Apr 29 2013

Is SETI Science?

I recently receive the following e-mail question:

Got a question for you: do you consider the Search for Extraterrestrial Intelligence to be science or pseudoscience? I recently got into an online debate and found myself in the minority because I maintained that the central thesis — that if intelligent life exists somewhere out there in the greater universe, we would be able to recognize it based upon patterns in radio waves — is not falsifiable.

It would seem to me that the only way to truly falsify SETI, we’d need to map quite literally every body in the universe and rule them out one by one and say that they don’t have anything there in terms of extraterrestrial intelligence.  Unlike other complex hypotheses that are limited by available technologies, I’m not convinced that the task of mapping the universe is even possible, even with a sufficiently advanced technology.

I have received some version of this question many times over the years, always by people who are trying to be skeptical and apply what they have learned about the differences between science and pseudoscience.  It therefore seems like an excellent opportunity to explore this important issue.

SETI is the search for extraterrestrial intelligence and refers to a number of programs over the years that have listened for intelligent radio signals from space. NASA for a time had a SETI program, but this was canceled in 1993. The SETI Institute now carries on this endeavor with private funding.

Whether or not you think SETI is a good idea, is it real science? The issue here is how do we define science. One major criterion for science is that a scientific hypothesis must be falsifiable. This, however, is not strictly true and is an oversimplification.

A hypothesis does not need to be falsifiable in the sense that it is possible to be proven 100% wrong. All that is necessary is that the hypothesis is testable – there is some observation or experiment that you can perform that will make the hypothesis more or less likely to be true.

Sometimes a hypothesis can be stated in such a way that a single counter-example will disprove it. The now classic example is that all swans are white. A single non-white swan will falsify this hypothesis. How thoroughly do you have to search, however, before we can conclude that all swans are white? Would you have to simultaneously survey every swan in the world? If it takes 10 years to conduct a thorough survey can you be sure that a black swan was not born in the last 10 years?

The problem here is in thinking in absolutes. Scientific theories, rather, often deal with probabilities and are not necessarily wrong when exceptions are found. In the case of swans, the more thoroughly we look for non-white swans without finding them the greater our confidence is that all swans are white, and we can certainly conclude that most swans are white and that any exceptions are rare.

Of course this is the classic example because black swans were discovered in Australia.

With regard to SETI the hypothesis is this – life arose spontaneously on Earth, there is nothing special about the Earth and therefore it is possible for life to arise elsewhere in the universe. It is possible that some of that life evolved intelligence, and some of that intelligence developed technology. One method for a technological civilization to communicate across stellar distances is through radio signals. Therefore, perhaps the Earth is being bathed at this moment with intelligent radio signals from other worlds.

Every link in that logical change is perfectly reasonable. The best way to test that hypothesis is to simply look. Looking is part of science. It is a valid way to test many hypotheses. It is not necessary to be able to prove that there are no intelligent radio sources anywhere in the universe in order for this endeavor to be properly scientific.

Like the search for non-white swans, a single example is all that is necessay, in this case to prove that the hypothesis is valid. The more we search without success the more information we will have about the density of radio-transmitting civilizations in the universe. This survey will never be complete, but that is irrelevant.

The broader issue here is the importance of understanding that science is not one method but a collection of various methods. It is important to a proper understanding of science not to have an artificially narrow view of what counts as science. As long as there are hypotheses that are testable with empirical evidence, you are doing science (whether or not you are doing rigorous high quality science is a separate issue).

Frequently the opponents of science try to limit what counts as science in order to deny legitimate science (it is a major tactic of denialism). To be clear, the e-mailer is not doing that here, and he states later in his e-mail that he supports SETI as an endeavor.

It is, however, a common ploy of creationists. They try to deny the legitimacy of all historical sciences because what has happened in the past was either not directly observed or cannot be run as an experiment in the lab. Historical sciences, however, can still make observations and generate hypotheses that can be tested with further observations. There is even a field of experimental archaeology that conducts experiments to test hypotheses about how things were done in the past.

So, yes, SETI is legitimate science. It is searching for evidence that directly tests a very interesting hypothesis. The fact that it can never prove a negative version of that hypothesis (there are no intelligence radio sources in the universe) is irrelevant.

31 responses so far

31 thoughts on “Is SETI Science?”

  1. mindme says:

    To get critics of SETI thinking about the importance of search in science and there can be a right way and a wrong way of doing it, I like to pose them this question: Is SETI is more like a search for a dinosaur in the Congo or a search for a previously unknown rodent like animal in the mountains of Indonesia?

  2. noswonky says:

    The hypothesis: “There is no intelligent life beyond Earth” can be falsified by a single counter-example.

  3. Bruce Woodward says:

    My understanding of SETI is that even if there were stray ET radio waves the chances of that part of the sky being scanned at the moment they blitz past earth are still very very small. I could be confusing this with something else though.

  4. Sherrington says:

    I think this is a good argument for SETI being science. One thing to add is that often in science, operation definitions are important. In this case, “intelligent life” is operationally defined as “life capable of producing radio signals that we can detect.” Thus, if the hypothesis “There is intelligent life on other planets” fails to be supported, it may not be that the hypothesis is “wrong,” but that we did not use a good operational definition of “intelligent life.” Of course, you have to start somewhere.

  5. I’ve had this thought about SETI before. The conclusion I’ve come to is that SETI is a project that uses science. SETI has a goal: finding extraterrestrial intelligence. And it has a method for doing so: using the tools of science to aid that search. Within the project of SETI, there are absolutely claims that are falsifiable. For example, are there artificial radio signals being sent from Alpha Centauri? This is definitively a question that can be answered scientifically.

    A useful parallel is the pharmaceutical industry. What is the goal of the pharmaceutical industry? The non-cynical answer is that their goal is to produce better drugs. That’s obviously not a falsifiable claim, but it doesn’t have to be. The pharmaceutical industry uses scientific tools in support of this goal, however. And again, within that goal, there are absolutely falsifiable claims. For example, does this mixture of chemicals have a clinically signifcant effect?

  6. SETI definitely uses an operational definition of – radio broadcasting technological civilization.

    We probably won’t be picking up any stray signals, and really need for a race to be deliberately broadcasting a signal – either a really powerful signal or they have to be aiming in our direction.

  7. Bruce Woodward says:

    Here is an interesting thought then Steven, as we find more and more planets in the goldilocks zone (is that what they still call it?), wouldn’t it be a good idea to send a powerful signal out to those planets, as narrow and as powerful as possible and to “aim” SETI there first? This must have surely been thought of.

    I wish I had better internet access at work, because I seem to remember an article about how the chances of SETI getting a hit make buying a winning lotery ticket seem like an almost certainty by comparison.

    It is science, I have no doubt about that, but whether it is good use of scientific money and effort is another question altogether.

  8. DavidCT says:

    @ Bruce

    The problem with attempting communication from this end is that is that we would be looking at hundreds to thousands of years for a return signal at best. Focusing will not make it go any faster.

    Have we discovered intelligent life on earth? Broadcast TV would argue against it. Sorry for the snarky remark but for an advanced variety of ape, we have quite a high opinion of ourselves. I wounder how we would stack up against beings who sent signals so long ago.

  9. Bruce,

    The SETI institute does a lot of other science. They are not just listening for signals, they’re doing good astronomy.

    The idea of targeting SETI at earth-like planets has been raised.

  10. Bruce Woodward says:


    The focusing would be for the signal to be stronger at the point of reception.


    Thanks for the link, I will check it when I get home.

    And glad to hear it is doing other good work. As I alluded to it is not a subject I know a lot about, it just seems a little futile to me when you really start thinking about the odds.

    And I am sure I had some other valid point for David, but I got distracted by an Astrologer giving advice via phone in on a radio show, saying how the movement of the planets will be key in the next 6 months… apparently my star sign is having financial difficulties… if only I was born a week earlier I could have been in for a romantic encounter.

  11. ghulse says:

    This is a good argument that SETI is indeed a scientific experiment that mostly relies on observation. However, it’s a bit like looking for a needle in the haystack.

    One of the main assumptions is that an advanced civilization will be using radio technology. It seems entirely possible that the use of radio technology is only a temporary behavior of a still-developing species. Who’s to say what our electromagnetic signature will look like in a few decades or a century if, indeed, we’re still around? So what are the chances that other intelligent life forms have emerged and are at the same technological plateau as we are at this particular point in time that we are searching for them in the vast reaches of space?

    So SETI is a relatively crude experiment, but with the potential for such a fantastic discovery, it’s arguably worth doing anyway.

    SETI does have something of a pseudoscientific flavor in that Carl Sagan used the so-called Drake Equation to justify the search for extraterrestrial life. There’s nothing scientific about the Drake Equation. It’s just a pretentious mathematical formula that ultimately means nothing.

  12. Kawarthajon says:

    While I like the idea of searching for extraterrestrial life and believe that there is a high likelihood that it exists, I don’t think that spending money on SETI is the right way to do it. The likelihood of finding a planet with life on it is already very low (not because they don’t exist, but because they are so far away and difficult to detect, not to mention limited budgets). To then narrow down the search for only extraterrestrials who are intelligent, use radio signals to communicate over long distances and who are beaming signals at Earth – wow, you are really narrowing down what you’re looking for. We are effectively reducing our chances of finding life on another planet by putting resources into finding intelligent beings that are beaming signals at us. I know the SGU folks are supportive of SETI and I don’t have a problem with that, but I don’t think it is a good use of resources myself.

  13. Why do you equate looking for life with looking for radio signals? These are not necessarily the same endeavors, nor are they mutually exclusive.

    SETI is also privately funded.

    Personally I would find contact with an alien technological species far more interesting than detecting possible signs of life in the atmosphere of an exoplanet. The latter would still be cool, but radio signals would be far cooler.

  14. locutusbrg says:

    It has always bothered me that seti uses “radio” as a basis of a positive finding. We have been producing radio signals for about 100 or so years. 100 years from now it may not be used as a broadcast medium for signals at all. What if we were focused on a radio transmission that only stays in the EM range that makes long distance transmission useless. Maybe were are the only tech species that used broadcast EMR for any period of time. What if we are too dumb to figure out how transmit information via quantum entanglement or some other exotic measure. It always seemed rather human-centric to suppose that this was a normal developmental stage for Technic civilization.

    SETI… not so sure it is broad enough to answer any real questions about technological life. Does that change my mind about it being a science. I do not think so. It seems to be a systematic approach to determine presence of extraterrestrial technology. Still seems far fetched.

  15. Wayne says:

    Note: There is a minor typo in your article, I think you meant to say “logical chain”, instead of “logical change”. Now please ignore the 20 typos in my post 🙂

    Good article. SETI is clearly science. But is SETI the kind of science that we should be spending our money on?

    I think the answer is yes, because even though it may be that SETI has a low probability of success, just knowing that an ETI exists would be of enormous impact.

    On the subject of using radio frequency detections, I am reminded of an 19th century (perhaps apocryphal?) plan of using massive bonfires to signal Mars. Perhaps future generations will view our attempts to find ETI with RF, as we now view using bonfires. (Who knows what new communication technologies maybe available in future centuries?)

    And from what I have read, the (too few) scientists working in the SETI field are well aware of the limitations of using RF and have attempted detections with lasers.

    I have also read that if an Earth-like civilization were located in a nearby star system, broadcasting at the same RF power levels we use, we would not be able to detect that civilization (with our current technology).

  16. Kawarthajon says:

    Steven Novella: “Why do you equate looking for life with looking for radio signals?”

    SETI is assuming that it is life that is producing the radio signals. SETI is looking at the problem of whether there is life on other planets on one end of a spectrum (i.e. intelligent life). The other end of the spectrum is looking for pond scum (or other such basic life form) on some distant world by analysing the light spectrum, or whatever technique they are using. Of course SETI is looking for life.

    “These are not necessarily the same endeavors, nor are they mutually exclusive.”

    I didn’t say that they are mutually exclusive. I’m just saying that the probability of success of finding any life on another planet is already low, and very resource intensive (again, I believe the life is out there, but it is really, really, really far away and hard to see). Why, then, jump to finding intelligent, radio signal producing life, when we haven’t even found the pond scum yet? Let’s put our resources into the endeavour that has the highest probability of success – finding basic signs of life on another world. If we’re successful at that, let’s work our way up to other endeavours.

    S.N.: “SETI is also privately funded.”

    I understand that SETI is privately funded, but I would rather see the funding (even if it is private) going into detecting basic life on another world. That’s just my opinion. Also, aparently, the opinion of the NASA bigwigs who pulled SETI’s funding. If there were endless space exploration resources to go around, sure, throw these guys a few extra bucks to do what they do. Should this be a destination for funding in the current climate of cut backs? I don’t think so, but I am just as entitled to my opinion as you are. If people want to fund SETI, go for it.

  17. thunktanker says:

    Putting the issue of mapping every body in the universe aside, SETI still advances science by mapping narrow regions, like systems close to us, for signals supporting the existence of intelligent life. Many projects include narrower hypotheses organized under the umbrella of an overarching mission.

    In this case, SETI’s broad mission of researching the prevalence of life in the universe does not mean it fails to put narrow hypotheses to the test. Falsifying whether in the Alpha Centauri system life exists that is of the sort that SETI could detect certainly seems plausible. Even if SETI discovers nothing suggestive of intelligent life of the sort it could detect in the Alpha Centauri system, that fact itself advances science by revealing something important about Alpha Centauri and falsifying one possible narrow hypothesis of the greater project.

  18. John Pieret says:

    One distinction that I’ve often made may be useful in this regard. There are (at least) two great objectives of science: 1) to determine if any proposed phenomena is real and 2) to determine the cause of real phenomena. SETI (in the narrow sense, not including the other good astronomy it does) can be thought of looking for phenomena (radio waves) that are “(human) intelligent-like.” That search is a scientific enterprise (just as surveying the color of swans would be). Once you have found such signals, however, you have to pursue the other objective, trying to determine its cause. This has actually happened. When pulsars were first discovered, the initial reaction was that they were intelligent-like. Looking at the sources of pulsars eventually produced evidence that they were closely associated with rapidly spinning neutron stars and, therefore, not likely to be associated with intelligent life.

    Examining the empiric evidence for phenomena is certainly part of, but not the be all and end all, of science.

  19. chriskonces says:

    The idea that we should not search for extra-terrestrial intelligence because the chance of success is small, is probably how people felt about humans traveling to the moon at anytime in human history before 1960.

    I think SETI is as pure a science endeavor as a science endeavor can be. The fundamental question SETI is asking is “If there is intelligent life on earth, and earth is one of many trillions of planets in the universe, then can there be intelligent life on any of these other bodies ?”

    Its a fundamental instinct for humans to use whatever technology we have to try an answer a question. From Copernicus using mathematics to explain the motion of the planets to Galileo pointing his telescope up to the sky instead of out to sea to look for ships coming over the horizon. When radio waves were discovered how long did it take for us as humans to listen skyward to see if, by chance, we could detect if any extra terrestrial inelligence may have sent us a signal our way ?

    Almost immediately – http://en.wikipedia.org/wiki/Search_for_extraterrestrial_intelligence#Early_work

    I predict within 20 years we will have definitive proof that life, maybe not intelligent, exists on another planetary body (SETI probably will not be directly involved in terms of the discovery). But within 40 years SETI or a (SETI like organization) will be a principal contributor in the discovery of direct evidence of intelligent life. I think this first discovery will be benign in nature, and will proabably come from an intelligence similar to ours in terms of technological maturity.

    Direct contact of extra terrestrial intelligence is another story – SETI may or may not ever be involved with that discovery. This may not happen for thousands of years or it may happen tomorrow. When it happens its because the extra terrestrial intelligence will have allowed it to happen- for one reason or another. An intelligence that we can actually communicate with will be so far advanced that ‘they’ will have the choice wether or not to make thier presence known.

    But at least SETI is listening. I cant think of a more fundamental scientific endeavor whos outcome could possibly be the greatest discovery in human history. Once this happens, would anyone ever question if this was good science ?

  20. Davdoodles says:

    I’ve little doubt that there is life beyond our planetary shores, but I am left wondering if there is “intelligent” life in the sense that SETI means it.

    I look around this planet, at all the animals and plants that are, more or less, my relatives. All grew up and developed in roughly this atmosphere, and settled in in various mildly differing niches within the envoronment. Even at the extreme end (deep sea vents), its still just evidence of life’s adaptibility. And yet the variety of life is enormous.

    Of all the millions (or billions) of living variants on this planet, all the bacteria, the mole rats, the orchids, the cockroaches and the whales, none is “intelligent”, even remotely, like us. None make (or importantly show any interest in making) radios, engaging in space flight or off-world exploration of any sort. They eat, sleep, hunt, flee, and procreate. Some play. That’s all.

    Oh, and some of our closest cousins poke sticks into ant honey mounds.

    Not saying its impossible of course, just saying that a co-incidence of big brains, opposable thumbs, obsessive technological fiddling and life-threatening drive to exploration, mathematics and language, near-surface smeltable metals and universal wonder may not be so common, even in a big universe.

    Add to that the potential developmental time differences involved. We were not dissimilar to orang-utans (technologically speaking) even a few generations ago. Probably radio’ll be largely obsolete within a few years. Frickin’ lasers will take over. Other intelligent, technological, exploratory species might have gone through that phase last century, a billion years ago, or in another billion yet. By which time we’ll likely be dead, or unrecognizable.

  21. Bruce Woodward says:

    @Chris, I can’t believe you are using a Galileo argument and don’t expect to be called out on it. Sure, he did stuff hundreds of years ago that was visionary, but honestly, it has very little bearing on whether SETI is meaningful or cost effective now. Making vague predictions is also a bit silly, and yes, I call Seth Shostak out on that too. You come off sounding like a True Believer and don’t do your side of the argument any favours.

    I am not against any kind of search for ET, but I do think that the probabilities involved in actually picking up a radio signal are so absolutely minute that it is not worth our time and money if this is the SOLE outcome of the SETI project. Ask most skeptics if they will buy a lottery ticket, and ask how many of them will spend a pound (or dollar) on that probability, and then reduce that probability even further and ask if they want to spend their life’s work on that possible outcome. Even if the maths for figuring out the probability is very vague, which has been argued quite well by some, you also have to look at the simple fact that SETI has been going for a fair while now and nothing has been found. The longer it doesn’t find something, the more likely it is that it will never find something, at least that is way I see it. And remember, whether ET exists or not is not the question here, it is whether ET can be discovered through searching for and picking up electromagnetic radiation signals.

    As Steve pointed out above, they do a lot of other good science and I applaud that and would encourage that. I think if anything will come from SETI it will not be from the scanning the sky for radio signals, it will be from an offshoot of the research they do in conjuction to that.

  22. Bomarc says:

    If I understand the workings of radio signals properly, they fade into nothing more than background noise after about 50 light years. Even laser principles and technology does not overcome this limitation. Consequently, SETI should not be looking at anything further out than this distance.

    Secondly, any civilization capable of interstellar travel, will likely no longer be using anything we could receive with our current level of technology. If tied to communications that cannot bypass the standard “speed of light” limitation, that is not helpful to an interstellar civilization. If they needed to send an urgent message to a colony located 20 light years away, using standard radio waves and await their reply, a total of 40 years would pass. That is not practical or worthwhile.

    I would therefore posit an “advanced” civilization would likely use technology based on quantum principals, to enable interstellar communications. I don’t think we are yet capable of finding such communications with anything in our inventory.

    Perhaps, at some point (if extremely fortunate) SETI may yet achieve success, but I won’t be holding my breath.

  23. eugenelb says:

    I think that SETI is searching the wrong spectrum for advanced life. Radio Waves are good for terrestrial communication, fail horridly as a means for interstellar communication. If SETI really wanted to find signals from intelligent life we would be hunting scalar waves which are superluminal. I would want to use a quantum entanglement and paired electrons to provide private communications. Life is common, the simian apes that inhabit the earth are arrogant to believe that they are the pinnacle of evolution.

  24. chriskonces says:

    @ Bruce The example of Galileo was just an illustration of man using new tools to make scientific observations and to help formulate new theories on the nature of the Universe. Similar to SETI and the use of radio astronomy to search for extraterrestrial intelligence. Galileo didnt immediately see the moons of Jupiter when he pointed his telescope skyward. He had to refine the instrument for astronomical observation, and ultimately discovered there were four bodies orbiting around Jupiter not the earth, further promoting the idea of a a heliocentric Universe. Was his refinement of the scope for astronimical use a cost effective endeavor ? Not to the Church I assure you, but to Galileo it made perfect sense. Do we question the costs effectiveness of his actions today ?

    I agree the chances are small of detecting intelligent life as well, and no I dont play the lottery for the very reason you stated. But ask the guy who won the lottery “Was it worth it ?”. I expect the answer to be yes. I like your lottery example though. Lets take it a little further. From a technological standpoint with SETI we are buying 5 tickets at a time in our search for intelligent signals, each week we lose. 5 years from now we will be buying 50 tickets at a time, probability of hitting the jackpot is still tiny. But as SETI progresses in thier understanding and techniques they continually accumulate better odds, 10 years they may be buying 10,000 tickets a week. One day they will hit the extraterrestrial jackpot as technology and computing powere allows them to buy more “lottery tickets” in any given week. And you have to play to win – this is why I believe in SETI and why the cost effectiveness is not really a question for me personally.

    As far a s vague predictions, I thought my 20 / 40 year timeframe was actually pretty specific, probably too specific. I just happen to believe that based on what I understand today. Would I bet my life on that specific prediction – no.

  25. eugene – we have no means of superluminal communication, nor does it seem to be possible with what we currently know. Quantum entanglement does not allow for instantaneous communication – so far no one has been able to design an experiment that allows for transfer of actual information through quantum entanglement.

    Bomarc – narrow band signals could have a range of thousands of light years (http://www.faqs.org/faqs/astronomy/faq/part6/section-12.html) It all depends on the power of the transmitter and the effective size of the receiver.

    SETI is not about two-way communication, but receiving a one-way message.

  26. Wayne says:

    Sorry, drifting off topic a bit… but thousands of light years? With existing technology???

    Hundreds of light years could be remotely possible (with some very optimistic assumptions), but only if we are “detecting beacons built by putative advanced civilizations and intended to attract attention”

    FWIW, That quote is from the same site you referenced.

  27. eugenelb says:

    Steven, I realize that the USA in general lags behind Russian and Europe in the development of a Logitudinal EM Wave Interferometers. The general knowledge of scalar waves is lacking in the scientific community, due to the fact that experimenting with this technology often leads to energy breakthroughs that are considered disruptive to the current energy oligarchy.

    Quantum entanglement has shown a faster than light effect, that may not currently be utilized as communication medium, yet proves that there are things that move faster than the theoretical speed of light. It has also been shown that the speed of light can be affected by the medium it is transmitted through. We have experiments that display that the speed of light can be slowed down.

    I know that radio waves are a poor form of interstellar communication and searching for them through the vast amount of background radiation is like shooting in the dark. It is amazing how much pseudo-science is preached to the public, while real phenomenons are ignored and not studied for the advancement of man. The more I know the more I don’t know.

  28. ThomasT says:

    Meaningless Q that assumes seti has the know-how to intercept interstellar communications of a tech. way beyond ours, ie with messages attached to tachyons. http://www.theyfly.com for that tech.

  29. SimonW says:

    Is there a convolution of motive with what they do?

    What they do is scanning radio signals from telescopes for patterns, and identifying what causes those patterns. (Well they do other stuff concerned with astro-biology, but lets run with the space telescope stuff for now).

    The motive is to uncover extraterrestrial intelligence.

    It doesn’t matter what your motive is, it is what you do, and how you do it, that makes it science.

    In the same sense looking for evidence of a creator in the Universe is a motive, that doesn’t of itself preclude “creation science” from being good science. Indeed many scientists (more so in the past) have seen their pursuit in exploring “creation” as some sort of worship.

    The issue is when the motive to do science gets in the way of doing science properly, whether that be money, or religious belief, or an overly excitable imagination concerning aliens. The motive may of course shape the science that is done, you may choose not to follow up results that don’t sit well with the motive, but that of itself is not necessarily bad science, not everything can be researched at once.

    Now if you suppress results that disagree with the motive, say your results say the drug is no good and this won’t make money for the funding pharmaceutical company, then that is a problem. So we only need worry about SETI when they start hiding their null results.

  30. norrisL says:

    If someone in the comments above has said something like this already, I am sorry. But the thing with SETI is that if we did find ET, that would be the BIGGEST news story ever!

  31. Aardwark says:

    I confess to having merely browsed the above comments (I am a bit pressed for time at my job right now), but I do feel I have to point out something that is missing from the above discussion (even though I find it a very useful one).

    Namely, SETI is not necessarily all about radio signals. There are many other, arguably more promising, avenues of research that would legitimately count as SETI. It is true that listening for radio signals has been, from the beginning, the main SETI methodology, and that it is still, by far, the most advocated one by the majority of SETI promoters (this oversimplification of SETI is partly to blame for the current prevalence of negative views toward SETI projects). However, these numerous other approaches to SETI – such as searching for signs of Dyson shells, stellar uplifting, antimatter burning and other astroengineering projects that are, by definition, detectable over vast (potentially even intergalactic) distances – do offer a cost-effective (since technology to be used is already there and already justified by other research) way to test the hypothesis that advanced civilizations may become capable to use the full resources of their native star systems (Kardashev type II civilizations) or home galaxies (Kardashev type III civilizations). This means, if we just look hard enough and find none of the above or similar artifacts, that would in itself have profound implications and beg the question why few or no civilizations ever reach these stages of development or do not retain such capabilities for long (provided, of course, that our regard of such ‘stages’, at least roughly, corresponds to reality). And if just one macroengineering artefact is found, well… It is hard to imagine a more important (and obviously valid) scientific discovery.

    Another point: a SETI researcher is not necessarily a ‘believer’, nor is a SETI critic necessarily a ‘skeptic’. It is equally correct to say that the former is ‘skeptical’ toward the notion that we are the only living/intelligent beings in the Universe, and that the latter is a ‘believer’ in uniqueness of our existence (which is, by the way, a deeply un-Copernican attitude).

    I highly recommend to all who are interested in critical analysis of SETI (as well as astrobiology in general) a highly enlightened book entitled “The Astrobiological Landscape” by Milan M. Ćirković.


    Among other things, there you will find a sharp and extensive analysis of the main anti-SETI arguments frequently encountered in the philosophical and scientific literature.

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