Monday, March 14, 2005

String controversy reaches the public

This is the first time I've seen these issues discussed in the popular press (SF Chronicle). (I found this link via Peter Woit's blog; he is quoted in the article.)

I have to say both critics and defenders of string theory make valid points in the article. It is not implausible to me that it could take generations to sort out any theoretical model of quantum gravity. On the other hand, how will we ever know whether a proposed model is right or wrong without experimental input? In order for the subject to qualify as scientific, there must be falsifiable predictions. This doesn't seem to be the case with string theory - in fact, things are moving in the wrong direction with the discovery(?) of more than 10^{100} possible vacua, each with different low-energy physics.

I am not against some number of theorists studying string theory, but by now most of the top departments in the world have string theory groups. If I had to guess I would say resources within theoretical physics are over-allocated to string theory. Even its supporters admit the work is speculative, and unlikely to be subject to experimental test in the near future. This being the case, why are funding levels for string theory research not closer to those in math departments, rather than physics departments? (Physicists, even theorists, generally teach less and get bigger grants than mathematicians. Shouldn't the stringers be lumped with the math guys until they come up with actual testable predictions?)

Nature's guiding hand manifests itself in the form of experimental data. Without this guidance, theoretical physics is in danger of reverting to a subjective field dominated by trends and fashion, like the humanities and social sciences.

Those interested in a sociological analysis of the political and cultural economy of the academic field should read the work of Pierre Bourdieu, who argued that academics mainly fight over the "power to consecrate" - that is, the power to determine which subjects or approaches are deemed worthy or unworthy. This is exactly what I see going on in quantum gravity these days.

My earlier posts on this topic are here and here.
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9 comments:

Anonymous said...

Wonderful. Much to think about as usual :) I avoid ever so clever string remarks, for now.

Anne

9:29 PM
Anonymous said...

Steve, I agree.

I think this is one reason NOT to embark on a career in theoretical physics (unless one believes in current trends) :)

Early on in grad school, it was clear to me (especially after SSC cancellation), that experimental guidance in high enegy physics could be unlikely in my lifetime. So I decided to move on to something else.

But it is sad to see the hype for certain subjects (like string theory) far outstripping what it has accomplished. There are too many popular books on the subject (soon to be more). I contrast that with "The Second Creation" where the achievements discussed were truly outstanding, and true science.

This hype is going to cause great damage to public's perception of objective nature of physics and the opinions of physicists.

MFA

12:55 PM
Steve Hsu said...

MFA,

I agree with you 100%. The claims made by string theorists might eventually undermine confidence in particle physics on the part of other scientists or even the general public.

Well-informed person with long memory, in 2020: "Gee, where is that extra dimension I was promised?" "Weren't we supposed to have a TOE by now?" "Well, I guess I can just ignore what those (string-)theorists tell me, no matter how excited they seem."

1:22 PM
Carson C. Chow said...

I rather like the fact that
there are 10^100 possible
low energy universes. It actually tells me that they have a glimmer of a chance to be right. If it predicted one theory I would think it was complete hogwash. That being said, it also goes with my suggestion that string theory even if completed and correct will say nothing about how our universe operates at large scales. It will just be a microscopic theory like the way quantum mechanics is the microscopic theory for economics. True but not useful.

2:32 PM
Anonymous said...

You are being pretty generous, lumping the stringers with mathematicians instead of philosophers.

6:30 PM
Anonymous said...

http://www.nytimes.com/2004/12/07/science/07stri.html?ei=1&en=e879d0ced0149fb8&ex=1111928394&pagewanted=all&position=

String Theory, at 20, Explains It All (or Not)
By DENNIS OVERBYE

ASPEN, Colo. - They all laughed 20 years ago.

It was then that a physicist named John Schwarz jumped up on the stage during a cabaret at the physics center here and began babbling about having discovered a theory that could explain everything. By prearrangement men in white suits swooped in and carried away Dr. Schwarz, then a little-known researcher at the California Institute of Technology.

Only a few of the laughing audience members knew that Dr. Schwarz was not entirely joking. He and his collaborator, Dr. Michael Green, now at Cambridge University, had just finished a calculation that would change the way physics was done. They had shown that it was possible for the first time to write down a single equation that could explain all the laws of physics, all the forces of nature - the proverbial "theory of everything" that could be written on a T-shirt.

And so emerged into the limelight a strange new concept of nature, called string theory, so named because it depicts the basic constituents of the universe as tiny wriggling strings, not point particles.

"That was our first public announcement," Dr. Schwarz said recently.

By uniting all the forces, string theory had the potential of achieving the goal that Einstein sought without success for half his life and that has embodied the dreams of every physicist since then. If true, it could be used like a searchlight to illuminate some of the deepest mysteries physicists can imagine, like the origin of space and time in the Big Bang and the putative death of space and time at the infinitely dense centers of black holes.

In the last 20 years, string theory has become a major branch of physics. Physicists and mathematicians conversant in strings are courted and recruited like star quarterbacks by universities eager to establish their research credentials. String theory has been celebrated and explained in best-selling books like "The Elegant Universe," by Dr. Brian Greene, a physicist at Columbia University, and even on popular television shows.

Last summer in Aspen, Dr. Schwarz and Dr. Green (of Cambridge) cut a cake decorated with "20th Anniversary of the First Revolution Started in Aspen," as they and other theorists celebrated the anniversary of their big breakthrough. But even as they ate cake and drank wine, the string theorists admitted that after 20 years, they still did not know how to test string theory, or even what it meant.

As a result, the goal of explaining all the features of the modern world is as far away as ever, they say. And some physicists outside the string theory camp are growing restive. At another meeting, at the Aspen Institute for Humanities, only a few days before the string commemoration, Dr. Lawrence Krauss, a cosmologist at Case Western Reserve University in Cleveland, called string theory "a colossal failure."

String theorists agree that it has been a long, strange trip, but they still have faith that they will complete the journey.

"Twenty years ago no one would have correctly predicted how string theory has since developed," said Dr. Andrew Strominger of Harvard. "There is disappointment that despite all our efforts, experimental verification or disproof still seems far away. On the other hand, the depth and beauty of the subject, and the way it has reached out, influenced and connected other areas of physics and mathematics, is beyond the wildest imaginations of 20 years ago."

In a way, the story of string theory and of the physicists who have followed its siren song for two decades is like a novel that begins with the classic "what if?"

What if the basic constituents of nature and matter were not little points, as had been presumed since the time of the Greeks? What if the seeds of reality were rather teeny tiny wiggly little bits of string? And what appear to be different particles like electrons and quarks merely correspond to different ways for the strings to vibrate, different notes on God's guitar?

It sounds simple, but that small change led physicists into a mathematical labyrinth, in which they describe themselves as wandering, "exploring almost like experimentalists," in the words of Dr. David Gross of the Kavli Institute for Theoretical Physics in Santa Barbara, Calif.

String theory, the Italian physicist Dr. Daniele Amati once said, was a piece of 21st-century physics that had fallen by accident into the 20th century.

And, so the joke went, would require 22nd-century mathematics to solve.

Dr. Edward Witten of the Institute for Advanced Study in Princeton, N.J., described it this way: "String theory is not like anything else ever discovered. It is an incredible panoply of ideas about math and physics, so vast, so rich you could say almost anything about it." ...

7:09 PM
Anonymous said...

http://www.nytimes.com/2005/01/04/science/04edgehed.html?ei=1&en=c8ae1177876f5e58&ex=1111928472&pagewanted=all&position=

Philip W. Anderson
Physicist and Nobel laureate, Princeton

Is string theory a futile exercise as physics, as I believe it to be? It is an interesting mathematical specialty and has produced and will produce mathematics useful in other contexts, but it seems no more vital as mathematics than other areas of very abstract or specialized math, and doesn't on that basis justify the incredible amount of effort expended on it.

My belief is based on the fact that string theory is the first science in hundreds of years to be pursued in pre-Baconian fashion, without any adequate experimental guidance. It proposes that Nature is the way we would like it to be rather than the way we see it to be; and it is improbable that Nature thinks the same way we do.

The sad thing is that, as several young would-be theorists have explained to me, it is so highly developed that it is a full-time job just to keep up with it. That means that other avenues are not being explored by the bright, imaginative young people, and that alternative career paths are blocked.

Anne

7:27 PM
Anonymous said...

Both from me :) Blogger is slower than snails.

Anne

7:28 PM
Anonymous said...

I assume that the article

"String Theory, at 20, Explains It All (or Not)"
By DENNIS OVERBYE

is a joke of sorts.

"They had shown that it was possible for the first time to write down a single equation that could explain all the laws of physics, all the forces of nature - the proverbial 'theory of everything' that could be written on a T-shirt."

What a whopper!!! It is scary thinking this article may have gone out to innocent people who don't have the technical background to understand such claims are bogus.

8:27 PM

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