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."
Yeah... (Score:5, Interesting)
That is to say, if you view that the proving of string theory to be true a positive step.
Re:Yeah... (Score:5, Insightful)
Parent
Re:Yeah... (Score:5, Funny)
Enlighten me, why would proving a theory that is another step toward a GUT be a negative step?
Well, you see, string theory is very complex, but really in the 2d universe we truly live in, it can be considered a negative step, but you won't understand it, because your used to only experiencing the 2 real dimensions and the incredible faux 3rd dimension, which is a construct of our brains to understand the space which we perceive. Anyway, the point is, if you really understand string theory, you see the negative step. But if you're standing behind the theory, it's a positive step. It's all relative.
Re:Yeah... (Score:1) Mod Parent +1 WTF? POP-PHYSICS
Parent
Re:Yeah... (Score:5, Funny)
Ignignokt: You and your 3rd dimension.
Frylock: What about it?
Ignignokt: It's cute, we have five.
Err: Th-thousand.
Ignignokt: Yes, five thousand.
Err: Don't question it!
Frylock: Well, I only see two.
Ignignokt: Well, that sounds like a personal problem.
Parent
Re:Yeah... (Score:4, Informative)
Also, you were Educated Stupid [timecube.com]
Parent
Re:Yeah... (Score:5, Interesting)
Parent
Re:Yeah... (Score:4, Insightful)
You can't simplify something until you understand it. Once we have a GUT it will probably reduce to PIRcubed of the universe expanding.
Parent
Re: (Score:3, Insightful)
It taking another step towards that theory good?
If it's correct, then yes, of course. Good luck with your chicken finger theory!
Re: (Score:3, Insightful)
That is to say, if you view that the proving of string theory to be true a positive step.
Pardon me for the semantics, but no science/scientific theory can be "proven" - even the theory of gravity can't be proven. If I take a rock and drop it on my desk a million times, that doesn't prove that it'll fall there again on the 1e6+1th time. The same goes with the theory of evolution: nothing can prove evolution, but we just have a lot of evidence (fossils, experiments, etc.) that support it. A theory is supposed to make robust predictions, not sense. You can't understand science, you can only apply
Re:Yeah... (Score:5, Insightful)
Your point about semantics and the word proof is understood. Of course, you are conflating proof in a mathematical sense with scientific proof. Scientific theories are proven repeatedly, when testable predictions are confirmed. (This is the traditional use of the word in science) They can still be disproven, but scientific proof is very different than mathematical proof. Of course, proof in the common sense meaning of the word is a completely different idea, and yet a third thing. If you're going to make semantic points, make sure the words you use are the ones you want. "Proof" is a bad one to pick apart semantically, because there are a couple different meaning depending on context and meaning. (Yes, in the same context, the same word can mean 2 different things. That's language for you.)
Of course, you then stop making sense. One CAN understand science. See many comments of Feynman about just that point.You may think you are a scientist, but you seem to think about science a hell of a lot like an engineer.
Parent
Re:Yeah... (Score:5, Informative)
Parent
Re:Yeah... (Score:4, Informative)
This is what makes evolution ... neither makes concrete testable predictions.
Really?
http://en.wikipedia.org/wiki/Tiktaalik#Discovery
"It's one of those things you can point to and say, 'I told you this would exist,' and there it is."
Parent
Re:Yeah... (Score:5, Interesting)
However you can disprove a theory quite easily just by finding one case that doesn't fit with the theoretical predictions.
I'd recommend taking a class or two on the philosophy of science. As it turns out, this just isn't true.
A theory is not, generally speaking, a single predictive proposition. It is a set of propositions which, when taken together, imply a single prediction. Discovering that the prediction fails does not tell you which of the propositions is incorrect. It is almost certainly impossible to isolate the incorrect proposition experimentally.
This principle is known in the philosophy of science as the Quine-Duhem thesis. The underlying logic has been found to be quite sound.
And it coheres well with our normal intuitions about how science is to be done. If, for instance, we were to find a heavier-than-air object that falls up from a state of rest, we would not scrap the entire theory of gravity. We would realize that this is a special case and try to figure out what the correct way to modify it would be.
Parent
Wow (Score:5, Interesting)
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.
Re:Wow (Score:4, Insightful)
It's because they look at how huge the universe is, how much energy is in it, how long it's all been around, how long it will most likely continue to be around, then truly comprehend how small, short-lived, and insignificant they are in the grand scheme of things.
That kind of realization will humble anyone, no matter how smart they are.
Parent
Re:Wow (Score:5, Insightful)
"The grand scheme of things", yeah, I love how people compare themselves to the hole universe as if it somehow was the objective way to look at things.
I don't compare myself to the whole universe, I compare myself to elemental particles. In that tiny scheme of things, I'm giant made of tiny molecules that make up cells that make up tubes and organs and shit, which millions of organisms and such living in me. I'm a world of its own.
I'm being serious here, I don't get how people can go "oh look I'm so much smaller than the whole fucking universe, and so much younger too, that just blew my mind". I for one don't see how the size of the world you live in is relevant to what you are. That's just a misplaced point of view to look at yourself from. Also, I think it's just an exercise of mental masturbation in the dimensions abstractions department, i.e. it's hard to really picture to ourselves what large numbers really represent rather than just a bunch of zeroes, so the exercise of picturing how many times bigger than you the universe really is is humbling, but still completely irrelevant to your life. The universe could stop 50 kilometres up in the sky, it could be only 6000 years old, what would it change to you?
Parent
Re:Wow (Score:5, Insightful)
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.
Parent
Re:Wow (Score:4, Interesting)
Well, I didn't get my physics degree. I stopped trying after Quantum Mechanics freshman year. I love relativity, but I felt like Quantum Mechanics was using one mathematical equation to prove another one which is used to prove a third. And so on. Eventually, you could plot the course of an electron around a hydrogen atom, but helium was too complex. Of course, a contributing factor might have been that my University didn't check the course requirements and realize that I didn't have the right level of Math to take Quantum Mechanics. I still love physics, but I still don't like Quantum Mechanics. (I passed the course with a C, but I think the only reason I didn't fail is that there were only 3 students in the course and the professor didn't want to have a 33% failure rate.)
Parent
Re:Wow (Score:5, Interesting)
For me, I came out of my physics education with a realization that the world is far far far stranger than anything our everyday experience would lead us to believe. It has also left me with a strong sense that none of our knowledge is absolutely certain. That doesn't mean that I believe that our scientific theories are necessarily completely wrong, but rather that our current theories may very well be incomplete.
String theory is definitely interesting. Gaining even a glimpse into it is far more humbling than learning quantum mechanics, and that is saying something! Where it will lead is completely unknown. For all we know, string theory may turn into a dead end (or into a massively complicated labyrinth with nothing but dead ends). Or it may turn into an immensely powerful predictive tool. Who can tell?
There are alternatives to string theory that show promise in uniting quantum mechanics and gravity. I haven't fully digested this yet, but this paper summary [physorg.com] argues that space-time may have fractal elements that have the potential to predict both quantum mechanics and gravity.
The bottom line is that the universe is immense, and immensely complicated, and we are small. In such a universe, certainty becomes an absurdity.
Parent
Only a 2D construct in anti-de-Sitter space! (Score:5, Funny)
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.
Re:Only a 2D construct in anti-de-Sitter space! (Score:5, Funny)
In mathematics and physics, n-dimensional anti de Sitter space, sometimes written AdSn, is a maximally symmetric Lorentzian manifold with constant negative scalar curvature. It is the Lorentzian analog of n-dimensional hyperbolic space, just as Minkowski space and de Sitter space are the analogs of Euclidean and elliptical spaces respectively. It is best known for its role in the AdS/CFT correspondence.
- http://en.wikipedia.org/wiki/Anti_de_Sitter_space [wikipedia.org]
Well, glad that's cleared up!
Parent
Re:Only a 2D construct in anti-de-Sitter space! (Score:5, Funny)
Then my head asplode.
Thanks a lot!
Parent
Re:Only a 2D construct in anti-de-Sitter space! (Score:5, Insightful)
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.
Parent
Re:Only a 2D construct in anti-de-Sitter space! (Score:5, Informative)
"Also, I think sometimes they like to show off by writing things people can't understand."
Definitely. E.g. the intro for "dot product" says "It is the standard inner product of the orthonormal Euclidean space." If you're trying to work out what a dot product *is* then that is a completely useless and confusing statement. Mathworld is usually much better than Wikipedia in this respect.
Parent
Re:Only a 2D construct in anti-de-Sitter space! (Score:4, Funny)
Parent
It's the math, stupid (Score:5, Interesting)
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.
Re:It's the math, stupid (Score:5, Insightful)
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.
Parent
Re: (Score:3, Informative)
Re: (Score:3, Funny)
Strings ARE flexible! You can even tie them in knots.
Re:It's the math, stupid (Score:4, Insightful)
So where's the competing theory, the one that explains things better, and is testable and whatnot? I hadn't heard that there really was one. My impression was that the one advantage the String theorists have is that they currently don't have any credible competition, though I confess that I haven't been keeping up with the debates.
Parent
Re:It's the math, stupid (Score:5, Insightful)
That's basically the, 'If you can't completely and convincingly prove my wild theory wrong, then it must be correct' argument.
"If God isn't real - then how do you explain ________"
'Well, I can't explain ________ but I'm saying that there are problems and contradictions in your religious beliefs like,'
"BWHAHAHA GOD EXISTS BECAUSE YOU CAN'T EXPLAIN WHAT STARTED THE BIG BANG".
A lack of a better theory doesn't make a theory right.
Parent
But... (Score:5, Funny)
on page 642 of the second book, they divide by zero, so back to the drawing board.
Re:But... (Score:5, Funny)
So far, Chuck's out there by himself.
Parent
Exciting (Score:4, Funny)
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.
Boy, long winter evenings must just fly.
Poster doesn't understand TFA (Score:5, Informative)
I lol'd (Score:5, Funny)
Explaining is not predicting (Score:3, Interesting)
Give it time (Score:3, Insightful)
Everybody gives string theory a hard time because it hasn't made any predictions, and because it can't be tested. Give it some damn time. It took ages before anyone could make useful predictions with quantum mechanics, and it was shunned for a while too (even by Einstein) and now it's an essential part of our scientific understanding. We shouldn't be so quick to cast out string theory either. Some time, eventually, maybe very far down the road (and if it turns out to be right), it too could be as useful as quantum mechanics has become. I wish scientists would just open their damn minds for once.
Re:Give it time (Score:4, Informative)
Planck's and Einstein's explanations for blackbody radiation and the photoelectric effect are generally not considered to be quantum mechanics. Essentially, they were phenomenological explanations for strange experimental data, and were not any sort of coherent, all-encompassing idea. Together with Bohr's model for the hydrogen atom, they are collectively referred to as the old quantum theory [wikipedia.org]. Actual quantum mechanics got its start with Heisenberg's matrix mechanics and Schrodinger's differential equation formalism. Their formalisms (which are equivalent) are what tied all of the disparate, baseless predictions of the old quantum theory together with a neat little bow we now call quantum mechanics.
But the GP should make no mistake: quantum mechanics began making useful predictions immediately. I suspect that they've simply mixed up QM and relativity, for it was relativity that was a "beautiful" theory without much experimental backing. At the time, it could do basically one thing: predict the anomalous precession of Mercury. That's why Einstein never won a Nobel Prize for his work on relativity, even though it was one of the biggest game-changers in the history of physics.
Parent
String Theory Predicts Something? (Score:3, Interesting)
The major problem with String/F/D/Dn/S/Brane/M/Multiverse/Whatever's-next Theory is that every time someone finds a problem that doesn't fit with experiments/reality they just go and find an excuse and then modify the equations until it mathematically works out in that general direction. They don't start with the latest and greatest and modify that. They just pick their favourite Theory-of-the-day and add an extra dimension here, or there, twist it there, or subtract another infinite from both sides, because the formula is inconveniently looking incorrect at the moment. In other words, Just squish the Jello a little here and make it come out over there instead, until someone discovers 'the new mess' on the floor.
If a theory has no basis in fact (i.e. no physical reality that can be described) then it is just Math. Math is not reality. You can model anything with Math, and it doesn't even have to exist.
Re:String Theory Predicts Something? (Score:5, Insightful)
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.)
Parent
an obvious joke (Score:5, Funny)
"Do you know string theory?"
"No, I'm a frayed knot."
Flying Spaghetti Theory (Score:3, Funny)
Spaghetti is tastier than string, and they could unify biology and physics with AdS/FSM spaces. How many dimensions has His Noodly Appendage?
Re:Science Fiction (Score:4, Insightful)
Umm, you've just described all scientific progress both past, present, and future...
Parent
Re:Science Fiction (Score:5, Funny)
Parent
Re: (Score:3, Insightful)
To be fair, the same could be (and was) said of Quantum Physics as well. Reality *is* fucked up after all.
Pity, Newton's equations were *so* much easier...
Re:Science Fiction (Score:5, Funny)
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?
Parent
Re: (Score:3, Insightful)
That's why this could be a big thing. If it's making actual testable predictions, you can almost call string theory a science. It's a massive breakthrough for the last decade of seemingly-pointless navel-gazing.
Re:Wow, the theory that matches all experimental d (Score:5, Interesting)
This remarkable, if bizarre, conclusion gains considerable support from the fact that black-hole entropy [wikipedia.org] (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.
Parent
Re:I don't understand (Score:4, Funny)
Parent