“From atom to quark into string”:
Rockefeller physicist Konstantin Goulianos, Ph.D., warms up String Fever audience with brief history of string theory
“Sex and the City” actor Cynthia Nixon recently was on stage in Rockefeller University’s Caspary Auditorium portraying a woman turning 40 years old and fascinated by a theory in physics, known as string theory, as a possible explanation for her life. Joined by five other accomplished actors, Nixon participated in the staged reading of the new play, called String Fever, by Jacquelyn Reingold, as part of a public lecture organized by Rockefeller’s Office of Communications and Public Affairs in collaboration with The Ensemble Studio Theatre (EST)/Alfred P. Sloan Foundation Science & Technology Project.
Immediately preceding the reading Professor Konstantin Goulianos prepped the crowd in Caspary with a colorful explanation of string theory — the so-called “theory of everything.” Following are excerpts from his remarks, which Goulianos, head of the Laboratory of Experimental High Energy Physics, organized into three acts.
Act One: Atoms
I don’t know if you remember the first time you heard about atoms. For me it was 1945. I was a kid in Greece. The son of the grocer who was a real nerd, with thick glasses, who knew everything, told me, “They split the atom today.”
I didn’t know what an atom was. “Atom,” in Greek, means a person; I didn’t think they could split a person. I was ashamed to show my ignorance and ask him for details, so I said, “Who did it?” He answered, “The Americans.” “Oh yeah?,” I said, as I realized it wasn’t a person, but an object. But what was this atom made of? This was my first theoretical question. And I visualized someone holding an atom down and cracking it, and energy coming out of it, enough to make a bomb. Whah!
Later I learned that the atom had been proposed by Democritus, who was born around 500 B.C. He thought everything was made out of constituents, and only one constituent was needed to make the whole world. He got it right. The different ways of combining atoms give different forms of the world: you and me and the sky and everything. This is what we do in physics: We try to see what is the most fundamental thing.
Later, of course, we found out there were more atoms; Then we found a scheme in which all the atoms fit: the Mendeleev scheme [the organization of known elements in a periodic table based on atomic mass]. We didn’t have one atom, but we had one scheme. Schemes are the real basis of theoretical physics: We look for a scheme into which the whole world fits.
Act Two: Quarks
The second act takes place around 1961 at Brookhaven National Laboratory, on Long Island, where I was doing my thesis experiment.
After I finished my qualifying exams at Columbia, I had gone to Professor Jack Steinberger [who shared the 1988 Nobel Prize in Physics with Leon Lederman and Melvin Schwartz] to ask if I could be his student. He gave me a thick book about elementary particles and said, “Read this, and come back when you know it all.”
The book was about all the elementary particles that physicists had discovered. There were several dozen particles. We called them the “particle zoo.”
I tried to read this book, and nothing happened. It was about a zoo, I thought! There was no scheme into which the particles could fit. So at the end of the summer I went to see Mel Schwartz and asked to be his student. I ended up working with Steinberger and Lederman, as well, in an experiment that won all three of them a Nobel Prize in Physics.
So I was doing this experiment. Meanwhile, we were all bewildered as to what it meant to have so many elementary particles. You had protons and neutrons, and when you collided them, other particles came out. It all looked very strange.
And then, this fellow named Murray Gell-Mann [winner of the 1969 Nobel Prize in Physics] at Caltech noticed that if you arrange particles according to their properties in a particular way they form beautiful geometrical shapes based on triangles. He proposed a simple scheme, called SU3, in which the basic constituents of matter are three quarks.
But the important thing was that these three constituents fit in a scheme. We had a scheme! We didn't have a particle zoo anymore. We had three quarks, and we could calclulate things using a mathematical scheme. And that was great.
But later on, some more quarks were discovered, and we had six quarks and the so-called Standard Model, a more inclusive scheme. Anything we can do in experimental physics, the Standard Model can calculate, which is just amazing. It’s a theoretical scheme, a so-called symmetry scheme, so if you know the symmetry, you can understand the world. But you have to know the quark masses and several other constants that don’t come out of this scheme and have to be put into the model by hand. And this is not very satisfying when you want to have one thing, like Democritus with his atom.
Act Three: String theory
In the late 1960s I was sharing an office with [early string theorist] John Schwarz at Princeton. One day, John explained to me what he was doing: “I’m working on this string theory of matter. You have a string, and the string is vibrating in different modes. Every mode corresponds to a different particle. If I can have a string vibrating in many modes in several dimensions (more than three!) then I can get a spectrum of particles pretty much like the one we know.”
This solves a problem. When you think of an elementary particle you think of a very small thing, the smallest possible. But that small thing must have some size, right? Could it be three-dimensional? A string is the smallest thing you can conceive, and has one dimension; if you go smaller than one dimension you can’t have anything. So that’s the simplest scheme: you have one string vibrating in different modes to make the different particles.
Later on, people found that it also solved another problem. Out of this string theory came naturally the graviton, a particle needed to explain quantum gravity but cannot fit into the Standard Model. So, string theory has the potential of unifying quantum mechanics and the theory of general relativity, the world of the small with the world of the large. And all we have to know, according to this string theory, is the principle on which this is based, the framework — the mathematical framework, which is a well-defined framework, like a symmetry principle — all you have to know to understand the universe is how to handle the mathematics of a string vibrating in a multi-dimensional space.
It’s not a new idea. Pythagoras figured out how music derives out of a vibration of a string, how you get different musical notes depending on whether you pluck it in the middle or one-quarter from the end or what have you. He figured out that the important numbers are one, two, three and four, and thought that was beautiful because one plus two plus three plus four make 10, and that could not be more perfect.
So everything was based on these numbers. And now Democritus had the atom, Pythagoras said everything is mathematics, but with string theory, you have both: you have the mathematics, and then you have the atom, which is a string, and the different vibrational modes give different particles.
So there is a very great hope to really understand everything, and some people call this the “theory of everything.” Think of string theory the next time you call someone on your cell phone. Electrons vibrate all around the world, but you can think of them as dancing a cosmic song that’s playing to a vibrating string. If you remember this, you will know string theory and you’ll enjoy this evening’s play.
