To someone looking at high-energy physics from the outside, its goal seems to be to find the ultimate constituents of matter. It seems a quest we can trace back to the Greeks’ atom, the “indivisible” particle. But with the big accelerators, you get fragments that are more massive than the particles you started with and maybe quarks that can never be separated. What does that do to the quest?
I don’t think that ever was the quest. Physicists are trying to find out how nature behaves; they may talk carelessly about some “ultimate particle” because that’s the way nature looks at a given moment, but…Suppose people are exploring a new continent, okay? They see water coming along the ground — they’ve seen that before — and they call it river. So they say they’re exploring to find the headwaters, they go upriver, and sure enough, there they are, it’s all going very well. But lo and behold, when they get up far enough they find the whole system’s different: There’s a great big lake, or springs, or the rivers run in a circle. You might say, “Aha! They’ve failed!” but not at all! The real reason they were doing it was to explore the land. If it turned out not to be headwaters, they might be slightly embarrassed at their carelessness in explaining themselves, but no more than that. As long as it looks like the way things are built is wheels within wheels, then you’re looking for the innermost wheel — but it might not be that way, in which case you’re looking for whatever the hell it is that you find!
But surely you must have some guess about what you’ll find; there are bound to be ridges and valleys and so on?
Yeah. But what if when you get there it’s all clouds? You can expect certain things, you can work out theorems about the topology of watersheds, but what if you find a kind of mist, maybe, with things coagulating out of it, with no way to distinguish the land from the air? The whole idea you started with is gone! That’s the kind of exciting thing that happens from time to time. One is presumptuous if one says, “We’re going to find the ultimate particle or the unified field laws” or the anything. If it turns out surprising, the scientist is even more delighted. You think he’s going to say, “Oh, it’s not like I expected, there’s no ultimate particle, I don’t want to explore it”? No, he’s going to say, “What the hell is it, then?”
You’d rather see that happen?
Rather doesn’t make any difference: I get what I get. You can’t say it’s always going to be surprising, either...
I’ve learned how to live without knowing. I don’t have to be sure I’m succeeding, and as I said before about science, I think my life is fuller because I realize that I don’t know what I’m doing. I’m delighted with the width of the world!
I don’t believe in the idea that there are a few peculiar people capable of understanding math and the rest of the world is normal. Math is a human discovery, and it’s no more complicated than humans can understand. I had a calculus book once that said, “What one fool can do, another fool can.” What we’ve been able to work out about nature may look abstract and threatening to someone who hasn’t studied it, but it was fools who did it.
It isn’t the philosophy that gets me, it’s the pomposity. If they’d just laugh at themselves! If they’d just say, “I think it’s like this, but Von Leipzig thought it was like that, and he had a good shot at it too.” If they’d explain that this is their best guess . . . But so few of them do; instead, they seize on the possibility that there may not be any ultimate fundamental particle and say that you should stop work and ponder with great profundity. “You haven’t thought deeply enough; first let me define the world for you.” Well, I’m going to investigate it without defining it!
And then there's this, which followed immediately:
How do you know which problem is the right size to attack?
When I was in high school, I had this notion that you could take the importance of the problem and multiply by your chance of solving it. You know how a technically minded kid is; he likes the idea of optimizing everything. Anyway, if you can get the right combination of those factors, you don’t spend your life getting nowhere with a profound problem or solving lots of small problems that others could do just as well.
I suppose in a way I've done a bit of "getting nowhere with a profound problem", though I'm managed to avoid messing around with small problems. That is to say, figuring our the mechanisms behind "Kubla Khan" is a profound problem, one I set for myself back in the early 1970s, and one that is, as far as I can tell, still substantially beyond reach. Yet, once it became clear that it would take awhile, I busied myself with various other things, while every once in awhile taking a look at "Kubla Khan." And last year I more or less declared KK solved. More or less. Let's say I've narrowed the search space considerably. I've reached a decision about the kind of problem it is and have decided on at least some of the terms of the answer. (Of course, I could be wrong....)
Earlier, you didn’t ask whether I thought that there’s a fundamental particle, or whether it’s all mist; I would have told you that I haven’t the slightest idea. Now, in order to work hard on something, you have to get yourself believing that the answer’s over there, so you’ll dig hard there, right? So you temporarily prejudice or predispose yourself — but all the time, in the back of your mind, you’re laughing. Forget what you hear about science without prejudice. Here, in an interview, talking about the big bang, I have no prejudices — but when I’m working, I have a lot of them.
Prejudices in favor of…what? Symmetry, simplicity…?
In favor of my mood of the day. One day I’ll be convinced there’s a certain type of symmetry that everybody believes in, the next day I’ll try to figure out the consequences if it’s not, and everybody’s crazy but me. But the thing that’s unusual about good scientists is that while they’re doing whatever they’re doing, they’re not so sure of themselves as others usually are. They can live with steady doubt, think “maybe it’s so” and act on that, all the time knowing it’s only “maybe.” Many people find that difficult; they think it means detachment or coldness. It’s not coldness! It’s a much deeper and warmer understanding, and it means you can be digging somewhere where you’re temporarily convinced you’ll find the answer, and somebody comes up and says, “Have you seen what they’re coming up with over there?” and you look up and say “Jeez! I’m in the wrong place!” It happens all the time.
One more question from your lectures: You say there that “the next great era of awakening of human intellect may well produce a method of understanding the qualitative content of equations.” What do you mean by that?
In that passage I was talking about the Schrödinger equation. Now, you can get from that equation to atoms bonding in molecules, chemical valences — but when you look at the equation, you can see nothing of the wealth of phenomena that the chemists know about. Or the idea that quarks are permanently bound so you can’t get a free quark — maybe you can and maybe you can’t, but the point is that when you look at the equations that supposedly describe quark behavior, you can’t see why it should be so. Look at the equations for the atomic and molecular forces in water, and you can’t see the way water behaves; you can’t see turbulence.