Nobel Physicist Steven Chu 6/6 | Asian American Innovators

Steven Chu
Nobel Physicist

PAGE 6 OF 6

Steven Chu
Laser Super-Cooler

     Then two-thirds of my effort is completely different. It grew out of the ability to hold onto atoms and the ability to hold onto micron-sized particles which enabled us to hold onto individual molecules with light, in this case, molecules of DNA. But then it led me into a series of polymer experiments over the last dozen years. Then it led me into saying, Okay we'd start discovering all sorts of new things in polymer physics because we can study the behavior of a molecule.
     Allowing us to optically tweeze single molecules of DNA led to the study of polymer physics at the single-molecule level which led us to then go into bio-physics again at the single-molecule level. That turned out to be on a parallel track with others in the sense that we first started this around 1990. In 1988 we got the patent for optical tweezing of dna. Also around 1988, '89, '90 other people were also looking for ways of looking at the fluorescence of single molecules. Over the last half dozen years this has become extremely fashionable, not only fashionable, it's become a very powerful tool for making new discoveries in biology.

GS: Allowing molecules to be held in place allows them to be studied more accurately, is that the advance?
SC: Well, we can simply see things we couldn't see before. The theories in polymer physics depended on what the confirmation the polymer was in. You couldn't see individual molecules so you would then derive consequences. Because polymers were moving in this way or doing that thing, they would exhibit themselves in the flow properties of a fluid. If you put polymers in a fluid, the flow properties would be different -- all sorts of things like that. Injection mold plastics, we want to understand how that works. We want to understand other polymers like corn starch. If you stir it there is this sheer thinning, it starts getting thin. Many properties of polymers, the fundamental aspect of them, start with what shape and how they're moving in the fluid.
     We couldn't see that. Now we can see it directly. That means there's certain models and conjectures about what they were doing that you can test directly. What we found is that the real behavior of polymers is not just the average behavior. The average height of a people in the room would be one thing. But you can have a room full of basketball stars and people who are very short and the average height can be the same, but it's entirely different. Once you're looking at billions of molecules all at the same time, you find only an average behavior, and there was a presumption that the average behavior was the same, especially at the molecular level -- that all the molecules did that. They don't. And that was a big surprise to us.

GS: What are the implications of this molecular individualism.
SC: It means that you'd better start thinking there could be different pathways, that identical molecules pasted under identical conditions could act differently. That many of the chemical and biological processes that we took for granted as being a very discrete pathway could have many paths. This is now out there and people really know it's happening. When we found it in polymers, others began to see it in other things. It just means that the dynamic behavior of the world is much richer than we had thought. In hindsight as in all things you say of course that must be true, but it never hits home until you actually say, I found a room full of pygmies and giants. In the abstract is that a possibility? The impact is that we simply can measure things we couldn't measure before but we have a deeper intuitive appreciation of the microscopic world.

GS: And this optical tweezing is based on the same technique of atom cooling?
SC: The optical tweezing has been very important in measuring forces and displacements of molecular motors, and I helped get that thing started. But what I'm doing now is fluorescence techniques to measure single molecules, something I didn't invent. But it's become a very powerful tool and also combining the tweezers or the atomic force microscopes that measure forces and displacements with fluorescence techniques. That's the part I'm most excited about because it feels like the early days of trapping. It's something very very new. Nowadays, there are hundreds of people in this field [of cooling and trapping], or thousands, and it's becoming mature. Now there is a lot of serious engineering you can do. One is still inventing new things. I'm not saying that the discovery period is over by a long shot. It's not, but the other stuff, the single molecule work in biology is in the very beginnings of discovery phase where everything we've looked at, every problem we've looked at there's been a little surprise. That's what scientists want more than anything else. They don't want things to come out the way they expect.

GS: Do you see this as an enabling technology for nanotechnology?
SC: Definitely.

GS: Few people have the slightest idea what a prominent physicist does day to day. Can you paint us a picture of what a physicist does day to day?
SC: I'll paint two pictures. One is what a practicing scientist does, and that's where, yes, you get up, you brush your teeth, you eat, you do things like that. But what you're doing is thinking about the problem at hand. And you're thinking about it not only day to day but hour to hour. It becomes so much a part of you that it's in your subconsciousness, which means that even if you don't intend to think about it, you are in the background. So you could be looking at an airplane or taking a shower or hiking or eating and all of a sudden you get this little flash. It's most apparent when you're bored or you're listening to a boring talk or if you're in an airplane trapped or you're sitting on the toilet or in the shower. Or in the early morning when you're about to wake up, you're half asleep, half conscious, and then your mind is mulling over these issues and problems.
     It's not really all-consuming because it's somewhere in the background and you know it's in the background because even when you're not forcing yourself to think about it you have thought about it because then there's a little lightbulb that blinks. It's under those conditions that creation actually occurs for the most part. There are other times when, yes, you're saying now is my time for thinking and you're doing this as well. But it becomes so much a part of your thinking that it occurs as part of your background as well.

GS: Physically what are you doing?
SC: Most of my days are frittered away by all sorts of things. Take yeserday. I got up early in the morning, I ate breakfast, I prepared my lecture, I had prepared most of it Sunday night.

GS: Which class?
SC: I'm teaching quantum mechanics to graduate students.

GS: Is that a weekly lecture?
SC: Three hours a week. Two lectures, an hour and a half each time. I must have spent four or five hours on Sunday and I spent another four hours on Monday.

GS: Is that at home that you do this preparatioin?
SC: Yes, sometimes at work, sometimes at home. Then I went and gave the lecture. That was from 11 to 12:30. I then microwaved a quick lunch. That took 10 minutes. I did my email. There was then a visitor from CalTech, a theoretical physicst who was giving a local seminar talk in our atomic physics group meeting slash seminar. So I talked with this visitor for an hour. We talked physics what he was doing. It's a very mathematical physics but it could be relevant. He's a young brilliant theorist type who wanted from me what could be the potential applications of the theory he was developing. We then heard a formal presentation of that. I talked with some students for a couple of hours. And then from about six to eight o'clock or eight-thirty I worked on a proposal, then I went home and ate dinner. I usually go home about eight.

GS: What's the favorite part of your day?
SC: Well, when I'm preparing a lecture, I'm trying to understand more deeply or better or more clearly or more precisely what's going on. Sometimes that's enjoyable. Certainly when I'm talking to the person about new ideas, then rehashing his talk with a colleague of mine, you always want to say, what was the new thing, what's new, what's old? And so we said okay, essentially this part is the new thing and we don't know why that is. That's a mystery, even the speaker doesn't know why that was. And that's part of his research and he discovered something and he's trying to figure why it is. So I think that's enjoyable.
     I spent forty-five minutes talking to a person who wants to work in my group who hasn't done that well. He's done a trial period and he's gonna have another trial period but I had a heart to heart with him, saying what did he want to do. He wants to be a professor. Okay, if you want to be a professor you have to understand that you have to have a level of commitment that's different than an ordinary job. I still work seventy hours a week.

GS: So you work weekends too?
SC: Yeah, I work 10-11 hours a day and also weekeneds.

GS: Both days of the weekend?
SC: It used to be one day, now it's one and a half which is not good.

GS: When do you exercise?
SC: Normally, I would have exercised today and I try to exericse every day.

GS: Doing what?
SC: This interview has gone on a half hour longer than we had planned. So I'm getting off now. Things like this are very time consuming. This is not a once a year kind of thing. It's once a month.

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“It's most apparent when you're bored or you're listening to a boring talk or if you're in an airplane trapped or you're sitting on the toilet or in the shower. ”