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SHOW 214 TRANSCRIPT
Will Intelligence Fill the Universe?

IN the fullness of time, there are three megaquestions that speak directly to the issues of human uniqueness, purpose, and destiny. 1) Does intelligent life exist anywhere else in the universe? 2) Will human beings ultimately spread across the galaxies and colonize the cosmos? 3) Is it an accident or a necessity that conscious, self-aware creatures like us have appeared in this universe? No questions carry greater meaning. Any real answers would change us forever. And here to suggest answers are people who know what they're talking about. But be prepared for some surprises from our distinguished guests.

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PARTICIPANTS

Dr. Francisco Ayala, the Donald Bren professor of evolutionary genetics at the University of California at Irvine, is a leading thinker in biology and philosophy. Francisco believes that humanlike intelligence is a unique event that will never repeat itself in the history of the universe.

Dr. Gregory Benford brings the dual perspective of a working astrophysicist and a leading science fiction writer to the question of life in the universe. Greg envisions the human species colonizing the galaxies.

Dr. Leon Lederman, who is the author From Quarks to the Cosmos, received the Nobel Prize in physics for his work on the fundamental structure of matter. Given the odds, Leon thinks the existence of intelligent alien life is likely.

Dr. Bruce Murray, a professor of planetary science and geology at Caltech, is president (and co-founder with Carl Sagan) of The Planetary Society. Bruce believes that intelligent life exists elsewhere in the universe--and that we should and will find it.

Dr. Frank Tipler, a professor of mathematics and physics at Tulane, has often written on questions of universal purpose and destiny. Frank believes that human beings are special and that if other intelligent beings existed they would have reached us by now. 

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ROBERT: Greg, as an astrophysicist and science fiction writer, you must often think about space travel. Do you believe that it is the destiny of human beings to colonize our galaxy and ultimately the whole universe?
GREG: Pretty much. Our species has always, as its main virtue, tried to move into new territories, take up new life sites, and I don't think anything's going to stop that.

ROBERT: Bruce, The Planetary Society supports the search for extraterrestrial intelligence known as SETI. What's the likelihood that intelligent life exists anywhere in the universe? And will we ever make contact?

BRUCE: I certainly think it must exist elsewhere; we're not some kind of scientific miracle here. That's an intuitive belief that I can't justify analytically. As far as whether we'll make contact--in the fullness of time, certainly. 

ROBERT: Leon, why do most astronomers believe that intelligent life must be abundant in the universe? 

LEON: It's a question of numbers--stars, planets, the likelihood of life formation, and so on--the workings of sheer chance with innumerable possibilities, even though our own existence on this planet is miraculous, in the sense of its low probability. Our judgment is that there are enough opportunities out there that intelligent life, broadly defined, is very likely.

ROBERT: Francisco, you're an evolutionary biologist who tracks the flow of genetic information. Why is the question of alien intelligence usually addressed by physicists and astronomers? Why aren't we biologists asked? Don't the physicists think we're smart enough?

FRANCISCO: Because when we answer, we answer no--that's why they don't ask us. For me it's an easy no, since intelligent life is a biological improbability. My answer would be like Leon's--it's the numbers. The numbers make human beings a unique historical contingency that will not repeat itself in the history of the universe. 

ROBERT: You're saying that the numbers--the probabilities--support the notion that human beings are unique, and Leon is saying, representing many physicists and astronomers, that the numbers suggest that there must be other intelligent life. 

FRANCISCO: No, the numbers we're using are not the same numbers--mine are a different order of magnitude. 

ROBERT: Frank, you're a cosmologist and coauthor [with British astronomer John Barrow] of The Cosmological Anthropic Principle, in which you claim that the universe is uniquely suited for self-aware life. Define the anthropic principle in the context of alien intelligence.

FRANK: The anthropic principle has several different meanings, one of which is just as a selection principle--that is, obviously we have to live in a universe that permits our sort of life to exist. But I have to agree with Francisco; even though I'm a physicist I think he's correct that the likelihood that intelligent life has evolved elsewhere in the cosmos is very small--in spite of the huge numbers that Leon correctly mentions. The number of stars in the visible universe is about one to the twenty-second power [a one followed by twenty-two zeros]. But in spite of the gigantic size of this number, if you multiply it by the probability of intelligence evolving on a planet orbiting any one of them, you still get a number substantially less than one. 

ROBERT: Francisco, what is it about biological systems that makes their improbability exceed the gigantic number of opportunities in the universe?

FRANCISCO: Start thinking about what we are and how we came about. The history of life in the universe is like a colossal bush, and we are a teeny-weenie twig at the extremity. Life on Earth began more than three and a half billion years ago. It was microscopic for most of its history--up to about one billion years ago. Then multicellular organisms came about, and for 90 percent of their history there were no mammals. Then came the mammals, and for 99.9 percent of their history, there were no human beings. So you have thousands and thousands of branches dependent on millions and millions of events. If any one of them were changed along the way, we would not be here.

ROBERT: Could other branches and events have produced a different kind of intelligence?

FRANCISCO: They didn't.

ROBERT: Certainly not here.

FRANCISCO: So that proves its improbability. We are here because we happened. And all prior events happen to have happened, and had to have happened. 

ROBERT: That's the one thing we know for sure.

FRANCISCO: But any change in this long chain of contingent events would not have produced human beings--or beings of any kind that we would recognize as intelligent. You have the immense improbabilities--on the order of ten to the minus twenty-two [10-22], multiplied again and again and again. So no matter how many stars there are in the universe, and how many universes there are, there are no other human beings.

BRUCE: I'm a geologist, so I'll give the geological perspective compared to the biological; and from my point of view this progression you mentioned of the development of different life-forms results in a couple of conclusions. One, there are no scientific miracles at all; we don't see anything that requires some kind of special event, like two stars passing close together. Everything we see is plausible, including the formation of the earth itself, now that we have space and meteorite information. And second--and I think this is an overriding perspective--we ourselves appear very early in the process. Let me give you an analogy. If I'm out hiking, and I see a bunch of ants crawling around, the ants seem to have a kind of intelligence, they have behavior patterns, they may have some kind of self-awareness. But there's no way that an ant could imagine the kinds of things in my mind and heart. I have far more awareness of the way the world is, of what's out there. Yet I consider myself a very primitive being--an ant, as it were--compared to what's really out there, to what's really necessary to understand things. The consequence of this is twofold. First, there's humility. But second, you become very suspicious of closed arguments--that is, "I know all there is to know, and therefore I can prove x is impossible." We're not smart enough to make that statement. 

ROBERT: Greg, what is the Drake equation? 

GREG: It's a basic argument that predicts the likelihood of intelligent civilizations in the galaxy by multiplying together a bunch of probabilities, all of which, of course, are crude estimates. Start with the number of stars that form, multiply that by the probability they'll have planets, multiply that by the probability that a planet will give rise to life, and so forth.8 

{FOOTNOTE}8 The Drake equation, a way to estimate the number of technologically advanced civilizations in our Milky Way galaxy that might be broadcasting signals, was conceived by Dr. Frank Drake, a radio astronomer who is now president of the SETI Institute, headquartered in Mountain View, California. The equation is given as N = R* . fp ne fl fi fc L, where N is the number of communicative civilizations whose radio emissions would be detectable; R* is the rate of formation of suitable stars in the galaxy with a large enouvh "habitable zone" and long enough lifetime to allow for the development of intelligent life (estimated at between two and twenty per year); fp is the fraction of suitable stars with planetary systems (recently increased to fifty percent, encouraging SETI people); ne is the number of Earth-like planets located within a habitable zone (where the temperature would allow water to exist as a liquid, assuming it's essential for life); fl is the fraction of those planets on which life actually begins; fi is the fraction of these life-bearing planets on which some form of intelligence arises; fc is the fraction of those intelligent species that develop sufficient technology and are able and desirous of communicating with alien civilizations; and L is the average number of years (lifetime) that a communicative civilization broadcasts detectable signals into space. The terms fl, fi, fc, and L are the most difficult and controversial to estimate. {/FOOTNOTE}

We've become increasingly tough in our estimates of the last term in the equation, which is how long civilizations last. Ours has lasted a few thousand years--I hope that's not the upper bound. 

ROBERT: Francisco, which of the terms do you attack?

FRANCISCO: The ones that go from simple life to intelligence and civilizations. I'm willing to accept simple life in many places in the universe, but not intelligent life. 

ROBERT: So you differentiate sharply between the existence of life and the presence of intelligent, self-aware life.

FRANCISCO: Right. The existence of life I'm willing to accept. But the existence of intelligent life, the kind with which we could communicate, is what I object to. The reason is that it's so highly improbable. You know, Bruce [Murray] was speaking of scientific miracles. I'm not speaking about any miracles. We aren't a miracle, we're just highly improbable. He was saying that I'm therefore concluding that alien human-level intelligence is impossible. It's not impossible, it's just highly improbable. But the probabilities against it are so high that no matter how many universes are there, you still won't have it.

ROBERT: Greg [Benford] is the one guy here whom I haven't yet interrogated about whether he believes in the existence of intelligent alien life. 

GREG: I noticed that. I think there may be a very large number of intelligent--

ROBERT: Not just to promote your science-fiction books?

GREG: Oh, sure, it's that too. But seriously, one of the numbers we forget about is that the Earth is a young planet, and that most of the stars in the galaxy formed before our sun. Planets around those other stars have had more time to work on the evolution of higher intelligence. If there's a certain down payment you have to make for intelligence, you have to develop a significant nervous system. On Earth, we didn't get into this brain game until roughly half a billion years ago. But other parts of the galaxy may have been players five billion years ago. 

ROBERT: Therefore?

GREG: They've had a lot of time to work on this problem, meaning that chance has had a much longer run there than it has here. Based on the numbers, intelligent alien life is just not doubtful. 

FRANK: We can use those same numbers to conclude the exact opposite, because if those other stars and planetary systems are billions of years ahead of us, and if what you say is correct, then because interstellar travel isn't particularly difficult, those beings would have reached us long ago. 

BRUCE: That's another argument. I'll take you up on that.

FRANK: I've got two arguments, one entirely from physics and one from biology. 

LEON: No, your argument is weak, because if we're talking about intelligence, then they may have decided they didn't want to come here. 

FRANK: Well, they wouldn't have the choice. The number-one feature of life itself, arising from its exponential growth, is the desire to expand.

LEON: Lower life-forms may want to expand, but more sophisticated life may not.

FRANK: But intelligent life, in order to survive, has no choice. For example, our sun is going to leave the main star sequence in five billion years. That means the sun will expand outward and consume Earth. If future beings have not left Earth, they're going to be destroyed. So because the crucial behavioral characteristic of life is survival--

ROBERT: --they must seek to travel in space, assuming they exist. Bruce?

BRUCE: I come at this from a different point of view, having been involved in deep space programs. And I've had to ask myself, What are the limits? How far out in space can we go? And it turns out, because the universe is so thinly populated with stars, that [to get anywhere] you have to travel at speeds approaching the speed of light.

ROBERT: Easy, for civilizations with millions or even billions of years' head start.

BRUCE: Well, it's not been easy so far. It gets to be a complicated, energy-intensive process. And where are you going to go? We just got through saying that there are billions of stars out there. You can't just go from one to another the way they do in a TV movie. No. You're only going to go--if you go at all--to a place that you already know is inhabited.

FRANK: Advanced civilizations could use self-replicating probes. They would send a robot probe to a nearby star to explore that solar system and also make copies of itself. These robot copies would go to other solar systems and replicate again, which would then produce other copies to send to other solar systems [and thus geometrically expand the volume of exploration relatively rapidly].

BRUCE: How do you know it has to happen that way? There's no way of knowing. No, of course not! You have no way of knowing. There's absolutely no way that process would work.

FRANK: Just as you can tell that our Earth is an inhabited planet from a hundred light-years away, by means of the strong [spectrographic] oxygen line, advanced intelligent life, when it moves out, would start to control the environment [in places that it landed]. Robots would obviously not need to create oxygen, but they would start to remake the solar systems in various ways.
ROBERT: Some people have said that you can make the assumption that it would take an intelligent civilization about a thousand years to travel one light-year. Does that seem to make sense? One thousand years for every light-year of distance?

BRUCE: I think that number may come from a different calculation. That's the idea that the species itself is spreading out and occupying new sites. Not just sending probes. 

ROBERT: OK, if that's true, then consider that our current galaxy, with a few hundred billion stars, is about seventy thousand light-years in diameter. So in about seventy million years--seventy thousand times a thousand; say a hundred million, to round up--any civilization in our galaxy, theoretically, could have visited us. And in galactic history, a hundred million years is a small fraction of the available time.

FRANK: Even with current rocket technologies, a thousand years per light-year is doable, so that, as you say, in only about a hundred million years an exploratory, self-replicating civilization would have covered the galaxy.

ROBERT: But that doesn't prove your point, Frank--the negative evidence of visitations doesn't justify the positive assertion that alien intelligence doesn't exist. As Leon said, they may not want to come here, especially after they've seen this show. 

LEON: Extrapolation won't work. What Frank's neglecting are technological advances beyond anything we can now imagine that might change this intelligent system in such a dramatic way that travel would be one of these obsolete customs you see in ancient movies. It's much easier to communicate than it is to travel.

FRANK: Still, there are limited resources in any planetary system.

ROBERT: I want to get a biologist's take. 

FRANCISCO: We have six billion people in the world. Let's assume that we have six billion times six billion people, and let me ask the following question. What is the probability that two human individuals, born from two unrelated sets of parents, will be genetically identical? I can make that calculation, and the probability is effectively zero. The probability that intelligent life would arise independently of the way it has arisen on Earth is even less probable than that. So what I conclude is that it's zero.

ROBERT: But aren't you limiting your definition of intelligence to humanlike life and basing your calculations on DNA sequences?

FRANCISCO: That's right. I have defined intelligent life as the kind that we can communicate with and understand. They'd need self-awareness and some kind of language. 

ROBERT: Certainly our form of intelligent life does want to explore space. The only arguments are over what we can afford and how we allocate limited resources. The issue, Bruce, that you've addressed often is, Should it be carbon or silicon? Should we explore space with human beings, who are very expensive to take on space rides, or with robots?

BRUCE: Both are involved so far. And that's natural, because we have barely become civilized on a geological timescale, so we're basically the same kind of animal that once hunted on the plains of Africa. Physically doing things, going out and exploring, is deeply embedded in our genes and will continue to be. But now our brains have produced, in just this remarkable century, an enormous breakthrough in information technology and robotics. Robots are better at this than the best of our astronauts--by at least a factor of two. So there's no question what the future holds. The future is mostly robotic, controlled by our intelligence, our attitudes, and our command systems. 

FRANK: Imprinted in the robots themselves? Artificial intelligence?

BRUCE: Perhaps. But in any case it's a symbiotic relationship between us, as highly evolved animals, and these new things, these intelligent machines.

ROBERT: Project into the future.

BRUCE: I'm talking about the future. Earth itself will get more like this, intermixing humans and machines. We're in the middle of an enormous transition, I think the most significant, in an anthropological sense, in human history--that's my gist. But when you say that there's no one out there because they don't come flying across the universe the way they do in our science-fiction movies, I just say that you have a very limited view of the future, because it's much easier to use robotics and communications.

ROBERT: You're doing that, though. You're actually involved in listening. Tell us about SETI. 

BRUCE: Right. Good point. So after we've debated whether intelligent alien life exists, after we each give our gut feelings, after Francisco and I disagree, then we do the experiment, then we search for real data. Well, the experiment is just beginning. First of all, because star systems are so very far apart, the only kind of signal we could receive is one that is intended to be received. It must a beacon. It can't be an accident. We're not going to get random interstellar communications; we're not going to get the I Love Lucy version on Alpha Centauri. What we'd get would be a civilization that wants to communicate with us--one that has spent a lot of its money to build an omnidirectional beacon, for example. That's what people are looking for now, with the microwave. An omnidirectional beacon. It's a very inefficient way to go, so an alien civilization could easily say, "Let's wait another hundred years; these people will get smarter, have more receivers in space, and know a lot more about communications. And then they'll find the signal that we want them to find"--if they want us to find them at all. It could be a primer for entry into the galactic community. So the assertion that since we haven't had any alien visits, therefore there isn't any alien intelligence--when there are so many other possibilities--means nothing. 

ROBERT: Frank, how do these two questions relate to the anthropic principle: whether there's intelligent life elsewhere in the universe, and whether human beings will ultimately colonize the cosmos? 

FRANK: I think that what science will tell us is that Francisco [Ayala] has given the correct biological answer--that we are alone in the cosmos. But I also think that life will expand out from this planet--particularly robots, which although primitive now will ultimately be the form of life that will spread out into the cosmos. And ultimately take over the universe.

ROBERT: How does that reflect back on the anthropic principle? Is there some precursor design working here?

FRANK: Well, this eventual colonization of the universe is actually locked into the laws of physics; in other words, the laws of physics are such that this will inevitably happen. I think that you have to have intelligent life near the end of the universe for the very consistency of the laws of physics themselves. 

ROBERT: That's a controversial position, to be polite. 

LEON: Yes, it is. Ask Francisco [Ayala} what the influence of natural selection would be in this context. Even if you believe that there's a huge reservoir of life in the universe, wouldn't natural selection [play a critical role]? Assuming the laws of physics are the same out there as they are here, which we believe, then even if the circumstances are very unusual, that makes physics conducive to the evolution of life, which would be everywhere. 

ROBERT: Must natural selection and the abundance of life ultimately produce some kind of intelligence? 

LEON: No. 

FRANK: Why are you so equivocal?

FRANCISCO: Natural selection is only part of the story. Some organisms reproduce more than others, and those that do will, so to speak, conquer the earth. But what directs natural selection to make some organisms reproduce better than others? There's a tremendous diversity of genes, which is what I was taking into account in considering the improbability of having two identical human genotypes. And then you have the additional complexity of the environment; each minute of each environment is different, and it's different everywhere in the world. You have different genetics, different environments. So you cannot possibly have the same intelligence anywhere. 
ROBERT: But couldn't we find a different kind of intelligence in the cosmos? Are we being too humanocentric?

FRANCISCO: Yes. But it would have to be a kind of intelligence with which we can communicate. It would have to have some kind of nervous system comparable to ours, and some form of language.

ROBERT: It has to be able to communicate, sure, though its nervous system doesn't have to be comparable.

BRUCE: That might be a transition phase also. 

ROBERT: What would an alien civilization need so that you could detect its signals on your current systems?

BRUCE: They'd need a technology capacity and the motive and will to build a communication system whose broadcasts can be received by our enfeebled early-detection devices here; they'd have to use some obvious signals, so we'd know it wasn't background noise. Signals that would be enough to demonstrate that they exist. 

ROBERT: What kind of signals would be obviously artificial?

BRUCE: Our favorite is a very-narrow-band frequency, because any natural process with any natural temperature will generate broad frequencies. And they'd have more sophisticated elements. I'd put a funny modulation on there: on, off, on, off, off, off, on, on. That's not likely to happen normally.

ROBERT: What about consistent signatures of matter identical throughout the universe, such as emission lines, that any intelligent civilization would recognize as a signal? 

GREG: There's an argument that you should look near natural frequencies, like hydroxyl or water lines--things like that. 

BRUCE: Carl Sagan did this with the images sent out on Voyager [i.e., two spacecraft, launched in 1977, that toured the outer planets and then became the first man-made objects to escape the solar system and journey into deep space]. The assumption is that hydrogen-line emissions would be known by any intelligent civilization, and so all other information, such as numbers, are set in relationship to it.

FRANK: Let me say something about sending signals. This proposal was made a hundred years ago, by an astronomer at Harvard named Pickering. He wanted to communicate with Martians, who everyone thought were there. They were going to build a huge dish, a mile across, to send light pulses. Now the problem, of course, was that there were no Martians. In recent years, as we know, we've sent robotic probes to Mars with great advantage. The robot probes can tell you something about your target systems that signals can't.

ROBERT: Leon, can there be noncarbon, nonbiological intelligence? 

LEON: Conceivably there can be, though we can't evaluate the probability. And there are neutron stars--collapsed cores of exploded stars--that are vast accumulations of very, very dense nuclear matter. Processes in these neutron stars take place a million or more times faster than in our chemically based biological systems. Could these enormously fast reactions possibly generate enough complexity to begin the evolution of intelligent life? Surely, such intelligence would be radically different, and although they might have interesting ideas, they'd be hard to communicate with, because one second of our time would be many, many, many generations of their time--so while we're discussing something, they would have the rise and fall of the Roman Empire.

ROBERT: Rapidly spinning neutron stars called pulsars broadcast enormously strong signals.

GREG: I used to work on pulsar radiation. And everyone was always wondering if in fact they were artificial beacons. They are very powerful.

BRUCE: The important point that Leon brings out is that there could be systems in which natural evolution might work a million times faster than in this creaky old biological world of ours. And because the rates of processes are much higher, the probabilities of producing intelligence are also much higher on any given timescale. So we ought to realize how ignorant we are before we close out possibilities. I want to pick on ignorance, because that's what we have to start with: we must recognize how little we understand, compared to all there is to understand. And we've been futzing around in this discussion, talking about a miraculous Earth-centered life. That's the biblical view of the origin of life. 

FRANCISCO: No. It's not what I was saying--

BRUCE: What you're both [Francisco Ayala and Frank Tipler] arguing is that intelligence only happened here. That it has happened nowhere else. If that's not the religious view, it bears extreme similarity. Don't reject what I'm saying. Leon is saying, "Well, maybe we can have other kinds of thinking things evolving." And that's all right, in some sense. The point is--what this is, really--is an argument about God. This is about meaning, about the whole enchilada. And my point of view is that we are so primitive ourselves--as recognizing, thinking machines--that we shouldn't expect to come up with strong answers to these questions. But the fact that we can conceive of some universal principle, or some universal connectedness, and sense some meaning in it, is itself a reflection of our basic approach--whether as a religious believer, or as a nuclear physicist, or as a geologist. It's the same sense that there must be something here that's larger than us, in our current primitive scratchings. 

FRANCISCO: The problem I have, Bruce [Murray], is that I know how to multiply. And I have to multiply with probabilities, which has nothing to do with miracles, nothing to do with religious views. It does have to do with the example that I gave you: What is the probability that two human beings, engendered by separate parents, will be genetically identical? Zero. It makes no reference to religion, none to miracles. It's just simply a matter of probabilities.

ROBERT: What I find fascinating, Francisco, is that people take what you say--which is clearly nonreligious, nonmiraculous--and interpret it to suggest religious concerns. Doesn't this suggest that we are beings who crave meaning? Wherever it comes from, this search for meaning is pandemic. I crave that. Do you crave that?

FRANCISCO: Absolutely. But you see, meaning is something that we need sometimes. And that's wonderful.

ROBERT: Just because we need meaning doesn't make it less real.

FRANCISCO: Absolutely. I don't think science is all there is to the universe. There's art, aesthetics, ethics, all sorts of other things that are real--and that's what I crave.

ROBERT: There's nothing miraculous about art, aesthetics, ethics, but they are all based on human consciousness and self-awareness, which are the instruments of search for such meaning. Project forward, how will this human craving--this search for mearning--develop? 

GREG: Well, certainly Bruce [Murray] is right. We are searching for meaning, but this is the first inning of the game, and I, too, have a dislike of arguments that close out possibilities. We ought to realize that it's a big universe out there, it's been around a long time, and our knowledge of even the rates of processes is so primitive that we can't eliminate options. So in fact I do think that, say, a billion years from now the galaxies are going to be packed. But probably packed with us, because--you know--we're ugly, we're mean, we're ornery, and we're damned hard to kill. 

FRANK: I think it's better to say "our descendants," since I don't think we'll still be Homo sapiens. 

GREG: Well, I was hoping that this panel might stick around till then. 

FRANCISCO: I'll have proved my point by then. 

GREG: Francisco [Ayala] knows how to multiply. And on this show, he also knows how to divide--politely, of course.

ROBERT: What kind of descendants, Frank?

FRANK: Our descendants in the far future will be more like artificial intelligences. One possibility is what we call human downloads, mapping our consciousness into a computer. Alternatively, we might create actual artificial intelligences. That's the form of life able to exist in the harsh environment of space. We are a species adapted to this particular planet, filled with water and oxygen. It's an utterly different environment out in space. Machines, however, can adapt to anything--even perhaps to neutron stars. 

LEON: Here's another approach. Our planet is gifted with supplies of iron and copper and other heavy elements, all of which came to us from supernovae--vast explosions of stars in distant galaxies. And we know that organic molecules also exist throughout space. So what's the possibility that this miracle of intelligent life--this low-probability event that happened here on this planet--might propagate? 

ROBERT: Would that be a miracle?

LEON: Yes, to me a miracle is a low probability event.

FRANCISCO: First of all, I recognize the possibility of many other kinds of life--for example, based on silicon. Second, I don't have a problem with the origin of life and with life being common in the universe, as I've said. But once you consider the kind of intelligent life that we've been speaking about--life that we could communicate with--that's where I have the problem. It's the power of probability.

ROBERT: By the year 2100, will Bruce [Murray] and his colleagues in SETI, of their descendants, have detected alien intelligence?

GREG: Yes. And I'll be right here to cheer them.

BRUCE: I don't think we can answer that question definitively, because it may take a thousand years. 

ROBERT: What's your guess on a hundred?

BRUCE: I sure hope so. 

ROBERT: If human beings are around for a million years??

BRUCE: Definitely.

FRANK: We will never detect alien intelligence.

ROBERT: Even in a million years?

FRANK: No, we will never detect alien intelligence anytime in the future, because they're simply not out there to be detected. And what's the reason we know that they're not out there? As we can see, no probes have ever arrived here. 

FRANCISCO: In a hundred years, will we have detected life in the universe? Yes, because life is not rare, considering the size of the universe. But we will not be communicating with any of this life, because none of it is intelligent--there is no other intelligent life in the universe. However, I'm an optimist; I believe that one hundred years from now, we will have found intelligent life on Earth.

LEON: Will we detect life? Absolutely, yes. I think. 


ROBERT: CONCLUDING COMMENT

LET'S restate our three megaquestions: Does intelligent alien life exist? Will humans colonize the cosmos? Did the universe "expect" conscious beings to emerge (the anthropic principle)? As you might have guessed, opinions are divided, with physicists, astronomers, geologists, and biologists lining up on both sides. What I've thought is that these killer questions may be related. Better is what the British geneticist J. B. S. Haldane thought: "The universe is not just queerer than we suppose, but even queerer than we can suppose." My purpose, here and throughout the Closer To Truth series, has been to spotlight fundamental issues of existence, dissect them, enjoy them, and link them if that's possible. In coming seasons, we'll continue to go after human uniqueness, purpose, destiny. Count on it; we won't stop asking these questions. I hope we'll nail them before we're through. Can obsessiveness like this get us closer to truth?

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