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String Theory a Disaster for Physics?
BlueCup writes "Mathematician Peter Woit of Columbia University describes string theory in his book Not Even Wrong,. He calls the theory 'a disaster for physics.' Which would have been a fringe opinion a few years ago, but now, after years of string theory books reaching the best sellers list, he has company."
I think ST is a very interesting and peculiar theory. I'm not sure it's a disaster. Even if ST is proved wrong in some way the math that resulted from ST is still worthwhile. However I think Woit's point is metascientifical, in that string theorists get more funding than those who are trying to provide alternatives to ST. That ST has become somewhat of a marketing term. This is surely damaging but again science is not excluded from human frailty.
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That's not the point. I could postule my own theory about microscopic gremlins holding atoms togheter, and, if physical observations match my theoric results, no one could really argue about its validity. In that sense, string theory could be as valid as any other modern theory.
The most important part of new theories is the verification of predicted results - that's it, things that should happen theoretically but we haven't seen (yet). I don't know about ST, to be honest, but, for example, Heim theory (which aims to be a "theory of everything") made some interesting predictions that haven't been put to test yet; one involved localized antigravity created by rotating electromagnetic fields and another predicted a couple of unseen new particles, if i'm not mistaken. I'd love to see someone try to verify them.
I am a cosmologist, albeit one who works "close" to string theory (I am not a string theorist, but many of my collaborators are), and I am familiar with Woit's arguments (and have met the gentleman himself several times).
However, my impression -- and I speak as someone who works inside a particle theory group, and who has served on faculty-level particle physics search committees -- is that string theory is far from having a "lock" on theoretical particle physics today. In the article, Woit is quoted as follows: "By his count, of 22 recently tenured professors in particle theory at the six top U.S. departments, 20 are string theorists." Looking at the Particle Physics Rumor Mill (http://physics.wm.edu/~calvin/) which assembles the short lists for faculty jobs in particle theory many of (and perhaps most) the people getting offers are not "hard core" string theorists. Many of them will have written papers with some string content, but have wider interests in cosmology, particle phenomenology, and/or physics "beyond the standard model".
This statistic differs from Woit's, in that it is not just counting "top" physics departments, and looks at Assistant Prof hires, and not tenured faculty (although *outside* the top six, most Assistant Profs can expect to be promoted to tenue). However, I suspect that the "twenty out of twenty two" statistic is either over a very carefully chosen interval, or reflect a very broad definition of who counts as a "string theorist".
My feeling is that string theorists have a *hard* time getting jobs. In general, many places outside the top ten (ande most of the jobs are outside the top ten) do not have string theorists on their faculty, and string theorists have a hard time differentiating themselves from other people in their field, which makes it hard for them to get hired -- especially as they are competing against other, very smart people.
The real issue here is that particle physicists have received no "surprises" in many years -- perhaps the only genuinely unexpected recent data point being the non-zero value of the cosmological constant. And this did not create a new problem, since the challenge for the theoretical community was always to explain why the CC was around 10^120 times smaller than its "natural" value, which is not much easier than explaining why it is actually slightly different from zero. In this enviroment, we have no good way to "prune" theoretical ideas, and the hope of many is that the LHC (Large Hadron Collider) will yield results that cannot be explained within the context of the so-called "standard model" of particle physics. In this sense *any* theoretical framework that had been worked on since the mid 1970s would risk falling into the same trap as string theory, since there is no data we can't explain with existing models -- if it was incompatible with the standard model it would have been dead on arrival, but any model which yields the standard model in some limit is not falsifiable with current data.
On the other hand, string theory does provide a rich mathematical structure with some very surprising results. The so-called "AdS/CFT" correspondence sets up a completely unexpected relationship between gravity and a particular class of field theories, and some calculations in QCD (the theory of the "strong" nuclear interaction) can be "organized" and performed using string theoretic ideas. This does not "test" string theory, but it does show that there are deep and unexpected consequences to what is ultimately a very simple idea and, in the absence of data, this motivates theoriests to keep working in this area.
The statement that string theory makes no testable predictions does not necessarily limit its usefulness. As I understand it, the mathematics behind quantum theory and relativity are irreconcilable, in that they lead to infinities and singularities when extended into each others' domain. The brilliance of string theory is that it provides a general framework that encompasses both quantum theory and relativity, and thus it may be a superset of the "true" framework of the universe, if not the most concise description. The idea that string theory is "bad science" only because our universe may be one of 10^500 possible configurations (and string theory can't predict which one it is) is like saying that statistics is bad science because it can't predict the exact run of cards I'll have at my next poker game. The development a framework within which our observed universe is possible at all (which cannot be said of relativity or quantum theory) is a tremendous achievement in itself.
Think of it this way. Many theorists predict that our universe may be one of many (e.g., in a much larger "multiverse"), and these universes are not all expected to be identical. Therefore, the variations between them represent quantities that are not exactly "predictable" by any theory, and the best we can hope for is a meta-theory that describes all possible universes, and says that ours is one of them. The earth is not the center of the universe; the prediction of string theory may simply be that our universe is not the center of the universe, so to speak.
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Newtonian gravity came about because Newton had an idea and then used math to express it. Relativity came about because Einstein had an idea and then used math to express it. Quantum physics came about in a similar fashion. An idea (or ideas) and then math to express it (them).
The problem with string theory is that some equations came along that fit the data in an intriguing way and so physicists pursued and continue to pursue the math. The problem is, it's not based on some sort of idea that someone had. The idea is the thing that's missing. Math is great at expressing ideas, but it's not particularly good at creating them.
It could be that at some point, someone will come up with an underlying conceptual idea that the math can then be used to express, but until that happens, I don't think string theory is really going to become a practical theory.
It depends on whay you mean by knowing everything. Knowledge can be somewhat compressed in comparison to raw reality. I can describe the chemical characteristics of a grain of salt in much less space than it would take to map the precise location of every single atom that makes it up. If I'm discussing the solubilty of salt in water, that level of detail is potentially superfluous. For the vast majority of purposes, much of the information in the universe is trivial and of no deep meaning except in aggregate. Atmospheric physics is complicated (Navier-Stokes equations, Rossby number, adiabatic lapse rate and the like), but the gross principles can become reasonably well understood. Applying this knowlege to global weather prediction is something else entirely, and is in that theatre in which the prohibitively comprehensive level of detail can become a problem if you desire extreme levels of precision. The same situation may well be applicable to the fundamental laws of the universe. We may be able to comprehend them without having to know the entire, exhausive state of everything.
Well, you forgot one other thing about science: If my science says that a "cat" by definition has a tail, then these things you call "cats without tails" aren't actually "cats" at all, but something else, perhaps yet to be named.
I have no idea why I felt the need to bring that up.
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Both God and String Theory have the same problems for the scientific method - neither of them is falsifiable - and neither makes predictions about things we don't already know that we can actually go out and test.
So (as a scientist) there is very little point in thinking about either of them for very long because they simply don't get you any further in making workable personal jet packs, or any of the other fun stuff that science is generally so good at.
Falsifiability is a reasonable requirement. It says: "OK Mr. Proponent of God/StringTheory. tell me one experiment I could reasonably consider doing that (if it hypothetically failed) would prove that God/Strings definitely doesn't exist." But there IS no such test for either thing. String theory is just so very flexible that it can accomodate almost any failed experiment by picking another one of the ten-to-the-power-500 possible variations on how space is wrapped up, and experiments that might manage to disprove it appear to require more energy than the entire universe contains in order to perform them. Meanwhile, God is claimed to be utterly omnipotent - so any experiment we think up to prove that he's not there, could merely be written of as him "testing our faith".
Lack of falsifiability doesn't prove or disprove a theory - it just makes the theory worthless for science.
So it's fine to believe in God and be a scientist - so long as you realise that your theory of the universe isn't going to help you make personal jet packs (which you still owe me by the way!).
If somewhere in all the religious texts it said "God can do absolutely anything EXCEPT make purple stars" - then we could all get out our telescopes and go look for purple stars. If we ever found one then the case would be closed. If we never found one - then we still wouldn't know for SURE that there was a God - but ultimate proof isn't something science can ever really provide. But as it is, we are told by the proponents of the God theory that he can do absolutely anything he likes - and we know that if he does exist then he has no compunction in planting REALLY convincing bogus evidence for the big bang just to "test our faith". So we can't make ANY predictions about God whatever and any theory that includes him in any way whatever is useless for our progress. If we employ our belief in God, we can't make a computer that works reliably because God might decide he doesn't like us calculating PI to a bazillion places so the machine would be useless for all practical purposes. We can't find out whether there was life on Mars because he does stuff like burying really convincing solid stone dinosaur bones to try to cheat us into a belief in evolution when he knows full well that it's not true. A world with a God in it is simply not open to doing any kind of useful science - so if we'd like to have personal jet packs (sorry to keep harping on about those - but really, they are a bit overdue), we'd better put God theories to one side while we're designing them. If we used a God-based universe as our model, the only really plausible way to get jet packs is to sit on our backsides and pray for them to materialise out of thin air.
String theory has similar problems - and I could understand why people are beginning to think it's a waste of time for such a large proportion of Physicists to be working on it. The theory is at the point where it certainly COULD be true - but if it doesn't tell us anything we don't already know and there's no way for us to ever disprove it - then it's just not very useful.
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That's actually an interesting point. If "cats", by definition, always have tails, then the statement "all cats have tails" is simply an arbitrary definition of "cat", rather than a useful scientific theory.
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My officemate pointed me to a paper the other day where the authors (Distler, Grinstein, and Rothstein) were saying it might be possible to falsify strig theory with WW and ZZ scattering measurements (although they don't talk specifically about these measurements at LHC). The paper is on lanl.gov and the reference is hep-ph/0604255. I'm not a theorist, but it looks to me like the basic argument is that if there is no light higgs, and certain bounds on the WW and ZZ cross-sections are not satisfied, then the S-matrix is either non-analytic, non-unitary, or not Lorentz invariant at some scale. And the authors say that since string theory is constructed to satisfy these assumptions at all scales, it would be invalidated if one of them were not correct.
But I do find it rather amusing that you'd have to give up something like Lorentz invariance or unitarity to disprove string theory.
The picture I have of gravity is that of a field, not a connection between the Sun and the Earth. So when the Earth is moving, it's changing its position in the sun's gravitational field. That field is spherically symmetric - so as long as you're at the same distance from the sun, you experience the same force - hence no matter where the Earth is, it's experiencing a force pulling it towards the present position of the sun.
Only when the gravitational field is not spherically symmetric, or if it is time-dependent, do complicated things start to occur.
Note that it doesn't matter if you're thinking in an Earth-centric way, or a Sun-centric way - they're equivalent, although the Earth-centric view is more complex.
First off, I should note that I am a nuclear/particle physicist so I actually know something about this stuff.
Yeah, the vast majority of string theory is probably crap. But what people don't seem to realize is that 99% of what all theorists say is crap. That 1% that actually manages to get something right gets all the fame and tends to be the only ones the general public hears about, but the sad truth is that most theorists take the shotgun approach: They try to come up with as many different theories as possible in the hope that one of them might actually turn out to be right.
The article seems to imply that the existence of string theorists is preventing advancement in particle physics. That's BS. The reason why there haven't been any new dramatic discoveries in particle physicists in the past few years is because there haven't been any new experiments! Science is experimental in nature. Progress is made with new experiments. The theorists can speculate all they want but no consensus will be reached until somebody tests it. Unfortunately experiments in particle physics have become so massive and expensive that progress has slowed significantly.
Actually, there have been many discoveries in less traditional aspects of particle physics...neutrino mass for instance. So I'm not even entirely sure what the article is complaining about. Yeah, traditional accelerator experiments haven't done much since the discovery of the top quark at Fermilab, but again it's because there haven't been any new experiments since then. Other than RHIC, which focuses on a very different kind of physics (and RHIC has also been producing many interesting new results).
When the LHC finally comes online expect a flurry of new discoveries. Until then the theorists can speculate all they want. If they weren't wasting their time on string theory they would be wasting their time on something else.
Physics is good