“There’s no lack of real estate” where life might spring up in the universe. So why has our search for ET turned up nothing?

Question: What is the SETI program?

PaulrnDavies: SETI is the Searchrnfor Extraterrestrial Intelligence and it addresses the question, “Are wern alonernin the universe?”  This is arnquestion which goes back to the dawn of history, but for most of human rnhistoryrnit has been in the province of religion and philosophy.  Fiftyrn years ago, however, it becamernpart of science and the trailblazing work of a young astronomer named rnFrankrnDrake set the trend.  Frank decidedrnto start scanning the skies with a large radio telescope in the hope ofrnstumbling across a message from ET. rnIt seemed a somewhat quixotic enterprise when he began, but over rnthernyears it has grown and grown.  It’srnnow an international effort and I think it is taken seriously by manyrnscientists and so it really consists of using radio telescopes, choosingrn targetrnstars where it is conceivable there might be some sort of advanced alienrncivilization and hoping that they might be beaming radio messages our rnway andrnso the 50th anniversary of this it seemed to me a good time to take rnstockrnbecause after all, we’ve had nothing but an eerie silence in 50 years, rnso thesernastronomers have been patiently pursuing this quest.  Irn might say Frank Drake himself is still in the game 50rnyears on.  Now this is heroism ofrnan unusual sort.  Who else do yournknow who has devised a scientific experiment and has pursued it for 50 rnyears,rngot a null result and is still smiling and optimistic? So Frank Drake isrn arngreat hero of mine and I admire his zeal and positivism, but it is just rnanrneerie silence and so the question is are we doing the wrong thing.  Should we be looking somewhere else orrnin some other way?  Should wernbroaden the search?  And myrnconclusion is really that I think what the SETI people are doing is justrn greatrnand I hope they go on doing it and doing it better, but meanwhile, we rnshouldrnstart thinking outside the proverbial box a bit to see if there are rnother waysrnin which we could try to track down ET.

Question: Is this silence more likely duern to aliens’rnnonexistence or to flaws in our search methods?

PaulrnDavies: If you ask thernastronomers of the sharp end of SETI why they think there has been an rneeriernsilence they’ll say, “Well we only have been doing it for 50 years. rnWe’ve justrnstarted. What more do you expect? It’s a big universe out there.”  And in fact, to put that into contextrnthey look carefully.  It’s just arnfew thousand stars.  There are 400rnbillion stars within our Milky Way galaxy alone, so it is a needle in arnhaystack search.  Of course it’srneasy to conclude simply that they just haven’t been doing it long enoughrn orrnhard enough—it’s no surprise they haven’t heard anything, but the rnalternativernis that we are indeed alone in the universe, and it’s impossible to rnanswer thatrnquestion because there are so many unknown factors.  Ifrn we’re looking for intelligence in the universe I thinkrneverybody assumes that this has to start with life and so the question rnis: "Howrnlikely is it that there will be life elsewhere in the universe?"

Now when I was a student almost nobody thought rnthere was anyrnlife beyond Earth.  Today it’srnfashionable to say that there is life all over the place, that the rnuniverse isrnteeming with it, but the scientific facts on the ground haven’t reallyrnchanged.  We’re still just asrnignorant as we were 40 or 50 years ago about how life began.  We’ve got a very good theory of thernevolution of life once it gets started, but how does it get going in thern firstrnplace.  We don’t need a blow byrnblow account of exactly how it got going on Earth, but we would at leastrn like tornknow whether it was a very probable event or very improbable event and rnin ourrnpresent state of ignorance we can’t even pin that down.  Wern can’t even bracket the odds.  It could have been arn stupendouslyrnimprobable fluke, a freak chemical accident that occurs just once in thernuniverse or it could be that life emerges automatically and naturally asrn partrnof the underlying scheme of things. rnMaybe the universe has intrinsically bio-friendly laws that rnbrings liferninto being all over the place.  Werndon’t know.   It’s onlyrnfashion that has said the pendulum has swung from extreme skepticism rnaboutrnextraterrestrial life to extreme credulity.  The rntruth is somewhere in between, but to pin it down we’vernreally got to address that question, how likely is it that life will rnarise onrnan Earth-like planet.  I should sayrnwe know that there are many, many other Earths out there. rn We’re almost certain that there will bernupwards of a billion Earth-like planets in our galaxy alone, so there isrn no lackrnof real estate where life might happen, but what we don’t know is how rnlikely itrnis given the real estate, given a wonderful pristine planet like Earth rnhowrnlikely is it that life will pop up inhabited?  We rndon’t know the answer to that.

Recorded April 15, 2010
rnInterviewed by Austin Allen