? Seems to me The Borg could grow whatever physical brains they wanted in a petri dish, so the only thing the Borg would gain by “assimilation” of us is abstract indeed.

    If we discover FTL tech, then it’s a new deal for sure, and, politically, our species might be far more “on the map” than if we merely signal ourselves with radar bursts outshining our star.

    Now toss in the omniverse concept and reality blasts into infinities to spare. I just don’t see ET wanting to come here except for spiritual — not religious — reasons. This may be my species blindness here. If we had evolved from reptiles instead of mammals how differently would we be seeing “others?” If we discover life on Mars will it not be a moment of incredible passionate — even sacred — attention, adoration, focus and nurturing of that “other?” Er, sounds like a mammalian projection!

    Yes, a Martian microbe could be a Satan Bug that would kill all life on Earth, but we’d figure that out pretty quickly with in situ experiments on Mars before we brought any “evil soup” home to Earth. Er, right? Fingers crossed, cuz many an astronaut has come back to Earth with contamination that was not controlled.

    The concept that METI folks are commandeering the will of the people of Earth without the above concerns being discussed first in some United Nations assembly, seems to be a straw dog in that a “peculiar ridiculousness” manifests when we consider, for instance, an ant in a colony being “yelled at” for trying contacting humans. We’re just so far from “being important” in so many ways, that the METI folks can be seen as “silly would be ambassadors.” Ants waving a leaf in hopes of getting a human to look at their “great achievement in leaf waving.”


  • stargazerdude22 January 3, 2008, 11:27

    I have a hypothesis that we are already detecting the powerful ETI radar scans mentioned above, ETI is looking for asteroids and comets, mapping planet surfaces, etc. We see it as a momentary, non-repeatable source amplified to our (primitive) level of detectability due to scintillation by other stars, planets etc.

    From above (way above now) article;

    “Planetary Radar: This one is quite interesting. Planetary radars like that at Arecibo are routinely used (when funding is present!) to study near-Earth objects like asteroids and comets. Such transmissions are not intended as communications signals, but Alexander Zaitsev at Evpatoria has examined their potential for detectability over interstellar distances, and Almár and Shuch consider them inadvertent but de facto METI signals. Here we have a powerful signal but little information content, registering at a 6 on the San Marino Scale for ‘noteworthy.’ ”

    A link for SETI and scintillation;


    My question to the readers is; at what frequency are these typical radar scanners? I’ll bet not at or near the “watering hole”. Perhaps we are picking up harmonics, sidelobes, etc? Perhaps we should be looking at these primary (hypothetical) “ETI radar scanning frequencies”???? Assuming they are at about the same frequency for Earth-like planets … or perhaps our atmosphere’s window is opaque to the best frequencies and we need a satellite (I’d love to see a GIANT dish on Luna’s far side myself).

  • Administrator January 3, 2008, 13:15

    Two points re Christopher Bennett’s interesting questions:

    1) My own view is not that contacting other civilizations should always be avoided, but that before we send any more directed communications signals, we should have considered our strategy and weighed the possible consequences. So I’m advocating getting this issue in front of a wider public and trying to solicit viewpoints from many different disciplines so our choice is an informed one. I’m not saying we should avoid all contact in the future.

    2) Christopher asks “…wouldn’t any propulsion system powerful enough to send a ship across interstellar distances within a human lifetime put out a pretty massive and detectable energy signature?” Not necessarily. It would depend upon the method used. Suppose we followed Robert Forward’s ideas and set up a laser lensing system to boost a lightsail to Epsilon Eridani. Would such a mission necessarily be visible to any other planetary systems? Remember that we’re talking about a highly collimated signal, very tight and widening only gradually. That’s one kind of mission, but we could also talk about magsails boosted by particle beam or other possible concepts. I doubt, for example, that a fusion powered vehicle would light up our presence to other civilizations. But still, this is a fascinating question that Christopher has raised. I wonder if there are any studies looking at just this issue?

  • Starfleet commander January 3, 2008, 13:23

    Howabout this naturalistic scenario:

    We implement METI. By doing so we unkowingly alert a relatively advanced species. They remain quiet and check us out. They train very powerful optical technology on the earth and start studying us. They notice we have some serious agression problems and fight a lot of wars. We continue to murder our own etc…

    They might just not want to take chances and they decide to kill us off quickly before we have the tech to spread our seed or colonise other planets in the solar system, or beyond. If they got paranoid about us I dont think they;d wait til we had discovered a hypothetical warpdrive before taking care of business. Obviously they may know about what technology is around the corner at what stage for a developing civilisation. That knowedge is very powerful. They could hit us because they suspect we are about to develop something which puts us into a very different category.

    Okay that is a ruthless scenario but no more improbable than the idea that they are going to be particulalry pleased to hear about us.

    Consider what may happen to our own atitude within say 1000 years. If we come to notice that life is relatively freely sprinkled across the galaxy then its no big deal to hear from developing species. And if we then noticed one particulalry close-by looked relatively violent we might decide its better to wipe them out quickly – before they become a problem.

  • Administrator January 3, 2008, 13:24

    stargazerdude22, the Shuch/Almár paper reports that “The Evpatoria Planetary Radar Telescope on the Crimea Peninsula in Ukraine boasts a 150 kW C-band transmitter, normally operated at 5.01 GHz…” The Arecibo message was transmitted at 2380 MHz. Goldstone is said to be using a frequency of 8.56 GHz for its own NEO work, so you’re right, we’re nowhere near the ‘waterhole’ (between 1420 MHz and 1660) region. As to that giant dish on Luna’s far side, amen! Claudio Maccone has worked out the best location for such a dish, which reminds me to get to that paper soon.

  • Christopher L. Bennett January 3, 2008, 13:37

    ^^It’s true that a propulsion beam wouldn’t give that strong a signature at the ship itself, but what about back home at the source station? The beam itself would be highly collimated, but what about waste energy from the generator? It would take a huge amount of power to create a beam intense enough to drive an interstellar vessel.

    For that matter, wouldn’t the beam be scattered just a bit off of the interstellar medium, or at least off the interplanetary medium and dust within our system? That would be a minor effect, but if the beam is really powerful, just the small amount that got scattered might be detectable (in the same way that, say, a really intense laser beam might be faintly visible in air even though a more ordinary beam would not).

    And what happens to that energy once it reaches the ship and “bounces”? I’d imagine that with a lightsail you’d want to send the beam as directly backward as possible, but might there be some scattering? As for a particle beam, I’m not sure what trajectories the particles would end up on after they interacted with the ship’s magnetic sail, but I’d imagine there might be a greater amount of scattering there.

    What about, say, a ship using magnetic braking against the interstellar medium to decelerate into its destination system? Would that leave a detectable “wake” or ISM disruption that an advanced civilization would know how to recognize?

    Of course, this could be flipped around — answering these questions could give us new ways of looking for alien space travel. All these effects would probably be quite faint and subtle, but if we (or they) knew what to look for, who knows?

  • Administrator January 3, 2008, 13:41

    I really like this line of questioning, Christopher, and I don’t have the answers to your specifics. I’m hoping someone else can jump in with thoughts on detectability in these scenarios — lightsail, magsail, etc. Subtle effects indeed, but as you say, bearing what would seem to be a truly characteristic signature!

  • philw1776 January 3, 2008, 14:04

    My position continues to be that we are neophytes in the galactic woods. Our technology is nascent and underdeveloped relative to a putative interstellar capable species, assuming that there are any at all. We’re like a rabbit venturing forth from its den. Why the hurry to advertise our presence now, before we’ve had a chance to understand a bit more about the surrounding forest and any potential dangers? Think of how much we’ve learned of our nearby environs in the short 50 years since Sputnik. Give science a chance to tell us something before we act overtly.

    The downside of geting this wrong is horrific. Me, I believe that Earths are rare, animal life rarer, intelligences rarer still, and intelligences with technology so rare that we are likely the only extant example in the Local Group. But I don’t have the hubris to bet the entire human race on this belief.

  • Ron S January 3, 2008, 14:43

    ljk & Paul,

    Detecting a one-time signal (Wow) is difficult for much of the EM spectrum, but not fundamentally unachievable. For example, we effectively do that today with GRB detection, although we require a high S/N.

    Imagine a large sphere liberally sprinkled with isotropic radio antennae. Now add in a massive quantity of DSP and time-integration processing capacity that is far beyond our present technology. This is an omni-directional Wow detector.

    We can’t do this, though we can imagine a somewhat more advanced ETI having this capability. With the quantity of potential Wow signals emanating from Earth, they could see us easily enough. The signals don’t have to have encoded information. All ETI needs to do is reliably differentiate between ‘natural’ and ‘not natural’, which isn’t all that challenging for even radar pulses. Such a detection would be sufficient to raise their interest in beginning a directed investigation.

  • Administrator January 3, 2008, 16:49

    Thanks for these clarifications, Ron S. From what you’re saying, it sounds as though the San Marino ranking of NEO-tracking radars — a 6 as compared to Evpatoria’s 7 and Arecibo’s 8 — isn’t far off. As you note, no encoded information is necessary for a detection to be made.

  • Mark January 3, 2008, 17:11

    We have no way of knowing whether allowing ETIs to find us would result in a calamity or save us from one, or whether we even have the option of allowing or preventing ETIs to find us. Given what we know about our own technological development (that it is rapid and accelerating and gives us ever more impressive abilities), it seems likely that if there are spacefaring ETIs interested in nascent technological civilizations, then they probably have already been here many times in the past million years, are well-informed about us already, and can do whatever they feel like doing with us at any time.

    Therefore, I feel we have absolutely nothing to gain by worrying about this matter. It’s clearly not a problem but an insolubility. If anyone feels like transmitting, let him do it.

  • tacitus January 3, 2008, 17:56

    Perhaps, in my previous comment “cowering in fear” was not the correct characterization of those who advocate caution before embarking on a METI program. :)

    But there is a real issue with “waiting to see what’s out there” — that is, we may well have to wait a very, very long time (centuries) before we detect anything via SETI, if we ever detect anything at all.

    If all the ETIs out there are taking the same cautious approach, then we could all be listening for one another without ever hearing anyone, which I think would be a crying shame. And it’s quite possible that the ETIs no longer use interstellar communications that we can detect. If they have moved on from the radio spectrum and lasers to something we can barely conceive of today, then we will be forever stuck at square one.

    I am all for spending a few years talking about and debating a viable, cautious, and effective METI strategy, but simply waiting to “see what’s out there” really doesn’t seem to make much sense to me. Unless by good fortune we happen across a SETI signal, then we could still be completely in the dark as to whether the galaxy is teeming with ETIs or if we are entirely alone even centuries from now.

  • Starfleet commander January 4, 2008, 9:48


    I understand your impatience and I’m the same way. I want proof and evidence of ET existence before i leave this world. I don’t know why but for some reason its important for me to know we are not alone.

    But I also realise that my impatience is driven by selfish sentiments. I know in the back of my mind that we need to think longterm on the issue of METI repurcussions. Because even if ET was agressive and we made contact within our lifetimes; they would likely need a few deacdes to do us any harm. You and I probably wont be around to feel the consequences,

    I know it sounds corny but i think we need to consider whether METI today means death to our future progeny and human existence.

  • Absolute_Zero January 4, 2008, 12:17

    The bigger question to me is… intelligent life on Earth?

    So, there’s a race of interstellar-capable, paranoid, psycho/sociopaths (clearly modelled on us, quelle surprise, vive le renaissance) within Earth threat range… don’t you suppose they’d be actively looking for would-be foes/lunch? And being interstellar-capable, paranoid, psycho/sociopaths… find us anyway? Don’t you suppose that we’re just as likely to be spotted via the spectrum we reflect as the EM we transmit? What are you going to do, build a Dyson shell? Comic.

    For the sake of my faith in human intelligence, I trust this is merely science promulgating irrational fear in the search/avoidance of, not would-be alien conquistadors, but research funding, right?

  • Starfleet commander January 4, 2008, 13:46

    “The bigger question to me is… intelligent life on Earth?”

    har har though I think Obama beat you to that gag.

    “So, there’s a race of interstellar-capable, paranoid, psycho/sociopaths (clearly modelled on us, quelle surprise, vive le renaissance) within Earth threat range… don’t you suppose they’d be actively looking for would-be foes/lunch? And being interstellar-capable, paranoid, psycho/sociopaths… find us anyway? Don’t you suppose that we’re just as likely to be spotted via the spectrum we reflect as the EM we transmit? What are you going to do, build a Dyson shell? Comic.”

    The point is we dont know. But we can as comically assume that they are not some sort of peaceniks just back from an anti-war march at Trafalgar sq.

    You have no more of a clue than anyone else about the existence, motives, or capabilties of an alien civilisation. The point is that METI automatically assumes that they are not agressive, paranoid and generally a nasty piece of work.

    We cannot possibly know either way – at this stage.

  • Administrator January 4, 2008, 15:25

    Thanks to all for many excellent posts on this topic, but for reasons outlined in my comment on the previous active SETI thread, it’s time to take a breather and move on to other topics. I knew this was a contentious issue when I began, but I do think we were able to get the major points under examination. Nonetheless, my e-mails make it clear that anger over these issues is brewing and flame wars are not what we are about here. So let’s look toward examining METI again in the near future.