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String Theory Predicts Behavior of Superfluids
schrodingers_rabbit writes "Despite formidable odds, condensed matter physicists have made a breakthrough most thought impossible — finding a practical use for string theory. The initial breakthrough was made by physicist and cosmologist Juan Maldacena. His theory states that the known universe is only a 2D construct in anti-de-Sitter space, projected into 3 dimensions. This theory manages to model black holes and quantum theory congruently, a feat that has eluded scientists for decades; but it fails to correspond to the shape of space-time in the known universe. However, it does predict thermodynamic properties of black holes, including higher-dimensional viscosity — the equations for which elegantly and almost exactly calculate the behavior of quark-gluon plasma and other superfluids. According to Jan Zaanen at the University of Leiden, 'The theory is calculating precisely what we are seeing in experiments.' Unfortunately, the correspondence cannot prove or disprove string theory, although it is a positive step." Not an easy path to follow: one condensed matter theorist said, "It took two years and two 1000-page books of dense mathematics, but I learned string theory and got kind of enchanted by it. [When the string-theory related] thing began to... make predictions about high-temperature superconductors, my traditional mainstay, I was one of the few condensed matter physicists with the preparation to take it up."
Enlighten me, why would proving a theory that is another step toward a GUT be a negative step?
Very simple explanation - nothing in the universe builds humility like an education in physics. If you don't walk out of a physics degree feeling like you know less than you did when you started, like all you've done is build layer upon layer of model and gained only modest flashes of insight into reality after marathon sessions of math, then you've done something wrong.
Any statistician will tell you that if you put enough free parameters in a model, you can calibrate it to the given data. Admittedly, string theory has some impressive parts to it, but it seems like it's just excess parameter fitting for a class of models that can all explain roughly the standard model.
But if somebody does come up with a particular string-theoretic model with new, testable implications that get verified that would be impressive - it would certainly indicate that they are barking up the right tree rather than just working on a pleasant geometric abstraction that can be set up to reduce to the messy realities of our fundamental forces and particles.
Gah! That's so common in technical topics on Wikipedia. The problem is that it is is written by undergrads and interested amateurs (I know, I'm one of them). Often they don't know the subject well enough to simplify it for a general audience, and are stuck putting it in the same language they learned it in. Simplifying a complex topic generally takes quite a degree of mastery, in order to know which simplifications are justifiable, and which would distort the concept too much.
Also, I think sometimes they like to show off by writing things people can't understand.
but then complain:
If theorists are continually modifying their theories in order to fit with experiment/reality, and rejecting theories that don't fit with experiment/reality, then what's the problem? At that point it's not "just math", it's "math that correctly matches reality and makes predictions", which is the gold-standard in physics.
Now, you may disagree with the particular mathematical formalisms the theorists are investigating, or the particular order in which they are checking them... but I don't understand how you can be upset at them for continually making changes in order to fit their theories with reality. That's what theorists are supposed to do: investigate a wide and wild variety of mathematical theories, and see which ones are able to make useful predictions consistent with experiment.
Again, this is an objection of procedure. If you can think of a faster way to uncover a mathematical theory consistent with all known experiments, then describe it. Until then, what's wrong with theorists checking a wide variety of theories (adding and subtracting terms/elements/dimensions as they go) until they find one consistent with observed reality?
(And of course, in reality theorists are not performing the random-walk through theory-space you describe. They have very good reasons for checking the equations they do; their analysis is informed by many experimental results, previously-successful theories, and the structure of mathematics itself.)