Leon Lederman Interview (page: 3 / 8) Nobel Prize in Physics	Print Interview

How would you tell someone who knows nothing about your field, what turns you on about it?

Leon Lederman: First of all, let me say that, beauty's in the eye of the beholder. People are turned on by many things in science, or in humanities, or any serious study. As an early graduate student, when it's the time to choose your field of research, you make an important decision. I was committed to physics, but physics has many sub-fields.

Get the Flash Player to see this video. Leon Lederman: I had spent three years in the army, and the first year in graduate school's a tough one, because I had forgotten how to study, and I wasn't doing that well, and the classes were very crowded. The professors were just getting back from their own war work, and didn't have much time for counseling. And so I was sort of at loose ends, and depressed, and my course work was poor, and I went around looking for my old college friends -- who were either in graduate school or already had graduated -- to get support, and they supported me. I remember trying to -- several of them were clustered up at MIT, and they said "Why don't you transfer here, and we'll help you?" So I tried to, but my early grades were so bad I couldn't get into MIT. People at MIT are a little embarrassed about that now.

[ Key to Success ] Perseverance

Then I had to make a decision. Which sub-field to go into? There was nuclear physics. There was what's called physics of materials. There was atomic physics, where you studied atoms. The guy who invented the laser was one of the professors at Columbia, and he was working on fields that had to do with that kind of research, which was exciting. There were so many fields it was like being a kid with his nose pressed against the glass of a candy store, looking at all these candies and saying "What's fun?"

Get the Flash Player to see this video. Leon Lederman: One of the fields was a brand new field which had to do with what you would call an atom smasher, and we'd call a particle accelerator. Columbia University was building a large atom smasher off-campus. But, they were building one which when it was in operation back in 1951, was the largest atom smasher in the world for a short time before somebody else built a bigger one. That field was brand new to Columbia. I was intrigued by that, that I'd be almost as up on the field as the professors who had determined to bring that subject to Columbia but were not experts. That was exciting, because it was a new field. It was a totally new field. It had to do with "what's inside." That's the title of it, "What's Inside." We know that if you take a small piece of chalk or any material and you start cutting it, you cut it into smaller and smaller pieces. If you keep cutting it and pretend that you can keep on doing this, eventually you get down to something which we call a molecule. This might be a molecule of some kind. Then we notice that a molecule is made of atoms, which are even smaller. It's kind of a zooming down. Now you're getting into sizes which the human eye can't see. So you go molecule, you go atom, then inside the atom it turns out that the atom itself is made of a nuclei and electrons around it. That part of the field was well-known. We were continuing that field into the nucleus of the atoms. So, you go zooming down, down into even smaller dimensions, like, if this whole room were an atom, then in the middle of the room there's a grain of dandruff. That's the nucleus. You zoom down on the grain of dandruff, you look at it, and you say, "What's inside?" So, it was the added business of search, of trying to understand the basic building blocks, which to me was the turn-on.

You eventually came down to what you yourself have described as "just barely a fact."

Leon Lederman: That's a particle that I have a great deal of affection for. That's an answer to a question that goes "How come you won the Nobel Prize, and what did you win it for?"

Here we go. What is a neutrino, and why did you win the Nobel prize for discovering one?

Leon Lederman: We don't have a blackboard here, and without a blackboard, a professor like me feels totally insecure. I don't even have a little piece of blanket I can hold against my cheek under these circumstances. But let's go anyway. What the heck.

Get the Flash Player to see this video. Leon Lederman: We learned about what's inside. Inside the nucleus there are protons and neutrons, two of the constituents. Don't panic, they're all right. They don't hurt. We looked inside those, too. But, in the course of this kind of study, we found, for example, something called radio-activity. You've heard about radioactivity. It turns out that radioactivity always involves a mysterious particle which escapes. When you see something radio-active in our research, it's a kind of explosion, a particle explodes and gives rise to other particles. You study these particles that come off from the explosion, and you reproduce what the event was. Now, there are certain guiding principles in all of this that help us. One of them is "the conservation of energy." It says that the total amount of energy should stay the same in any process. Like, if you put 14 people in a room, they can interact with each other, they can yell at each other, scream at each other, but hopefully, at the end of the day, there are still 14 people. The number of people is conserved in that sense. In the same way energy, if you keep track it, it should balance. And in these reactions, it didn't balance. Something was missing. For awhile, physicists jumped out of second story windows, they got very upset because they really loved conservation of energy, and it looked as if they were going to lose it as a principle, until somebody said, "Maybe there's a particle escaping. Let's assume it is, and since it doesn't show up in our apparatus, it must be electrically neutral, and because it doesn't show up for other reasons, it must be very small. So they used the diminutive ending, "ino," which is Italian. It's a little, little guy, so a neutral, little particle.

Get the Flash Player to see this video. Leon Lederman: It became a very mysterious particle head. The neutrino had no electric charge, it turned out that its mass was almost zero, if not zero. Even today in 1992, we think the neutrino may have zero mass, or if it has any mass, it's a teensy, weensy amount of mass, not much. Lots of particles are detected because they make collisions. A proton hitting into some piece of lead three inches thick will never get through the lead because it will hit something, some other nucleus and be stopped. Neutrinos didn't have this ability to collide, so it didn't seem to have any forces. So here it is, almost not even a thing. It had no charge, no mass, no strong force, and yet, we knew it was robbing energy from reactions and it was very important. As we got to know more and more about it, it became crucial.

Get the Flash Player to see this video. Leon Lederman: For example, why does the sun keep shining? The sun has been around for four billion years, and there was no mechanism which would keep it shining, unless neutrinos were involved. So whereas it became harder and harder to come to grips with the reality of neutrinos, conceptually, it kept taking an increasing important role in our understanding of important processes like the sun shining, like radioactivity. In the late 1950s, the neutrino was becoming an increasingly irritating concept, which we had to come to grips with. It was confusing us. There was data that was contradictory, it didn't make any sense. There were reactions that should have taken place, but didn't take place. That's when a group of us at Columbia came on the idea that we should actually see, try to detect neutrino collisions.

Get the Flash Player to see this video. Leon Lederman: Now that's a hard job because if you try to calculate, using the best information we had, how much material, let's say steel, how thick of steel wool do you need if a given neutrino coming into a steel wall should have a very good chance of never getting out? How long does that steel wool have to be? Ten feet, 100 feet, a mile, ten miles? Turned out the answer is 100 million miles. So, we went to the authorities and we said "We need one hundred million miles of steel. We want to catch neutrinos." No, of course, we didn't do that! We thought more clearly, and it turns out, if you have two neutrinos, you only need half that thickness. And if you have a billion neutrinos, or a billion, billion neutrinos, then you might need a kind of detector that you could think of building. It would still have to be very massive and detailed. It turned out that we hit on a way of doing this with a detector which, for that time, the 1960s, was very massive. It was ten tons of material, and it's not just ten stupid tons of steel sitting there. You had to look inside to see the collision. So it had to be, in some sense, semi-transparent. Anyway, the experiment was wildly successful. We discovered, in fact, that they weren't one neutrino, but there were two kinds of neutrinos, and that's what was giving us all the confusion. The number of neutrinos was doubled. And that, these two types of neutrinos really set us on a road towards what we now call the "standard model," a compact summary of all of this data that I've been telling you about. The data - lots of data that came out in the laboratories all over the world since 1960. So it became known as the "two neutrino experiment." Of course, when you tell somebody who's not a scientist about two neutrinos, they say it sounds like an Italian dance team. "Ladies and gentlemen, we now have the Two Neutrinos!"

That's the story, and eventually it came to the attention of the King of Sweden, and we were invited to a great party in Stockholm.

Leon Lederman Interview, Page: 1   2   3   4   5   6   7   8