≡ Menu

Should SETI Turn Active?

Centauri Dreams admits to troubling new doubts about a variant of SETI called METI — Messaging to Extraterrestrial Intelligence. The notion, also known as ‘active SETI,’ is backed by some members of the SETI community and is especially strong in Russia. Its premise is that rather than listening passively for signs of extraterrestrials, we should actively try to achieve contact through messages of our own. This would constitute a ‘brightening’ of our civilization in the radio sky, making us more noticeable by many orders of magnitude.

A number of intentional signals besides the famous Arecibo message of 1974 have already been sent. The so-called ‘Cosmic Call 1’ message was transmitted from the Evpatoria Planetary Radar site in the Crimea in 1999, targeting four Sun-like stars and sending an overview of terrestrial life written in a code called Lexicon. Cosmic Call 2, sent to five Sun-like stars, followed in 2003. Based on the target list and the distances involved, the window for a possible response to these messages opens in sixty years.

Is this a good idea? We are only beginning to have some understanding of how many planetary systems are out there and to learn about the properties of their largest planets. Knowing what we know now about the tenacity of life on Earth even in the most extreme environments, and knowing that there may well be Earth-like worlds in solar systems throughout the galaxy, we face the real possibility of alerting other civilizations to our presence before we know anything whatsoever about them. This may or may not prove dangerous, but it seems like something that deserves wide discussion.

But the conversations now going on in the SETI community focus on the work of a small committee of the International Academy of Astronautics (IAA), one chaired by the SETI Institute’s Seth Shostak. You may know of this committee from its earlier work, as it developed the so-called ‘First SETI Protocol’ that outlines a rational response to the detection of an extraterrestrial intelligence. Such protocols are highly productive, for they bring the scientific community together before such a paradigm-changing event can occur, allowing for a thoughtful look at the issues and encouraging debate.

But there is a second protocol under discussion, one that asks METI proponents to hold back from deliberate transmissions until their plans can be examined in open gatherings by a broad community of experts in various disciplines. What is now under debate is whether such restraint is sensible or simply represents a paranoid response to a non-existent threat. The IAA meeting this October in Valencia may well ratify a protocol that accepts METI transmissions without requiring any further discussions to occur.

It is striking to me that there is only one science fiction author — astrophysicist David Brin — on the IAA committee that will decide these things. I would argue that writers like Brin, Gregory Benford, Greg Bear and others have spent years pondering the possibilities of interstellar contact and its ramifications. Their contribution would broaden this debate, which seems from my perspective to be focused on a tightly defined group of SETI proponents whose work could nonetheless have serious repercussions for the human future.

It would be useful to find out what readers think about this issue. Some have argued that it is already too late, that the broadening sphere of our radio and television transmissions is already well past numerous star systems and in any case cannot be called back. But such signals are far less visible than the beacon-like effects contemplated by some proponents of active SETI. METI proposes a genuine change in tactics, one that seems to cry out for sustained and highly visible debate before we raise Earth’s visibility.

Your thoughts?

Comments on this entry are closed.

  • Marko Cebokli September 29, 2006, 9:42

    I like the idea of a galactic immune system, taking care of us parasites….
    BUT if it relied on radio to detect “parasites” it would be extremely inefficient – like if the human immune system relied on a single type of molecule to detect intruders – we’d be all dead by now.

    The Darwinian perspective: I don’t think it can be applied to a “population of civilisations”, becuse very probably they are not offspring of each other with inherited traits.
    But just for the debate, let’s try to see what it would imply. I agree that in a dangerous universe (dangerous through “biology”, not physical environment), evolution would favor the development of silent civilisations.
    HOWEVER this very fact would exert a significant adaptive pressure on the predators to develop “senses” for detecting silent civilisations.

    So, especially the “predatory/hostile” entities are extremely unlikely to rely on “cooperative” means of prey detection (like deliberate radio transmission).

    It is very naive to think we can evade detection by keeping radio silence.

    Marko Cebokli

    PS I should probably set this straight – I am NOT an advocate of METI – I am indifferent about it.
    I just don’t like the scare-mongering, which I am already being fed big quantities by our own earthly politicians.

    Anyway, it is extrememly unlikely that anybody will hear our transmissions – just compare it with SETI. We have receivers with many millions of channels, which operate almost continuously, listening in a few directions. With the array antenna systems, we will also listen in many directions simultaneously.
    In contrast, METI will be, for transmitter economy reasons, single channel.
    Also because of power economy, it will be single direction (small solid angle).
    Unlike the receivers, which are cheap to operate, the electricity bill alone will limit
    the amout of time the transmitter will be on.
    Ergo, the amount of search space covered will be billions of times less than receiving SETI. In 40 years we haven’t heard nothing – so figure what is the probability of somebody hearing our METI. Many zeros behind the decimal point!

    I don’t plan to transmit, but if others feel happy transmitting – I won’t object. Let them have their fun, it is a harmless passtime.

  • Joseph Baneth Allen September 29, 2006, 9:49

    Don’t be too sure that the “Star Chamber” tactics would be strongly derided by Dr. Brin.

    To directly quote Dr. Brin in his own written words above: “There are responsible people — adults — who are hoping to mediate this dispute in semi-private, using collegial persuasion to resolve the issue, without bringing too much unfavorable attention to SETI. I am eager to see these efforts succeed.”

    Again, I propose my originial question directly to Dr. Brin: Why are SETI scientists the only ones qualified to hold a debate on a course of action which could greatly impact the human race? If SETI and astrobiology has a tradition of cutting across scientific disciplines, certainly METI needs broader input from the public.

  • Tibor September 29, 2006, 14:44


    I do not believe that any rigorous risk assesment procedure does exists concerning METI. To my knowledge, the San Marino Scale is the very first attempt to deal with this issue quantitatively at all, motivated by the ideas of the Torino Scale on Asteroid and Comet Impact Hazards:


    May I cite what he proponents of the San Marino Scale say:

    “The San Marino Scale is neither an adopted standard nor a firm proposal, but merely a suggestion thrown out for consideration and refinement by the SETI community. … (….) … While SETI, the Search for Extra-Terrestrial Intelligence, is a widely accepted science, the reciprocal activity sometimes called METI, Messaging to Extra-Terrestrial Intelligence, remains a controversial area, and receives much discussion and debate within the SETI community. It has been argued that a civilization which hopes to detect radio evidence of other civilizations in the cosmos is obligated to reveal its own presence. Others maintain that it is suicidal to shout in the jungle. Heretofore, there has been no analytical tool to quantify the impact of transmissions from Earth. The authors of the San Marino Scale, while not particularly endorsing either side of the transmission debate, propose a tool to give such discussions a modest analytical basis.”

    The official website of the IAA SETI Permanent Study Group is:


    Here is, to my opinion, a fairly balanced account on the group’s work.

  • Joseph Baneth Allen September 29, 2006, 18:43

    Don’t be too sure that the “Star Chamber” tactics would be strongly derided by Dr. Brin.

    To directly quote Dr. Brin in his own written words above: “There are responsible people — adults — who are hoping to mediate this dispute in semi-private, using collegial persuasion to resolve the issue, without bringing too much unfavorable attention to SETI. I am eager to see these efforts succeed.”

    Again, I propose my original question directly to Dr. Brin: Why are SETI scientists the only ones qualified to hold a debate on a course of action which could greatly impact the human race? If SETI and astrobiology has a tradition of cutting across scientific disciplines, certainly METI needs broader input from the public.

  • JD September 29, 2006, 18:52


    Wasn’t trying to insenuate that. If it seemed I did I apologise.

    Good points by all. Meti probably would not accomplish anything. I, as do some others here, do take exception to any group that I didn’t have an option to vote for taking it upon themselves to act for me. Thank you very much but I can still competently do things that may or may not be dangerouse to me without the help of self annointed “leaders.”

    Admittedly even if something did come of METI I’d probably be long below ground when the consequences arrived but I take the same track in relation to my granchildren and great granchildren. Perhaps if put to public comment the majority would support the concept but that’s the rub. The simple curtesies have not been extended to us peons to even voice our opinion. It’s assumed that wiser and abler people can decide for us. That designation as wiser and abler comes from simply have an esoterical degree and is not proven in any other fashion. If there are any other facets that qualiefy these people to make decisions for us I’d like to hear them.

    Hopefully we are either the first or among the first higher tech users. Hey I’m biased enough to want humanity to have a big slice of the pie :) Even life being extraodinarly rare would not necessarily be terrible. A well populate, as was dubbed galactic ecosystem, is another matter entirely. As a species we are extremely vulnerable, hell we can’t even run away and hide if something goes wrong. I would tend to be cautious at this stage of our species. If they’re out there are they saints or devils? I defy anyone to give a dependable argument on this.

    As a final thought advanced society/science doesn’t imply that someone/something is more benign. It does however allow a more precise, effecient and philosophical approach to killing.

  • Joseph Baneth Allen September 30, 2006, 16:10

    One of the most curious arguements in all the pro-METI counterpoints listed above is the accusation that people are acting out of fear in not wanting to contact ETIs.

    No one seems to be distubed that Dr. Brin and other SETI scientists want to discuss METI protocols behind closed doors until they reach a decision on how they are going to act on the better good of all of Humanity.

    When scientists often deny their fellow humans basic rights when they take on the role of active do-gooders for all of Humanity. It wasn’t just NAZIs that practiced the so-called science of eugenics. Even up to the early 1980s, people who were considered to be “below average” were forcibly seterilized – their basic human right to have children taken away from them – all across the globe by well meaning doctors who were often mistaken about the mental and physical capablities of their patients.

    And who can forget the horror of soldiers being untreated for syphillis so that medical doctors and biologists could observe the effect the untreated S.T.D. had on the human body?

    History is littered with other horrible examples of how scientists created misery, death, and dispair, all while acting in the cause of the greater good. Is it simply too much to ask of Dr. Brin and his colleagues to let all of humanity, not just a predetermined few, have a voice in what they are proposing to do with METI?

  • Marc Millis October 2, 2006, 15:57

    Tibor, Eric;

    Thank you for your leads.

  • W. M. Bear October 4, 2006, 1:40

    I don’t think we have to worry. The scenario in Carl Sagan’s “Contact” is probably not far from the truth. As Ellie Arroway’s father-image tells her in her wormhole vision, “It’s been done this way for billions of years” — it being “contact” of course. The implication (as is the case in Kubrick-Clarke’s 2001 as well) is that the “Singularity” was reached aeons ago and the intelligences that originally reached it are so far “advanced” they might as well be gods and we might as well regard them in that light. Which means, of course, that they know all about us already and are just “holding back” (the solution to the Fermi Paradox) for inscrutible reasons of their own. (It wouldn’t be because we’re nuke-toting apes who haven’t yet learned their “lession” now would it?) At any rate, this sort of consideration makes the whole argument seem pretty academic and beside the point as far as I’m concerned. (Seems that we can all look forward at some point to being “assimilated.” Big whoop.)

  • Stephen October 4, 2006, 18:19

    The problem with SETI is that the sky is big, and we’re looking for a weak signal. And we don’t know how the signal might be sent. So, where to look? And how?

    The problem with METI is that the sky is big, and it takes alot of energy to cover it. So, where do we aim it? One idea was to aim it a alot of stars – a globular cluster. But these clusters have been shown to have stars with low metalicity, suggesting no life. Another idea is to beam at Sun like stars, or even Sun like stars known to have planets. A friend suggests we beam messages where others are likely to look. His idea is that when you see a nearby supernova, assume that others will watch it. Turn around and beam your message at them. They’ll be able to figure it out.

  • Alexander Zaitsev October 7, 2006, 3:22

    Dear Colleagues,

    Recently I put my paper “Proposing a METI Institute” into e-archive at

    By request of arxiv.org moderator, I re-named it into”Messaging to Extraterrestrial Intelligence” Please find it at:

    I ask you to make link on


  • Jared Johnson October 25, 2006, 17:31

    Just out of curiosity. Has anyone considered the possibility that predatory species are unlikely because it simply way more efficient for them to process all the materials and food they need by stripping planets without life or even asteroids and meteors for everything they need?

    Why go through all the trouble of seeking out life bearing planets for resources when you can use mechanical processing on a cosmic scale to constantly churn out all the resources you could ever need from just about any clump of rock and minerals you can find?

    I have a hard time believing that any species, no matter how wolf like they may be behaviorally would want to take all the risks of attacking other sentient species for the scattered bits of resources that a planet like ours would have. Why would someone want to be dependent on regularly finding new sentient life bearing planets for their resources? Why would they want to risk biting off more than they could chew or facing potentially painful retaliation from even a technologically inferior species to get there resources?

  • Philippe guglielmetti December 29, 2006, 5:12

    Any living species tends to grow exponentially if enough resource is available. But ultimately, resource available to an intelligent civilization is bounded by a cubic function of time : the volume of a sphere centered on its origin planet, and growing at the speed of its spaceships. I call this the “cubic saturation principle”
    A simple calculation shows that if we could build ships traveling at speed of light, we would reach the saturation in about 5000 years. History as shown that we ARE “wolves” : humans never let less developed tribes survive. If any alien civilization is intelligent, it won’t answer any signal. And it cannot take the risk of letting us expand exponentially : they will have to destroy us preventively if they can, or hide. Emitting METI signals prooves to the univers that we are dangerously naive, not intelligent.

  • ljk January 5, 2007, 15:57

    An Introduction to Planetary Defense – A Study of Modern Warfare Applied to Extra-Terrestrial Invasion by Travis S. Taylor, Bob Boan, R. C. Anding, and T. Conley Powell

    Paperback: 216 pages
    Publisher: Brown Walker Press (March 2, 2006)
    Language: English
    ISBN-10: 1581124473
    ISBN-13: 978-1581124477

    Contents: The Statistics – Probability of an Alien Invasion; Warfare with ET – Humans vs. Aliens Weapons, Tactics, & Strategies for Human Defense; Motive Based Classification of Extra-Terrestrials; The “Need to Know”; First Response, Second Response, Third Response – Did We Get It Right? Did We Win?; The Sixth Column – Somebody Should Be Preparing; Conclusions and Discussions; Bibliography; Index


    For anyone who has read the book, do they discuss the concepts of
    dropping space rocks and aiming a relativistic vehicle at Earth? Both
    scenarios would be relatively easy in comparison to, say, a full-scale
    invasion of our planet by ships with lots of laser rifle-weilding aliens,
    and we would have virtually no defense against such an attack.

    Do I think an advanced ETI would actually do such a thing to a fellow
    intelligent species? Only if they have some kind of version of Asimov’s
    psychohistory and predict that humanity may become a galactic threat
    to them at some future date, or they picked up our broadcasts of Jerry
    Springer and knew that something had to be done for the sanctity of
    the Greater Universe.

    We always assume that the Universe is full of conquesting aliens out
    to take over and destroy Earth and humanity, but I often wonder if it
    is we who will be the invading conquerers of the Milky Way one day?

    If we do not evolve in any major capacity as we spread into space,
    I can easily see our species “appropriating” other systems in the name
    of manifest destiny. Even if the highest extraterrestrial life forms are
    no “better” than the animals and plants on this planet, does that give
    us the right to invade their domains in one form or another? What if
    a colonizing ETI landed on Earth say 4 million years ago and decided
    that those chattering primates in the trees of Africa did not qualify
    our planet as being off limits to their galactic expansion? I can easily
    see our ancestors (and we with an alien species) being disregarded
    as not sufficiently advanced, especially if the ETI were not and never
    were humanoid.

    Or maybe that is the “destiny” of all life everywhere, to expand and
    fill every available niche in the galaxy and beyond, and to push out
    any competition, either on purpose or indirectly.

  • johnF October 16, 2007, 11:30

    To carry on a thought I tried to express rather badly in a different thread: An idea (or meme if you give credence to meme theory) that is accepted by all individuals, but destructive to the functioning of society as a whole, could be a much more deadly weapon than physical invasion, and make a highly efficient preventative measure should someone want to stop us before we become a wolf or competitor. Could (perhaps by a small orbiter jacked into our internet or TV signals) such a thing be deployed already?
    Afew other thoughts that occured; if we are looking for an ETI does that mean we know what intelligence is? Could an ordered radio signal be produced by an animal, plant or even bacterial life form (of the non-intelligent kind)? If SETI is becoming a religion perhaps we need a kind of ETI buddhaism: We are not really here we are just another aspect of the universe, if we dont ourselves exist how can an ETI? lol :)