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CNN PRESENTS

Is There Anybody Out There?

Aired August 6, 2005 - 15:00   ET

THIS IS A RUSH TRANSCRIPT. THIS COPY MAY NOT BE IN ITS FINAL FORM AND MAY BE UPDATED.


GERRI WILLIS, CNN ANCHOR: I'm Gerri Willis in Atlanta. Here what's happening now in the news.
Rescuers pulled at least 22 survivors from a Mediterranean plane crash today. At least ten people were injured. A Tunis airplane went down in the water after trying to make an emergency landing on Sicily. The twin-engine turbo prop was on a flight from Bari, Italy, to Tunisia in North Africa.

And former British Foreign Secretary Robin Cook died today. The one time member of Prime Minister Tony Blair's Cabinet resigned from the House of Commons in 2003 in protest over the war in Iraq. Cook was 59 years old.

I'm Gerri Willis at the CNN Center in Atlanta. More news at the bottom of the hour. CNN PRESENTS begins right now.

(BEGIN VIDEO CLIP)

PAUL DAVIES, AUTHOR "ARE WE ALONE?": The speculation about life beyond Earth has been going on for literally thousands of years. I think sometime in the last 10 or 15 years, it has turned into a serious pursuit.

KELLY SMITH, CLEMSON UNIVERSITY DEPARTMENT OF PHILOSOPHY AND RELIGION: The universe is such an incredibly huge place that the chances that there isn't life anywhere out there are virtually zero.

STEVE SQUYRES, MARS ROVER PROJECT LEADER: If you can go to just another planet in this solar system and find that life has independently arisen twice, then it requires no great leap to believe that it may, in fact, be common, when you consider the multitude of worlds that there are out there.

JILL TARTER, SETI INSTITUTE: Is there some other intelligent creature out there that looks up at its universe and wonders as we do?

CHRISTOPHER CHYBA, SETI INSTITUTE: We slowly, by exploring, learn things about what might be possible.

DAVIES: And it could be that we are the generation that will actually know the answer.

(END VIDEO CLIP)

MILES O'BRIEN, CNN ANCHOR, CNN PRESENTS: You may have seen the startling news on your newspaper's front page last month. The announcement of the discovery of a new planet outside our solar system. Excited scientists call it Earth's bigger cousin.

Welcome to CNN PRESENTS. I'm Miles O'Brien. This planet is news because it is made out of rocks, like Earth unlike the nearly 150 Jupiter-like gas giants found before. And that makes scientists believe they are one step closer to finding out whether there is life outside Earth.

You know it is not such a far out idea anymore. In fact in the past few years, mainstream scientists have done a complete turn around on the notion where they once viewed our planet as the only living example in the universe, many now say they would be surprised if something else wasn't out there somewhere. Little green men? Well, maybe. But more likely it would just be some microscopic green mold. But even that would be a huge breakthrough and it could be just around the corner.

So strap in for a wild ride to the far reaches of the universe. We're going search for an answer to that eternal question, is anybody out there?

(BEGIN VIDEOTAPE)

O'BRIEN: Greetings from the deadest place on Earth, Chile's Atacama Desert.

Don't bother packing your bathing suit or golf clubs if you're joining us. Might as well be walking on the moon, or Mars.

These researchers are probing the limits of life, trying to understand why there is nothing living in the dirt they're digging, while just over the hill life is thriving.

The big question is, are we alone in the universe? Is there life anywhere other than Earth?

And the scientists tell me, mapping the limits of life here makes it easier to chart a clever course to troll for it out there - on Mars and possibly other planets.

And this is why scientists in this field are so excited right now. The more they look for life in all the wrong places, the more they find it.

In the scalding hot acid springs of Yellowstone. In the deepest, darkest depths of the ocean. In the cold, dry valleys of the Antarctic. Even in radioactive waste pools.

We now know all of these places are home to some hale, hardy critters. Life is much more tenacious than we once assumed.

SQUYRES: There used to be this idea that life really only could take hold in a very narrow range of conditions, sort of like a Goldilocks kind of thing where, you know, it can't be too warm, it can't be too cold, it's got to be just right.

But what you find is, as long as you can get liquid water there and some source of energy - whew - man, I mean, life is happy on this planet.

KIM STANLEY ROBINSON, SCIENCE FICTION WRITER: The fact that life is so tenacious, and that from the top of our atmosphere to the very deepest rock we can go in to, there's life there, there's something nice about it. There's something encouraging, I guess you could say.

O'BRIEN: And this has fundamentally changed the way scientists look at the universe. Suddenly, Mars looks a lot less dead than we thought in the '70s, when the Viking missions failed to find life there.

SQUYRES: It's an incredibly cold, dry, desolate, barren place. It's beautiful. It's breathtakingly beautiful. But it's desolate.

And the surface of Mars, right now, today, is not very well suited for life. But it could have been quite different long ago.

O'BRIEN: Or what about Europa? Beneath the thick ice that covers this moon of Jupiter, there's a big, deep, dark ocean. Could there be creatures here, huddled near hot vents as we see beneath our seas?

CHYBA: They'd be living off of chemical energy, not sunlight.

And then the question becomes, are there enough sources of chemical energy on Europa for a Europan biosphere in that ocean?

We've begun to look at that question, based on what we know about Europa now. And the answer looks like "yes."

O'BRIEN: But when scientists look beyond our solar system, the prospects seem even more intriguing. We now know there are more than 100 planets that orbit a star like ours, the one we call Sun.

TARTER: I never as a child had any doubt that the stars up above were somebody else's suns. It just seemed to be a natural kind of thing.

O'BRIEN: Imagine that. Someone else's sun.

Someday soon, perhaps we'll see another pale blue dot like Earth. Will anyone or anything be looking back at us? Or are they already?

And could they be trying to reach us?

TARTER: And the result of 5701 ...

O'BRIEN: The searches for extraterrestrial intelligence soldier on, systematically homing in on likely celestial suspects, hoping to hear a signal from another intelligent civilization. Maybe it will be tonight.

FRANK DRAKE, SETI INSTITUTE: We're always doing much better than we did the year before. And we know that at some point, we're going to cross the threshold - the threshold where you do have the capability of detecting them.

And that could happen tomorrow. It could happen a year from now, maybe a few decades from now.

UNIDENTIFIED MALE: And there are unique ventures (ph) involved in the exploration of six.

O'BRIEN: Put all these developments under one big tent, and presto! You have a field called astrobiology, which studies all life in the universe.

It's a hot field. All kinds of things cooking. Although when I went to their big meeting, I needed a little expert help deciphering the developments.

I asked physicist Paul Davies to guide me.

DAVIES: People have speculated about life beyond Earth for centuries. But it's become a scientific venture only relatively recently.

Where do you go on Earth that is most like Mars?

O'BRIEN: Davies is a big thinker. He writes books as often as I change socks, including one of my favorites, "Are We Alone?"

He was in this field long before it was cool.

DAVIES: When I was student, I used to go around talking about the possibility of life elsewhere. People would laugh at me. They thought this was a crackpot subject.

But I think sometime in the last 10 or 15 years, it has turned into a serious pursuit, not only for NASA, but for scientists interested just in the nature of life.

O'BRIEN: The field of astrobiology is exploding at a time when our knowledge of the origins of the universe is, as well.

The Hubble space telescope has now taken pictures of galaxies and stars as toddlers, just a few 100,000 years after the Big Bang.

Pretty, isn't it? Have you ever seen a Hubble image that wasn't?

Perhaps we think they're beautiful because they are, after all, the ingredients of us. We are made of star stuff. Mix and blend and throw in a crock pot for 13 billion years or so, and out we come - an intelligent, sentient souffle.

Surely, in this vast universe, we aren't the only successful living proof of the pudding from this cosmic kitchen. Right?

KELLY SMITH, CLEMSON UNIVERSITY DEPARTMENT OF PHILOSOPHY AND RELIGION: Well, I think the universe is such an incredibly huge place, that the chances that there isn't life anywhere out there are virtually zero.

How frequent intelligent life is, is another question.

O'BRIEN: There are some people who need no convincing, no proof that we are not alone. But this is not by, of or for the UFO crowd.

This is about the real hunt for alien life, not just for little green men. Even a little green slime would be a big deal.

The scientific bloodhounds are hot on the trail. And if they find what they're looking for, it's hard to imagine anything will be quite the same.

DAVIES: If we were to discover just a single microbe on another planet, and if we could be sure it didn't get there from our planet, or vice versa, if we discovered a second sample of life - somewhere where life has begun from scratch, even just a microbe - it would transform our worldview beyond the discoveries of Copernicus and Galileo and Darwin and Einstein put together.

O'BRIEN: When we return, we begin our search for alien life here on Earth, at the bottom of the sea of all places.

(COMMERCIAL BREAK)

O'BRIEN: If you want or need proof life on Earth is hardy and ubiquitous, take a look at these odd creatures.

They live a mile-and-a-half below the surface of the Pacific in a place where no one expected to find anything alive. And the mere fact that they exist, actually thrive, in such a harsh environment, is sparking a new belief that life must also be ubiquitous throughout the universe.

TIM SHANK, WOODS HOLE OCEANOGRAPHIC INSTITUTION: The mouth is around here and it's scraping along with the seafloor.

O'BRIEN: Tim Shank is with the Woods Hole Oceanographic Institution. He's just back from his fiftieth voyage to the bottom of the sea in the tiny Alvin submarine.

This is where the sun don't shine - ever. The strange creatures that make a living here draw energy from underwater geysers called black smokers.

The murky water that spews out is well over 700 degrees Fahrenheit and filled with hydrogen sulfide, the gas that makes a sewer smell like rotten eggs. Breathe enough of it, and you'd be dead.

SHANK: Life down there thrives on chemistry, the toxic chemicals that are there. Toxic to us, anyway.

O'BRIEN: This is a scientific biggie. As it so often goes, researchers happened upon this extreme neighborhood by accident in 1977. They were simply trying to figure out how the Earth expels internal heat, and stumbled into a thriving community of animals large and small.

The scientists call them extremophiles - creatures that live in the harshest environments on Earth. SHANK: It's not sunlight-driven. It's not flowers and trees. It's deep and where there's no light and where the planet is breathing. You've got this fantastic abundance of life that's thriving.

And it's that same abundance of life that could be thriving on other planets, that has evolved to do the same thing.

O'BRIEN: Learning about life at the edge here on Earth defines and broadens the search for life all throughout the universe. The more places they find living things here, the more the odds improve that we'll find them on another planet.

DAVIES: There are organisms that survive incredible amounts of radiation. Radiation that would kill you or me within a few minutes, they're able to survive on the longer term. And then there are other organisms that live in extreme colds.

So, one by one, we've pushed the limits of life away from the sort of comfort zone that you and I experience to literally hellish conditions.

O'BRIEN: Which brings us to Yellowstone, of all places. The world's first national park may seem like almost heaven, but it offers a unique brand of boiling, steaming hell.

BILL INSKEEP, GEOCHEMIST: These features are common in Yellowstone. And basically we're looking at boiling battery acid.

O'BRIEN: Yes, those boiling mud pots - battery acid and all - are brimming with microscopic life.

Nothing more fun than that if you're geochemist Bill Inskeep.

Leave the elk, wolf and grizzly bear counting to others. Inskeep is fascinated by the rare creatures of Yellowstone that you won't find on postcards in the gift shop.

INSKEEP: These types of environments are considered potentially primordial environments that represent organisms that are very ancient, very old organisms that branch very closely to the tree of life.

O'BRIEN: Until recently, it did not occur to the experts that the vivid colors of Yellowstone's toxic springs camouflaged one of the big secrets of life.

JOHN VARLEY, DIRECTOR, YELLOWSTONE RESOURCES, YELLOWSTONE NATIONAL PARK: And a lot of people thought it was minerals. A lot of people thought it was light refraction, you know, basic physics.

No one thought that it was necessarily life, and especially new life - life that had never been described before.

INSKEEP: These are some of the best examples here of what we call yellow streamers.

O'BRIEN: Yellow streamers are tiny, living filaments with the right stuff to be alien life. They live on sulfur.

You almost think like your eyes are fooling you when you see this.

INSKEEP: Yes, the shades of green are beautiful here.

O'BRIEN: Bill Inskeep took us all over Yellowstone and introduced us to a rainbow coalition of tiny living things that are at home amid hydrogen, arsenic and methane - all elements that are out there everywhere fueling the universe.

INSKEEP: These may be as close as we can get to environments on other planets. And so, why not study them, understand the life forms here and get as many clues as we can about looking for those types of life forms that might be on other planets?

O'BRIEN: This is the end of the line for life as we know it on this planet - the Atacama Desert of northern Chile.

A place once known for nitrate strip mines, now a gold mine for those hot on the trail of extraterrestrial life.

CHRIS MCKAY, NASA GEOLOGIST: Here is the only place where we've really crossed a threshold where we find no life.

O'BRIEN: NASA's Chris McKay is in his element here. His focus is Mars. And this may be as close as he can get to being there - for now.

MCKAY: It's sort of crime scene investigation. There was life here. It's dead. They're gone.

They've left a very trace record, a very small, slight fingerprint. We've got to pull that out.

O'BRIEN: You're certain there was life here.

MCKAY: Yes. We know that. This is Earth. There was life here.

It's just a matter of time. Continents moving, Andes going up and down. At one time, there was life here.

O'BRIEN: But somewhere along the epochs, this core region of the Atacama dried out and then died out, big time.

Today there's not so much as an occasional patch of fog here, much less rain. And so it went on Mars.

At one time, it was warm and wet and perhaps alive. And now, well, looks like the Atacama to me.

MCKAY: Where does everybody die? Where does life check out and say, this is too much for us.

Well, this desert, we can - we can, by driving across this desert - take a trip in time on Mars. We can start on the wet end and imagine, here we are on Mars with water. We can drive to this end and say, here we are. Mars is dead.

And we can chart where that transition occurred, and then we can apply it to Mars.

O'BRIEN: This soil isn't just dead. It is quite literally killer. Let me explain what I'm talking about.

The soil, even though you can't see it, is filled with oxidants. That's essentially bleach or peroxide.

And when a living microbe gets blown in by the wind and lands on the surface here, it isn't too long before it's killed, toast.

And that's what makes this place as much like Mars as anyplace on Earth.

MCKAY: The more we understand about life on Earth - its limits, its capabilities, the record it leaves behind - the more we're in a position to do a search somewhere else.

Really, the proper place to learn about life is Earth. We have no choice and that's where we are. And that's the knowledge we need to go search on Mars.

O'BRIEN: Ah, Mars. A good place to start our trip off the planet.

(COMMERCIAL BREAK)

O'BRIEN: Mars is a place of contradictions. Alien, yet familiar. So close it seems reachable, yet far enough to protect its secrets.

For as long as we have looked at the night sky, we have wondered about that reddish star. What mysteries might it hold? And whether one day we might pay a visit.

A lot of people we talk to trace modern-day interest in Mars to a man of great wealth, keen intellect and a vivid imagination.

ROBINSON: Right from the start with Percival Lowell back in the 1890s, he found these supposed canals that he saw through his telescope and he basically went nuts, and invented this entire dying culture that had built the canals to get the water down to the equator, because the planet was drying out.

And that was all science fiction. But because he was a respected scientist, people took him seriously, and it spawned this giant surge of interest.

O'BRIEN: Robinson is among those who believe Percival Lowell, though misguided, sparked a century's worth of interest in Mars and space exploration from pulp fiction, comic books, movies ...

UNIDENTIFIED MALE: Three, two, one ...

O'BRIEN: ... to now - the real thing.

UNIDENTIFIED MALE: ... and lift off.

O'BRIEN: Meet the real thing, 21st century.

Steve Squyres is the top scientist for NASA's Mars Rover expeditions, which rolled out the Intrepid robots, Spirit and Opportunity, on the Martian surface in January 2004.

SQUYRES: Here we go. Keep going. Keep going. Keep going.

This mission has been the adventure of a lifetime in a very literal sense of that phrase. That's not hyperbole. It has been the adventure of our lifetimes.

And it has been satisfying beyond words to have found what we've found and to have been able to do what we've done and be able to share it with people.

All right. Great stuff, man. Thanks.

UNIDENTIFIED MALE: All right.

O'BRIEN: That's more than just lip service for this Cornell astronomer and protege of the late, great Carl Sagan.

SQUYRES: So, these two spots to the north and the south are the ones that we've been looking at as ...

O'BRIEN: The red planet for him is a means to an end, a great place to answer some questions that have burned inside him all his life.

SQUYRES: How common is life throughout the universe? And how does life first arise?

O'BRIEN: Do you remember the first time you asked that question of yourself?

SQUYRES: I can't remember a time when I didn't. It's from day one.

Yes, I mean, and I think that just speaks to how normal and natural it is for anybody. You could ask that question of anybody. I think you'd get almost the same answer.

A six-year-old kid. Go out and look at the sky at night. Look at the stars. You know? What's out there? Didn't you wonder?

O'BRIEN: Sure.

SQUYRES: We all have.

O'BRIEN: Mars may be just the place to find the Holy Grail.

SQUYRES: If you can go to just another planet in this solar system and find that even just in this one solar system, life has independently arisen twice, then it requires no great leap of faith or anything else to believe that it may, in fact, be common, when you consider the multitude of worlds that there are out there.

What you'd like to do is start off with a blank sheet of paper.

O'BRIEN: Squyres and his team weren't even looking for life, just some signs that Mars could have supported life billions of years ago. And they found it. Evidence of an ancient shallow sea.

SQUYRES: What we have shown is that we have found evidence that there was liquid water there. Liquid water, we believe, is a necessary condition for life, but we don't know that it's sufficient.

OK. It may not be - you may need more.

O'BRIEN: This is a very big deal.

MATT GOLOMBEK, MARS ROVER SCIENTIST: Yes, I mean, for the first time we can say with certainty that we had a habitable environment on another planet. And that's never been able to say with certainty before.

So, how's that for discovery? In three months on Mars.

O'BRIEN: But not everybody is so willing to believe in the possibility that there was life on Mars.

RALPH HARVEY, GEOLOGIST, CASE WESTERN RESERVE UNIVERSITY: For a while, I became the poster child for a dead Mars.

O'BRIEN: Since 1987, Ralph Harvey has been collecting Mars meteorites, which landed in Antarctica.

HARVEY: When we argue about signs of possible life on Mars, it's always the most subtle thing you can imagine, something at the very edge of measurability.

And life did not proceed that way on Earth. Life is in your face. Life is something we have to scrape off the rocks to get to the story of the rocks.

And I don't see that on Mars. I don't have that sense about Mars.

So, life on Mars is going to have to get in my face for me to believe it.

O'BRIEN: But what if life on Mars is hiding deep beneath the surface? Say, in an underground aquifer.

SQUYRES: Then, it's entirely possible that there is a habitable - not necessarily inhabited, OK - but a habitable niche on Mars today. Life is very tenacious stuff.

And if life ever developed on Mars, it's not a stretch at all to say that it could still be there. But it's probably not going to be easy to find.

O'BRIEN: Remember Chris McKay in the Mars-like desert of northern Chile? He believes the next step on Mars is to dig deeper.

MCKAY: The more time I spend here, the more I think it's unlikely that there's life on the surface.

But I don't think I'm becoming any less optimistic that there's life underground - deep underground - or frozen in the ice.

O'BRIEN: In fact, McKay wants to be the Steve Squyres of 2011, and designed a robot digging project on Mars. And if there are signs of life there, this story could take yet another twist.

SQUYRES: It's entirely possible that if life evolves on one planet, it could get transported to another.

Mars and Earth have been swapping rocks for billions of years. Now, it's easier to send rocks from Mars to Earth than it is from Earth to Mars, but they go both ways.

And so, you've got to admit the possibility that life could have actually arisen on one planet and been transported to the other. It could go other way. You and I could be Martians.

O'BRIEN: When we come back, we'll up the ante. The long-shot search for an alien civilization.

(END VIDEOTAPE)

(COMMERCIAL BREAK)

MILES O'BRIEN, CNN CORRESPONDENT: It is late at night, or perhaps by now, early in the morning. The coffee is hot, the Champaign on ice. Just in case tonight's the night Jill Tarter and her team make contact with an alien civilization.

TARTER: We actually detected two CW signals on that.

O'BRIEN: For Tarter, all the optimistic talk about finding microscopic life out there somewhere, is just fine, thank you very much.

TARTER: But when people ask the question, are we alone? They are really not talking about is there some pond scum out there that we can find? The are really asking the question, is there some other intelligent creature out there that looks up at it's universe, and wonders as we do.

O'BRIEN: Jill Tarter is all about answering that question. For years she has made pilgrimages here to the world's largest radio telescope in Arecibo, Puerto Rico. Hoping to tune into a signal from an intelligent civilization. WUFO, if you will. This is the search for Extra Terrestrial Intelligence, or SETI (ph).

UNIDENTIFIED MALE: And the white dots are just noise, background noise, right?

TARTER: They are noise. They are just like the snow on your television.

UNIDENTIFIED MALE: OK.

TARTER: And the question is whether embedded in that noise, there is any faint signal.

UNIDENTIFIED MALE: All right. Tell the truth. Do you get bored doing this ever?

TARTER: No. Actually I don't.

If you put a transmitter up there, and there is a radar transmitter in there.

O'BRIEN: At this point, you might be thinking Jill Tarter seems familiar. She is. She's the real-life inspiration for the Jodi Foster character in the movie, "Contact". Remember how they described her?

(BEGIN VIDEO CLIP)

UNIDENTIFIED MALE: Brilliant. Driven. Major pain in the ass.

(END VIDEO CLIP)

O'BRIEN: Typical over-the-top Hollywood, right?

TARTER: No. I mean I am stubborn. I'm obsessional a bit. You have to be to continue on with something like this in spite of the fact that everybody tells you, or many people tell you that it's a waste of time.

O'BRIEN: Speculation about life in the universe has led brilliant people throughout history to come up with ideas to reach out to aliens. Were they wasting their time? Or just using the science available to them? In the early 1800s, Austrian physicist, von Littrow called for canals to be dug in the Sahara and set on fire as a signal to aliens.

French inventor Charles Cros proposed a series of mirrors across Europe in the shape of a constellation, which an observer on Mars could see. Marconi inventor of the wireless believed his radio stations were picking up signals from beyond the Earth. Nonetheless...

DRAKE: Until very recently, SETI was considered a somewhat suspicious, dubious scientific enterprise.

The experiment was to put a transmitter on the radio telescope.

O'BRIEN: Frank Drake is the "mack daddy" of the modern Search for Extraterrestrial Intelligence.

DRAKE: Those of us who were in it knew that it was perfectly legitimate, and we maintained the normal high standards of scientific research. But the rest of the world wasn't quite sure about that.

O'BRIEN: Drake's first attempt to make the hunt for aliens more like science came in the form an equation that bares his name. It factors in estimates, ballpark guesses, and simple shots in the dark, on the rate of star formation, the number of stars with planets, the number with a habitable zone. The fraction with life. The fraction of them with intelligence life. The fraction of them that might communicate. And the longevity of a civilization.

Drake determined there should be somewhere between 1,000 and 1 billion civilizations in the universe. Talk about a margin for error. Drakes equation clearly defines the question more than the answer. But even the low number was enough to get him excited.

So in 1960 Drake started listening for possible alien radio signals at a radio telescope in West Virginia. On the very first night, he thought he heard a transmission from another world. It turned out to be just background noise. The first of more than four decades of late night false alarms.

Matter of fact, on the night I visited Jill, they got a signal. Things got quiet, and we got tingly. Was it possible we were there for the scoop of the epic?

TARTER: We had a signal that we saw. We verified it was a signal. We moved off. We didn't see it. And then we came back. We moved back onto the star. Unfortunately, the signal had gone away by that time. So it was quite likely a satellite which was now beyond reach.

O'BRIEN: Since Frank Drake aimed at that first star in 1960, he and various SETI searchers have pointed telescopes at about 10,000 others. Not bad, until you consider there are 200 billion possibilities.

O'BRIEN (on-camera): And you though Hollywood had stars. Matter of fact, if the SETI search were a stroll down the Hollywood Walk of Fame, that's about two miles collectively. All the SETI searchers to date would have traveled one-sixth thousandth of an inch.

O'BRIEN (voice-over): And there is no way to be certain they aren't missing an alien radio beacon. Impressive as the world's largest radio telescope may be.

O'BRIEN (on-camera): That dish is 20 acres. The biggest in the world. Now how does it work? You might ask. Well think about being in a crowded room and trying to understand somebody, a lot of noise. A lot of times you do this. You'll cup your hands behind you ears, and it helps hear. Well that is a 20-acre version of that.

Essentially it is taking in all of the noise that is coming in from the cosmos (ph), and then focusing it on that globe there. It gets bounced around a few times. Then sent back into that control room.

O'BRIEN (voice-over): But you still have to know what frequency an alien civilization might use. There are literally millions of possibilities. SETI searchers long ago decided to tune their receivers to a part of the radio spectrum where there is not a lot of interference. But maybe WUFO is on another bandwidth entirely. Or using some other means of communication that we can't even conceive of. Or maybe they cannot send a beacon at all.

O'BRIEN (on-camera): The SETI search is kind of like the hunt for the perfect seashell. Now sure, there may be some great shells out there underwater. But it's a whole lot harder to get them out there, isn't it? So just as you and I search for seashells at our feet, SETI is looking for radio frequencies that are most easily detected.

TARTER: We would love to get out of our skins as humans, and think totally rationally outside the box or the body. And be able to say well, in the abstract, this is what we should look for. And we try and do that. But in fact, we can't concede what we can't concede. We are human. And we are limited by what we understand at the moment.

We can reserve the right to get smarter as time goes on.

DRAKE: When your resources are limited, you have to make a decision on what to search for, and what you search for is what you know exists. Not what might exist. And so sure, we would really like to look for all these other things. But we don't have the means to do it.

O'BRIEN: (voice-over): At one time, the SETI Institute received funding from NASA. But in the mid-90s, congress pulled the plug. And it now relies on private donations. Big universe, long odds, small budget.

DAVIES: It's a glorious but almost certainly hopeless quest. It is something that we must do. We should do. It's worth spending the money. But it is one hell of a long shot. And I will be astonished if it succeeds. But, the real value of SETI in my opinion is not how are we going to pick up a signal? That will be one hell of a bonus. It is -- because it forces us to think very deeply about what is life? What is intelligence? What is our place in the universe?

DRAKE: No doubt, we are the riverboat of gamblers of science. But we are making the experiment that is a real long shot. But it's one of these things, like a long shot in a horserace. Your chances of winning are very small. But if you win, you win really big.

O'BRIEN: It's a gamble all right. When we come back, what are the odds?

DAVIES: I have no doubt that there are many, many million, and certainly billions, in fact, Earth-like planets that have just the right conditions for life.

(END VIDEOTAPE)

(COMMERCIAL BREAK)

(BEGIN VIDEOTAPE)

O'BRIEN: Next time you are savoring a sunset on the water somewhere, consider this. The star that warms all our days here on Earth is wobbling. And that's not the tequila talking. It's Sir Isaac Newton. DAVIES: There's a major tug-of-war going on. Planets tugging on stars. Stars tugging on the planets. And frankly, the planets tug on each other, which leads to some very interesting dances among the planets.

GEOFF MARCY, U.C. BERKELEY: The mass comes from the amount of wobble.

O'BRIEN: Astronomer Geoff Marcy was among the first to use the dance of the planets top waltz his way into a cosmological blockbuster. Marcy is a successful planet hunter. So far, he and others like him have bagged more than 120 planets outside our solar system. But he has never actually seen his quarry.

These extra solar planets are drowned out by the light of the star they orbit. So Marcy watches for wobbles.

MARCY: You watch the star. And if the star is stationary, no planets. But if the star moves and wobbles, there is probably a planet. And here is the key. The star will wobble toward you, and then away from you, and then toward you, and then away from you. Over and over again. Only something going around and around would cause the star to wobble over and over again along the same racetrack.

O'BRIEN: So far, Marcy's planetary trophies have been giants made of gas, like Jupiter or Saturn, unlikely abodes for life. But Marcy is undaunted.

MARCY: I have no doubt that there are many, many millions and certainly billions in fact. Earth-like planets that have just the right conditions for life.

O'BRIEN: Billion of planets just like ours? Isn't it likely at least one of those would be home to intelligent life?

MARCY: I think advanced intelligent technological life is rare. I think you have to go tens or hundreds of light-years. Maybe thousands of light-years to find the next advanced civilization. And the main reason for this, is an old argument frankly, which is if there were advanced civilizations close, a few light-years away, we'd know about them. They would have signaled us. We would signal them.

O'BRIEN: Where are they? It is the simple provocative paradox famously posed by the legendary nuclear physicist and Enrico Fermi in 1950. His point, if the universe is filled with intelligent life, why haven't we seen it? Well, perhaps they are too far away. Or they don't exist at all? Or how about this?

TARTER: They could be here. I mean, they really could. We've not seen any evidence that they are, but as we're fond of saying in SETI, absence of evidence is not evidence of absence. And until we better explore our own neighborhood, we shouldn't be making very stern and stringent remarks about they are not here.

DAVIES: For me, the hardest step in this whole life business is getting going in the first place. It's that first big leap from non- life to life. It seems such an enormous leap when you look at the simplest living thing on Earth. It is so immensely complex.

GOLOMBEK: The way our solar system formed, and the way the Earth got to be that way, may be an incredible fortuitous series of events for the last five billion years.

MCKAY: Then we look at intelligence, and it just appears out of the blue. It appears to be associated with random things like meteor impacts at just the right time. And climate change, and wandering continents. And population shifting. And you think, you know, but for a tiny grain of sand, it may never have developed.

It doesn't seem like it is an easy or an automatic or geologically controlled thing. It seems like it is sort of a wild card.

O'BRIEN: And maybe that is the answer to Fermi's paradox. We are incredibly fortunate. The winners of a cosmic game of chance that would make Lotto seem like a sure bet.

Planet hunter Geoff Marcy doesn't mind those odds a bit.

MARCY: And I can't wait for the day when we open up the newspaper in the morning and see a picture of that nearby star, and the little blue water-laden planet. And you will know that there is another abode like Earth. Where there may be intelligent species thinking about us.

O'BRIEN: When we return, what if there really is somebody out there?

UNIDENTIFIED MALE: I think it will change everything.

DAVIES: It's going to mean back to the drawing board, as far as religion is concerned.

(END VIDEOTAPE)

(COMMERCIAL BREAK)

(BEGIN VIDEOTAPE)

O'BRIEN (on-camera): Unless you have circles in your crops, mutilated cattle, or you were forced to take a ride in a flying saucer, you'd probably agree with me there is no proof of life anywhere outside our planet. But don't tell that to my fertile imagination, as it would be crestfallen. I suspect you might feel the same way.

ROBINSON: We live in a world that seems so fraught, so screwed up, so much in trouble, that it is somehow comforting to think about elsewhere in any way that you can. Usually in one fantasy form or another.

O'BRIEN (voice-over): Let's start with the most likely near-term scenario. Scientists find a fossil on Mars. But let's assume that life found on Mars is no different than what we find here. Just a red planet branch, (UNINTELLIGIBLE) of life that hitch hike two or fro on meteors.

DAVIES: That's biologically very significant. But it is philosophically absolutely no significance at all. It is no different than finding that life extents to Antarctica, or deep into the Earth's crust. Or up into the upper atmosphere. These things are all scientifically interesting. But they don't tell us any more about who we are, and whether we are alone in the universe.

The key thing is to find a second sample of life that represents a second Genesis. That is, life starting from scratch. (UNINTELLIGIBLE).

O'BRIEN: Now, let's ratchet up the what-if machine. Let's assume a space probe lands on Jupiter's moon Europa in a few years, melts it's way through the ice, and sees some things looking back. Because Europa and Earth are not swapping rocks, these critters would be completely distinct, a truly alien family of life, a second Genesis.

CHYBA: That would be extremely exciting because it would tell us that there are many places, in presumably many different ways that life can begin. That would hint that life could be extremely common in the galaxy.

O'BRIEN: And from that discovery, a cascade of revelation.

BRO. GUY CONSOLMAGNO, VATICAN ASTRONOMER: Imagine you were interested in trees. And you only had one tree in the universe to look at. You might think that all trees have leaves. You wouldn't know about trees that had needles. You might think that all trees give you apples. You wouldn't know about trees that gave you walnuts. Until we have more than one example of life, we are never going to know what it essential for life, and what happens to be peculiar to this one kind of life we see here.

PETER STEEVES: I mean, it will change everything because it will pull us together. It will force us to see what we do have in common here that makes us an us. It is a question of increasing that boundary of communal identity. And this will be a next good important step.

TARTER: Kids would still go to school. I don't think the stock market would collapse. So things wouldn't change overnight. But in the fullness of time, I think that we would understand a bit more about how we fit into the universe. It kind of calibrates humans. Who we are, how we fit in. And how long we might be here.

O'BRIEN: But before we join hands and sing "We are the Worlds", consider how it would rock our world. How it might say, change the world's religions.

DAVIES: If we get something out of the blue like that, an alien message, it is going to mean back to the drawing board as far as religion is concerned.

O'BRIEN: Unless the message is "Merry Christmas".

DAVIES: Yes. They are already Christians. Yes. Well of course that is beyond belief.

CONSOLNAGNO: Sometime in my most science fictional moments, I am a big science fiction fan, I can picture a world 10,000 years in the future when we found a dozen civilizations. And all of them are followers of Jesus except the human race, which is still not quite too sure about this all. You know. That is also possible. We don't know. It is great fun to speculate.

On But clearly we are getting ahead of ourselves with that fiction thing again. The fact is there are no facts. We know life is here. We know it is hardy. And we are constantly looking and listening in new ways for proof we are not alone. The facts may catch up with our imaginations very soon.

DAVIES: There is a very real possibility that in my life time, this issue about whether there are or was life there is going to be settled. And so that is an incredibly exciting thing. Because speculation about life beyond earth has been going on for literally thousands of years. And it could be that we are the generation that will actually know the answer.

(END VIDEOTAPE)

O'BRIEN: So what is next? Man mission to Mars perhaps? Most scientists we spoke to wouldn't hazard a guess as to when that might actually happen, or what it might cost. But Paul Davies did. According to him, we could launch a one-way mission to Mars in about 10 years, for about $20 billion. But that is one-way. No return.

Believe it or not there are some pioneers out there who would jump at the chance. Something to think about as we say good-bye. As always, there's more on this, and all of our documentaries on our web site, cnn.com/presents. I'm Miles O'Brien. Thanks for joining us.

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