James Peebles Interview: Conversations with History; Institute of International Studies, UC Berkeley

A Cosmologist’s Intellectual Journey: Conversations with James E. Peebles, Professor Emeritus of Cosmology, Princeton University; October 12, 2006 by Harry Kreisler

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Theory and Observation

I want to emphasize again something you said it in a lecture -- this synergy between theory and observations. It's an important part of this work that you're doing.

It is so important. This is what science is, in my way of thinking, the synergy. It's been there since the beginning. When we run out of synergy, then science goes in a very different direction, and one that I'm not sure I want to follow.

There was never any guarantee that this synergy would be useful. No one ever guaranteed that we'd be able to make sense of the world around us. It's a striking thing that we've come as far as we have. We've come an amazingly long way. All of modern technology, so much depends on that curiosity research, the synergy of a decade ago, a century ago. Will it continue? We'll find out.

You were talking yesterday in your second lecture about what science is, and you said science is a search for successive approximations, good approximations, to reality; but [there's] a long way to go, [there's] no "absolute truth" in the physical sciences. So, you have to live with uncertainty and frustration, if you're going to live by that ethos.

Oh, yes. There is talk of the Theory of Everything. I think it's poorly chosen words. They don't really mean that. No one in physical science fools themselves into thinking we know absolute truth. Always, always we have to accept that although we have brilliant successes, we also have amazing gaps in our understanding. The gaps are being filled, and it is characteristic of our subject so far that as you fill gaps, you open new ones, new questions arise. I wanted to emphasize that because one misconception about science often is that, "If you can't answer all my questions then you don't know what you're talking about." But that isn't true in science. We can answer some questions very well and we can prove it by the technology to which these answers bring us, but at the same time, there are open issues. Of course, if there weren't those open issues there'd be no more science to do, and we're not in any danger of being in that state.

This relates to a problem that science probably has in its broader environment. Basic science is very important, [but] the people who fund the science, whether it's the government or the foundations, say, "Well, what's this for? Why should we [fund purely theoretical work]?" So, [the application of basic science] is a key element. So, this uncertainty, as one looks for the approximations to move toward truth, is also enveloped in big questions whose relevance might not be clear to people who are not doing the work.

And we must emphasize the excitement, the adventure of exploring new questions and on occasion, finding answers. That excitement, I believe, carries on to excitement in more applied areas of physical science. I've got to hope that an engineer who develops the next generation of cell phones -- they should only make them not work in automobiles! -- will be in part excited by what the engineer sees around herself of advances in other fields, including the most basic.

I would never claim -- maybe I'll be wrong someday -- I'd never claim that my subject is going to be of any practical use. Who cares what's going on in that distant galaxy? Except that you really do care. Isn't it neat to think you can deduce properties of a galaxy way over on the other side of the observable universe? Neat to think that we can understand its nature in broad outline, even though we'll never be able to go over there and poke our finger on a planet in that galaxy and ask who's home? Intellectual excitement, I hope, is an essential part of our society and of its growth.

You're touching on something, because people who don't do physics are really interested in the stars, they're star-gazers. We know the interest in science fiction, and what's beyond what we can see with the naked eye, and so on. And then of course it gets into a moral dimension: who are we, what is man, how were we placed here, and so on. So, any thoughts about how physics can lead to a place where other people are posing questions although they have no interest in the physical sciences?

A remark about physics and astronomy. Many people are fascinated by astronomy. It's astronomy's secret weapon. Surely congressional aids are a little [predisposed] toward astronomy. I am now a naturalized citizen. I was for many years a landed immigrant. I actually had a green card that was green -- that old.

In those days, when arriving from a trip overseas, I would have to explain to customs and immigration what I did for a living. I would sometimes say, "I'm an astronomer." "Oh, isn't that interesting?" Or I might say, "I'm a physicist." "I took physics in school and I hated it!" You notice that there are amateur astronomy clubs. These people are marvelous. They work all day at a job and then at night they do what they love, astronomy. (I'm so embarrassed: I do what I love during the day!) I know of no amateur physics club, amateur particle physics. Wouldn't it be marvelous if there were such a club? But there aren't. So, that's the way people are.

I don't really draw a distinction between astronomy and particle physics, and I don't see any moral aspect to it at all, either, to be blunt. It's all part of the world around us, the small, the big, they're both neat. But I wouldn't give precedent to one over the other.

I wonder if you would compare the awe that you feel as a scientist, as you come to understand these structures of the universe, to the awe that somebody feels who emotionally appreciates what they see by just looking at the stars.

Or looking at a giant redwood.

Yes.

Is the awe any different?

That's the question.

To me, no. There is the awe of realizing that we can make sense of the world around us. Sometimes when I look at our political situation I don't have that awe. But when I look at what can be done in astronomy I am awed, and when I look at what can be done with the subatomic nature of matter I'm awed, too. Both are neat, and so is a tree or a person. I've just been reading a wonderful history of the discovery of DNA. What an awesome set of work, brilliant, and I'm awed by the structure of DNA.

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