Slashdot Mirror
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."
That is to say, if you view that the proving of string theory to be true a positive step.
I'm always amazed that theoretical physicists can manipulate such immensely complex abstract objects in their heads and still be able to breathe and maintain bladder control. It really makes software engineering look like a piece of piss. Much respect.
I would also say that having worked with academic medics, chemists, mathematicians, computer scientists and biologists, physicists are almost always the coolest, most down to earth and least douchey scientists out there.
Umm, you've just described all scientific progress both past, present, and future...
the known universe is only a 2D construct in anti-de-Sitter space, projected into 3 dimensions
Well if THAT'S all it is, I see no reason to upgrade my video card.
Rich And Stupid is not so bad as Working For Rich And Stupid.
String theory works because the math works. There isn't anything special about the string theorists' model of humming cosmic strings that makes it work. All particle behavior is explainable using mathematics.
What makes this interesting is that the model allowed for the construction of mathematical constructs that explain the behavior correctly. But it still doesn't say anything about the predictions that the model completely blows.
What String Theory has, more than anything else, is a great set of marketeers behind it. Michio Kaku is a smart and articulate guy. It's not the steak, it's the sizzle.
on page 642 of the second book, they divide by zero, so back to the drawing board.
The Maldacena duality can't be used to 'make predictions' with a string theory, its just a correspondence between a string theory and a conformal field theory. It's useful because sometimes calculations which are hard in a CFT can be made in the corresponding string theory which is sometimes easier (or vice versa). It cannot be used to support the physical validity of some string theory.
That's because your mind is still constrained by our 2D universe.
I'm sorry, I'm not familiar with "pc keyboards back-to-back" as a system of measurement, could you translate that into Football Fields for me?
Rule of Slashdot #0: You and people like you are not representative of the larger population. - A.C.
The holographic principle doesn't mean that the universe has only 2 spatial dimensions, but rather that the universe can be modeled using one less degree of freedom than our view of spacetime would imply. Again, these kinds of theories are not suggesting that our space is two-dimensional, rather they are saying that the 3 dimensions we observe are emergent from a lower-dimensional description. All of the 'information' in a given region of space can be described as being encoded in the surface of said region.
This remarkable, if bizarre, conclusion gains considerable support from the fact that black-hole entropy (and entropy is a measure of information content) is related only to the surface area of the black hole. So this is a case where we know with some confidence that we can indeed reduce all the information about a 3D region of space (the black hole) to an expression that only relies on 2 dimensions (the surface of the black hole). The holographic principle appears in numerous theories that imply that this holds generally for any region of space, not just black holes.
Now, whether you view this is 'just a mathematical trick' or 'a deep insight into the actual structure of the universe' is in some sense a matter of taste. (The same goes for all other physical theories: e.g. do electrons exist or are they just mathematically-useful constructs? How about photons? Gravity waves? Spacetime?) If you take the math seriously then this may mean that our universe is in some sense 'actually' 2-dimensional, with the three spatial dimensions we see being emergent instead of fundamental.
But in no case is the theory saying that there are not 3 spatial dimensions. The predictions it makes are for particles moving through a 3+1 spacetime.
Oh, I think you know the answer to that.
Is something burning?
Oh, it's my karma.
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.)
"Do you know string theory?"
"No, I'm a frayed knot."
"Omnis tuus capsa sunt inesse nos"