The eerie silence: Are we alone in the Universe?

Charlie thank you very much for that kind and greatly exaggerated introduction and ladies and gentlemen it's a pleasure to be here in foggy and chilly Canberra after Phoenix Arizona so where whether or not we're alone in the universe is surely one of the oldest questions that human beings have ever asked but for the majority of history it's belonged to the provinces of religion and philosophy but fifty-two years ago last April fifty-two years ago it became part of science when a little-known astronomer radioastron a'mma by the name of Frank Drake began to sweep the skies with a radio telescope in the hope of stumbling across a message from an alien civilization when this is a picture of the said Frank Drake in April 1960 with the Green Bank radio telescope in the background which is what he used and this rather quixotic quest wasn't done on a whim radio telescopes were a byproduct of world war two in particular radar research and in the immediate post-war years the astronomers and radio engineers began building these big dishes and they soon realized within a few years that they had in their grasp instruments capable not just to communicating across terrestrial distances but across interstellar distances and then in 1959 in the landmark paper in the journal Nature Giuseppi cocconi and Philip Morrison at MIT suggested that astronomers could use radio telescopes to search for radio messages coming from alien civilizations out there in the galaxy and they conceded that although the probability of success of this surge would be exceedingly low nevertheless if nobody tried the probability would be zero and so Frank Drake took up the challenge knowing that with an instrument like this he did have the power to detect radio messages should an alien civilization be be at us with an instrument presumably rather more powerful than this one and so thus began the subject of SETI the search for extraterrestrial intelligence and I'll be using this acronym SETI many times in the lecture today and so it addresses the question about is there anybody out there and if there is are they trying to communicate with us via radio well most people have heard about SETI and I expect you have come here today for the simple reason that you've heard about it too a lot of people get their information about SETI from Jodie Foster here she is as starring in the movie contact so this movie was based on the novel written by Carl Sagan he was sort of like an arch evangelist of absently and she plays the part of the starstruck astronomer who manages to pick up the message from ET and by and large this movie follows scientific respectability it's more or less what the SETI community do with one obvious exception that the great moment of discovery when Jody finally hears the message from the aliens is picked up on headphones which is why she's doing this she's wearing headphones too to discern the messages coming in from space well when Frank Drake started this in 1960 he had a couple of loudspeakers in the observatory and then if he picked up a signal they would would start shattering and booming today SETI astronomers routinely monitor about 1 billion radio channels simultaneously and so trying to pick this up in headphones is pretty ludicrous it's like listening to a billion radio stations all at once I'm picking out the one that's got the message so but that aside the movie is more or less in the direction of what the SETI research program has been doing now a number of radio telescopes have been used for this purpose the one closest to here is a parks in New South Wales this movie was this dish was famous for the movie called the dish I'm sure you've you seen that and which whether the first moonwalk but it's also been used on and off for SETI searches and let me just tell you what they do a typical SETI search will consist of manipulating a radio telescope like this you'd have a wish list of stars and inventory of likely looking sun-like stars in our neighborhood of the galaxy point the telescope at a particular style listen for about half an hour if you don't hear anything move on to the next one and so on that's what they do in the event that they pick up a signal then the procedure is to tip the dish a little bit to one side and then back again and if the signal fades and comes back on then that is good news and then to follow it for a while to see if it is following the rotation of the earth relative to the Stars rather than relative to the Sun which would indicate it's coming from deep space and then using another radio telescope on a different part of the world to cross-check and so that's that's a procedure it's really rather time consuming which is significant for reasons I'll explain in a moment this is another dish that's often used by for safety purposes by radio astronomers this is the Arecibo radio telescope in Puerto Rico it's the biggest in the world it's not steerable though it's a dish that's just stuck staring straight up at the sky so as the Earth turns it monitors a strip of sky this was also famous for featured in the the movie with Jodie Foster and also in the James Bond movie Goldeneye so all of this is very familiar from Hollywood the jewel in the crown of the SETI program is this array of radio telescopes here in Northern California place called Hut Creek and this is called the Allen telescope array because Paul Allen co-founded Microsoft gave from the 35 million dollars for this to be built the plan is eventually there should be 350 of these dishes and that and if it reaches its design specifications it will be better than any other radio telescope on the planet for this particular job 42 have being completed now and it's operated by the SETI Institute in California and they've run out of money so if you've got any rich friends who are interested in cornering the market on searching for et just get in touch with me or send me your check now I'll pass it on to the to the people who need it so this array here is currently hibernated or mothballed whilst they're waiting for the two million dollars per year running cost so it's a maybe a tragedy that this wonderful system this this instrument here is lying idle when it could be could be used for safety purposes anyway the the upshot that is a broad-brush summary of what SETI has been up to in the last 52 years and of course you'd know all about it if they have been successful that is to say after 52 years all the radio astronomers have got to show pride is an eerie silence hence the title of my book which I wrote for the 50th anniversary of SETI because I wanted to do a number of things one was to give a critical evaluation of the SETI program and a little pat on the back to my friends who do this stuff but then I wanted to to ask whilst we're waiting for this heroic and tiny band of radio astronomers to come up trumps and open the bottle of champagne that they keep on ice whilst we're waiting for that is there anything else that the broader scientific community can do to expand the search for et must we leave it just to this little group and the answer is yes there's a lot of things we can do I've got to tell you about it in a moment so the fact that there is an eerie silence what does that mean does it mean that we are in fact alone in the universe or at least alone in the galaxy after all or might we be looking for the wrong thing or in the wrong place at the wrong time now I think it's very good reason why SETI radio SETI as it is I've described it to you would not have succeeded it's very simple reason and that is ET may be out there but ET doesn't know that we are here now what's the reason for that well let me take you through some simple arithmetic I regard Frank Drake as one of the most optimistic in the world who else do you know has designed an experiment run it for 50 years got a null result and is still upbeat about the future and he is he's now in his 80s he's still an active SETI radio astronomer so I'm just couple of weeks ago sitting at his desk he's still in the game and he's remains confident that this method of searching for et is going to succeed and so if you ask a SETI optimist like Frank well give me a guesstimate of how many civilizations are out there in the the galaxy transmitting radio messages of course nobody knows he has no basis for giving me any numbers we'll see in a moment but if we take his number which is 10,000 in the Milky Way at this time then a bit of simple mathematics can tell you how far away the nearest such civilization is likely to be and it's a few hundred light-years away so let's take a thousand light years as a round figure so maybe over there somewhere in the galaxy thousand light years over there is a community of aliens interested in communicating with us you can imagine that they're going to be far in advance of us they've got some super duper instruments and they can observe it very closely and they know this intelligent life on earth how do they know it because they can see the pyramids and the Great Wall of China and the beginnings of Agriculture but now we hit a problem that the fastest speed in the universe is the speed of light you can't observe another planet in a time less than it takes for the light from that planet to reach you so if they're looking at earth now they see earth as it was a thousand years ago there were no radio telescopes a thousand years ago so put yourself in the position a thousand years ago of a SETI enthusiast in this hypothetical planet going to the government or the funding agency and saying we know there's intelligent life on that plan is over there and we think that any millennium soon they will have radio technology can we have some money to start transmitting messages and I could tell you about the answer would be I know the committee would deliberate on this and they say that's a very wonderful project you come back in a thousand years or ten thousand years or whenever you know that they have the capability of detecting our messages and we'll give you the money so when will et over there thousand light years away now that we are here with our radio telescopes and the answer is when our first our first radio messages reach that now every time you broadcast a radio or a TV show some of the radio waves leak out into space we can't do anything about that we can't get them back they golf out the galaxy and in a hundred years they've traveled a hundred light-years and so on so we imagine that there is this sort of wave front of the first feeble radio messages broadcast on earth that are leaked out into space and they've got about a hundred light years out there so quite a long way to go still before they reach this hypothetical nearest civilization then about another nine hundred years maybe et over there will start broadcasting to us and then in another thousand years we pick up their first message so you see the problem the fact that it's silent out there might simply mean that it's not worthwhile any extraterrestrial community spec is speculatively beaming messages and a planet on which they know this intelligent life but they don't know that there's radio technology so that's that's the problem so how do we get around this is there something we can do and I think the answer is yes so now let me take you through this formula here is his Frank Drake as he appears these days as standing in front of his eponymous equation this equation uses to deduce his 10,000th and this how he comes up with that number now this is not an equation in like the physic sense of the term this is more a list of things we don't really know so it's a catalog catalog of our ignorance and when I got interested in SETI way back in the 1960s when I was a student we're II didn't know any of these numbers well we're now in better shape the first one is the rate of star formation in the Milky Way we know that number rather precisely now it's about seven per year the next one is the fraction of those stars with planets gain and 60s nobody knew whether there are any planets outside of the solar system there was a theory that the formation of planets was some freak event that would not be likely to occur anywhere else in the galaxy there was an alternative idea which is that most stars have planets and I think probably astronomers believe the planets are out there but they didn't know well as you're probably aware in the last 20 years we've actually found many of these extra solar planets so that's the fraction of stars that have planets and that's very close to one the one after that in subby is the number of those planets that are earth-like in some sense so small rocky planets with atmospheres on which life might emerge now you may know there's a satellite NASA satellite in orbit at the moment called Kepler and it's looking for these extrasolar planets and it's finding them by the hundreds and it's finding them by the transit method when if a planet passes across the face of its parent star there's a slight dipping in the light from the star as a result of they've been blotted out by the planet and so this thing just stares at 300,000 stars day after day after day and looks for those little blips in the light curves and as a result of that many many planets have been found and it doesn't quite have the capability of finding other planets just like Earth but it's getting close and so you see newspaper headlines much like this one this was just last month new estimate billions of earth-like planets in our galaxy and that's I wouldn't disagree with that I think it's probably true that there are billions of earth-like planets out there in the Milky Way alone that's a lot a lot of real estate on which life might emerge so now we get to the next term in the Drake Equation f sub-l that's the fraction of earth-like planets on which life actually emerges what is that well our Frank Drake likes to put that equation well there are a lot of a lot of scientists certain a lot of SETI astronomers who say given an earth-like planet life will obligingly pop up in other words it confuses habitability with inhabited an earth I planet might be habitable but that doesn't mean its inhabitant and unfortunately a lot of media reports just gloss over they treat those two terms as if they're the same just grammatically incorrect and so how likely is it then that given an earth-like planet life will pop up well then that has to do with the problem of life's origin how did life begin we need to know how it began and if we know how it began then we can estimate the odds that it would happen on a planet like the earth if you don't know how it began you can't estimate the odds so how did it begin well what did Darwin have to say on is my favorite Darwin quote it's me rubbish he said thinking a present of the origin of life one might as well think of the origin of matter so Darwin of course famously gave us a wonderful theory that explains how life on Earth has evolved over billions of years from simple microbes to the richness of the biosphere we observe today but he pointedly left out of account how life got started in the first place mere rubbish he said so Darwinism only works once you've got life going from non-life to life is a big step and it's the first step without that step Darwinian evolution simply can't happen so we have to get life in the first place now it's interesting that we physicists have now explained the origin of matter so not rat one off where are we with the origin of life 150 years after Darwin express these sentiments well we're just as much stuck today as Darwin was in his day we haven't a clue how life began plenty of theories a few scrappy experiments but basically we are in the dark about what it took for life to get going now when SETI began and when I was a student searching for et was considered so bizarre while might as well have said that one was searching for ferrets and the reason it is that biologists almost to a person said that life on Earth is a bizarre complex freak accident and therefore unique in the universe but life even the simplest form of life is so stupendously complex it would never happen again anywhere else that it must have required a sequence of very peculiar circumstances to bring life into existence from non-life so it was a chemical accident of such low probability that nowhere else in the observable universe would it happen when sometimes here's the quite fallacious argument voiced that oh the universe is so vast there must be life out there somewhere simply isn't true within the volume of space that we can a maximum in principle have access there may be 10 to the 23 potential sites for life it's easy to imagine that the odds against life forming are much much lower than 1 in 10 to the 23 very easy to imagine that just imagine for example that it's a farm life from non-life requires 10 a succession of 10 chemical reactions surely will be many more but supposing it was just 10 supposing each of these required a temperature range of say 10 degrees so one might have to be between 10 and 20 degrees and one between 40 and 50 degrees and so on and you need to have them in the right sequence well a bit of arithmetic will soon show you that the chances of getting that right sequence are going to be exceedingly exceedingly low and so it doesn't take very much for life to be seen as a bizarre freak and that's the way it was treated for most of my scientific career but in recent years the pendulum has swung the other way and we now have scientists like Christian de Duve saying life is almost bound to arise wherever there are conditions like the earth fact he even calls life a cosmic imperative wonderful idea that somehow life is built into the nature of the universe in a fundamental way it's a life friendly universe and so life is going to pop up obligingly wherever we find it wherever we find earth-like planets I'd love to believe that the thing is that this sentiment that the universe is teeming with life and contrasting with what it was like in the 60s that life is confined to earth that switz switch and sentiment is not based on any science it's not like we now understand how life began we're just as much in the dark as we were so it's entirely fashion that is leading people including very distinguished scientists to declare that there must be life all around the universe and we cannot know the error bars are infinite we simply don't know how life came to exist and therefore we can't estimate the odds so that the big take-home message be I get infuriated people say well do I believe there's life out there the whole point is that we can't know until we do something about the error bars on the origin of life and I'm going to tell you about what we can do how can we test this hypothesis of the cosmic imperative wonderful if it's true how can we test it well the answer is we need a second sample of life while Chris McKay at NASA Ames calls life 2.0 we need to find a second sample of life that started from scratch independently of life as we know it so we want life but not as we know it we want to find a different type of life with a second Genesis because if it's happened twice in the universe then surely it's going to happen all around the universe so we just need one other example so how do we find out where do we look how to find life two pi day one is across setting if we should pick up radio signal well they can tell us how life began the other is that something called the terrestrial planet finder this is a would be if it was funded a space-based system they could take that inventory of planets that Kepler is compiling at the moment and observe them in such a fine level of detail that the atmospheres of those planets could be imaged and the and the spectrum of the atmospheres could be measured and then perhaps this would reveal oxygen or something like that which might be a telltale sign of life but that's going to be a long time coming many many decades it has to be a huge very expensive space-based system a lot of people thing let's go to Mars but you may find life on Mars and then if there's life there doesn't that mean it's happened twice once on earth once or Mars unfortunately it doesn't mean that as the following picture explains Mars on earth take a hit from time to time from comets and asteroids with enough force to splatter rocks all around the solar system and this means Mars rocks come to earth earth rocks go to Mars so if you get life on one of those planets it's going to spread to the other one pretty quickly for my money I think like probably started on Mars and came to earth later so if we go to Mars and we find there's life there chances are it's good old Earth life so we're still no better off all it says is that life we know start at once and it's spread around a bit we need a second sample of life some people pin their hopes on synthetic biology so if we can make life in the lab in a test tube wouldn't that show it's easy to make not at all we want to know how nature did it without a big science ground without a test tube without all the fancy equipment without the lab technicians and in particular without an intelligent designer for the sake of argument we could call craig Venter without intelligence idaho knew what he was trying to achieve and could move towards it step by step we've got to figure out how nature does it so even if we managed to make life fairly easily in the lab it doesn't show that it's easy to make in the great wide world out there so what do we do well what is the most earth-like planet in the universe that we know that's the most promising place to go to find a second sample of life what's the most earth-like planet we know it is of course earth itself if life pops up readily in earth-like conditions as many scientists assert then surely it should have started many times over right here on earth right on our home planet how do we know it did has anybody actually looked well astonishingly until a few years ago the answer was no nobody had thought to look on earth for life but not as we know it all the textbooks will tell you what I'm sure teacher told you when you're at school that all life on Earth is the same life we're all interrelated and even the bizarre agrees into the deep ocean volcanic vents same life as us well that's not true all life on Earth so far studied is the same life as us the problem is that most earth life is microbial we've only just scratched the surface of the microbial realm we notice the elephants of the oak trees and so on but actually that the life that is teeming on the surface and beneath the surface of our planet is almost all microbes you can't tell by looking what makes a microbe tick you've got to dig into its innards to discern its biochemistry so if you go looking for microbes of our form of life then of course that's what you find if you go looking for a you find a you don't find B which is what we're interested in a form of life that is microbes with a biochemistry so radically different that it could not possibly have had a common origin people always want example I can give you a very simple example very easy to understand though maybe not a realistic one or life that we know is based on left-handed amino acids or right-handed sugars the laws of physics are indifferent between left and right and so you can make right-handed amino acids and left-handed sugars you buy them commercially if life were to start over again maybe there's a 50/50 chance it would be mirror life that is with right-handed amino acids and left-handed sugars you wouldn't find those if you went out if you have a normal sort of culture medium a basis of on the left and right stuff you wouldn't find these this mirror life so that's one possibility you see and there are as many others as well I don't have time to go into it because I want to get back to to the to intelligent life which is well I think most people are interested in and so the issue then is that if life had started many times it could be literally aliens under our noses aliens not in the sense of coming from space so it may have done as I explained I think maybe even our life came from from space from perhaps and Mars but alien in the sense of a different tree of life and a different origin so not just another branch on the known tree of life but it's a whole separate tree sometimes called the shadow biosphere and it could be all around us it could be that intermingled among the microbes under a microbe slide you know which you get from a cubic centimetre of soil but intermingled among the the microbes that we can identify my be some which are this radically alternative second Genesis very hard to find but I want to move on to get to get back to SETI because if we do find the shadow buyer so let me just make a strong claim if there is a shadow biosphere if we have life on earth of a radically different form when we actually make an effort to look for it I think we could find it within about ten years and that's ham then in the Drake Equation that really problematic f sub-l that would go away so if we found a second sample of life the way will be open then still plenty of other problems given you've got life what are the is the probability of intelligence evolving we don't know how to to work that out but at least we know what the mechanism is it's Darwinian evolution we understand that mechanism we don't understand the mechanism the turn on life into life so we be in with a chance so would be greatly boosted but meanwhile what can we do to help out these poor cash-strapped SETI astronomers and well the answer is that we can I think give up on worrying about messages deliberately directed towards us and look instead for more general signatures of alien technology and by intelligence we really mean we're looking for technology that is is there anything out there in the universe that looks fishy or could not possibly have a natural origin it could be anywhere and because well I think arthur c clarke famously wrote that a sufficiently advanced civilization will be indistinguishable from magic because we have no idea what alien technology that there's a million or ten million years of in advance of ours how about manifests itself it pays to be as broad-minded as possible so what i'm about to tell you is exceedingly speculative for the simple reason that we have to remove all our prejudices about what would alien technology be like so traditional SETI is rooted in radio messages radio telescopes it's very very anthropocentric anthropocentric very parochial i want you to expand your minds and think much more broadly about in general terms how might alien technology leave a footprint in the universe how would it manifest itself in a way that we might be able to detect as something fishy well there's one way that does involve actually using radio telescopes so I've been talking about ET beams a message directly at us with deliberate intent but there's another way of beaming which is birds better compared with a the lighthouse the lighthouse sweeps around the horizon for the benefit of anybody who's out there but the lighthouse keeper standing up here isn't waiting to get a reply it's simply there as as a altruistic symbol so is it possible that an alien civilization has built something like a radio beacon or even a light become that's sweeping the plane of the Milky Way maybe once every few months or few years and it would just go bleep it would sweep around and go once every year or two you'd hear a bleep is that possible something like this the Milky Way is very flat like a disc and so where you don't have to go in every direction just sweep the plane in the Milky Way is that possible well this would show up in a radio telescope if it's a radio beacon as just a bleep or maybe a series of bleeps repeating after a long period of time now I told you about the SETI astronomers so what they do is say they look at a particular server half an hour and then move on they don't have the resources to stare at a fixed patch of sky for months or years on end but that's what you'd need to do to discover these transient events pulses now what makes sense to stare at the center of the galaxy because that's where the oldest stars are so potentially where the oldest son and therefore richest civilizations are likely to be that may have made a radio telescope well there was one moment of excitement in 1977 when after the event it was discovered that the Big Ear radio telescope in Ohio had picked up a bleep rather a long bleep it lasted I think 72 seconds and the astronomer who looked at this dives back in the days when computers literally printed out this stuff on it's a paper and the astronomer concern wrote Wow in the margin because it was exactly that sort of thing they were looking for all those days they just listened to one particular frequency Frank Drake's original choice and and it was a narrowband signal for very strong 72 seconds and nobody of course knows what it was it's never been heard again in spite of the fact that the radio telescopes occasionally appointed of that part of the sky once that a beacon was that something that will repeat maybe in ten years what we don't know because we haven't got the resources to keep monitoring that part of the sky but let's go beyond radio astronomy is it anything else that we could look for out there in the universe well if we can imagine that our very advanced technology or very advanced civilization would expand beyond the confines of its own planet and engage in large-scale Astro engineering that we've done terrestrial engineering which as I told you we could it could be seen from many light-years away things like the Great Wall of China maybe in another 10,000 years or million years we would be doing Astro engineering or planetary engineering so this is an old idea one example is due to Freeman Dyson the physicist at Princeton it's called a Dyson Sphere so he said imagine that a civilization expands and become so hungry for energy that it dismembers its planetary system and smears it out around the star traps all of the light coming from the star so this is like a solar energy project with a vengeance don't just have him mirrors out in the Arizona desert what you have is you're capturing everything although all of the light and Dyson spheres would show up as infrared objects and some astronomers virtually and a half-hearted way gone to look for them so there would be distinctive they would have this distinctive thermal footprint if they're out there so just shows that there are things that we can look for it's not a message it's simply a signature of alien technology because if we saw something like this we'd sit up and take notice or something like this perhaps but you know it's a big universe and it's very hard to know where to look and I've pondered all this and discussed it very often with my wife and we're talking about Dyson spheres one day and she said well why would why would the aliens be so stupid as to wait and you know pull their own planetary systems a system to bits why not go to somewhere where planets are forming and plan the rule that good stuff before it gets scooped up into planets so I thought well that was pretty neat idea and here's a picture of one such this is beta Pictoris so it's a protoplanetary disc so this is a place where planets are forming if you come back in a few million years this will be a star with planets going around it but it's still in the process of getting together so if there is only alien civilization millions of years ahead of us they'll be out there with their sky trucks and other heavy equipment harvesting that material maybe turning this into a Dyson Sphere maybe taking it away for some other purpose we don't know so that's a great place to look for something fishy because we have to understand the system well enough to know what is fishy but that that's the sort of thing I have in mind that this is would be a place to look but now of course all of this is a long way away it's all out there in the galaxy wouldn't it be nice if we could search closer to home and that brings me to something that often goes by the name of the family paradox and the the reason it's called the family paradox after Enrico Fermi who the Italian physicist genius who just after the Second World War Oh incidentally I'll show you you know Fermi must be famous because here he is on an American postage stamp and for the physicists in the audience so you probably know this but the deliberate mistake up here this is supposedly the fine-structure constant but he's got it wrong and so they've conveniently cropped the picture so as not to give the game away but anyway that's family I don't know what's firming up through this well and I think 1948 he was sitting around at Los Alamos where they made the first atomic bomb he worked on that project sitting around talking to some colleagues the UFO reports which were very popular at the time and he said well where is everybody and what he meant by this is that the galaxy we now know is about 13 billion years old the solar system is only about four-and-a-half billion years old so there were stars and planets around long before Earth even existed if the universe is teeming with life has said the optimist hope then there will have been planets with life and maybe intelligent life long before Earth came into existence and so we've been around four and a half billion years that's plenty of time for life to spread across the galaxy so if there's just one civilization out there that thinks that it wants to spread beyond the confines of its home planet and maybe colonize others it could have easily colonized the whole galaxy in the age of the solar system and so Fermi reason that as they weren't here if the earth wasn't colonized a long time ago by aliens therefore the aliens don't exist in the softn called the Fermi paradox not paradox at all it's one possible explanation because there are many ways in which the reasoning might be flawed that is in which the universe could have lots and lots of intelligent life but they still haven't come here not attenders a book fifty resolutions to the Fermi paradox so you can take your pick but what I want to do is explore the scenario that that may be et did come to the solar system but but they're not here they're not still here that is Earth or the solar system release has been visited sometime in the past by not necessarily flesh-and-blood aliens but maybe by their robots or their machines or something of that sort the products of their technology and so then the question is could we find traces of that visit and it could have been an exploration it could have been a colonization wave it could have been an attempt at a colonizing earth and they're moving on could be all sorts of reasons might be reasons we can't even imagine but let's suppose that the solar system had been visited by this advanced alien community when would that have been well I've explained to you that these communities if they're out there will have been around a long period of time four and a half billion years the earth has been here any time in that four and half billion year window earth could have been visited so what's the expected time that they might come you know if you say well to do the mathematics and work out the expected terms about half that time well that's a bit pessimistic and I think if there are civilizations out there and they're accumulating in number you might expect visits more rather more likely in the recent past so it's like a hundred million years as a good ballpark figure so if eet have been here 100 billion million years ago would we know about it is there anything left that we could find that would be a trace of alien technology that would survive for a hundred million years and the answer is not very much but when I wrote the book I thought up three things and I'm open to suggestions about others just take you through them briefly before bringing this to a conclusion there are three things I thought of that would be as you were alien footprints the first is nuclear waste so if these aliens had used nuclear rockets and they dumped some of that fuel we could find that now nuclear waste famously lasts an immense period of time and we could actually go and find it in principle we can find it for example if a lump of plutonium this would be a dead giveaway because there's only one place plutonium comes from these days and that's nuclear reactors when the earth formed they would have had natural plutonium but it's long since decayed so if we found any plutonium anywhere it's got to have a human or alien origin and just give you some idea of the power of this method of looking for ancient nuclear waste this is a uranium mining gavel in West Africa and this is famous because this uranium went critical two billion years ago was a natural nuclear reactor it's not not running anymore the uranium is depleted but the point is that by studying this the scientists have been able to reconstruct the nuclear history of this particular configuration way back two billion years ago so you see we have the power to be able to reconstruct if alien technology of being in the solar system we find this this nuclear waste we have the power to reconstruct the story behind it now there are another couple of things on this side quarry's our minds on earth or near neighbors in space if they're big enough they would survive for a long period of time let me give you an example you probably know that the dinosaurs were done in when a comment smashed into the earth 65 million years ago and made a crater 180 kilometers across it what is now the Yucatan Peninsula of South America Central America that crater was only discovered recently because it's not in your face you don't see it it's you fly over you need geological survey instruments but you can find it even those buried deep beneath rock strata so any large enough mining or querying work even if it's 100 million years old and buried could still show up in geological surveys if if you take trouble to look now obviously it would make sense if you if you saw something like this on an asteroid and as you probably know this is now a hot topic we're going to go to the asteroids and mine them and all become rich so if you if you got out there and you saw something like this someone had been there already then that that's a bit of a giveaway the great thing about asteroids and the moon is their airless and so there's no erosion only what happens when smaller meteorites hit and eventually those features go away so the moon is another great place to look for signs of alien technology and by happy coincidence the Lunar Reconnaissance Orbiter which is currently mapping the moon to 1/2 meter resolution let's go run around Mission Control is my University Arizona State University just across the way from my building is Mission Control for the Lunar Reconnaissance Orbiter and they have these wonderful pictures taken of the moon it's better than Google Earth high-resolution pictures of the moon they're out there on the internet you can go look and see if you can see signs of artifacts on the moon now I can tell you that the LRO people have found many artifacts on the moon many but they're all human they've said they can see the Apollo landing craft they can see tracks left by astronauts and so on they see the rush craft so we know it has the power to detect artifacts on the moon but of course there are tens of thousands of features they haven't looked they deliberately look that knew where to look for the human artifacts there's been no systematic search done for any alien artifacts or alien engineering works or in any sort of strange anything fishy let's put it that way so this Sam Center at Arizona State University applies half a dozen students whose job it is they pay them to just look through these pictures so see if there's anything worth remarking on of course they're not really looking for et and I'm sure they tell us if they did they found it they're looking for things I lava flows and rock formations so the point is that this has the power the point I'm generally trying to make here take-home message number two is this is all crazy isn't it well yes am I suggesting the aliens visited the moon no I'm not suggesting it at all what I'm saying is that there that if there are alien civilizations there's a tiny tiny chance they would manifest themselves by having sent technology to the moon sometime in the very distant past and because the moon is almost inert we have the means of detecting the signature of that technology and it doesn't cost any money and that's the point is the money is the point costs us nothing if we mobilize say school students get them to look at these pictures and report what they see it's not actually hitting the taxpayer dollar so my feeling about doing SETI or in fact doing any sciences doesn't matter how speculative it is how crazy it seems so long as it doesn't cost anything why not look anyway and so that's the spirit in which I'm approaching this expanded SETI effort we just do what we can do now let me turn to the third thing I won't bother to go back to the side the third thing which is the possibility of a message in a bottle could it be that et has left us a message for posterity that's a nice idea humans do this if you're on an island you put the message in the bottle fling it into the sea you don't expect to get a reply you don't sit around waiting for a reply so again like the beacon is a one-way might an ancient civilization have left us a message in a bottle well maybe so we have to think what would the bottle be and how would the message be configured and so as the message in the bottle and and I think there's a very obvious answer very happily nature has provided us with bottles and a means of messages and the bottles are called living cells and the medium for the message is called DNA and so could it be that instead of sweeping the skies with radio telescopes in the hope of getting a message from the stars we should be sweeping the genomes of terrestrial organisms in the hope of a message in the DNA of terrestrial organisms uploaded a long time ago by ET maybe in person more likely remotely viruses for example upload their DNA into cells all the time retroviruses so we know the means of doing it you put the message in a virus get the virus to upload it into the cell now the point about this is that some of these messages in our genomes are billions of years old we have genes that are hardly changed in tens of millions or hundreds of millions or even billions of years so it's it's a great way of preserving a message there is nanotechnology these are nano machines which will replicate and multiply reproduce the message the content for immense periods of time now there's an issue about mutations we can come back to and question time so is this all pie-in-the-sky just totally fanciful could intelligent beings upload messages into the genomes of organisms is that credible absolutely it is craig Venter just did it he uploaded his email address into the genome of an organism called mycoplasma laboratory so it's very famous so it's email address and a quote from Feynman and some poetry or something it's phone number maybe so we can do it so if craig venter can upload messages into microbial genome and surely ET can do it with millions of years of technology so how do we go about finding this message well same deal as looking at the move it doesn't cost anything or very much we're sequencing those genomes anyway it's all put out free on the internet you can look through it for messages now you I wouldn't recommend looking through it line by line because you know typical genome of a higher organism has been a bit billions of bits of information but if you look through you know the famous four letter alphabet if you look through and you saw something like that you'd certainly take notice because that's like as in Jodie Foster in the movie that's a sequence of prime numbers so if we found that in a genome we would surely think that that's sign of alien tinkering and so that's all it all it needs it just needs a systematic approach to look through these these genomes so again let me just health warning am I suggesting that et has left a message in the genomes of terrestrial organisms no I'm saying that there's a tiny tiny probability that if et wanted to communicate with us or leave us a message that would be a good way to do it and that because we're sequencing we're building up the database anyway this genomic data it costs us nothing to look through it who knows what else we might find we mind our Phi DT we might make some other discovery so that's the spirit in which I think we should search through now I want to close there are other examples as well you can read them in the book but I want to close by asking the question as people often do that what would ET be like because we try to second-guess a civilization on intelligence or a sentient being that might be millions and millions of years in advance of us and the problem is always the people tend to think well what would we do and what will we be like in a million years or ten million years and so most of the speculation about alien intelligence is this sort in other words that these are scarcely decided the disguise human beings and which with minds very much like human minds now sometimes people agree that artificial intelligence and robotics will get to the point that we'll have some sort of instantiated post biological intelligence of this nature but it's still unmistakably humanoid both in its architecture and in its its outlook is mentality and I've had to get away from all this my own feeling is that biological intelligence will be a very transitory phase in the evolution of intelligence of the universe you can see at the moment a lot of the intellectual heavy lifting is being done on our own planet not by human beings anymore but by things like Google and supercomputers that in another hundred years pretty much all the smart decisions in pretty much every area of human activity will be made not by human beings themselves but by some designed and distributed system and I don't like the word computer and I don't like the word robot because we're talking about a future technology here that has no words to describe it except that it's designed and probably it's been designed by the designer of the design of the design of the designer and so on many generations into it and that it come back to earth if we survive for another thousand years come back in a thousand years and almost all of the important intellectual effort will be done by these design systems there may be biological I mean it may be components biological components grown and fused with electronic components it could be other types of technology we can't even guess at but the ultimate would surely be to harness quantum physics you probably have heard of the the hope of building a quantum computer which would represent a leap over a conventional computer as big as the conventional computer over the abacus so the search for the quantum web would search but the quest to build a quantum computer is a multi-billion dollar industry worldwide and so if we can do this if we can actually build a quantum computer then the question is can we build intelligent quantum buta so really advanced intelligence might well be quantum mechanical in that nature it's what Frank were check the physicist at MIT cause Quinn intelligence and so this is an artist's representation of Quint elegance it's the whole of well if if it were a conventional computer it could be the whole of a surface of a planet or maybe the whole of a dyson sphere turned over to some gigantic circuitry a great throbbing global mega brain if you like but if it's a quantum computer quint elegance it may be no bigger than a car and that's because quantum computers work at the atomic level and one quantum computer harnessing 300 atoms would already out compute the entire universe as a conventional computer so only takes 300 atoms and you've got a universe full of computational power and so that doesn't leave much of a technological signature quantum computers are best built where it's very cold in the coldest places on the intergalactic spaces so if there's something the size of a car in intergalactic space sitting there merrily doing its quantum computing intelligence introspection whatever quantum computers like to do then chances are we're not going to know about it and chances are that they're not going to be communicating so that's rather depressing note to end on I hope that if there's a hierarchy of intelligence in the universe and it's out there and it may not be I have to say that my default assumption is that there is no intelligence out there but if there is I would like to think that there is some thread connecting us with them some commonality of purpose that were been that even if they don't go out of their way to send us messages they wouldn't go out of their way to conceal their existence I want to finally finish by just mentioning and this may come up that the only authority I have to speak about SETI apart from being a well-wisher and a bystander for these last 50 years is I chair something called the SETI post-detection task group so it's if ET calls on my watch it's my job to make the neck step like who did we tell and should we reply things like that and so this task group I was lumbered with this job because Rayne Norris Australian radioastron amah was doing it first and he got bored and handed over to me so it consists of scientists and journalists and we have a priest and a couple of lawyers and some science fiction writers and we meet from time to time to sort of wrestle with the problem supposing we picked up some strange signal tomorrow or supposing we had incontrovertible sign of alien technology what next are we prepared for it and it pays to be prepared so that's my own active involvement in SETI otherwise I'm just a commentator well you may have come to the conclusion then from this talk that it's all rather hopeless that SETI is a glorious but almost certainly doomed quest and why would anybody bother to do it why do we do SETI we're looking for a needle in a haystack when we can't even be sure that the needle is in there I think the answer is is shown by the people here today you come here today because like me you're deeply fascinated with the question are we alone in the universe you like to ponder on what it would mean if we share this universe with myriad other life-forms because in a way looking for et is like a glimpse into our own future if there are many civilizations that have made it through their little mini crises and have gone on to a glorious future well then we see in the sky a projectory of the future of humanity and so I think searching for them out there is in a way just searching for ourselves and I think it's good particularly for young people to ask questions like what is life what is intelligence why are we here are we alone these are all great things to ponder these are the big questions of existence we may not find the answers but it's great that people ask those questions and I can express it no better than in the words of Frank Drake himself SETI is a search for ourselves who we are and where we fit into the universe I think at that point I will stop and take thank you you might have already touched on this but if the universe is so vast you know infinite surely there must be more forms of life that daddy hid surely it's just not occurred on earth I mean the probability must be huge that right right you're throwing concepts and numbers around with gay abandon here so of course if the universe is infinite if it's infinite and homogeneous and it's simple mathematics to show that not only is there going to be intelligent life out there there'd be an identical copy of you in fact there be an infinite number of identical copies of you so that's just a matter of probability but I was very careful to say the observable universe we can see out as far as what is called a Hubble distance it's a 10 billion light years throughout 13 billion light years something like that we can't see beyond that because of the finite speed of light and so within that volume that there are mentioned 10 to the 23 potential sites that's a finite number and so the probability of life emerging has to beat that finite number and it made it if we knew how life began we could attempt to answer that but as we don't it's entirely possible that it doesn't beat that number and that's what was believed 50 years ago and it may be right we just don't know that's why we need to find second sample of life I'm interested in your views of the opportunity that could be offered by this upcoming Square Kilometre Array to look for a T given the death of the radio telescope array in America that you mentioned earlier that died because of lack of funding yes what it does a Square Kilometre Array have an opportunity there it's been much discussed that the square of the people who here who might not know what this square K let me to raise it's a proposal to build over many dishes together a collecting area equivalent to a square kilometer and there's a tassel going on between Australia and in South Africa too as to whose host stays but anyway if we get it then of course we would have a very powerful instrument with a big collecting area and certainly some attention has been given to using this for safety purposes of course it would have to piggyback on the more mainstream type of radio astronomy but it's true because it is designed to pick up what started out as light just before the first galaxies formed that are now stretched by the expansion of the universe into the sort of middle radio bands that that's exactly where you would expect to find radio messages if they are being broadcast to us so it's it's it's in the right ballpark and the question is it's going to boil down to you know money and sensitivity and I think I come back to the point that it would even the Square Kilometre Array would not have the power to pick up say a TV studio even on the nearest star planet going around the nearest star does not have that sensitivities only if ET is beaming the message directly at us and this is the point I want to make they had to make a conscious effort that they know we're here on their beamy asses but I think that's not credible for another thousand years or so yep just a question back to the probability of life we know on earth that life arose quite soon after the formation is rather than one or two billion years after so doesn't that show us that they first of all doesn't know and I actually have a slide debunking that but I didn't have time to show it so Carl Sagan was funded making this argument that no suit life must be easy to make you said no sooner than was earth ready for it that up it popped now the argument against it is a little bit subtle but I think it's an important one and one way of putting it is that well it's a better of study quickly or we would not be here now in another 800 million years so some will get too hot it'll boil the oceans dry and there can be no life on Earth so it's only a finite window of opportunity for life to emerge evolve and be observed and so if life hadn't started until say three billion years after earth began and it wouldn't have made it to intelligence assuming there the time it takes again intelligence on earth is typical we don't know that Charlie would be the first to argue that we can't really read anything into that and so the rapid formation of life on Earth is consistent with life being easy to make and it's also consistent with it being very hard to make you can't let you tell anything it's a sample of while Andy we need more so well following up a little bit on that what will be your opinion on there on the suggestion that has been made that life on earth might have formed a few times independently and then wiped off and inform again right is there any chance we could ever you know find a bit more on that yes yes and no if you buy my book you will read all about this because people say well give me a scenario where there could be many origins of life on Earth and I usually cite that one that between about 4 and 3.8 billion years ago the earth was being bombarded quite mercilessly by very large asteroids called the period of heavy late heavy bombardment and the biggest of those impacts would have bored the oceans and possibly sterilized the whole planet so there's a scenario that maybe life gets going in aqueous interior between two such impacts and then WHAM it gets wiped out and then it starts up again wham it's wiped out but maybe I haven't stuns of times and then finally we are the descendants of the one that just didn't get wiped out but that was published back in the 80s since then the feeling is that even the biggest of these impacts would not totally sterilize the earth for the simple reason that it would propel a lot of material into solar orbit and some of that material would carry the microbes with it and cocooned inside the material they would be safe in space conditions and eventually some of that would come back so now we have the interesting scenario that life starts up life one starts up when swept off of the earth around the Sun things go quiet life 2 starts up life 1 comes back so now we have life 1 and life to carry existing on earth and then WHAM again live three and so on and so by the time all this settles down you may have 50 different forms of life from 50 different origins came England and then the question is would any survived to this day and that's another story okay um I was wondering if if life one and life two are going to be detected wouldn't we always say they have a common ancestor because life the board the origin and evolution of life is dependent on the environment and all of the earth if we consider that as one environment regardless of where life started with say it has a common ancestor right sounds like a lineweaver argument so we we have to of course define life so the big problem about the origin of life is we don't even know whether this this is a well-defined transition I've been talking rather glibly about the transition from non-life to life once it's like a phase transition in physics going from water to steam something like that or flame bursting forth at some particular critical temperature so was there a critical threshold of complexity complexity below that not living above it boom there's life or was it like a seamless transition from simple things through more complex things more complex more complex so it's a little bit like what is a mountain you go walking in the hills you're in style at the valley you end up on the mountaintop where did the mountain begin it's not very well defined so we go no there but I'm assuming when talking about multiple origins that the inside the phase transition and you can then say no life down here life above it and that this is a separate transition from no life to life and so they they have a common ancestor in nonliving things but not in living things so that you have to take that point of view I think to answer their question right is there a factor in the Drake Equation that talks about the potential longevity of a society that yes the last one Capital Ale is how long would civilizations with radio technology last and there's not a very good example of the anthropocentrism that plagues is subject because back in the 1960s when SETI began everyone's preoccupied with the Cold War nuclear annihilation and so on and so Carl Sagan used to argue gloomily well probably any civilization that develops radio technology with develop nuclear weapons and then they blow themselves up so we could expect them to be around only for a few decades you see well then the Cold War went away and people now are preoccupied with environmental degradation so now when people talk about SETI they say well et so they won't blow themselves up but surely they will manage their environment in a green and responsible manner they would not be building radio transmitters that don't optimize the power output so we should look for optimal beacons and so you know we're applying our prejudices now from from the 21st century so in another 20 years or another 100 years we may be preoccupied with something else and I think Oh a t-shirt we'll be worried about that that thing whatever that is so I think the upshot is we simply mustn't have any preconceptions about what an alien technology should be like and that their proposed to look in the broadest possible terms or anything fishy as I keep putting it I was discussing a you know left-right shadow biospheres with colleagues five or ten years ago and I say me that if each side was eating on its own sort of food except they had a common one common requirement water or a cable something then you'd get a drift if you had a random fluctuation to one of the sides being larger the last day and you get a inexorable drift towards eradicating the other side right just because some reproduction is geometric and fluctuations right right so this is the famous problem of the origin of Homo chirality and I have a postdoc from now so she did her PhD thesis in exactly that subject and so this is something that I'm very familiar with you just need a tiny seed asymmetry and an amplification process but the point is that that seed asymmetry might be random there's no nothing to say that if it happens again on earth it's got to be fluctuate the same way could fluctuate the other way now we don't know that because we don't know what imprinted that asymmetry could be that it was imprinted in space already and that the dimino acids were delivered to earth with the preponderance of one over the other already built in and maybe that that's what tipped the balance but we don't know that and I gave the example of mirror life not because I think that that is the most likely way that life might be different but it's a very easy example to imagine and it's very easy to see why a common origin will be ruled out so it's very clear-cut example even if not a very a very likely [Applause] you

Channel: ANU TV

Views: 113,135

Rating: 4.6331363 out of 5

Keywords: space, science, universe, physics, cosmos, astrobiology, cancer, black holes, mars, life on earth, big bang, Ufo Alien Aliens, The Eerie Silence, ANU, The Australian National University, 'are we alone', alien life, Extraterrestrial Life (Film Genre), education, public policy, SETI Institute (Organization), Big Picture Science, Paul Davies

Id: z5vPLSj3cNs

Length: 66min 59sec (4019 seconds)

Published: Tue Jun 12 2012

Reddit Comments

[u/captainjimboba]

Can confirm that the book (Paul Davies) was a mind-blowing read. I had never heard of looking for life with reverse helix chirality.

[u/Crimfants]

I read the book, and even wrote a review of it, but I really think "Eerie Silence" is a bit of an exaggeration. The search space that we know of is vast, and we've only covered a small part of it. Sometimes absence of evidence really is evidence of absence, but I don't believe this is such a case.

[u/braneworld]

You should check out the book/audio book. One the best SETI books out there, if not the best. It's like the 10 hour version of this lecture.