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[PROFILE] Steven Chu - Nobel Laureate in Physics

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  • madchinaman
    Steven Chu – Autobiography http://nobelprize.org/physics/laureates/1997/chu-autobio.html My father, Ju Chin Chu, came to the United States in 1943 to
    Message 1 of 1 , Nov 13, 2004
      Steven Chu – Autobiography

      My father, Ju Chin Chu, came to the United States in 1943 to
      continue his education at the Massachusetts Institute of Technology
      in chemical engineering, and two years later, my mother, Ching Chen
      Li, joined him to study economics. A generation earlier, my mother's
      grandfather earned his advanced degrees in civil engineering at
      Cornell while his brother studied physics under Perrin at the
      Sorbonne before they returned to China. However, when my parents
      married in 1945, China was in turmoil and the possibility of
      returning grew increasingly remote, and they decided to begin their
      family in the United States. My brothers and I were born as part of
      a typical nomadic academic career: my older brother was born in 1946
      while my father was finishing at MIT, I was born in St. Louis in
      1948 while my father taught at Washington University, and my younger
      brother completed the family in Queens shortly after my father took
      a position as a professor at the Brooklyn Polytechnic Institute.

      In 1950, we settled in Garden City, New York, a bedroom community
      within commuting distance of Brooklyn Polytechnic. There were only
      two other Chinese families in this town of 25,000, but to our
      parents, the determining factor was the quality of the public school
      system. Education in my family was not merely emphasized, it was our
      raison d'être. Virtually all of our aunts and uncles had Ph.D.'s in
      science or engineering, and it was taken for granted that the next
      generation of Chu's were to follow the family tradition. When the
      dust had settled, my two brothers and four cousins collected three
      MDs, four Ph.D.s and a law degree. I could manage only a single
      advanced degree.

      In this family of accomplished scholars, I was to become the
      academic black sheep. I performed adequately at school, but in
      comparison to my older brother, who set the record for the highest
      cumulative average for our high school, my performance was decidedly
      mediocre. I studied, but not in a particularly efficient manner.
      Occasionally, I would focus on a particular school project and
      become obsessed with, what seemed to my mother, to be trivial
      details instead of apportioning the time I spent on school work in a
      more efficient way.

      I approached the bulk of my schoolwork as a chore rather than an
      intellectual adventure. The tedium was relieved by a few courses
      that seem to be qualitatively different. Geometry was the first
      exciting course I remember. Instead of memorizing facts, we were
      asked to think in clear, logical steps. Beginning from a few
      intuitive postulates, far reaching consequences could be derived,
      and I took immediately to the sport of proving theorems. I also
      fondly remember several of my English courses where the assigned
      reading often led to binges where I read many books by the same

      Despite the importance of education in our family, my life was not
      completely centered around school work or recreational reading. In
      the summer after kindergarten, a friend introduced me to the joys of
      building plastic model airplanes and warships. By the fourth grade,
      I graduated to an erector set and spent many happy hours
      constructing devices of unknown purpose where the main design
      criterion was to maximize the number of moving parts and overall
      size. The living room rug was frequently littered with hundreds of
      metal "girders" and tiny nuts and bolts surrounding half-finished
      structures. An understanding mother allowed me to keep the projects
      going for days on end. As I grew older, my interests expanded to
      playing with chemistry: a friend and I experimented with homemade
      rockets, in part funded by money my parents gave me for lunch at
      school. One summer, we turned our hobby into a business as we tested
      our neighbors' soil for acidity and missing nutrients.

      I also developed an interest in sports, and played in informal games
      at a nearby school yard where the neighborhood children met to play
      touch football, baseball, basketball and occasionally, ice hockey.
      In the eighth grade, I taught myself tennis by reading a book, and
      in the following year, I joined the school team as a "second string"
      substitute, a position I held for the next three years. I also
      taught myself how to pole vault using bamboo poles obtained from the
      local carpet store. I was soon able to clear 8 feet, but was not
      good enough to make the track team.

      In my senior year, I took advanced placement physics and calculus.
      These two courses were taught with the same spirit as my earlier
      geometry course. Instead of a long list of formulas to memorize, we
      were presented with a few basic ideas or a set of very natural
      assumptions. I was also blessed by two talented and dedicated

      My physics teacher, Thomas Miner was particularly gifted. To this
      day, I remember how he introduced the subject of physics. He told us
      we were going to learn how to deal with very simple questions such
      as how a body falls due to the acceleration of gravity. Through a
      combination of conjecture and observations, ideas could be cast into
      a theory that can be tested by experiments. The small set of
      questions that physics could address might seem trivial compared to
      humanistic concerns. Despite the modest goals of physics, knowledge
      gained in this way would become collected wisdom through the
      ultimate arbitrator - experiment.

      In addition to an incredibly clear and precise introduction to the
      subject, Mr. Miner also encouraged ambitious laboratory projects.
      For the better part of my last semester at Garden City High, I
      constructed a physical pendulum and used it to make a "precision"
      measurement of gravity. The years of experience building things
      taught me skills that were directly applicable to the construction
      of the pendulum. Ironically, twenty five years later, I was to
      develop a refined version of this measurement using laser cooled
      atoms in an atomic fountain interferometer.

      I applied to a number of colleges in the fall of my senior year, but
      because of my relatively lackluster A-average in high school, I was
      rejected by the Ivy League schools, but was accepted at Rochester.
      By comparison, my older brother was attending Princeton, two cousins
      were in Harvard and a third was at Bryn Mawr. My younger brother
      seemed to have escaped the family pressure to excel in school by
      going to college without earning a high school diploma and by
      avoiding a career in science. (He nevertheless got a Ph.D. at the
      age of 21 followed by a law degree from Harvard and is now a
      managing partner of a major law firm.) As I prepared to go to
      college, I consoled myself that I would be an anonymous student, out
      of the shadow of my illustrious family.

      The Rochester and Berkeley Years
      At Rochester, I came with the same emotions as many of the entering
      freshman: everything was new, exciting and a bit overwhelming, but
      at least nobody had heard of my brothers and cousins. I enrolled in
      a two-year, introductory physics sequence that used The Feynman
      Lectures in Physics as the textbook. The Lectures were mesmerizing
      and inspirational. Feynman made physics seem so beautiful and his
      love of the subject is shown through each page. Learning to do the
      problem sets was another matter, and it was only years later that I
      began to appreciate what a magician he was at getting answers.

      In my sophomore year, I became increasingly interested in
      mathematics and declared a major in both mathematics and physics. My
      math professors were particularly good, especially relative to the
      physics instructor I had that year. If it were not for the Feynman
      Lectures, I would have almost assuredly left physics. The pull
      towards mathematics was partly social: as a lowly undergraduate
      student, several math professors adopted me and I was invited to
      several faculty parties.

      The obvious compromise between mathematics and physics was to become
      a theoretical physicist. My heroes were Newton, Maxwell, Einstein,
      up to the contemporary giants such as Feynman, Gell-Man, Yang and
      Lee. My courses did not stress the importance of the experimental
      contributions, and I was led to believe that the "smartest" students
      became theorists while the remainder were relegated to experimental
      grunts. Sadly, I had forgotten Mr. Miner's first important lesson in

      Hoping to become a theoretical physicist, I applied to Berkeley,
      Stanford, Stony Brook (Yang was there!) and Princeton. I chose to go
      to Berkeley and entered in the fall of 1970. At that time, the
      number of available jobs in physics was shrinking and prospects were
      especially difficult for budding young theorists. I recall the
      faculty admonishing us about the perils of theoretical physics:
      unless we were going to be as good as Feynman, we would be better
      off in experimental physics. To the best of my knowledge, this
      warning had no effect on either me or my fellow students.

      After I passed the qualifying exam, I was recruited by Eugene
      Commins. I admired his breadth of knowledge and his teaching ability
      but did not yet learn of his uncanny ability to bring out the best
      in all of his students. He was ending a series of beta decay
      experiments and was casting around for a new direction of research.
      He was getting interested in astrophysics at the time and asked me
      to think about proto-star formation of a closely coupled binary
      pair. I had spent the summer between Rochester and Berkeley at the
      National Radio Astronomy Observatory trying to determine the
      deceleration of the universe with high red-shift radio source
      galaxies and was drawn to astrophysics. However, in the next two
      months, I avoided working on the theoretical problem he gave me and
      instead played in the lab.

      One of my "play-experiments" was motivated by my interest in
      classical music. I noticed that one could hear out-of-tune notes
      played in a very fast run by a violinist. A simple estimate
      suggested that the frequency accuracy, times the duration of the
      note,did not satisfy the uncertainty relationship. In order to test
      the frequency sensitivity of the ear, I connected an audio
      oscillator to a linear gate so that a tone burst of varying duration
      could be produced. I then asked my fellow graduate students to match
      the frequency of an arbitrarily chosen tone by adjusting the knob of
      another audio oscillator until the notes sounded the same. Students
      with the best musical ears could identify the center frequency of a
      tone burst that eventually sounded like a "click" with an accuracy
      of .

      By this time it was becoming obvious (even to me) that I would be
      much happier as an experimentalist and I told my advisor. He agreed
      and started me on a beta-decay experiment looking for "second-class
      currents", but after a year of building, we abandoned it to measure
      the Lamb shift in high-Z hydrogen-like ions. In 1974, Claude and
      Marie Bouchiat published their proposal to look for parity non-
      conserving effects in atomic transitions. The unified theory of weak
      and electromagnetic interactions suggested by Weinberg, Salam and
      Glashow postulated a neutral mediator of the weak force in addition
      to the known charged forces. Such an interaction would manifest
      itself as a very slight asymmetry in the absorption of left and
      right circularly polarized light in a magnetic dipole transition.
      Gene was always drawn to work that probed the most fundamental
      aspects of physics, and we were excited by the prospect that a table-
      top experiment could say something decisive about high energy
      physics. The experiment needed a state-of-the-art laser and my
      advisor knew nothing about lasers. I brashly told him not to worry;
      I would build it and we would be up and running in no time.

      This work was tremendously exciting and the world was definitely
      watching us. Steven Weinberg would call my advisor every few months,
      hoping to hear news of a parity violating effect. Dave Jackson, a
      high energy theorist, and I would sometimes meet at the university
      swimming pool. During several of these encounters, he squinted at me
      and tersely asked, "Got a number yet?" The unspoken message
      was, "How dare you swim when there is important work to be done!"

      Midway into the experiment, I told my advisor that I had suffered
      enough as a graduate student so he elevated me to post-doc status.
      Two years later, we and three graduate students published our first
      results. Unfortunately, we were scooped: a few months earlier, a
      beautiful high energy experiment at the Stanford Linear Collider had
      seen convincing evidence of neutral weak interactions between
      electrons and quarks. Nevertheless, I was offered a job as assistant
      professor at Berkeley in the spring of 1978.

      I had spent all of my graduate and postdoctoral days at Berkeley and
      the faculty was concerned about inbreeding. As a solution, they
      hired me but also would permit me to take an immediate leave of
      absence before starting my own group at Berkeley. I loved Berkeley,
      but realized that I had a narrow view of science and saw this as a
      wonderful opportunity to broaden myself.

      A Random Walk in Science at Bell Labs
      I joined Bell Laboratories in the fall of 1978. I was one of roughly
      two dozen brash, young scientists that were hired within a two year
      period. We felt like the "Chosen Ones", with no obligation to do
      anything except the research we loved best. The joy and excitement
      of doing science permeated the halls. The cramped labs and office
      cubicles forced us to interact with each other and follow each
      others' progress. The animated discussions were common during and
      after seminars and at lunch and continued on the tennis courts and
      at parties. The atmosphere was too electric to abandon, and I never
      returned to Berkeley. To this day I feel guilty about it, but I
      think that the faculty understood my decision and have forgiven me.

      Bell Labs management supplied us with funding, shielded us from
      extraneous bureaucracy, and urged us not to be satisfied with doing
      merely "good science." My department head, Peter Eisenberger, told
      me to spend my first six months in the library and talk to people
      before deciding what to do. A year later during a performance
      review, he chided me not to be content with anything less
      than "starting a new field". I responded that I would be more than
      happy to do that, but needed a hint as to what new field he had in

      I spent the first year at Bell writing a paper reviewing the current
      status of x-ray microscopy and started an experiment on energy
      transfer in ruby with Hyatt Gibbs and Sam McCall. I also began
      planning the experiment on the optical spectroscopy of positronium.
      Positronium, an atom made up of an electron and its anti-particle,
      was considered the most basic of all atoms, and a precise
      measurement of its energy levels was a long standing goal ever since
      the atom was discovered in 1950. The problem was that the atoms
      would annihilate into gamma rays after only 140x10-9 seconds, and it
      was impossible to produce enough of them at any given time. When I
      started the experiment, there were 12 published attempts to observe
      the optical fluorescence of the atom. People only publish failures
      if they have spent enough time and money so their funding agencies
      demand something in return.

      My management thought I was ruining my career by trying an
      impossible experiment. After two years of no results, they strongly
      suggested that I abandon my quest. But I was stubborn and I had a
      secret weapon: his name is Allen Mills. Our strengths complemented
      each other beautifully, but in the end, he helped me solve the laser
      and metrology problems while I helped him with his positrons. We
      finally managed to observe a signal working with only ~4 atoms per
      laser pulse! Two years later and with 20 atoms per pulse, we refined
      our methods and obtained one of the most accurate measurements of
      quantum electrodynamic corrections to an atomic system.

      In the fall of 1983, I became head of the Quantum Electronics
      Research Department and moved to another branch of Bell Labs at
      Holmdel, New Jersey. By then my research interests had broadened,
      and I was using picosecond laser techniques to look at excitons as a
      potential system for observing metal-insulator transitions and
      Anderson localization. With this apparatus, I accidentally
      discovered a counter-intuitive pulse-propagation effect. I was also
      planning to enter surface science by constructing a novel electron
      spectrometer based on threshold ionization of atoms that could
      potentially increase the energy resolution by more than an order of

      While designing the electron spectrometer, I began talking
      informally with Art Ashkin, a colleague at Holmdel. Art had a dream
      to trap atoms with light, but the management stopped the work four
      years ago. An important experiment had demonstrated the dipole
      force, but the experimenters had reached an impasse. Over the next
      few months, I began to realize the way to hold onto atoms with light
      was to first get them very cold. Laser cooling was going to make
      possible all of Art Ashkin's dreams plus a lot more. I promptly
      dropped most of my other experiments and with Leo Holberg, my new
      post-doc, and my technician, Alex Cable, began our laser cooling
      experiment. This brings me to the beginning of our work in laser
      cooling and trapping of atoms and the subject of my Nobel Lecture.

      Stanford and the future
      Life at Bell Labs, like Mary Poppins, was "practically perfect in
      every way". However, in 1987, I decided to leave my cozy ivory
      tower. Ted Hänsch had left Stanford to become co-director of the Max
      Planck Institute for Quantum Optics and I was recruited to replace
      him. Within a few months, I also received offers from Berkeley and
      Harvard, and I thought the offers were as good as they were ever
      going to be. My management at Bell Labs was successful in keeping me
      at Bell Labs for 9 years, but I wanted to be like my mentor, Gene
      Commins, and the urge to spawn scientific progeny was growing

      Ted Geballe, a distinguished colleague of mine at Stanford who also
      went from Berkeley to Bell to Stanford years earlier, described our
      motives: "The best part of working at a university is the students.
      They come in fresh, enthusiastic, open to ideas, unscarred by the
      battles of life. They don't realize it, but they're the recipients
      of the best our society can offer. If a mind is ever free to be
      creative, that's the time. They come in believing textbooks are
      authoritative but eventually they figure out that textbooks and
      professors don't know everything, and then they start to think on
      their own. Then, I begin learning from them."

      My students at Stanford have been extraordinary, and I have learned
      much from them. Much of my most important work such as fleshing out
      the details of polarization gradient cooling, the demonstration of
      the atomic fountain clock, and the development of atom
      interferometers and a new method of laser cooling based on Raman
      pulses was done at Stanford with my students as collaborators.

      While still continuing in laser cooling and trapping of atoms, I
      have recently ventured into polymer physics and biology. In 1986,
      Ashkin showed that the first optical atom trap demonstrated at Bell
      Labs also worked on tiny glass spheres embedded in water. A year
      after I came to Stanford, I set about to manipulate individual DNA
      molecules with the so-called "optical tweezers" by attaching micron-
      sized polystyrene spheres to the ends of the molecule. My idea was
      to use two optical tweezers introduced into an optical microscope to
      grab the plastic handles glued to the ends of the molecule. Steve
      Kron, an M.D./Ph.D. student in the medical school, introduced me to
      molecular biology in the evenings. By 1990, we could see an image of
      a single, fluorescently labeled DNA molecule in real time as we
      stretched it out in water. My students improved upon our first
      attempts after they discovered our initial protocol demanded luck as
      a major ingredient. Using our new ability to simultaneously
      visualize and manipulate individual molecules of DNA, my group began
      to answer polymer dynamics questions that have persisted for
      decades. Even more thrilling, we discovered something new in the
      last year: identical molecules in the same initial state will choose
      several distinct pathways to a new equilibrium state.
      This "molecular individualism" was never anticipated in previous
      polymer dynamics theories or simulations.

      I have been at Stanford for ten and a half years. The constant
      demands of my department and university and the ever increasing work
      needed to obtain funding have stolen much of my precious thinking
      time, and I sometimes yearn for the halcyon days of Bell Labs. Then,
      I think of the work my students and post-docs have done with me at
      Stanford and how we have grown together during this time.


      Welcome to a Conversation with History. I'm Harry Kreisler of the
      Institute of International Studies. Our guest today is Steven Chu,
      who is a Nobel Laureate in Physics and Geballe Professor of Physics
      at Stanford. He is the 2004 Hitchcock Lecturer on the Berkeley

      Steven, welcome to Conversations.

      Thank you.

      Where were you born and raised?

      I was born in St. Louis. Not raised there; I only spent a few years
      there. My parents then moved to Long Island. I was raised in suburb
      of New York City, Garden City.

      Looking back, how do you think your parents shaped your thinking
      about the world and about science?

      Oh, that's a tough call, because most of how they shaped -- how
      parents, all parents, shape people -- is very under the table.
      You're not really aware of it. I was aware of many things, though.
      My parents came from China. They were students. They came here as
      graduate students to go to MIT. Like many Chinese in higher
      education, they had a reverence for education. They communicated
      very clearly to me and my two brothers that one of the high things
      you could aspire to be is a scholar, just for the scholarship's
      sake, not so much as a stepping stone to some other job. That was
      communicated very well. While we were young, they would always
      say, "Read." They didn't care that much what we read, as long as we
      read. And that, again, was something that helped.

      You didn't necessarily take to school like a fish to water; I read a
      short biography. You were a good student when you got interested, I
      guess, is the way to summarize it.

      Well, you have to normalize this to what was happening in my
      [family]. I had an older brother who was an excellent student. He
      was two years older than me. We were in a school in Garden City. It
      was a very good public school, an excellent public school, and he
      went through this public school setting the highest cumulative
      average in the record of the school.

      I see.

      So I followed along two years later and the teachers would say, "Oh,
      you're Gilbert's brother. We expect you to do just as well." That
      was hard to really live up to. While he was setting records, I was
      kind of coming from behind. I was an A-minus student, and by my
      family's standards, this was appalling. He was very good. He was
      very structured and he would study the things he was supposed to
      study. And he was fundamentally a very good student.

      I would get very interested in one thing and let something else lay
      [aside]. It wasn't really until I went to college where they didn't
      hear of my older brother that I was able to [come into my own].

      But in high school you were turned on to science? How did that come

      There were two things. One is I had a fantastic physics teacher as a

      In high school?

      In high school. And then the same teacher as a senior in high
      school. This is someone who is naturally recognized. He was winning
      prizes for being an outstanding science teacher.

      And his name was?

      Thomas Minor.

      I had two excellent mathematics teachers -- one in ninth grade, in
      geometry, and then a calculus teacher in the twelfth grade. And
      there, the mathematics was different than the other mathematics.
      [In] the other type of mathematics you learn how to do algebra and
      trigonometry and things like that. In those two subjects, it was
      mostly about logic and thinking, and putting together logical
      arguments. It was very different.

      The physics and the logic/mathematics courses, I got very excited

      You also, early on, liked to build things and do experiments, and
      litter your mother's living room with projects. Tell us a little
      about that and how that ultimately contributes to what you've become.

      I don't know what it was, but since I was very young I loved
      building things. I loved building things with my hands. I would be
      given for Christmas a model set of airplanes or boats and things,
      and I loved to put them together. I would ask my parents for things
      like Erector Sets; these are little pieces of metal and screws.
      Unlike Lego blocks, you actually have to screw something together,
      it wasn't all pre-designed to make a boat or something like that. I
      loved doing those things.

      In that respect, it was somewhat different than my two brothers. In
      many respects, my brothers and I are very similar, but in that
      respect, I seemed to love mechanical things in a way that was
      certainly nurtured by my parents, in that they said, "Okay, he wants
      to do these things. We'll buy toys like that for him." But my other
      two brothers didn't seem to like that.

      Now, it turns out that working with your hands and building things
      gives you a spatial intuition that turned out to be invaluable once
      I became a scientist. I could see things in my head very clearly and
      rotate them around. This idea of picturing things geometrically has
      always been a part of my thinking. The layperson doesn't think of
      that in terms of physicists; they think in terms of mathematical
      equations. I only discovered later that most physicists do that.

      So you went on to college, and you were freed of your brother, so to
      speak, as a model to emulate. Where did you do your undergraduate

      I went to the University of Rochester. I applied for the Ivys; they
      didn't accept me. The University of Rochester was wonderful because
      it was an excellent school, and, as I said, my brother was an
      unknown; I could be my own person. I started working very hard in a
      regular way, still, but in a very directed way. What's wonderful
      about college is that beyond a few required courses, you can take
      what you are interested in.

      There was another thing that happened in college that I wasn't
      really thinking of, and that is, as I studied more mathematics it
      actually affected my writing. My writing became more linear in its
      thinking, and you could definitely see logic in the writing that I
      didn't have when I was in high school or grade school. In my
      humanities courses the professors were [saying], "This is a coherent
      paragraph." I wasn't really thinking about that, but it was almost a
      magical transition from the mathematics I was studying.

      Being a Scientist
      Why is it that the public understanding of science doesn't proceed
      at a higher pace? Is it because there are not enough scientists who
      are doing the writing?

      That's a difficult question. As I give more public talks, as I get
      exposed to these issues more and more, I think that there are two
      things: One is, unfortunately, there is a public fear of science,
      especially physics. They think, "Oh, my gosh, physics ... it's hard.
      It has math in it. It's going to be very difficult for me to
      understand what's really going on." That, I think, is something that
      might have happened in grade school or high school.

      If you didn't have the right teacher ...

      Yes. And the trouble with learning physical science and mathematics
      is, once you slip behind a little bit, and you just didn't get this
      concept, or it's not quite firm in your mind about this mathematical
      thing that you have to know, well then, next week you're on to
      something else. But they really expect you to know something about
      last week. And so that's one of the issues.

      The other issue is that the ideas are complex. Now, if you step back
      and if you spend some serious time thinking about it, the kernel of
      the ideas are clearly not complex. The essence of an idea is what we
      try to work with most. As a professor with my graduate students, we
      would read a paper and look at the paper and say, "What's the
      essence of the idea? What's something new? Forget about the
      equations. Forget about the complicated argument and try to identify
      the kernel of the idea." That can be communicated, but it takes

      You did your graduate work here at Berkeley. So in a way, you're
      coming back to deliver the Hitchcock Lectures.


      What contribution did your Berkeley education make overall? I'm sure
      you could go through a long list. Who was your mentor here?

      My mentor was Eugene Commins. He was a wonderful professor. He has a
      history of having many graduate students who have gone on and done
      wonderful thing. He's revered as a classroom teacher as well, and,
      also, in the way he does things, the way he goes about life. In
      every respect that I can think of he was a mentor, not only in terms
      of the science but how you handle yourself in situations and in the

      He had one remarkable quality that I wish I could copy, and that is,
      he made all of his students feel special, and that they could do
      something. He got all of us to live up to the highest we could do,
      without saying, "You must do this," or without making us feel
      pressured or guilty, or something like that. He would work side by
      side with us, often late into the night, as a colleague more than as
      a professor. That was a remarkable experience to grow up in that

      The other thing I learned here is to try to think of things to do
      that would be important in science. There are many things you can
      study in science; some focus on big questions. Try to identify the
      correct questions. It was not only my advisor but the Berkeley
      professors around here at that time; there were six or seven Nobel
      Laureates in the physics department who were active, and you could
      watch they way they approached problems. This would come out not in
      a formal lecture or something, but in casual conversations when
      they're maybe giving a colloquium -- how they approach it, and how
      they thought about it. This enters in a very subconscious way. That
      is probably why there are so many distinguish graduates in Berkeley.

      Help us understand what the prerequisites are for doing science
      well. If a student or students were to watch this, what should they
      know about this way of life and what they need to bring to it --
      training and so on?

      The first thing is, they have to be interested in it. They have to
      be genuinely interested. They have to have curiosity. Science is
      really about describing the way the universe works in one aspect or
      another in all branches of science -- how a life form works, how
      this works, how that works. You're really trying to understand
      what's around you. You have to have a natural curiosity for that.

      In certain types of science, there might be prerequisites. In
      physics, you should have some mathematical ability. Otherwise, I
      think it would be very hard. But beyond those prerequisites that a
      lot of people do have, you need to have, first, this curiosity, a
      driven curiosity. You want to know the answer. With that curiosity
      comes a certain doggedness, because there are going to be setbacks,
      you're going to be discouraged. Things aren't going to work. You're
      going to have trouble understanding them. Things are going to be
      hard to understand, especially the first time. Science doesn't come
      naturally to people.

      I had the hardest time in my first few years as a
      freshman/sophomore, and also in high school, understanding physics
      in a really deep sense. I could do well in exams, but to get it
      inside your stomach and to say, "Okay, I have a real feel for it";
      it took a while to develop that intuition. But there were other
      drivers for that. It seemed like a beautiful way of understanding
      the world.

      But I'll go back to the other thing -- this doggedness, this
      saying, "I'm not going to quit. I really want to find out." It
      enters in other walks of life. If you think of an athlete who wants
      to become a good athlete, well, there's going to be a lot of
      training involved. Sometimes you don't feel like getting up early in
      the morning or staying late in the afternoon and spending the hours

      That turns out to be one of the most important things that separate
      [students] in graduate school. At graduate school at Stanford, you
      have some of the best students in the world, who you can see are
      going to go on and become world-class scientists, and who are very
      smart and are going to be good. But the thing that really
      differentiates [among them] is this passion to find out what the
      answer is: "I'm not going to quit." After those prerequisites, the
      thing that separates the people who are going to excel from people
      who are good and not, is that internal drive.

      In a joking "aside" yesterday in your lecture you said that in
      science, once you announce something, first, everybody tells you
      you're wrong; then they tell you it's trivial; and then that you are
      not the first to discover it. It emphasizes what you just said, that
      there has to be an inner drive. But also it suggests an element of
      courage, that you're going to stand up to people and say, "This is
      what I think," and then keep on going even if you're proven wrong.
      And then try to adjust what your experiment has shown.

      That's right. When you make something that's unexpected, and it's a
      little bit out of people's expectations, they're first going to
      reject it. And, actually, that's one of the strengths of science.
      You have to say, "No, it's not [just] because I said it is"; you're
      going to have to convince them. And by convincing them, it's really
      through discussion and additional experiments, because in the end
      the experiment is going to be the final arbitrator. There's no high
      priest or priestess of science that says, "You're right; you're
      wrong." You go back and you do more experiments. So the reaction, if
      you're a little bit off center or a lot off center, is, "No, that's
      preposterous. You've got to be wrong." The more outlandish you are,
      the more unexpected the finding, the more you're going to get that

      Now. in the end, after one understands what's going on -- and it
      goes back to understanding the science -- then you say, "No, no, no,
      it's all right. Yes, we could have foreseen that." That's where it
      becomes trivial. It's sort of, "Well, sure." It wasn't trivial at
      the beginning, but after you see it, then it becomes easy. But
      that's actually a mark of really understanding something, to then
      say, "Of course."

      The final one is, "You're not the first to discover this." That is
      also true. There are always precursors. There's always someone
      before you who had a glimmer of this and a glimmer of that. Science
      is based upon a lot of rediscovery.

      But going back to your point, namely you're going to be rebuffed and
      oftentimes rejected, and it's not a personal issue. You've just got
      to stand up to it and go back; now, you could be wrong, but you're
      going to go back and convince yourself you're right. The rule I tell
      myself and my students is, we have to be our worst critics, and once
      we convince ourselves that we're right, then we should have no
      problem convincing everybody else we're right. Good scientists are
      their own worst critics. They're always trying to prove themselves
      wrong, which is hard, because sometimes you've got an idea and you
      think you're right and you have to force yourself [to ask], "Where
      are the weak points of this argument, or the weak points of my

      One of the points that came out in your lecture for me, a non-
      scientist, was the importance of collaboration, not only with your
      own students but with other scientists, and even other scientists
      who are in subgroups within physics, but even beyond that, to
      scientists in other fields of science, that those sets of
      communications working together are important to push this process

      Yes. That's another misconception that many people have about
      scientists, or doing science and learning science. The misconception
      is you go to school, you take classes, you study -- years and years
      of study. You learn everything there is to know in a certain sub-
      field, a very narrow sub-field, and then you do work in that area.
      That is the form, but it's rarely taken. It's especially not true
      the way I do it.

      Maybe it goes back to my high school days, when I was not such a
      good student. In actual fact, if one wants to go into a new area
      beyond your school days, you can pick up a classic textbook and
      begin to read, and begin to read in the literature; but it's not as
      much fun. When I was going into biology maybe a dozen years ago, I
      did try that. I picked up a big, fat tome called Biochemistry, a
      classic textbook. I started reading; it was 1,500 pages. I got to
      page 150, and I was deciding, "Well, it's beginning to slip out of
      my head as fast as it's going in now." I reached a "steady state!"

      So I said, "Well, this isn't going to work." So I would look around,
      and I had some [knowledge] from reading newspapers and magazines
      such as Science, Science Times, The New York Times, Scientific
      American, things of that nature. I had an interest in these
      biological problems, and I would pick something that I was
      interested in. But, of course, since I wasn't an expert in biology,
      I didn't know, "Is this a stupid question? Is this a deep question?
      What?" I would say, "Well, I think I can do something here and I
      have some interest." So I'd trot over to the biology department or
      medical school and say, "Is this something we're studying? I think I
      want to do this." And they would tell me sometimes, "No, no, it's
      silly," or "It's been done before." Or sometimes they'd say, "This
      is a central problem in biology." That rarely happened.

      But what happened is then I would start to collaborate with these
      people who spent their career in this specialty, and who grew up in
      this culture. They would say, "You should read this article, and
      that article, and that article." We would talk, and it was wonderful
      to learn that way. So you could sort of leapfrog over the years of
      school. Now to be sure, I'm not pretending I have as broad or deep
      as knowledge of that. But you start with a little, thin sliver of a
      particular problem, and you start to build knowledge around that
      thin sliver. By the time you've done the experiment and you're
      starting to write the paper, you better have some knowledge of
      what's around, because you won't even get to publish in the paper if
      you haven't referenced the right people or the precursors before
      you. But it's learning in that way.

      Then you go back to the books, but now you use the index. You
      say, "I want to learn about this." So now I've begun to teach my
      students -- many of my students are physicists wanting to go into
      biology. I say, "Okay, we'll use the index. This is the problem. Why
      don't you look here, read these five pages in this book, and these
      ten pages here, and these fifteen pages here." By the time you read
      this review article, within a month, you're reading the primary

      In biology.

      In biology, without the three years of courses. Within a few months
      to a few years, you're beginning to get a feel for it. It's very
      important that you get this feel, because you have to ask the right
      questions. One of the most important things that a scientist does is
      ask a question that's important and that has a chance of being
      solved. You can ask important questions like, "How does a brain
      work?" but that's not sufficient. You have to pick a part of that
      question where you can make you a contribution, a serious
      contribution, and something that others would be interested in.

      Working at Bell Labs and at the University
      Before we talk about your research (and in a way that I can
      understand, and maybe the public, too) in your career there was a
      period when you went to the Bell Labs. I want to understand how that
      contributes to your research, and understand exactly what the
      difference is between being in a place like Bell Labs versus being
      in a physics department at Berkeley or Stanford.

      Well, the reason I went to Bell Labs, I was here as a graduate
      student at Berkeley and I was a post-doctoral fellow here. After two
      years of that they actually made me a faculty member in the Physics
      Department. But this was a bit unusual, because I had spent eight
      years at Berkeley, and I was essentially toilet-trained here, and
      had a very narrow vision of science. What a department really wants
      is to bring in people from different [scientific] cultures. But they
      decided they wanted me as a professor. It was a beautiful place, so
      I accepted.

      But then they did something very unusual. They said, "You can start
      your group and go about your business. Or, because you spend so much
      time here and this was your only real experience, you also have an
      opportunity to go somewhere else for a year or two." I
      thought, "Well, that's wonderful. I have a job at the best physics
      department in the world, and so I'll go off and spend some time and
      broaden myself." So I decided to go to Bell Telephone Laboratories
      which, at the time, was one of the premier research industrial labs.
      When most people think of industrial labs, they think of, "Oh,
      you're making better widgets. You're making something that's going
      to be good for the phone system." Now, ultimately, that's true. But
      at Bell Labs in that time -- this is in 1978 -- allowed a small
      fraction of us -- fifty, sixty, eighty -- to do whatever we wanted;
      really to do whatever we wanted.

      So I joined Bell Laboratories. My department head said, "Steve, you
      can do whatever you want. It doesn't even have to be physics. All we
      ask is that you don't go to a high-energy accelerator and do high-
      energy physics, because that would be hard on the stockholders." (My
      thesis project, and when I was working as a post-doc, addressed a
      high-energy physics problem.) He said, "And by the way, don't do
      anything immediately. Spend six months. Talk to the people around
      the labs, and just keep an open mind." This was a devastating
      experience for me, because of the freedom to do whatever you want
      and being told, "Don't do what you think you want to do now, but
      explore." So I spent some time exploring and thinking. And there, I
      really felt pressure, because he would say, "We expect great things
      out of you." I didn't want to hear that. It's much nicer to have a
      little problem to work on; it's very cozy.

      But it did have a real influence on me, because it got me in that
      mode of going and talking to people outside of my field. When I
      finally started doing things at Bell Laboratories ... and I started,
      first, in an area that was in condensed matter physics that I knew
      nothing about, but using techniques in my old field, atomic physics
      and laser physics. But it got me into the mode of, "I've got this
      crazy idea." I'd go to some colleague in Bell Laboratories and
      say, "How does this sound?" And they would tell me, "No, this is the
      stupidest thing I've heard," or "Yeah, maybe you have something
      there." It set the tone for what I've done for the rest of my life --
      collaborating with people, especially outside my local expertise.
      It was a wonderful experience.

      I also should say, in the years I was there, '78 to '87 -- there was
      an economic slump in the mid-seventies; Bell Labs just started
      hiring people -- and there were a group of us, maybe a few dozen,
      two or three dozen, and we all were young, energetic, bright-eyed,
      bushy-tailed. We were all being put in this position: "Do something
      important. Here are the resources of American Telephone and
      Telegraph System. We expect you to do something wonderful." We were
      there at night. We were there on the weekends. We knew what each
      other's cars looked like, so we knew who was in there, let's say, on
      a Saturday or Sunday. We would party together. [Looking back,] I
      think either five or six of us [later] got Nobel Prizes. Over a
      dozen are in the National Academy of Sciences. It's like this: we
      all were growing up together. And we had these really wonderful
      senior scientists there as well.

      It was a remarkable period of time. Everything was exciting, and
      something would come along that was not in my field, and I would
      say, "Wow, this is really interesting." We'd go in, we'd discuss it.
      People would jump fields, or jump areas. There was this feeling of
      the excitement of the science, that even though we were doing this,
      it was all right to move and do that. You wouldn't be considered a
      failure because you gave up this, because something else even more
      exciting came along, either from your own laboratory or from a
      colleague's lab, or from the outside world.

      So freedom in the best sense, but in an environment where it could
      lead to new levels of understanding.

      A positively electric atmosphere. You'd go in the lunchrooms and
      over lunch ... everybody went there around noontime. You'd sit in
      these big round tables and, "Okay, what's new?" People would leave;
      other people would come. You would be sitting there chatting,
      socializing, but talking a lot about science. A lot of ideas were
      invented on those lunchroom tables. And so there, again, it was
      something where there was this real community.

      It was pretty magical. People who are close to science and
      especially in the areas that Bell Labs was touching knew that there
      was something magical going on at the time.

      How can we distinguish that experience from, say, being at Berkeley
      in the Physics Department, or being at Stanford? Was it just a
      question of there being enough resources to bring all these people
      together to create this magical moment?

      No, there were other things. For example, in a university, like
      Berkeley or Stanford, you're a professor, you have students. Part of
      your job is to teach undergraduates; part of your job is to teach
      graduate students. You teach graduate students by developing with
      them their own projects. A lot of energy and time is spent nurturing
      students. Because of that, your first duty is to look towards your

      In Bell Laboratories we didn't have groups. The biggest you could
      have would be a technician and a post-doc, and usually not both. If
      you wanted to do something that required more than one or two
      people, you would have to work with other people. That builds
      collaboration into the system. And because no one had an empire,
      even a mini-empire -- in the basic science areas of Bell you're one
      and two or three -- you have a lot of time. You're not taking care
      of people. You have a technician or a post-doc, and so it's a very
      different structure.

      We are trying to do something like that at Stanford, in a
      multidisciplinary way. We're bringing people interested in biology,
      physics, chemistry, and computer science, centered around biological
      problems, where people from very many disciplines will come and have
      their own genres of what to do. One of the things is to limit the
      size of your groups. In the university, let's say you're a synthetic
      chemist; you can have groups of forty. And with a group of forty
      people, you're not going to have much time to interact with
      colleagues. You're not going to have much time to explore elsewhere.
      So [we've] limited the size of the group to fifteen, which is still
      very large. You couldn't limit it to three, because there are very
      few professors that have [only] two or three graduate students in
      something related to the biological sciences. There are typically
      more. So the structure is slightly different. It's not clear how
      much you can create the structure we had at Bell Laboratories,
      because you have these other responsibilities and duties.

      Nobel Research in Physics
      Before we talk about this new link that you're working on between
      physics and biology, let's talk a little about your research that
      led to the Nobel Prize. Give us a sense of how you came upon that
      problem set and what you, in fact, did. It's related to atoms,
      lasers, cooling, and so on.

      [It began when] I was at Bell Laboratories. There are two main
      branches of Bell Laboratories. The main research branch was in
      Murray Hill, New Jersey. In 1983, a director [at the other branch]
      in Holmdel asked if I would become a department head in his division
      in Holmdel. The director, by the way, is Charles Shank, who's [now]
      the director of LBL. He said, "Well, Steve, why don't you consider
      coming down and starting a new department which would be a basic
      science department here?" Holmdel had excellent laser science and
      laser engineering, and a lot of the great things that have come out
      of optical communication were spawned at Bell Labs in Holmdel and
      Murray Hill. I said, "That sounds like a great job." So I went down
      and started this department, and started hiring people, and also
      inherited some very talented people. Actually, two of them are here,
      also: Daniel Chemla for a brief moment was in my department, now a
      division leader at LBL; and Jeff Bokor, who's a professor in
      Electrical Engineering, was also in this department.

      There was another really wonderful scientist there named Arthur
      Ashkin, an older department head. I started talking to him casually,
      in the hallways. He had this dream: "Wouldn't it be nice if you can
      hold on to an atom with light?" He had tried to pursue this dream in
      the early seventies, in the mid seventies, but it wasn't really
      working. They did some very key experiments demonstrating the
      fundamental forces, but it wasn't looking like they were getting
      closer to really holding on to atoms with light. Finally the
      management told Ashkin, "It doesn't look like it's going to work;
      you've got to move on to other things." But then I came on board,
      and I was this new, young person who he could corrupt.

      "You go do this."

      I started thinking, "Okay, this sounds pretty interesting," and I
      started having a look at it. I started doing a lot of calculations.
      It was getting to be bad, and I was thinking, "I can see why you
      quit." I didn't tell him that, but I was thinking to myself, "It's
      not looking good."

      There's a few "eureka" moments you're going to have in science.
      Mostly they're gradual eurekas, which I can come back to later. But
      there was this time.

      It was not looking good at all; I would try it this way, that way.
      It's all on paper -- not looking good. And finally, there was a big
      snowstorm in New Jersey. They said over the P.A. system the forecast
      looked very bad. There's going to be nine inches or something; the
      lab is going to be closed, you should all go home. Now, I live very,
      very close to the lab, so I said, "Oh, heck." Everybody left, and it
      was very quiet. It was one of those beautiful things where you can
      see the snow falling down and everything's turning fluffy white, and
      maybe it was appropriate [to think about cooling an atom] because it
      was snowing.

      I found you can do an end-run. The [conventional wisdom] was first,
      you hold onto an atom; then you get it cold; and then you can do
      what you want with it. I said, "Well, what if you reversed it? What
      if you cooled down the atom first? Don't hold onto it, but maybe in
      the process of cooling it down, it's going to hang around for enough
      time that you can have a chance of grabbing onto it." And so [after]
      a little calculation I said, "Holy smokes. This looks like it's
      going to work."

      And then I said, "Well, I want to refine the calculations." So then
      there's the gradual "eureka." I wanted to refine the calculation. So
      you're surrounding this atom with light, and it looks like it's
      getting very cold, to the point where your feeble little trap that
      was going to hold the atom could work. But it needed to hang around
      for a while. So I started to say, "Okay, tomorrow I'll come in and
      I'll start to write a program to predict how long it will hang
      around." I start to write the program. Luckily, I'm not that good at
      writing programs -- I'm good until about three lines -- because if I
      was really good at writing programs, I wouldn't have thought about
      it at all and just written the program. So I get to three lines of
      code and said, "I've seen this problem before. Einstein solved it."

      Good old Albert.

      What he did is, he looked at a dust particle in the fluid; he was
      studying Brownian motion. Here's this dust particle being battered
      from all sides by atoms and molecules. He said, "If I take this
      particle and I move it, there's a viscous drag in the fluid, and
      that slows it down. The reason it's being battered around is because
      of random imbalances between pressure from the left and pressure
      from the right." What I wanted to calculate was how this particle
      would wander around, because the previous day, I'd shown it had this
      viscous drag on it. and that you do have these fluctuations. I was
      going to write a computer program to say, "Okay, step to the right,
      step to the left, and balance all the forces," but I thought, "No, I
      can use this solution. I know where it is. It's in an elementary
      textbook, an undergraduate textbook. It's the 'random walk' in a
      Brownian motion medium. You just plug in those numbers, and voila,
      you get ... wow, it's hanging around for a long time, because it's a
      random walk!"

      And so I got very excited. I went to my boss, Chuck Shank, and
      said, "Look, Chuck, I know you're not keen on this, after years of
      research, but this is so simple it has a shot at working. You can
      get it cold, you can hold onto it, and we can go from there." He
      thought about that and he said, "Well, okay, you've earned the right
      to do something crazy, but don't try to recruit someone else." So I
      said, "Okay, okay, just my post-doc and my technician. " Because if
      you're onto something really big, you want to bring in your friends
      and say, "We want to go fast; we want to do this and ... "

      So we puttered along for a few months, going like the blazes. I
      talked to Art about it, and he went, "Hmm, hmm, okay. It's not the
      way I dreamed it. Okay, that sounds promising." After a few months,
      it began to look like it was going to work, really going to work.
      And I said, "Come on, join in, and it's going to be a lot of fun."
      As I indicated in my lecture, it worked much better than anybody

      What are the implications of what you discovered in a layman's way
      of understanding?

      Once you get an atom very cold ... and cold is really the average
      speed that an atom moves. The atoms in this room are moving at
      speeds of supersonic jet planes. In fact, that's why the speed of
      sound is what it is. It's just determined by the speed of molecules.
      Once you get an atom really cold, so it's moving as fast as an ant
      walks, a fraction of an inch per second, then very, very weak forces
      can push them around, and you can do what you want with them -- for
      example, using electric or magnetic fields, or light. You can hold
      them, you can push them around, you can do things that you simply
      cannot do when they're whizzing around like supersonic jet airplanes.

      The ability to hold onto and control and manipulate these atoms
      means, for example, you can toss them up; they can turn around due
      to gravity in a vacuum can where there are no other atoms around,
      and you can make better atom clocks. You can make what are called,
      atom interferometers. You quantum-mechanically split the atom apart,
      so one part of the atom is the quantum wave going to one region in
      space; the other part is the quantum wave going to another region of
      space. That atom interferometer can be used to measure acceleration
      or gravity or rotations with very high accuracy -- in fact, in terms
      of acceleration or gravity, better than any other way of doing it.
      And in terms of rotations, certainly better than any commercial or
      even laboratory grade laser gyroscope.

      So all of a sudden, you can measure changes in gravity so accurately
      that it's going to become competitive with the current ways of
      measuring changes in gravity, which is useful in all exploration.
      You can probably put it on an airplane or a helicopter. And with
      global positioning satellites to tell you the height and changes in
      distance, and inertial sensing systems, and something that measures
      change of gravity over distances on a scaled meter, it opens up the
      opportunity to do map gravity drains and pockets of oil, diamonds,
      things of that nature, minerals, on a very fast-moving platform like
      a slow-moving plane or helicopter. So there are real practical
      implications. Already the world is on the atomic clock standard,
      defined by so-called atomic fallons of atoms.

      The atom interferometer was totally unexpected. It just popped out.
      People, even the researchers in the field, [find it] hard to think
      about what you can do with it, even if you force yourself, until you
      have it in hand, and you can then begin to see the abilities of this
      new method or technique. It's only after we had it ... and then not
      only me, my group, but the world in general. No one was talking
      about any of the applications that came out until we actually had it
      and we saw how powerful it was, and then began to appreciate it. You
      can force yourself to think of what might come about, and you can
      write down a few things, but you're going to get only a small
      fraction of them. That's the wonderful thing about science.

      And actually, it harkens back for me to what you had said about your
      high school experience, in a funny way, that learning to look at
      something and think logically about it, and "Wow!" you're taking it
      to a new level. Not that you were doing Nobel Laureate a work in
      high school, but some of the elements are there in this work.

      Yes, I think that is true. But it's also just letting something
      happen. This is one of the things I did learn at Berkeley, and I
      watched great scientists here. Many of them were doing something
      that, in hindsight, looked very natural. They would say, "Here's an
      emerging technology. With this emerging technology, can I ride piggy-
      back on it? Can I use this technology to turn it backwards and do
      some new science?" Normally, you would think, "Oh, basic new science
      discovery; turns into a technology; you make a better widget." But
      what I appreciated when I was a graduate student here was that
      that's all true, but you can also take that technology, turn it
      around, and you can use it. A good example is radar. During World
      War II, the U.S. and Great Britain, especially, developed microwave
      engineering methods to have microwaves transmitters that allowed
      radar, so that we can measure and see things far away. The scientist
      who helped develop that radar, and other scientists who could see
      the power of that technology, seized on that shortly after World War
      II. A string of Nobel Prizes came out of people who used this new
      technology to do great science. Charlie Townes here [at Berkeley] is
      a prime example of that. His knowledge of microwave science --
      during the war he was working on microwaves.

      At Bell Labs, too

      At Bell Labs, that's right. After the war, he said, "I want to do
      microwave spectroscopy, because here's a new tool." We now control
      of short-wave multi radiation. And he became one of the leaders in
      microwave spectroscopy; wrote a classic book with his brother-in-
      law, Arthur Schawlow, and then invented an idea of stimulating the
      emission of microwaves called the maser. The extrapolation of those
      ideas from microwaves to optical wavelengths led to the laser.

      That's one example of using technology -- first, building on
      technology during the war, saying this is a wonderful way, a new
      scientific tool; use it to do science. Then wanting to improve the
      tool to get to show the wavelengths, and voila, you had the laser. I
      saw this over and over again. When Charlie came to Berkeley, he
      wanted to use his knowledge in lasers and microwaves to do
      astronomy. So, again, he was going to ride the technology. And I was
      looking around and saying, "Yes!"

      Now, he's a brilliant scientist, but the lesson I learned was you
      don't even have to be brilliant if you're the first to look at
      something with a new tool. So I said, "Okay, what are the new
      tools?" When I was graduate student there was something called a
      tunable dye laser. I told my advisor, "This is a wonderful thing.
      It's only a few years old. This is a tool that we should be using,
      now let's go figure out some science to do with it." Luckily, there
      turned out to be some very fundamental physics questions you can
      address using this tool.

      It's the fundamental physics that drove [Townes]. From my side, yes,
      I was drawn to the fundamental physics, but also "Let's use a new
      thing to do it." If you use an old tool to tackle a problem, you've
      really got to be smarter than the rest of the folks, because
      everybody has this tool. If you're the first to look at something
      new, it's like discovering your world. You just look around and
      everything you see is going to be new.

      Bringing Physics to Biology
      Bring us now to where you're moving, because you are going into
      biology; you already touched on that earlier. You are bringing
      physics to the table of biology, so to speak. Tell us a little about
      what you're seeing. You quoted Yogi Berra yesterday about that; that
      it's amazing what you can see when you look ...

      Well, Yogi is one of my heroes. He's the great American philosopher
      of the twentieth century. One of the things he said is, "You can see
      a lot by watching." He said other wonderful things like, "If you
      come to a fork in the road, take it." Or, "We may be lost, but we're
      making great time." And many, many other things.

      But, anyway, my entrée into biology was exactly what I was telling
      you about. I was working on atoms -- cooling atoms, holding onto
      atoms with light. I said, "Well, the same technology can be tweaked
      a little bit, and we can maybe hold onto individual molecules with
      light if you play some tricks. What could you do with these
      individual molecules?" Naturally, I thought about biology: "Let's
      first try to hold onto a piece of DNA." It's strictly a
      technological thing, and that worked. Then I had some ideas of
      looking at enzymes, proteins walking up and down the DNA and seeing
      what you could do in biology. But first we glued little plastic
      spheres to the end of this big DNA molecule -- so big that it's
      length was something like 15, 20 microns, which could easily be seen
      in an optical microscope. Now, you can't really see a piece of DNA,
      because sideways it's only 20 angstroms, and it's not resolved by an
      optical microscope. But you do a trick, you put little dye
      molecules, florescent molecules; think of it as a string of
      Christmas tree lights. You can't really see the string; it's too
      thin. But you see the light coming from that. It shines very nicely
      in an optical microscope, and you can move it around. So the first
      thing we did was, "Okay, let's stretch it out. Wow, it's stretched
      out. Well, let's see if we can break it." So we stretched and
      stretched it harder and harder, and we couldn't break it. It's very
      strong along that dimension, which is good because it holds your
      family jewels. You don't really want to break it that way.

      In the end what happened, it pulled out the optical tweezers, which
      were these plastic handles we'd glued onto the ends of the DNA. And
      it sprang back like a rubber band. It just went "boink" and crumpled
      back up. I said, "Holy smokes! It looks like a rubber band. Why does
      it look like a rubber band?" And the reason it looks like a rubber
      band is because when a molecule is straight, it's in a very unlikely
      state. If it were up to its own devices, it's being battered around
      by water molecules, it wants to do some random coil geometry. That's
      a much more likely state. So the reason it springs back has nothing
      to do with chemical bonds and forces pulling it back; it has to do
      with whether it's more likely to be found in some random coil or
      straight. It's the same reason if you push all the molecules of the
      air into a corner of the room and let go of them. They don't even
      have to bounce on each other. They would say, "Where would I likely
      be?" Well, equally likely anywhere in this room. And so the pressure
      evens out very quickly. That's why it would spring back like a
      rubber band.

      I said, "Well now, I can do this on a single molecule." What things
      could you do there? Well, you can understand polymers. Polymers are
      long, skinny molecules. You can look at it one at a time. So it was
      a back-door entrée into polymer physics, and we did that for a half-
      dozen years. Finally I started getting back into biology be<br/><br/>(Message over 64 KB, truncated)
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