Short of 'All,' String Theorists Accused of Nothing A provocative branch of physics called string theory might explain everything in the universe, such as how matter came into being and why space and time exist. But others say string theorists have zero proof to back their ideas.

Short of 'All,' String Theorists Accused of Nothing

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From NPR News, this is ALL THINGS CONSIDERED. I'm Michele Norris.


And I'm Melissa Block.

A provocative branch of physics called string theory might explain everything in the universe - how matter came into being and why space and time exist. Or the theory might explain nothing. For more than 30 years, it has captivated some of the best minds in physics.

NPR's Richard Harris reports on an intellectual feud that has spilled out of the towers of academe and onto the soccer field.

RICHARD HARRIS: Imagine if you spent your days pondering a universe that has nine or 10 dimensions of space - not just three - or if you spent your time trying to understand how our universe could be one of a jillion. Well, it must feel pretty good to get out on a soccer field and kick around a true to life three dimensional ball.

(Soundbite of whistle)

Dr. ROBERT KIRSHNER (Harvard University): All right. Where is the captain of the string team?

HARRIS: Twice a year, string theorists visiting UC Santa Barbara take on their colleagues in a friendly game of soccer. They have never lost a game. It has become a point of pride, especially now. Off the field, string theory is under attack.

Dr. KIRSHNER: These are the string theorists. Two, four, six, eight - that's close enough to 11, the way they count.

HARRIS: Astronomer Robert Kirshner, on sabbatical from Harvard, agreed to referee the most recent game. It takes place on a strip of grass between the beach and the barbecue pit.

Dr. KIRSHNER: The rules of the field are rather complicated and I'm making them up as I go along. The ball touches the lifeguard stand, it is out of bounds. The trees are in play. Try not to hurt them. They will be some of your best defenders.

HARRIS: For this match, string theorists here for a conference are taking on another group of visitors - high power laser physicists.

One of the players is Albion Lawrence from Brandeis University. He may not be a soccer star, but he does have a passion for string theory. He says the idea was really born in the late 1960s. That's when a physicist wrote down a mathematical formula that described one subatomic particle.

Physicists puzzled over this formula for a while, and then came to realize that it was not only describing a particle, it was describing vibrating strings, like the ones on the guitar on Albion Lawrence's lap.

Dr. ALBION LAWRENCE (Brandeis University) Among other things, the higher the frequency that the string vibrates, the more mass of the particle.

HARRIS: So could you play me a particle?

Dr. LAWRENCE: Yeah, this could be a particle.

(Soundbite of guitar)

Dr. LAWRENCE: Essentially, it would be like all the particles of different masses.

HARRIS: So if I were to write a mathematical formula that described what you were doing with the guitar string, would it end up looking somewhat like a string theory formula?

Dr. LAWRENCE: Roughly speaking, if you don't pluck the guitar string too hard, it would look similar.

HARRIS: The theory had immediate appeal. How tidy to think that all the fundamental particles, like quarks and gluons and leptons, were actually the same string, just vibrating differently. And all the forces of nature were just variations on this string theory.

Of course, there are a few odd problems with this. For example, string theory math suggests that there are nine or 10 dimensions of space, not just the three we perceive.

(Soundbite of cheering)

HARRIS: Back on the soccer field, the opposing team quickly scores a goal. The string theorists are stunned. They've never even been behind in the nine year history of this game.

And these days, the theorists are not only being challenged on the soccer pitch. In the past year, critics have written three books attacking the basic premise of string theory. Lawrence Krauss at Case Western Reserve University wrote one of them.

Dr. LAWRENCE KRAUSS (Case Western Reserve University): I kind of think of string theory as being like a promising young assistant professor, you know, who looks really smart. But we usually don't give them 30 years to produce something.

HARRIS: Sure, he says, their ideas are provocative. The problem is they are all unproven, and may be untestable with the current technology. By some reckoning, you'd need an atom smasher the size of the galaxy to see strings directly.

Dr. KRAUSS: As I like to say, there's at this point as much experimental evidence that quarks are made up of little pink elephants as they are of strings. So I think that it behooves us to be honest and not claim for our theories more than we produce, because ultimately that's going to come back and bite us.

HARRIS: And string theory has grown vastly more complicated over the past few decades. Every time a new problem arises, string theorists weave astonishing new and complicated explanations to get around them.

For example, the theorists get around one problem by saying there are more universes out there than there are atoms in our universe. Krauss says it's hard to know whether to be amazed that we live in such a bizarre place or worried that theorists have lost their way.

Dr. KRAUSS: To the extent that we even understand string theory, it may imply a massive number of possible different universes with different laws of physics in each universe and there may be no way of distinguishing between them or saying why the laws of physics are the way they are. And if I can predict anything, then I haven't explained anything. If I have a theory of everything, then in some sense, I have a theory of nothing.

HARRIS: And on the field, the string theorists are still out of sync.

Dr. KIRSHNER: Okay. That's the first half.

(Soundbite of whistle)

Dr. KIRSHNER: The score is what?

HARRIS: At the half, the score is two to one, with the string team losing and looking none too happy about it. Referee Bob Kirshner comes to the sidelines for a beer.

Dr. KIRSHNER: There was actually a brief moment where someone was playing with skill, and I blew the whistle immediately to stop the game, because that was way overboard.

HARRIS: David Gross, the director of the Kavli Institute for Theoretical Physics and the picnic's benefactor, is concerned that the game will end before the meat is off the grill.

Dr. DAVID GROSS (Kavli Institute for Theoretical Physics): We've got to keep going until 5:00.

Dr. KIRSHNER: I know that. We'll give them 10 minutes. And then we'll play. You know how it is. It's not only the time on the clock, there's the out of bounds time, there's the injury time, there's the relativistic correction.

HARRIS: The institute director occupies a curious place in the string theory debate. Gross won a Nobel Prize a few years ago for work in a conventional branch of theoretical physics. But now he's a strong proponent of string theory.

Dr. GROSS: Even those of us who work in the field aren't really sure what string theory is or what it's going to be. So when you're in this kind of speculative, exploratory science, it's important to have faith, because you're out on a big limb. So I think it's really a question of whether we believe this is the right direction. And that I do believe rather firmly.

HARRIS: Gross has heard all the criticisms of string theory and he has ready rebuttals.

Dr. GROSS: One is rather flippant but correct, and it's that there's nothing else. There's no other game in town.

HARRIS: Nothing else, in his view, really provides a way to think about the biggest and most interesting problems in physics.

Dr. KIRSHNER: Okay. Quarter kick. Now stay away from that garbage.

HARRIS: Back on the soccer field, things are still looking grim for string theorists.

Santa Barbara scientist Steve Giddings is pacing on the sidelines.

Dr. KIRSHNER: Getting nervous, Steve?

Dr. STEVE GIDDINGS (University of California Santa Barbara): We'll give them some more time. We'll start using the extra dimensions to catch up.

HARRIS: Okay, so string theory jokes tend toward the obscure.

Giddings is actually feeling somewhat more optimistic about the fate of string theory these days. That's because in a year or two, a powerful new atom smasher will open up near Geneva, Switzerland. And there is at least a remote chance that the accelerator can finally provide some real evidence for string theory.

Dr. GIDDINGS: The best we'll probably do is get some indirect hints for what string theory is all about. But then there's always this jackpot scenario where we could actually start seeing direct evidence.

HARRIS: Giddings says if the strings turn out to be relatively large, particle collisions in this accelerator could start to pluck the string of gravity, if you will. And if the scientists are extraordinarily lucky, Giddings says black holes could form and then quickly evaporate.

Dr. GIDDINGS: So it's not something that we would worry about in the context of, say, planet Earth, but we would really see these as very unusual looking events in the particle detectors there.

HARRIS: And string theory would not only be vindicated, but great excitement would ensue. Even most string theorists say this is a real long shot.

Now the question is whether they can even hit the jackpot on more comfortable turf: the soccer field.

With moments left, the game is tied at two.

HARRIS: Suddenly, string theorists get a huge break. One of the guys on the opposing team thinks play has stopped, so he picks up the ball. String theorists get a penalty kick.

They score, keeping intact their perfect record - on the soccer field, at least.

(Soundbite of whistle)

HARRIS: Kavli Institute director David Gross looks on approvingly from the sidelines.

Dr. GROSS: Proves string theory is right.

HARRIS: So that's what it takes, huh?

Dr. GROSS: We have experimental confirmation.

HARRIS: And he'll take the win any way he can get it.

Richard Harris, NPR News.

Dr. GROSS: The guy picked up the ball. What can I say? I'm pretty familiar with that, you know, at that level.

Unidentified Man: Shall I pay you off now?

Dr. GROSS: Not here, not now.

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