The Trouble With String Theory

By | June 24, 2006
2 Comments

This is about to get ugly (link requires paid WSJ subscription):

Nobel physicist Wolfgang Pauli didn’t suffer fools gladly. Fond of calling colleagues’ work “wrong” or “completely wrong,” he saved his worst epithet for work so sloppy and speculative it is “not even wrong.”

That’s how mathematician Peter Woit of Columbia University describes string theory. In his book, “Not Even Wrong,” published in the U.K. this month and due in the U.S. in September, he calls the theory “a disaster for physics.”

Interesting. Of course, I knew that string theory has its critics, but isn’t this excessive? What is the objection, precisely?

String theory, which took off in 1984, posits that elementary particles such as electrons are not points, as standard physics had it. They are, instead, vibrations of one-dimensional strings 1/100 billion billionth the size of an atomic nucleus. Different vibrations supposedly produce all the subatomic particles from quarks to gluons. Oh, and strings exist in a space of 10, or maybe 11, dimensions. No one knows exactly what or where the extra dimensions are, but assuming their existence makes the math work.

String theory, proponents said, could reconcile quantum mechanics (the physics of subatomic particles) and gravity, the longest-distance force in the universe. That impressed particle physicists to no end. In the 1980s, most jumped on the string bandwagon and since then, stringsters have written thousands of papers.

But one thing they haven’t done is coax a single prediction from their theory. In fact, “theory” is a misnomer, since unlike general relativity theory or quantum theory, string theory is not a concise set of solvable equations describing the behavior of the physical world. It’s more of an idea or a framework.

Partly as a result, string theory “makes no new predictions that are testable by current — or even currently conceivable — experiments,” writes Prof. Smolin. “The few clean predictions it does make have already been made by other” theories.

When I read that, I can’t help but be reminded of some of the arguments raised against intelligent design. It has been described as not so much a theory as a critique of the Darwinian model. One reason it falls down as a theory is that it can’t make predictions.

But surely, this weakness in string theory would have been evident from the beginning? How is it that the scientific community is able to quickly dismiss one proposition for having a particular weakness while spending years fiddling around with an idea that suffers from, essentially, the same weakness?

Well, I’m painting in almost ridiculously broad strokes here. Obviously, string theory and ID are not the same. There is no questionable group like the Discovery Institute pushing string theory; string theory isn’t joined at the hip with a pseudoscientific movement like Creation Science; no one is fighting to have string theory taught in schools for religious reasons.

But then again — none of those issues go to the merits of the case. If scientific methodology and the scientific community were as objective as they are generally presented to be, would intelligent design have recived the same kind of hearing that string theory has before being rejected? (Not to say that string theory is about to be rejected. This is just one book, after all.)

The answer: no. ID would never have been as warmly welcomed as string theory. This is partly due to the fact that ID commits the much more egregious error — from the standpoint of mainstream science — of allowing for the possibility of some reality outside of that which can be accounted for in purely naturalistic terms. Moreover, it has this overall guilt-by-association relationship with red states and bad haircuts and people who go to church.

Unfortunately, the second part of that equation is the reason why even a purely naturalistic take on some of the same ideas presented in ID — for example, the selfish biocosm hypothesis — is not likely to get a fair hearing. It turns out that science is subject to the assumptions and prejudices of the scientific community.

Fortunately, given time, it is a self-correcting model.

  • Karl Hallowell

    Actually, even if String Theory never really generates a theory with accurate and novel physical predictions nor achieves the formal rigor of mathematics, it still is quite interesting from the mathematical point of view. It has implications for differential geometry and topology. For example, the construction of several classes of topological invariants (things which don’t change under transformations of the space in a continuous way). And some slick structures, eg, exactly six 10-dimensional distinct models of superstrings (string theory plus supersymmetry between boson and fermion objects) that in turn are special cases of an 11-dimensional theory (“M theory”).

    Also, I dimly recall some types of perturbation of particular differential geometry objects lead to string theories.

    My take is that most of the effort in modern superstring theory is merely in understanding the mathematics of the structure of the theory. They are a long ways off from a genuine application of the theory to the real world unless experimentalists can jump to experimenting at the Planck scale where these theories would apply.

    One of the objections raised in the story is the dependence of the theory on which local minimum (lowest energy state in the neighborhood) it resides in. Ie, the theory, if it applies to the real world, is probably at our scale trapped in some dip in what is called the “energy landscape”.

    The idea is that you have something similar to a surface in 3-dimensions with ripples and low lying pits. Left to its own devices, a very small marble with a minor amount of energy could be trapped in one of these pits. If you were to attempt to extrapolate the entire surface from the behavior of the marble in that pit, you might get the idea that the entire surface must be some sort of parabola centered at the pit since the little bit you could see looked like that. Your impression of the surface would be greatly dependent on where the marble was and how much energy it had.

    In our case, a genuine model of everything might be highly dependent on the Anthropic Principle. Ie, the pit we happen to be in is one that would support life, and more generally generates the physical laws we observe. At some point, the Anthropic Principle does intrude. After all, it’s doubtful that there’s a simple theory of existence that explains the innumerable conincidences that lead up to us discussing this subject here. But the question is are basic physical constants similarly dependent? Generally it’s undesirable from a theory viewpoint because that’s an extremely hard (assuming that you can at some point generate another local minimum somehow and observe it). And predictions of the theory can be iffy merely because you might have too much flexibility in the theory to ever make a firm prediction.

    On the other hand, future theories down the road may end up being special cases of string theories or vice versa, much as newtonian mechanics is a special case of both special and general relativity as well as some variants of quantum mechanics.

  • http://home.pacific.net.sg/~topchoice Huen

    String theories had at most a thirty years’ history. Why are its detractors so hasty in predicting its doom? In history there were well known hypotheses which never delivered the predicted results and yet these have not faced the onslaught of critics such as those faced by string theories. Why? Let me describe using two historically famous cases:

    (i) Erastosthene (276-196BC) – A sieve for prime numbers?

    A Greek mathematician named Erastosthenes of Cyrene (276-194 B.C.) discovered a clever technique called the “Sieve of Erastoshthenes,” for finding all primes below a given integers n.

    Erastosthenes had wrongfully labelled his technique as “Sieve of Prime Numbers” when in actual fact the technique should be labelled as sieves for composite numbers. This inappropriate description had misled number theorists in their endless search of the holy grail … a formula for predicting prime numbers. Up to this moment of writing, no one has succeeded in developing such a globally accurate formula. So Erastosthenes had led number theorists in a wild-goose-chase for more than twenty two centuries!

    (ii) Riemann’s hypothesis

    Riemann’s hypothesis predicts that there are deep connections between zeroes on the critical line and the distribution of primes but for more than a centuary this problem still remains unsolved. The problem is that no one could prove that all the infinitude of zeroes will lie on the critical line.

    Compared to the above two examples, why are we fussing over a trivial thirty year period in string theories? Time has changed. In Erastosthene’s and Riemann’s time, there was no Internet. So detractors would have difficulties airing their views. In fact the global formula for predicting prime numbers was successfully developed by the author using QNT which exploited quantum superpositions in its derivation. Unwittingly, Erastosthenes had discovered prematurely superposition algorithm used in quantum mechanics. Please visit: http://home.pacific.net.sg/~topchoice/index.html under the heading:
    Predicint The Prime Sequence

    Compared to the above two examples, why are we fussing over a trivial thirty year period in string theories? Time has changed. In Erastosthene’s and Riemann’s time, there was no Internet. In fact the global formula for predicting prime numbers was successfully developed by the author using Quantum Number Theory (QNT)which exploited quantum superpositions in its derivation. Unwittingly, Erastosthenes had discovered prematurely superposition algorithm used in quantum mechanics which only materialized in early 20th centuary. My opinion is that String theories had dropped into the 20th centuary when its birth should have been scheduled for the 22nd centuary. Do not harass these poor string theorists, give them time. Maybe a breakthrough could be imminent!

    Huen from Singapore