Bunyan Lecture 1993 - Carl Sagan

thank you good afternoon ladies and gentlemen and welcome to this 12th annual Bunyon lectures and by petrosyan chairman of astronomy program at Stanford which sponsored this lecture series these lectures and some other activities of astronomy program at Stanford are supported by added by an endowment from state up mr. James T Bunyan a longtime employee of Stanford University mr. Banyon a manufactory modest means left his life saving to us he also a student philosophy with keen interest in evolution and origin of the universe and evolution of life in the universe and he requested that we conduct this lecture with their primary purpose being and I quote to explore the philosophical implications of scientific disciplines such as astronomy astrophysics emissary geology biology and to present a coherent and reasonable account of structure and inner working of the cosmos as well as the dawn of life the scent of man and the status of the human spirit in the scheme of things the tall order well my colleagues and I in the started program wholeheartedly agree the important about the importance of this issues and we are grateful for mr. Bunny's contribution which has allowed us over the the past twelve years to have distinguished the lecturers come to Stanford to share with us in fact for a general audience to share with the general audience the latest finding in astronomy there have been many and very exciting finding indeed and to explore with us the meanings of these findings and their significance of relevance for Humanity as I said indeed it has been a very exciting time in astronomy especially the past few decades not a year passes that a new discovery hasn't made which completely changes our understanding of the universe it is also an exciting time at Stanford in this field of astronomy as we are in the midst of as modest expansion we hope to increase the number of faculty yet in the next couple of years we also have just become a member of a consortium universities to build their 10 meter telescope which when actually completed will be the largest telescope in the year and indeed in the earth or I wouldn't say the universe probably in the universe still but who knows in fact this will be slightly larger than the 10 meter Keck telescope which was just completed and top of Mauna Kea in Hawaii by University of California and Caltech well without speaking much longer let me sell that we are very fortunate and this great privilege for us to have a professor Carl Sagan of Cornell University was agreed to give the lectures this year so at this time I would like to ask professor walk-back Wagner of astronomy department asked only program and physics department to come up and introduce our speaker thank you bye at a time when the need for rational dialogue concerning the nature and implications of science has reached a critical level we here today and the global community are fortunate to have Karl with us it is striking to me how closely the focus and profound effects of much of Karl's efforts match the goals of mister bunion which waha is just elucidated two years after receiving his PhD in astronomy and astrophysics from the University of Chicago Karl established his first association with Stanford as a visiting assistant professor of genetics in the School of Medicine in the academic year 1962-63 expanding his investigations in biology with Joshua Lederberg our world lines - briefly merged for five years after we joined the Cornell astronomy faculty in 1968 I will always be thankful to Carl for his generosity and warmth toward me and my family at that time of social and scientific upheaval I also thanked him for expanding my consciousness in both of these arenas Carl established the laboratory for planetary studies and became editor-in-chief of a leading journal of planetary research Icarus at that time and I wish I could recall how he induced me immersed in esoteric odd studies like the physics of the early universe general relativity and the structure of neutron stars to referee a few of his papers he has been the David Duncan professor of astronomy and space science at Cornell since 1977 and is a distinguished visiting scientist at the Jet Propulsion Laboratory at Caltech Carl has played a leading role in the Mariner Viking and Voyager spacecraft expeditions to our planetary neighbors for which he received the NASA medal for exceptional scientific achievement and twice the medal for distinguished public service he was the co-founder and his president of the Planetary Society the largest space interest group in the world of as many other scientific awards I will mention only one of the most recent the herald Mazursky meritorious service award of the American Astronomical Society for in part and I quote his seminal contributions to the study of planetary atmospheres surfaces the history of the earth and exobiology of course Carl is most widely known through the media of books lectures and television I note just a few examples the dragons of Eden whose stimulating and provocative exploration of the evolution of human intelligence earned him the pure surprise the cold and the dark an analysis of the global effects of nuclear war here is another Stanford connection two of Carl's co-authors were Paul Ehrlich and Donnell Kennedy cosmos the book and the Emmy and Peabody award-winning television series that influenced an unprecedented audience around the world shadows of forgotten ancestors written with his wife and ruin the first in a new series which examines what we can learn about ourselves by tracing the evolution of life on Earth in such ways Carl has enabled millions of citizens of the earth and many of our political leaders to become aware of the cosmic context of their lives in space and in time he has lifted their view to our terrestrial planetary and astronomical environment his efforts and those of many others have borne fruit most recently in President Clinton's announcement on Wednesday that the United States will finally follow a specific timetable to reduce the threat of global warming and sign an international treaty protecting rare and endangered species he has marshaled what has been learned about the evolution of life and that of our galaxy to illuminate the potential of a carefully organized search for extraterrestrial intelligence this has also borne fruit in the growth of the SETI program we scientists also owe him a great debt for his leadership in our common obligation revealing to the public the fundamental differences between science and pseudoscience and now without further ado the meaning of today's title is there intelligent life on Earth will finally be revealed to you welcome Carl thanks Bob for that very generous introduction could I ask for the lights in the audience to be all the way up these good eye I have this need to see my audience feedback everybody sleeping I know it's time to change the subject well I'm very happy to to be here and renew my long term association with Stanford also very pleased at the conditions of the will of mr. Bunyan I read his charge as blending as turn on the astrophysics photochemistry geophysics biology and allied sciences to give a broad context of the human species in a way that the public could understand and that's quite a task I will do my best and even try to at one point mention a word that includes photochemistry I'd like to do this talk in two parts the first without slides and the second with both of them intended in different related ways to provide some sense of perspective and and context and both halves in different ways we'll address this issue of is there intelligent life on earth the question about which you doubtless have certain opinions of your own it is a widely debated subject nevertheless every human culture without contact with its neighbors has drawn the same conclusion about our place in the universe it's extremely simple you stand outside and you look up and pretty soon unless you're an extremely impatient person you notice that the Sun the moon and the stars are rising and say rise me across the sky set in the West the only plausible interpretation is that we are stationary at the center of the universe and all of these bodies circle us the Sun is certainly a very impressive body we recognize that light and heat emanate from it and still despite its evident power it pains a kind of how much to us Wow we must be we must be really something it's very impressive we're at the center of the universe what's more what is the function of the Sun the moon and the stars the only possible function is to help us the sunlight he says daytime the moon is a little Persian story about the wise Vizier asked which is more important the Sun or the moon answering the moon because it shines in the night time whereas the Sun shines in the daytime when it's white anyway and the stars the stars you can navigate by the stars you can tell when it's time to plant and when it's time to reap matters and win the the herds of wild animals are going to do with migrate matters of life and death for our ancestors so the universe was put here for us and this naturally resonated was a sense of our own importance there was a kind of geocentric conceit which arose all over the planet and with the exception of a tiny blip associated with the name of Aristarchus of Samos everybody all over the world understood this to be true and famous philosophers famous scientists meters of religions everybody unquestioningly we're at the center we're important we are wonderful and if you could imagine a dispassionate extraterrestrial observer looking down on this world with everybody saying daily we're wonderful we're at the center they move you might think though they would consider us the planet of the idiots here's the earth going around the Sun on the Sun with its proper motion through the galaxy in the galaxy fleeing as part of the Hubble flow and all these little beings on this world were at the center we're stationary we're wonderful that would be too harsh or judgment because there was this unlucky coincidence but common sense observations and what we secretly wished would be true resonated converged and it was not until the sixteenth century that Nicholas Copernicus the alternative model and here he was cautious enough to publish it on his deathbed and because there were penalties associated with demoting us from some central position introduction to Copernicus's Dave Luciano this written by a guy named Ozzie ender I think argued like this now I don't anybody to get the wrong idea don't think that Copernicus really thought that the earth went around the Sun it's not like that we all know the Sun goes around the earth as the Bible says it's just that if you want to calculate where Mars will be in the sky six months from Tuesday then there's an easier way by pretending that the earth goes around the Sun even though it doesn't and this was a viewer for the next century century and a half of those who except for the most radical blowhards like Galileo Galileo using the first astronomical telescope found some disquieting stuff we found there were moons going around Jupiter being Jupiter it seemed an analogy to big Sun little planets they discovered the Mercury and Venus going through phases which is wholly incompatible with the standard earth-centered universe with everything else laid up there was a a pathetic compromised proposed by Tycho Bryan in which the Sun goes around the earth but Mercury and Venus go around the Sun in order to explain the the phases but Galileo sworn to me taught that Copernicus was right for which the church took him to their dungeons and pointed out the instruments of torture whereupon the Asian astronomer at least officially AB dude this abominable hypothesis but time passes the evidence becomes stronger and stronger and well before the definitive evidence that the earth goes around the Sun namely the annual parallax of the stars which was discovered not until the 19th century but long before that I mean scientific and to some extent popular view made this very heavy transition from us at the center to the Sun at the center but every step was a kind of compromise in which people attempted to rescue centrality in some other way and let me just a few examples okay this is in crude chronological order but not not precisely okay okay so we're not at the Sun of the Suns at the center but we're close to the center right well me because we're close to the Sun the Sun is at the center of the universe so we partake of centrality maybe not as much as we want and there's nothing else like the Sun right and there's nothing else like the earth right but then further telescopic observations show that those other planets that features clouds polar caps and weird rings them the idea that those were worlds on equal footing with the earth but with different environments grew and there were people some people deeply depressed by that and then the finding that the stars were Suns just far away and that since planets are small and shine only by feebly reflected light maybe many most all of those other stars have planetary systems going around them okay but maybe but we're at the center of the collection of stars of the Milky Way galaxy and and that's worth something no don't knock it but then observations in the 19th century showed that wasn't true that we were in some pathetically remote spiral arm in the Galactic boondocks we couldn't even rescue a central position from that and it turned out we weren't even the only the only galaxy although spiral nebulae turned out to be other galaxies as well then the expansion of the universe was discovered and then for a moment it looked as if everything was saved because all those other galaxies were running away from us as if we had some loathsome cosmic disease but at least we're at the center you could see it and for a moment it resonated beautifully with what we hope was the case but then it was pointed out perfectly properly that an astronomer in any one of those galaxies would would see precisely the same thing and the motion again now not only was this deep provincial ization of attitudes occurring in astronomy but in many other fields the most striking example is evolution okay maybe there's nothing central about us astronomically but as far as life goes we're central we're big time we are the top dog all the life on Earth was put here to serve us and they are supposed to get out of our way near us as the book of Genesis says and they're there for us to use as we like and we are especially creative and a great deal of reassurance was drawn from us but then 130 or so years ago the Origin of Species was published and it became clear that there was a mechanism which involved no supernatural intervention by which it could be understood how all the beings on earth had evolved by slow processes for much humbler means and with the publication of the descent of man us to Darwin was very cautious in the Origin of Species all he said about our evolution was something like and these ideas might prove relevant to our origins as daring as he was willing to go in that book but 10 years later yeah about 10 years later he he went the whole way and talked directly about human evolution as well and in physics from the time of Newton it had been conventional to describe our velocity framework as a privileged frame of motion that was the word used privileged something special about our not position but velocity and Einstein growing up in a Russian dominated Central Europe as a member of a despised minority knew something about the emotional resonance of the idea of privilege and was suspicious of the idea from the beginning and he started thinking what would physics look like if there were no privileged frames of reference and yet the laws of nature had to be the same from the point of view of every moving observer and this is the central starting point of special relativity so it could be argued and there are a number of other cases like this that many of the central debates in the history of science have to do with the challenge to the emotionally satisfying sense that we're somehow sensual or special and in every case these are not issues just argued by scientist off by themselves the public is deeply engaged almost always on the side of don't change anything it's been bad enough rescue at least a little special privilege sensuality for us and in each case the evidence unfortunately for those who have that point of view has gone the other way now I don't want to suggest that that scientists get overwhelming evidence and then everybody agrees far from it for example the the geocentric consensus with us still built into the language the Sun rises the Sun sets I was up before sunrise what is the location by which instead of pretending that we're stationary we recognize in the language that it's the earth spinning say what the Sun below our tangent plane because of the spin of the earth I mean some four year old kid is gone by the time you tried you have to say that be back before the Sun passes below the tangent plane wit can't figure out a way to build it into the language we're so geocentric li designed it's so natural for us we talk about new world the world's serious world a billion worlds in the Milky Way maybe a trillion by the way I never said that that billions and billions stuff Johnny Carson said I never said it it's too imprecise it's vague there's billions and billions of stars what did that doesn't mean anything you say you know 400 billion stars okay wow you're getting there and when the cosmos series was recently reconfigured for you know video cassette sales and a new new updated version on the term network I had to listen to everything I said I didn't think I said it but who knew and so I was sitting there on tenterhooks for all 13 episodes am I gonna say it am I gonna say it I never said it where was it yeah the world the language has it built into it that what around us is special and as far as as evolution goes you know that there's in this country especially a devoted rearguard action to prevent it from being taught in the schools there's a subject with the oxymoronic name scientific creationism which you know first and second words contradict each other which there are a lot of people who are very strong but they don't want to hear we were evolved from ohms whose is not uplifting mud we don't want to come from their angels that's where we belong and I believe that that's the emotional roots behind the the wish for us to be central now this debate the expanding weave of scientific progress and ghosts in different centuries in different ways this same debate and today we're where is that that debate the search for extraterrestrial intelligence that Bob mentioned is clearly one there are a lot of people who don't want there to be extraterrestrial intelligence or if they're gonna be there they should be dumber than us because if they're smarter especially a lot smarter that's demoralizing at least let us be the smartest being in this beings in the universe that's not asking a lot is it it's only know four hundred billion stars in this galaxy 100 billion other galaxies maybe most stars have planets for us to be the smartest isn't asking a lot sort of reasonable don't you think also maybe we're evolved from other beings but there are characteristics of humans that are completely different not matters of degree but radical differences in kind from the other animals nobody uses tools except us nobody makes tools except us nobody is rational none of those other animals they can foresee the future consequences of present actions they're not altruistic as long as my arm of things that are said to be special about us enunciated by all the great philosophical and scientific figures in the history of the West from Aristotle and Plato to Augustine and Aquinas to leading figures today all of which turn out to be wrong I mean observational II wrong chimps make tools with a clear I to what the future use will be there is a chimp termite fishing industry which which involves a technology so difficult that gays it to Leakey a a competent anthropologist and primate researcher spent four months apprenticed to a chimp named Leakey in Tanzania and the Gumby preserve following the chimp around watching with the gym so he could learn the technology in the four months nowhere he couldn't do any of it there were about ten steps you can manage one of them Jim since men you know their entire lives watching other chimps do it learner to Lake you just been there a few months it was hard likewise for the other things the other characteristics presumably making us weak now I'm not pretending that that there are some pansies who have jet aircraft or nuclear weapons or other signs of high intelligence but remember but remember we didn't have those for most of the tenure of humans on earth and biologically we were the same a hundred thousand years ago as we are today so building civilization can't be what distinguishes us and it's hard to find what it is maybe it's my image except chimps and bonobos are showing great facility these days and there is even a gorilla on the Stanford campus or led to with Amazon talk well another area of this dispute is what is called the anthropic principle where a desperate attempt in my view is being made to rescue some centrality for us the argument is if you change in your mind notice how to do it in reality the laws of nature or change the values of the fundamental physical constants then in many cases you produce a universe inimical to the evolution of human beings the Stars you don't get sparse atoms don't hold together or you get stars but they evolved through their entire stellar evolution and in in a week and so life is impossible now there are two ways of looking at this one is yes we are the product of the kind of universe we live in what did you expect and the other is the laws of nature and the physical constants are made the way they are in order that we shall 15 billion years later you're off and if that were true then that rescues the entire anthropocentric conceit may we're not at the center but the laws of nature were designed for our benefit you can't look up and see it for the most in the phone but if you're a really smart physicist you can examine the laws of nature and see that it was all made for us one of the many deficiencies of this argument and for the reasons I've just mentioned in a historical framework we should be suspicious of it from the beginning the human to clear is that Dolan has made a systematic effort to look at all those other hypothetical universes and see if they're consistent was so quite different kind of life than us and you know it's very hard thing to do of course but the idea that if the precise sequence of events that led to us is not duplicated then life is impossible it's like I don't know saying that if extraterrestrial intelligent beings are not pressed batarians and they're not intelligent we could imagine that they don't have to exactly follow cultural motifs of our civilization and could still be smart ok well it's been a painful history and the pain is still with us many people compare this idea of a universe on unstructured for us with the idea that that comforting helpful more friendly family oriented universe in which everything was done for us and of course the latter is more friendly than the former but it seems to me we have an obligation to understand how the universe really is because the universe has no obligation to conform to un conceit I'd like now to narrow the focus and talk about a particular question which as I said before most people believe and for good reason they know the answer to and that is is there intelligent life on earth now what I mean specifically is if you were an extraterrestrial beam examining the Earth from space for the first time would you be able to detect life how easy would it be you detect all the aspects of life we consider important or just some minor or frivolous aspects of life now this is something that I enjoyed speculating on for many years but of course difficult to actually do until there was a kind of failing in NASA namely it was unable to send sizeable payloads to the planet Jupiter just on rocket own alone and so to get there had to do gravitational assist maneuvers in which you fall into the gravitational potential of Otherworld and it speeds you up and if you do your gravitational billiards right you eventually can speed up so you can get to Jupiter which otherwise you might not do the mission involved is called Galileo it's on its way to Jupiter and it made two closed passes to the earth by close I mean a few hundred kilometres from the surface and one close pass to Venus as I say only for as a propulsion maneuver but it seemed to me here was the opportunity I had been waiting for let's turn on those instruments and look at the earth and see if we can detect life the instruments are all designed for looking for Jupiter and therefore this is a way to calibrate the conclusion tentatively drawn from other missions as we fly by world after world that there's no life there it's a suspect conclusion unless we've done the control experiment of looking at our own planet and seeing if that we can indeed detect life so in the remainder of this talk I'm going to mainly use the Galileo results for the very high-resolution pictures I won't because Galileo's greatest surface resolution was about a kilometer but for most of it I will and I won't always say where the where the pictures come from but as I say most of them are our Galileo so I asked you to free your mind of all prejudice and imagine that you have no idea what kind of a place the earth is the first data except its distance from the star and so on come from this flyby what can you find so the first slide we can have the lights out now it's for orientation only so here we are this is our moon notice that the artist is neglected to draw any of the other moons of sixty other moons or so here's Jupiter where Galileo is going and to do it it did something like this well it has to go around the Sun and finally it gets the Jupiter next slide please here is a lovely photo taken just last January of the earth and the moon together by Galileo and here we have a resolution of what a few hundred kilometers or something like that it's a blue and white planet and beyond that heart to tell what's happening at least just from looking next slide this is not a gala picture I'm not gonna and that's what is and what isn't here you can see that there is evanescent white stuff in the atmosphere clouds just to take a picture ten minutes later and you'll see that there are some changes a few hours of being changes there's some blue stuff and there's some brown stuff the blue and brown stuff doesn't change the white stuff does I can't tell if there's anything alive here can you I mean there's certainly meteorological interest there is if you look closely a permanent polar cap it's something that freezes out down there where it clearly it's cold colder that doesn't freeze out or at least not as much up here what is the oven white stuff what is the polar cap what is the blue stuff what is the brown stuff that's certainly something you would want to to find out about this picture is taking an ordinary reflected visible light the next picture is exactly the same view from the same satellite next slide please taking in the thermal infrared here we are looking at the emitted infrared radiation of the earth in which the temperature scale is grays are cool and Reds are hot than yellows are still hotter and sure enough this it's pretty hot here except for this region which was covered by clouds in the previous picture and this region is covered all the time with clouds and what we are looking at is at 10 microns the thermal radiation of the earth being emitted pretty unimpeded to space the next slide shows the same view again next slide please but at a wavelength of 2.2 microns where carbon dioxide and water vapor absorb and you can't see anything about the surface you're looking entirely into the atmosphere and this means that there you don't know that it's carbon dioxide and water yet I occasionally gonna slip and say what we know from other other date I'll try to be explicit when I do that and this immediately means that this should be a greenhouse effect that in the infrared there are places which are opaque or semi opaque to the infrared thermal radiation that the earth tries to radiate to space to cool off and as a result the mean temperature the earth has to rise to a higher temperature than its equilibrium would otherwise be you can readily calculate what the equilibrium temperature ought to be just from the heliocentric distance of the earth and its albedo and find that it is some 30 degrees centigrade warmer than it ought to be and the obvious answer for that 30 degrees centigrade is the greenhouse effect which molecules are responsible next slide here is Galileo data and the first thing I want to point out this is from 0.72 1 microns in the very near infrared this is an intensity scale and you can see this set of absorption features due to atmospheric water vapor you can quickly calculate that the amount of water vapor imply but I wonder what that noise is implied by these spectra is the amount you'd expect in equilibrium above a a watery planet and therefore the idea of the oceans are water that the clouds are condensed water vapor and that the polar is that the sound system or just somebody getting up coming down and and that the annul I'll say if I stay put over here nothing will happen then okay I guess I'll do that then and that the polar cap well below the freezing point of water is frozen water so that's very nice we've identified this this principle is important constituents of the earth and in fact it's unique there is no other water covered planet in the solar system now there's something else that shows up here at about 0.75 microns suppose a band and that is molecular oxygen which is another unique circumstance know where the planet has any significant amount of molecular oxygen and immediately we have to ask how does it come about that there is all this molecular oxygen where does it come from now the first thing you think about is and here I'm going to do a photochemical remark is that it's the ultraviolet photodissociation of water vapor that UV photons come in break the water apart the hydrogen atoms escape to space from the upper atmosphere or exosphere the oxygen builds up and that's why you have 20% molecular oxygen but when you look at that in detail including worrying about oxidation of the crust of the earth it gets to be very difficult maybe not impossible it's very difficult to understand how over all of geological time you could accumulate that much oxygen and if that's the case if there are not enough UV photons from the Sun to break water apart enough then you have to do it some other way there are many more visible photons than UV photons but a single visible photon doesn't break water apart you have to add two of them up and there's no non-biological way of doing that but if you had biology if it could use two visible light photons to break a water molecule apart releasing the oxygen then you could explain it now this is not I want to pretend this is a very strong argument there are a lot of uncertainties if you don't have ground truth but the large amount of molecular oxygen is a hint supports a suspicion that there has to be life on Earth and it would have to be very widespread in order to grab so many photons over geological time now the infrared spectrum gives us another hint of life and in quite a different way next slide please here is the infrared spectrum from 2.4 to 3 point 8 microns and here from 4 to 5 point 2 and notice the presence of methane nitrous oxide carbon dioxide all greenhouse gases and in fact those greenhouse gases along with co2 and water very nicely explain the observed greenhouse effect but I want to say something about the 2.33 micron methane feature maybe I can have the lights for Justin is the chemical equilibrium for methane and the presence of an excess of oxygen is to convert the methane to carbon dioxide in water it just gets oxidized and it does it very quickly and there's no kinetic barrier to it and you can then calculate I'll show you a table in a minute what the thermodynamic equilibrium abundance of methane ought to be in this excess of oxygen where it would naturally tend to and it's something like one methane molecule in every ten to the hundred thirty-fifth molecules in the Earth's atmosphere the mixing ratio should be ten on the - under 30 v but there are not ten to the hundred thirty-five molecules in the Earth's atmosphere in fact there's nothing like ten to 135 elementary particles in the entire universe it's only something like 10 to the 79th or 88 so this is the same as saying that there should not be a single molecule of methane in the Earth's atmosphere and yet make a little survey the molecules right here excuse me which kind of you which kind of huge kind of you find that one in the million are methane so that's what a hundred and twenty nine order of magnitude discrepancy even in planetary astronomy this is a significant discrepancy and what must the answer be it must be that methane is pouring out of the interior of the earth and it rates so fast that it overwhelms the tendency of thermodynamic equilibrium to oxidize the methane now what must those sources of contemporary methane be first of all you look at Mars and Venus and essentially no methane there at all so those planets are not making methane the the to other planets closest to the earth and in a wide variety of senses and in fact now my ground truth hat is on in fact all the sources of methane are biological leakage from natural gas and petroleum wells that's old biology and then a whole bunch of new biology Bogg methane methane bacteria in bogs as an ancillary to the cultivation of rice and trying to put this delicately bovine flatulence now thanks for just a moment here's a spacecraft zooming by the earth trying to find life on earth and what shows up among other things these intimate intestinal activities of luminous it is not high on our list of what we consider the most important activities of life on earth we might not have guessed that that's what's detectable I don't at all pretend that that you see the 3.33 micron feature and you conclude aha bovine flatulence but still but still it's very unexpected what we consider important and what shows up don't agree perfectly well the next slide shows a table of the thermodynamic this equilibria lights down next slide please and oh I underestimated it's ten to one hundred forty fifth so it's a hundred and thirty nine orders of magnitude discrepancy in other areas what Galileo found and what are the standard ground truth values are are just the same and this is just another way of saying that Galileo was able to characterize for the molecules that detected what we have here now I want to move to a quite different area next slide please and that is photography can you find by looking signs of life what would it be by the way there is there's a fundamental reason why flash photography of projected slides won't work let's go to the next slide next like this now when we the Galileo imaging system has a wonderful filter wheel in front of it with lots of filters and we can take pictures in any three filters we want and then reconstruct a color picture in which let's say we assign the 0.72 micron channel to blue and as long as we make a we've a pictures sanal simultaneously in three colors and then converted into blue green and red we can make lovely color pictures which will show up what observe what absorbs in the right region when we take such pictures of the earth we find that there are crudely three general kinds of regions on the continent severe area a in which there is a steady increase in reflectivity with increasing wavelength slightly reddish surface material which is consistent with a wide range of minerals and mineral assemblages that's the geology part of the lecture and an area B where there's it's flat through some of the visible but very steep right here in the in the end of the red and then Area C which is extremely steep at the red edge at 0.7 microns and this means that there is some widely available pigments which is absorbed in the red and there is no mineral or mineral assemblage known which plausibly can explain that and therefore this pigment is presumptive evidence of life on Earth and maybe is the pigment that absorbs the visible light so you can add up to visible photons in order to photo dissociate water and explain the oxygen as well so I want now to show you four especially prepared and garishly coloured Galileo photographs of the earth in which areas with this steep absorption our colored orange next likely so here is South America and Central Sun of North America and we could focus this jar slightly please good and you can see that ground truth had on again that for vast regions of South America under the white clouds there is a vivid orange is the core the year and the Andes are our grave they are not heavily vegetated the rest is noticed in Amazonia which used to be deep orange there's lots of fading of the orange by the way the magenta colors are because of the water vapor band in this region the magenta colors are cloud associated water vapor next slide here is the Central Pacific Australia New Zealand Tierra del Fuego and what's this maybe Hawaii and the little bit of land that you can see has New Zealand certainly looks heavily pigmented we're just gonna move around the earth next slide here is Australia and a little bit of pigmentation we saw it turns out to be a not an anomaly the vast bulk of it is not pigmented not vegetated but Indonesia certainly is Southeast Asia certainly is India certainly is next slide and here we are at Africa maybe focus again please you went too far go back okay and here you can see the Sahara and the Saudi Arabian desert unvegetated a sharp line of demarcation between desert and vegetation is a transition region but and and there's some clouds but there's a lot this was all very heavily vegetated at one time can't see much but Namibia and the Kalahari Desert in - Botswana over here you can see not very highly vegetated and and if we had a time series of pictures of this sort over the last few decades we would see the orange diminishing so the earth turns out from this kind of photography to be loaded with biological pigments photosynthetic pigments and of course the pigment in question is chlorophyll it's the red mane of chlorophyll and if we had had filters for there the blue the blue man would have shown up equally well now next slide I want to go to a different way to look for life on Earth mainly to see it directly let's go to higher and higher resolution pictures of the earth and see if we can find at what point do we find signs of life so not to not to be parochial this is where I live right there no sign of life or intelligence at all this false color photography which is a conventional that will be used in a number of other pictures has liquid water black clouds white and vegetation red next slide shows a perfectly typical situation in which there is a break in the surrounding of vegetation and big cities turn up as dirty it's mainly non vegetated I don't know if you can see it but there is a kind of rectangle of red right there which is New York's Central Park at this resolution a few kilometres something like that no sign of life next slide brings us to California this is the Salton Sea this is the Imperial Valley and those of you not beyond the Rayleigh resolution criterion will make out that there is a kind of checkerboard pattern of reds and blacks here which looks on the words at least of showing something highly geometry when you get down to this about 100 meter resolution when you get down to tens of meter resolution suddenly all over the earth deserts and oceans aside similar related patterns show up next slide this is Aragon and these are circular irrigation is not the right word you know they spray water with these circular things there's a technical word I've forgotten it and all over the planet you see circles squares rectangles triangles are in short supply and I'm not sure what an extraterrestrial would deduce I guess the most could be deduced is that the dominant organisms on the planet whoever they are have a simultaneous passion for territoriality and Euclidean geometry beyond that you would not know much but that's already quite far along in understanding us I think now if you could do better next slide please and go to say ten year resolution then the geometrical patterns become glorious this is a spot imaging picture of Washington DC and the question long debated about whether there is intelligent life can be answered tentatively in the affirmative you'll recognize this is the run through the famous part including the nation's capital lots of straight lines and not just lots of straight lines within the cities but lots of straight lines connecting the cities in fact the straight lines crisscross the planet there's huge numbers of it's clearly important if you're resolution could now improve another order of magnitude so you get down to one meter resolution you would find that the straight lines are clogged with little beings very patient one behind another that at night sign two little lights in front of themselves so they know where they're going and sometimes go into little houses to sleep at night someone I'm unfortunately just sweep out on the street okay most of them seem to sleep out in the street homeless dominant organisms is the is the conclusion but they have clearly rearranged the planet for their own convenience and we extraterrestrials would take great pleasure in finally plumbing the resolution depths so that we can actually see the dominant life-forms on the planet and in fact we could do better than that there's a kind of parasitology we can do because we got to better than a meter resolution you could see little parasites entering and exiting the dominant organisms I think we would have every reason to be extremely satisfied with ourselves okay I want now to to mention two more signs of life on Earth the next one is visible light at night this is visible light from daylight what happens if you photograph the earth at night next slide please this picture of course was oh no that was a groan or an ooh this picture of course was not taken all at once since this is a mosaic but it's in Mercator projection what the night side of the earth looks like side so let's let's try to quickly go through it the brightest region of the earth at night has absolutely nothing to do with life or intelligence that's the aurora borealis everything else every other spot of light you see is due to intelligent life you can see this lovely outlining of the shape of the major continents conforming exactly to what we see in the daylight for some reason the dominant beings have lit up the continental margins and we we know that their cities we looked at that one if you look closely right here you can see us talking right here in this and you can see that there are continental interiors that are not lit up but lots of places are I want to show you two there are several but two kinds of lights at night not due to cities one you can see here in North Africa and the Middle East those are not extremely densely populated with with city lights what we're looking at there is the burn off of natural gas and petroleum wealth the flaring and it's very interesting that that is and this of course time variable and it would in the long term many pictures like this show up as something different take a look now at Japan you can see it illuminated the stem to stern the only other as densely lit place in terms of cities is right here in Western Europe but I want to call your attention to this you see this triangle right here now what is that that's the Sea of Japan that's not cities that's not even the land what is it can I have the lights please that is in fact the Japanese squid fishing fleet they shine bright lights at night over a vast area of ocean so is to trick the squid into thinking that it's daylight the squid come to the surface and there get killed it's a mass murder of invertebrates in fact another way to say it is one of the signs of life on earth visible from space is sushi who would have figured sushi is visible look what isn't visible but sushi is now the the other way in which life was detected by Galileo the this by the way is the defense meteorological satellite this is not Galileo Galileo has a plasma wave spectrometer which detects radio emission designed for the synchrotron emission from the trap radiation belts around Jupiter as we approached on the night side above the plasma frequency that is at a at a frequency of four five six megahertz there's a set of modulated radio emissions because it's above the plasma frequency it can be coming from the surface because it's at night the ionosphere is not very the electron density is not very high as you fly by the planet from the dark to the light side the ionosphere electron density increases and the signals go away and it is very hard to understand that in terms other than technology and intelligence and it may be it's not clear it may be the very low frequency radio signals that the u.s. Navy gives to distant nuclear armed submarines let us assume that's the case now look at what's visible from space bovine flatulence sushi and the means for for launching missiles that can any one of which can destroy 200 cities now and some other things as I say now that just isn't at least my sense of of the significant signs of life on earth you cannot see an enormous amount of our art music literature culture science compassion from this altitude in this way it's a kind of parable of what gets seen and what doesn't in any case the the conclusion is wildly positive you can from a spacecraft like Galileo detect life on Earth many different aspects of it in many different frequency ranges and therefore the negative conclusions drawn with similar instruments from other planets are probably right we have calibrated the search for life on other planets in our solar system says nothing about other solar systems now having gotten this far in your search for life on Earth it would make sense to go into orbit around the earth and to to look more closely and to look for changes and I just want reef Lee in the remainder of the talk to give a sense of that next slide please so here is the Delta of a river in Madagascar soaked with topsoil and in fact the rate of loss of topsoil into the Indian Ocean is so great that you can calculate from this and other rivers in Madagascar that you can calculate that at this rate there will be no more tops off in Madagascar in another few decades and something similar not this spectacular is too many places on the earth the extraterrestrials would discover that we're losing we're permitting to be lost the kind of soil necessary to grow the vegetation surely that seems bad next slide this is a former Czechoslovakia and former East Germany but it could be any industrialized place and you can see enormous amounts of industrial pollutants and carbon dioxide pouring out of smokestacks into the atmosphere the next slide is a twilight photo of the amazon basin every spot of light you see here is forests being burned down and it again you could do a calculation which shows that these vegetated places these bright orange spots especially at regions especially the equatorial latitudes are being lost at a phenomenal rate cannot go on for very long until there's none of it left couldn't have been happening for long otherwise it will all be gone now we have arrived with this planet at some critical time in its evolution when the dominant organisms are putting themselves at risk the next slide shows what you could determine from Earth orbit this in fact was determined from the ground the annual variation in the amount of carbon dioxide in the atmosphere the up and downs are due to the northern deciduous forests putting out leaf which takes you out of the atmosphere and then the leaves falling off and fall and more co2 going in so there's an annual oscillation but the overall trend is alarmingly steep the amount of carbon dioxide mean pour into the atmosphere consistent with burn all this vegetation and fossil fuels but we know co2 is a greenhouse gas and the next slide shows that not only this happening for co2 but for methane but the cows are busy and for chlorofluorocarbons which are not only a potent greenhouse gas but also we would perhaps know an extremely effective agent for depletion of the protective ozone layer so something really strange is happening on this planet there denuding the topsoil there destroying the protective ozone layer they're polluting the atmosphere and they're doing an uncontrolled and massive experiment on the climate put all this together and it surely would be necessary to reassess the preliminary conclusion that there's intelligent life on Earth I have I haven't given this lecture very often but I have a few times before and and when I stopped here I find it's a real downer so I will not stop here and I want to try to end on and up so permit me just two more slides the next slide is focus please you can't be focused too much but we can do better than that oh that's it okay this is the last photograph taken of Neptune and its enigmatic moon Triton as the Voyager 2 spacecraft left it after its epic journey through the outer solar system photographing and obtaining other data of 60 roughly world many of them brand new to us the opening of the outer solar system to the human species these two Voyager spacecraft and two spacecraft that preceded them pioneer 10 or 11 have such high velocities that they are inexorably going to escape from the solar system and become the first artifact of the human species to make for interstellar space they're traveling very slowly surely but nevertheless it is a triumph of our engineering that were able to do that and an example of what our science and technology could do given a real chance I wanted from the early days of the Voyager mission to look back and try to take a picture of the earth from the outskirts of the system only voyager only was guaranteed by the manufacturers to work as far as saturn but again because of the brilliance of the JPL engineers and the fact that they got smarter faster than lloyd they've got dumb it worked at uranus and it worked at neptune and only after this picture was taken only after we passed neptune was i able to convince of the project to turn the cameras back and take one last look at the earth and a few other planets i didn't imagine that there would be a great deal of science but I thought nevertheless we could learn something from that picture and so my last slide is the result this is Venus Jupiter Saturn Uranus and Neptune motions neared and here momentarily in a sunbeam is here look at that's us appeal everybody you know everybody you love everybody you ever heard of every human being who ever lived lived there every couple in love every child every Prince and pauper every professor and student every corrupt politician every revered religious leader every conqueror intent on Empire lived on that little blue dot again our pretensions our Manifest astronomy is sometimes described as a humbling experience and I believe that's what this picture says to me this blue dot is fragile vulnerable and a reminder to us that we have an obligation to care for and cherish this world the only home our species has ever known thank you very much Carl for a wonderful trip through universe now that we all know how important we are in the scheme of things or how intelligent we are as a species you're all invited to ask some questions if you have any self esteem left then you can muster the courage please go to one of the microphones in the aisle go beforehand and we'll take question from different aisles or anything else that you think might be of interest and I ask you not to not to be demoralized by the talk I was just that was reality I didn't mean it to be demoralizing we can if we want some way in which we're special in which we're significant then it's up to us to make that way and we can certainly do it I was arguing only against an undeserved central position something that we want to know dint of effort on our part yes no you're absolutely right we we didn't have we didn't have detectors at those frequencies but in fact the earth is ablaze at those frequencies from that little part of the radio band that gets through the ionosphere at television military radar and astronomical radar all that gets out not only easily seen by a spacecraft a few hundred kilometers from the earth but detectable over interstellar distances which is one of the reasons why it makes sense to listen for signals from other civilizations if our inadvertent radio leakage at our relatively new radio civilization can be detected with our own level of detection equipment at the nearest star and more advanced civilizations might be detectable at much greater distances yes you didn't mention is whether our little probe would notice that there's other stuff in orbit now whether there's weather there it wasn't alone in orbit after all we put okay it was it was a flyby wasn't in orbit and no nothing like that there's a lot of debris up there but very little of it big enough to see remember a kilometer resolution at a few hundred kilometres away so in space you would have to be have a kiloliter sized spacecraft only a few hundred kilometres away to be detectable and there are not as far as I know you talk into the microphone so everybody can hear this is a general category of question which often gets asked and I don't know which particular model you had in your mind but what a lot of people have in their minds is don't give away our position because the expert rescue will come here and eat us because we weed guys read other animals so don't come here and eat us let me say why I think this is nothing to worry about first off what is it that's worth crossing interstellar distances about us do we have such a delicate flavor that it's worth crossing these immense interstellar distances together seems to me unlikely but I could be wrong suppose we are a gourmets delight why not just steal one human being sequence the amino acids and manufacture the sequence on your home planet why have to steal lots of human beings it's just a question of cost-effectiveness now another concern which comes most people having a deep understanding of human nature is that extraterrestrials will recognize that sooner or later will be a danger to them and maybe they should come and preempt not what you think here is the earth in absolute radio silence for four and a half billion years except for an occasional sporadic or war Oh kill me the radiation or something like that and then sudden starting in the late 40s with widespread commercial television there gets to be an expanding spherical wave traveling at the speed of light a light year a year and then encompassing the nearby stars and right now it's 45 light years out and there's whatever there is 45 light years out of hundreds of stars something like that maybe it's worth more than a thousand already and if there's anybody there they will listen to find out what this is and what will they hear they'll hear Howdy Doody Milton Berle the army McCarthy hearings and other signs of intelligent life on earth I'm sometimes asked if there's a lot of intelligent life how come they aren't here now you know it's a sign of their intelligence not I'm only joking but in any case it is absolutely too late and a lot of times you get letters to newspapers saying for heaven's sake astronomers you don't know what you're doing keep quiet you'll give us away those letters should be directed to television stations to the Department of Defense and to planetary radar and I'd like to suggest that Len Tyler who's in the audience would be glad to hear any complaints about planetary radar only talking I think this kind of question is is interesting because it's a kind of Rorschach test you know we project on the extraterrestrials what we're worried about about ourselves and for good reason for perfectly good reasons just as the Orson Welles 1938 broadcast about alien invasion was a concern about what was happening in Europe and that's why the resonance was so was so high these these questions illuminate what we're worried about about ourselves well if there are yeah I wanted to ask you we're getting really good at looking at ozone holes and increasing co2 and all that give any I guess good ideas of what we can do with this information other than inform the public I mean so we know that the ozone hole is getting bigger people's you know we're still using our cars and I mean legislation is slowly occurring changing this but do you have any insight as to what other things we can do this information informing the public but in a democracy that's what you want to do I mean see the theory is that the people who run the country and the people in Washington work for us rather than the other way around which is more often the reality but to the extent that the Jeffersonian ideal is valid then the people are exactly who we should be talking to because we're the guys at risk you know the bureaucrats will we'll just stay inside the Capitol and let other people go out for them so what what can we do first thing we can do is absolutely BAM chlorofluorocarbons and kindred compounds that are efficiently destroying the ozone layer you know how it works that I got a lot of things to say on this I'm trying to bite my tongue the CFC molecules be precisely because they're so inert they would brilliantly design they don't occur in nature because they don't chemically react that was their the reason they were safe survived to the stratosphere were more photochemistry where they are photo dissociated and the released chlorine atoms preside catalytically over the destruction of large numbers of zone molecules remarkably I mean in a way it's astonishing and very hopeful the principal industrial nations the planet have agreed to phase out CFCs and they did it in the Montreal Protocol before it was completely clear that there was a substitute that could run our refrigerators and air conditioners and so on and for industrial nations to do that on the such circumstances is a sign of how dangerous it is it's not talked about as that dangerous but the fact that it was done in what was it 87 is is a clear indication of how dangerous it isn't and it's dangerous for three four categories of reasons one the one you hear about a lot increased skin cancer and especially for light-skinned people like me absolutely right if you have more melanin you're better protected and skin cancer is serious likewise cataracts that's that's one category a second much more serious category is that prolonged exposure to ultraviolet light compromises the human immune system and in that sense it's like eight and the third way is that prolonged exposure to increased ultraviolet light attacks the primary photosynthetic producers the plants at the base of the food chain the phytoplankton in the oceans who have to live right near the surface in order to harvest sunlight with them they are not protected against ultraviolet light few centimetres of seawater doesn't doesn't absorb the near UV if they go then the Zul plankton who eat them go and the little fish you eat and the the shrimp who eat the little fish in the sack the shrimp who eat the Zula plankton and the little fish to eat the shrimp and the big fish eat little fish them and dolphins whales people at the top of the of the pyramid all of that for all we know might unravel similarly on the land it's very serious and the stopgap so called HCFCs which do not destroy the ozone layer and nearly as much still do and the big danger there is that you put the CFCs in the atmosphere and it's about a century before they go away on their own so stop by the year 2000 is the present to goal and by 2100 we can go out of doors I'm exaggerating but but so anyway the the first the thing we can do is pretty much being done it ought to be sped up a little bit but apart from that we're doing global warming is much more difficult because there it's not just taking on the DuPont company the principal manufacturers this yes it's taking on principle sources of income for the owners and workers in the coal oil gas auto rubber and chemical industries put those together and that is a very potent political force and so that by itself means this is much tougher it's like if we were serious we would be committed to much more efficient use of fossil fuels why do we drive 25 mile an gallon cars when you could drive 50 70 90 mile per gallon cars that technology is within reach fluorescents instead of incandescent lamps and so on that that's a vast area where we save money greater efficiency and also free ourselves of this slavish dependency on foreign sources of petroleum which causes wars among other things every reason to do it even if you didn't buy the global warming greenhouse argument then beyond that alternative sources of energy beside besides fossil fuel including solar electric wind turbines biomass conversion hydrogen fuel and so on I don't include nuclear power on that list although it's perfect as far as the greenhouse effect goes because it has other other problem that's what we ought to be doing that's what the President Clinton two days ago in a small way towards we will reduce our co2 emissions by the year 2002 what they were in the year nine 19 okay better than the officer and that's the sort of thing people ought to be encouraging governments to do and also there is a way to discourage corporations by not buying the products that destroy the ozone layer or reduce global warming that's a very long answer I am sort of on i'm spring-loaded for that question thank you for asking me yes we seem to think of intelligent life of potential extraterrestrials on our own terms is there any valid reason to project our concept of sentience and our assumption that all life should be carbon-based on extraterrestrials there is nothing in this argument that I've presented that is based on that kind of chauvinism thermodynamic disequilibrium you could have with life based on on anything if the surface of some planet was covered with the most silicon-based giraffes if they made big geometrical reworking of the surface of that planet we'd see it that doesn't depend that doesn't make assumptions about the kind of life likewise radio transmission so I don't think we're as parochial as as there might be a tendency to think we are we think it's the most important aspect of the space program right now is it programs like Galileo or Cassini that go out too far planets and look at them or is it exploration such as the manned mission to Mars which a lot of us hear concerned about or is it other missions about planet Earth type things which look back on the earth the question I will be talking tomorrow on the you got rollerskates another sign of intelligent life on earth roller skates are great you don't take them off when you come into lectures them you might have to leave fast my greatest difficulties are in justifying the men's and women's program and I'll talk about the arguments pro and con tomorrow they clearly involve the largest amount of money and for that reason are immediately vulnerable themselves the other things that space does and let me not restrict myself to NASA but but broadening but let me just briefly mention them and see if I believe that everyone resonates to at least some of the things on on this list I think it's wildly cost effective communication satellites which link up the planet we can talk to almost anybody on earth now the D provincial ization of the most distant countries happens because of communication satellites weather satellites which save billions of dollars every year in just the avoidance of crop losses by a little lead time to farmers to take precautions military reconnaissance and treaty verification satellites which calm the paranoids and hotheads on all sides worth their weight in gold as Lyndon Johnson once once said satellites that monitor the environmental health of the earth which we're just beginning to do in a serious way satellites in Earth orbit that look out that like Kobe for example which addressed some of the most profound questions of the origin nature and fate of the entire universe questions human culture has asked one way or another and then the thing that that I like spacecraft that visit other planets for their own sake but also to compare them with their own I think all of that makes even in rather short-term sense a terrific investment even if you didn't have an ounce of exploratory spirit in you and I can help me a question that you do but even if you don't it would make sense to support NASA in these things sending people is the place where the arguments are not as clear-cut and that's also where it's most expensive yes after all that you've seen in experiences scientists do you believe in God a timeless creator something that is omnipotent but something that you cannot prove empirically probably well if I can't prove with empirically how could I believe in it there's no evidence there's no there's no empirical evidence what I'm having what other kind is there faith faith but faith means belief in the absence of evidence right everything that is what you just said okay so then people could believe in absolutely anything without evidence and would that be okay to you we're not necessarily scientific what what kind of evidence is there besides scientific I don't mean we do on the spot but no what kinds of evidence are there that's not scientific just personal feelings may be personal types of Revelation anything that you have experienced in a spiritual realm okay let me not let me not argue with you but try to to respond to what I know you want to hear but but I personally have a problem with the idea of gut religion religion based on on Revelation so-called because anybody can say that God told them anything and justify any kind of statement with no self correction and the the most impressive aspect of the scientific method is that it has a built-in error correction machinery and that humans are deeply vulnerable to error that's why experimentalists check their instruments that's why scientists check each other's results that's why graduate students go through agonizing PhD oral exams that's why when when we submit papers to scientific journals unpleasant referees reports come back to us this is the built-in error correction mechanism designed to steer us away from fallacy including the fact that we are fully capable of deceiving ourselves I find none of that error correction machinery in bureaucratic religions now having said that let me ask you a question there is a why I will not talk on the basis of evidence there is a wide range of quite different ideas which go under the same rubric God and let me give you to end members of that spectrum one is that there is an outsized male with white skin and a long white beard who sits in a throne in the sky and tallies every Sparrow I have no op priori problem with this idea and in the way it takes me straight back to Java but it's like my grandfather but I know of absolutely no evidence absolutely nothing that supports that notion none of our spacecraft photograph just just nothing the other end member that by its practitioners is called God is the god of Einstein and Spinoza which is pretty closely the sum total of the physical laws of the universe it would be madness to deny that there are physical laws of the universe that apply everywhere I mean ten billion light years away same gravity same quantum mechanics very impressive fact but if that's what you mean by God then of course I believe in God the evidence is superbly good that there are physical laws have I answered your question so on the issue of creation you gave a very good few fewer description there is an open question of whether the universe needs a creator and let me just say a few words about that first off if you say yes the universe was created fifteen billion years ago from nothing and I say how was it created and you say God created what happens when I say to you and who created God you might say well wait a minute that's not fair that's beyond our ability to understand why not save a step and say the creation of the universe is beyond our ability to understand what exactly is gained by saying that some being about whom I have no other evidence called God created it and and if you say nobody created God God was here always then why not save a step and say nobody created the universe the universe was here always again what exactly is it we learn from the notion that God created the universe so I I don't pretend have answers to these questions I mean the notion of the universe being created from nothing in the notion of the universe being infinitely old both are very hard to grapple with intuitively and likewise if you replace the word universe with the word god but that's at least some of the way that I go about thinking about these knotty questions and I'm glad you raised it thank you I wondered if you also would address psychology a while ago you wrote in Parade magazine about the phenomenon of the stories of people being kidnapped by extraterrestrials and one of the things I appreciated about the article is that you didn't just say well these people are crazy you you examine it as a human psychic phenomenon over time would you say a little more about your thinking about okay well as maybe some of you know I'm not opposed to the idea of extraterrestrial life I think it's so fast eclis interesting subject it illuminates our view of ourselves in the universe I've invested some some effort in trying to see if it exists with spacecraft or and with radio telescopes um nobody would be happier than me and there is this low-level Rumble since 1947 mainly in the United States saying we're being visited we're being visited we're being visited and lately there's a new newest wrinkle or at least it's gotten to epidemic proportions lately in which people say not only we being visited I personally they say have been abducted by small grey beings with very large eyes and expressionless mouths taking aboard their flying saucer and experimented on for unspeakable sexual purposes and and it was an awful experience and I'm sorry to have to tell you about it but in the interest of truth to the fairness and so on I would like to go on your television show and tell the world about it now I have met with some of these people I met with the prototypical experience there is Betty and Barney Hill who claim to be abducted in the 60s and the first thing that's clear is these people are feeling deep emotions this isn't just ha ha let's play a little hoax something emotionally profound doesn't mean as any corollary in the exterior world has happened to them and for that reason oh there is some level at which they should be taken seriously as you were saying but I ask myself I don't know if you know the the UFO enthusiasts commissioned a Roper poll the conclusion of which was that 2 percent of all Americans have been abducted even though most of them don't know it and it's easy to do a little calculation to show that over the last 40 years unless the aliens have some special preference for Americans that somebody's been abducted every second all over the planet it's surprising that more of the neighbors haven't noticed so the issue is which bearing in mind our profound ignorance about hallucinations or other unfamiliar internal states and our profound ignorance about extraterrestrial life I mean we're ignorant in both cases if you had to choose which is more likely that we're being invaded by alien sexual abusers or that there is an unfamiliar mental state that hundreds maybe thousands maybe more of people mainly American are are experiencing and if that's the choice the answer is clear to me I mean people do hallucinate people hallucinate it's a fact and I myself I lost my parents both of them about ten years ago a little more and about I don't know six times since then I'll be walking or doing work something and just for a minute I hear one of them saying Carl yes just that but it's clearly either my mother and my father and I heard that so many time in my childhood I it doesn't seem to me that there's anything so peculiar about having a vivid recollection of it and I killed Rijn hallucinate all the time monsters the shadow in the closet is a monster every two-year-old three-year-old four-year-old feel feel that I'm positive that most people in this audience if you think back will recall vivid frightening hallucinations in childhood there's no reason why all of us should lose that altogether in an altered I think it's something like that and what's more it's of great scientific interest among other things touching on how easily we can be misled touching on the origins of religion there is real scientific paydirt here but it's not about extraterrestrial life I think the SETI project had discovered unequivocal evidence of extraterrestrial life we would have read about it in the Stanford daily but has there been any tantalizing anomalies that perhaps aren't conclusive but that might hint of I Love Lucy reruns from another civilization except for the I Love Lucy the answer is yes there certainly have been tantalizing events which passed some criteria for us retinal intelligence but the thing about them is they do not repeat and a signal that does not repeat cannot be examined by skeptical colleagues you cannot test it that it's really from way up there and not a glitch in your electronics and therefore it is close to worthless if we had such a thing and it stayed around for a few days that would be completely different but there are much more capable survey going on now than we're available ever before and hang on in to a nature reserve essentially evacuate large portions of population to other world wind yeah okay first question to ask is what is the disparity of births over deaths on the planet how many more people are born than die every day and the answer is 250,000 so if we were to make a significant dent in world population growth by shipping people to other planets we would have to ship 250,000 people or a little less off the earth every day you will recognize that this is significantly beyond masses current capabilities or any capabilities of all the spacefaring nations at any foreseeable time in the future therefore we cannot possibly in the foreseeable future address population growth by shipping people elsewhere we have to solve the problem right here I believe this is a soluble problem and without going into the details the key part of it is to increase the economic self-sufficiency of the billion poorest people on the planet if you worry about world population growth you have to be worried about economic injustice this all has to do with what's called the demographic transition if if you want to look that up I don't want to spend the time right now to go through it have I answered your question thank you yes does our move away from egocentrism in biology have any implications in your mind regarding our use of animals for food and research among other things hard hard to see that it wouldn't you know Darwin's view was that the idea of an unbridgeable gap between us and the other animals plays the function of not making us unhappy when we kill them eat them where them and so on and if we recognize the deep connections then it would be more painful for us to to treat the animals as if they were our property that we can deal with us we like and and I think many people would say well you got to draw the line somewhere and the question is where do you draw where do you draw the line the fact that chimps and bonobos now look to be so similar to us is making it very hard to draw the line between them and us I think and the question of why all over the planet the chimps are in jail now the further the follow genetic distance from us for most people the more easily we can kill mutilate wherever we want the animal or plant in question and I don't want to pretend this is something other people do not me I eat meat and and I enjoy it and I recognize that our ancestors did and it's built into me but it's become a somewhat less enjoyable experience of especially since I've written shadows a forgotten ancestors with with any dream I'm from Europe and we're in Europe sorry Ireland some of us are taking down borders no there is opening of borders the question is do you think that will bring our borders that we have on earth with us into space and is there anything we can do to stop it if we are I apologized the keyword that you used three times that sounds like borers I didn't understand orders orders I use between countries borders yeah separate this country this country right thank you it's a remarkable fact that it's so hard to see national borders from space it's so clear that these are man-made and nothing natural also it is a remarkable fact that carbon dioxide and chlorofluorocarbon molecules are too stupid to appreciate the profound idea of national sovereignty they effortlessly cross borders you you produce CFCs in Seattle and the people in Argentina are getting fried it the in that sense the planet is one and the national boundaries don't count at all and in trying to deal with the environmental problems it's completely clear no one nation can do it poses a very powerful and upright nation I'm not gonna make any more CFCs I'm gonna make wholesale conversion to alternatives to fossil fuels what do they get for their trouble almost nothing if nobody else does it so these problems are not created by any one nation or generation and cannot be solved by any one nation or generation we're reaching a point where the problems that face us are fundamentally planetary global and all solutions must be planetary global and that means it's not an ideological point like it or not the differences between nations are going to erode that clearly it's clearly happening all the time the European X now in you know attire a willing member and Britain somewhat less so is is one example the Montreal Protocol and see if sees that I mentioned before is another the the worldwide spread of the AIDS epidemic is another it's another thing that doesn't obey national boundaries and communications transportation you

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Carl Sagan gives a lecture blending the sciences and examining mankind's place in the Universe.