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Paul Davies:

The Eerie Silence


Posted: 14 December, 2009


Professor Paul Davies is a world-renowned cosmologist and astrobiologist at Arizona State University, where he has set-up BEYOND, the Center for Fundamental Concepts in Science. He’s frequently on television and writes for newspapers and magazines, as well as a number of best-selling science books, and he is the Chair of the SETI Post-Detection Science and Technology Taskgroup. His latest publication is The Eerie Silence, published by Allen Lane and due out in March 2010. In his new book, Prof Davies takes a look at the Search for Extraterrestrial Intelligence (SETI) as it enters its fiftieth year. Keith Cooper spoke to Professor Davies to get the lowdown on where he sees the future of SETI.

The Eerie Silence would suggest that the silence is odd in some way. Do you believe that?
It depends on your assumptions. Given that in the book I take a fairly sceptical line, I don’t think it is odd that we haven’t picked up a radio message directed at us because I think the chances of that are so small that it is no surprise to me. Of course for those people who do really believe there are a vast number of civilisations in radio communication with one another, then it is odd. So the title serves the purpose really of directing the attention of SETI enthusiasts who really believe that the Universe is abuzz with radio traffic – for them it is an eerie silence. What I do feel might be odd is if there are no signs whatsoever of any extraterrestrial technology.

So you don’t put too much credence in Fermi’s paradox?
That’s right. My feeling is that on reflection it would be truly astonishing if there were any messages being directed at us, because I don’t think that is credible. I don’t think we have the sensitivity yet to pick out random radio traffic buzzing between civilisations. What I think is a big lacuna in the search so far is that beacons have not been actively searched for. It is much more probable that we would pick up a multidirectional beacon than random messages between civilisations or domestic radio traffic or anything deliberately directed at us. All those scenarios don’t stack up, but beacons do. We can imagine a long vanished civilisation that has left a beacon, and this could go on for millions of millions of years. There really has been no systematic search for them, and yet we have the technology to do that.

Is what we are searching for limited by our technology and scientific knowledge?
The traditional answer to this is that if aliens were deliberately trying to communicate with us they would recognise our level of technology and be using radio rather than something that they would guess is far beyond our capabilities. I don’t think they are going to be directing messages at us because they don’t know we are here! A civilisation a 1,000 light years away, even if it is incredibly altruistic and prepared to dumb down to old fashioned radio just for our benefit, isn’t even going to know we have radio technology for another 900 years [because our radio signals are still travelling out at the speed of light].
    That said, my feeling is that we know enough about the physical Universe to guess that radio and optical communication are still a good way to go, no matter how advanced your technology is. The laws of physics are the same everywhere: radio and optical light penetrate a lot of the gunk that is out there in the galaxy and beyond, so they are actually a very good means of long range communication. Just as we still use ropes to tie knots, even though it is thousands of years old technology, it doesn’t mean we stop using rope. We still use the wheel, that doesn’t become redundant just because we have aircraft. I don’t think there is any problem in pursuing radio and optical, but my theme in The Eerie Silence is that we should continue searching for messages because we are set up to do that, but that we should also be looking for the most general signatures of technology right across the board. In other words, instead of looking for messages we look for signatures of technology, and we should look at anything that is weird, anything that looks out of place, anything that looks fishy or not right; wherever it is, we should use the whole panoply of science, everything from nanotechnology and molecular biology right across to radio astronomy and everything in between. It is really a plea for people to think more creatively about what a signature of alien technology might be like, bearing in mind the question of how we distinguish technology from nature. The chances of finding a deliberate message, however it is presented, are much lower than our chances of stumbling across some unintended signature of technology, I’m not saying that the aliens would deliberately try and conceal their activity, but they may not deliberately try and draw attention either. In the same way, we on Earth mostly use radio and, apart from on a few occasions, we are not deliberately trying to communicate with the aliens.

What kind of alien technology should we be looking for?
There may be many giveaways of alien technology from astro-engineering to just subtle signs, and what I try to do in The Eerie Silence is to draw the analogy between a detective at a crime scene, who’s not sure if somebody died of natural causes or if there was a culprit involved; the signs that it was murder may be very subtle. In the same way we are looking out at the Universe and we see all sorts of wonderful products of nature, but what we are interested in is if there are any subtle signs that suggest that it is not natural, but artificial.
     All the examples I give in The Eerie Silence (missing magnetic monopoles, cosmic strings etc), one can read them and have a chuckle, because they are tended to be illustrative rather than serious suggestions, but they are the sorts of things we should be on the lookout for. And it is true that it is a mystery as to where all the monopoles [magnets with just one pole] are in the Universe. Most people want a cosmological solution, but then again you have to ask, if they were a useful energy source then maybe we shouldn’t be so surprised that they are not around in our region of the Universe. What we would really like is to find some anomaly that was inhomogeneous across the Universe, so that there were domains where some things are missing that should be there, or something is are there that shouldn’t be, and this has a sort of lumpy appearance across the Galaxy. That might make you think, “oh, that’s because they’ve been deliberately tinkered with in some way”. So if we found we were in a region of space that was anomalously low on magnetic monopoles, then it raises the chance that this is a sensible explanation.
     What I try to do is shake people out of traditional SETI thinking, to be looking at all these sorts of things. Much more dramatic and much easier to understand examples are things like artificially square craters or signs in our backyard, literally in the Solar System, of an alien visitation some time in the remote past, that has left its mark in some way that is almost but not completely obliterated.

How could you get funding to look for things like this?
Basically it is impossible to get government funding to look for any of this stuff, including mainstream SETI, so the attitude that I take is that we piggyback off existing projects. For example, Mars is pretty well surveyed, right down to a resolution of a metre or so. If there is anything peculiar, people are going to spot that. Now, more likely is that there would be something weird in the Asteroid Belt, but it is really hard to know how we could search through it all. What I’m saying is that all scientists should be a little bit aware of looking out for something that just doesn’t seem to fit, and it doesn’t have to be in space; I give this other very speculative idea of a message in genomes, and then say, well we are sequencing genomes anyway, so it costs next to nothing to run a computer algorithm to see if there is a message there or of there is something artificial about it. It could be like SETI@home, and you could do that without any funding at all. The chances of success are incredibly slim as this is a really wild idea, but I think I agree with Freeman Dyson when he says that in science you do what you can do, and if something is easy to do, it doesn’t matter how wild it is, you might as well do it anyway, because who knows what you may find? If people can be simply open-minded enough to keep their eyes open for anything that looks peculiar, and instead of rejecting it and throwing it out like bad data, just bear in mind that somewhere in the Universe there may be signatures of alien technology, and we have no idea where we will find those signatures, so we should just be aware that they might be there and not automatically reject anything that looks like it doesn’t fit.

You have spent a lot of time researching the possibility of a ‘shadow biosphere’, a second genesis of life on Earth that occurred separately to the life that eventually evolved into us. How does this help with SETI?
I think it is the most crucial factor in the entire SETI programme, because when you look at the Drake Equation it is a completely meaningless equation because the error bars on the probability of life emerging on an Earth-like planet are huge; we have no idea whether it is zero or one, or somewhere in between.
     It is traditional, and it has become very fashionable at the moment, to suppose that given an Earth-like planet, life is going to obligingly appear. We have absolutely no evidence in favour of that and it remains completely conjectural, and back in the 1960s there were almost no scientists anywhere in the world who would have said such a thing. The prevailing view was that life was a stupendously impossible and bizarre fluke that has happened just on Earth and you would never expect it to happen anywhere else. Now the fashion is to believe that life is all over the place, but the science hasn’t changed, we know just as little about how life began now as we did then. So if we can establish that life has emerged more than once on Earth, then we can be pretty sure that it will be on most Earth-like planets all around the Universe. Then the major problem for the Drake Equation goes away.
     Of course you could argue that there is something very, very special about Earth that means life pops up many times here but never anywhere else. I think we would all be convinced that if we’d found that life has started on Earth umpteen times then it would be bound to have happened on another Earth-like planet elsewhere in the Galaxy. So searching for that shadow biosphere is, I think, the most obvious and direct thing we can do. Microbial life is by far the most common form of life on Earth and we have barely scratched the surface of the microbial world, so nobody knows what all those little things are, and it is entirely likely that some of them are life as we don’t know it.

Even if it could be shown that microbial life could form on other planets, what are the chances of it evolving into intelligent life?
It’s curious; some people think that life is inevitable on an Earth-like planet (though they make that claim without a shred of evidence), but that the evolution of intelligence is very rare. I take it the other way around, I think the big unknown is that first step, and that once you have got life it is obviously in with a chance of evolving intelligence because we already know of a mechanism to do that – Darwinian evolution – which can take you from a microbe to a human being. We know of no mechanism that takes you from non-life to life. That doesn’t mean there is no mechanism, we just don’t know what it is. So at least we have an understanding of how life will evolve. Whether it will evolve intelligence is another matter entirely. In The Eerie Silence I try to point out that there is no law of nature that says you are inevitably going to get intelligence from evolution, but if intelligence turns out to be one of those things like wings or eyes, which have sufficient survival advantage, then nature is likely to rediscover it again and again and again, so maybe it is not unreasonable. But you first have to get multicellular life, and I think one of the major unknowns is, what did it take for multi-cellular life to form? That is something we may make progress on over the next decade or two.

Would the discovery of ET really have much of an effect on humanity?
I’ll give you three scenarios and it depends very much on which it is. If it is simply that tomorrow an astronomer says, “well I’ve been studying this object on the other side of the Galaxy for a long time, and there is no other conclusion, this must be the product of some sort of intelligent manipulation”, then I think you and I would be blown away by it, but go down to the pub and you’ll just hear people talking about it as a curious thing, no big deal. That’s because people are primed for it from a diet of science fiction, and probably half the population believe that such a discovery has already happened! So it is not going to cause riots in the street, but I think just like with Copernicus and Darwin, over the centuries it really will colour the way we think about ourselves and the way we fit into nature. It is going to become part of people’s world view, part of their education; it is going to change in many subtle ways the way they think about the Universe, just like the way that knowing we are products of evolution changes in subtle ways how we feel about our planet.
     If it were the Carl Sagan-type scenario of a message for mankind, then I think the effect on society would be stupendous, and it would be impossible to judge what the consequences would be if there really was a message with content.
     I think the one thing that would be clearly affected would be religion. That might not be terribly relevant to you or me or to contemporary society in Britain, but on a world-wide basis it is surely significant. Christianity would be badly affected because of the claimed uniqueness of the incarnation. I was at a conference at the Vatican about SETI, and we didn’t go into the theology of this, but that fact that the Vatican is interested in astrobiology shows that there is an issue. There was a vigorous debate for hundreds of years amongst Christian theologians about how to reconcile the uniqueness of the incarnation with the presumed need that very ethically advanced aliens might deserve to be saved. For people who are not Christians this all seems like a daft quibble, but don’t forget that Christianity has an enormous hold over people and it could prove very disruptive. They try and sweep it under the carpet, but as soon as you confront that issue of the incarnation, it clearly becomes problematic. Maybe they would adapt and change some of their fundamental ideas, but my warning to them is that they ignore this at their peril, and I’ve been trying to prod the Church for a while into taking this seriously. There are one or two theologians who do, but I don’t see how you can live with it and retain the core of Christian belief. The only way is to have some incredibly arrogant view that we alone in the Universe have been singled out for special treatment and I don’t think many people find that credible. As I point out in the book, in the case of Darwin and Copernicus, society had decades to slowly come to terms with it, because these were theories for which the evidence was contestable and took a while to work through, whereas if you get a message from an alien civilisation, you’ve got it, its right there, and suddenly all the rules of the game have changed. It is a good indication that when I was at this Vatican meeting there was quite a bit of press coverage, and the only thing they really wanted to talk about was, “oh, is the Pope interested in ET, and is this a problem for Christianity?” When I told them that it was just a science conference and that we’re just looking at the prospects of getting spectral signatures of life from the atmospheres of extra-solar planets, they seemed very disappointed. What they wanted to know about was the effect on religion. For the public, that is what they care about.

You can join in the search for ET by signing up for SETI@home, which is run by the University of California, Berkeley. It is a downloadable programme that runs in the background on your computer, analysing real data from radio telescopes for a sign of a signal from ET. Astronomy Now has its own SETI@home group, which already has 500 members, and you can join the group here. Who knows, you may be the one who detects the first radio signal from another world!

You can read more about Professor Paul Davies and his new book, The Eerie Silence, in the January 2010 issue of Astronomy Now.

For more information about SETI, you can visit the following sites:
SETI Institute
Paul Davies’ website
Research into the shadow biosphere
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