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Cosmic Imperative for Life?
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Origin & Evolution of Life
Posted:   08/02/02

Summary: Life began on Earth almost as soon as it was possible, almost as soon as the intense early bombardment by asteroids and comets tapered off and a stable environment emerged. Is this evidence for a chemical inevitability for spawning biology?

Interview with Ann Druyan and Steven Soter
Life beyond Earth


Complex organic molecules such as ethylene glycol have been detected in interstellar space. Organic molecules are the building blocks of life. Credit: NRAO
Kathleen Connell: What are your personal feelings about the possibility of the existence of life outside of our Earth?

Steven Soter: The problem is, of course, we have no direct evidence. And [in terms of theory] we're not much better off, because we do not know how life began on Earth. We're almost clueless there. If we knew that, we would have some grounds for knowing how common the process is. But I'm basically a Copernican; I believe that there's nothing special about the Earth's position in the universe. I'm impressed by the ubiquity of the chemistry that makes life. We see complex organic molecules in interstellar clouds. It's everywhere. And I'm impressed by the fact that life began on Earth almost as soon as it was possible, almost as soon as the intense early bombardment by asteroids and comets tapered off and a stable environment emerged. The oldest evidence for life follows very soon after that, which suggests that where it's possible, it will take hold. And then on top of that you've got, it now looks like, something on the order of a trillion planets in our Milky Way galaxy alone, and a hundred billion other galaxies. Those numbers are staggering. My own opinion-and it's, I stress, still only an opinion-is that the universe is full of life, that we're not alone. And, that we may be close to finding out in our own solar system if there's other life; and, on a somewhat longer time scale, whether there's life on the planets of other solar systems.

Kahtleen Connell: In other words, are you saying you believe that life is a cosmic imperative, in a way?

In a universe brimming with stars, it is difficult to imagine that life exists nowhere else. Credit: NASA/STScI/ESA
Steven Soter: Oh, no. I don't think it's an imperative. That's going too strong. But I would be surprised, very surprised, if we found that life is very rare in the universe.

Kathleen Connell: And Ann, what are your feelings about it?

Ann Druyan: Well, not surprisingly, I agree with what Steve is saying. It would be a giant surprise. You look at any image of a star-choked field in the sky, and the notion that life and intelligence only came to be on our one particular planet, when we're talking about hundreds of billions of stars, and then perhaps five to ten times as many planets, is just untenable. The odds just don't sound likely that this is the only place where life has come to be. And then of course if you factor in the ubiquity of organic molecules, the building blocks of life, it makes it even more of a stretch to imagine that life only happened here. It just doesn't make any sense. I think it's very likely that there's life. I second what Steve says. I don't believe that there's any imperative for life. I think it's a natural process of the universe, and therefore probably widespread.

I guess I so desperately want to see us put this planet right. It's so horrifying to me that a fifth of us are starving every night, and that forty thousand children die every single day. This planet seems to be in such sorry shape. And I can't ever think about the rest of the universe without coming back home and thinking what the implications for life here would be if we were to really have some definitive proof of extraterrestrial life. All of science to me, everything that we have learned, is important to the extent that it brings us to our senses. So when I think about it, at least I know enough to know I have no idea what it would be like. But beyond that it's just a kind of a dream. And it's only really meaningful to the extent that it makes us treat each other better. Once we get our act together that way, then I can think of countless ways to be interested in the possibility of life elsewhere.


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