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String Theory Put to the Test
secretsather writes to mention that scientists have come up with a definitive test that could prove or disprove string theory. The project is described as "Similar to the well known U.S. particle collider at Fermi Lab, the Large Hadron Collider, scheduled for November 2007, is expected to be the largest, and highest energy particle accelerator in existence; it will use liquid helium cooled superconducting magnets to produce electric fields that will propel particles to near light speeds in a 16.7 mile circular tunnel. They then introduce a new particle into the accelerator, which collides with the existing ones, scattering many other mysterious subatomic particles about."
The tests proposed would not "prove" string theory. They are only testing some of the fundemental assumptions on which string theory is based.
If the test shows that one or more of these assumptions is incorrect, however, then it would probably force a very fundamental rethinking of string theory... essentially disproving it.
I'm by no means an expert in string theory. I barely grasp the basic concepts. However I am an engineer who has taken a LOT of physics classes over the years and I'm not completely ignorant either.
String theory has always struck me as a modern day version of epicycles before it was realized that planets follow ellipses instead of circles. It just seems like we're trying to fit the math to the model instead of modifying the model so that the math makes sense. Add in the fact that it makes no testable predictions (not yet anyway) and it's bordering on not being science anymore. Maybe technology advances will change that but then again maybe not.
Maybe string theory is right, I don't honestly know. But it seems like a lot of group think is going on and little progress is being made.
I wouldn't call that junk science so much as failure to make a pedantic distinction.
If experiment can show that string theory makes predictions more accurately than current models, I'd say that proven is a good enough word to describe what has happened. Not in the sense that it's been shown to be an absolutely correct description of the machinations of the universe. Proven in the way that General Relativity was proven - decades before all of its predictions had been tested. Proven as in "it's been shown to be a better model," i.e., proven in about the same sense a person can "prove himself."
I don't think it's whining. The public's confusion about science surely stems in part from sloppy reporting.
How often have we heard someone claim that we shouldn't allow something because it has never been proven to be safe? Such comments show serious misunderstanding about the nature of knowledge.
Actually, ALL of the experimental data in the universe could do that.
Of course, how would one know when they got there?
Tags != Comments, and -1 (Troll) != -1 (I Would Respond Angrily To This Poster So They Must Be Trolling)
From the wording in the article it sounds like they actually want string theory to fail. . .
.despite the fact that we have few alternatives so far.
A test in which a theory fails is the most useful sort of test.
. .
I cannot accept a theory simply because I don't know what to replace it with. Make the tests, generate failures; and then new theories which take the failures into account. That's how the alternatives come into being in the first place. That's why the "failures" are the most useful.
"Successes" only make us complacent with the state of our knowledge, which might well be wrong anyway. "Failures" let us know where we lack knowledge. Science is not done where we know, but where "here there be dragons." It's about exploring the dark corners of the map, not sitting in our offices diddling with ourselves.
We leave that sort of thing to the engineers.
And think about this:
Who says we need an alternative? The quest for a Unified Field Theory is an asthetic desire on the part of physicists. The universe is well known for taking our asthetic desires and shoving them up our collective arses.
Perhaps there can be only two.
KFG
Not so fast -- for a start, you'd need all data from the universe's future, too. But even then, you still won't have proved your theory, unless you count all possible parallel universes too. Even if every event in the history of the universe fails to falsify a theory, it is still possible that you just got lucky, and nothing ever happened in such a way as to disprove the theory. Of course, I'll concede that in that situation, you've got a pretty useful theory and the errors it contains are moot for someone living in the universe in question.
String theory has one particle - the string. It has one force which emerges from the very simple dynamics put into it at the outset. A wide spectrum of particles and interactions emerges from it in a natural way. There is little choice for the dimension of spacetime - the theory locks it down from the beginning. Gravity emerges from it naturally - something that doesn't even get mentioned in the standard model. There are close to zero arbitrary constants. And at bottom, the initial assumptions of String Theory are really simple. Simpler than other quantum field theories.
The problem with String Theory is that taken at surface value it doesn't match the universe we see. We don't see a 10-dimensional universe, we don't see the predicted spectrum of particles and so on. The publicised problems we see with String theory are from all the attempts to make our 4D universe emerge from it - and the incredible freedom we have in doing so (eg. by folding up dimensions in various ways). At core, String theory is simple, beautiful and as far from arbitrary as you can imagine. There are all kinds of things wrong with String theory. But they have nothing to do with "adding as many dimensions and undefinable, physically meaningless constants as possible", which sounds more like the ramblings of someone who doesn't have a clue what String Theory is about.
Note that I am neither for nor against String Theory, which makes me part of a tiny minority in the physics world. I certainly doubt it's the ultimate theory of anything, but I also think that there is a lot of uninformed criticism of it. I'm just telling it like it is without my own ax to grind.
Doesn't it make you feel good to know that our freedoms are protected by politicans, lawyers and journalists.
1. Which string theory? There's a few. Anyone who says "M-Theory" will get slapped.
2. What predictions does the string theory in question make?
3. Are the predictions unique to string theory?
Of course they want it to fail. It's called science, you wouldn't understand. If you prefer the kind of ideology where people are afraid to test their "theories" in case they might turn out to be wrong, I recommend religion.
woosh
As a minor nitpick, I think you meant Occam's razor. More important, you clearly don't understand it. Occam's razor simply says that you shouldn't add more assumptions than you need. To pick a real-world example, don't assume there's a Vast Conspiracy behind the War in Iraq if everything can be explained without it. Yes, atheists use Occam's razor to show that you can explain the universe without assuming the existence of God, but that's not all it's good for by any means.
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Unfortunately, that site is totally bogus.
Mod parent up. I've seen tons of people pass that link around and it has nothing to do with 10 dimensions in the string theory sense at least.
"...always new atoms but always doing the same dance, remembering what the dance was yesterday." -Richard Feynman
THE EARTH REVOLVES AROUND THE SUN?? You must be joking. I can clearly see the sun rising and setting. Any theory that interferes with the perceptions that I am comfortable with, is obviously bollocks. Last time I checked I couldn't see any evidence for the earth revolving around the sun, even when looking under the sofa.
Censorship is telling a man he can't have a steak just because a baby can't chew it. --Mark Twain
Then just project that down so you're only considering a 9-dimensional space. Easy.
As I always like to point out, the most important thing to remember about Occam's Razor is that it's a rule of thumb, not a Law of Nature. If two proposed theories otherwise seem to work similarly well, but one introduces fewer assumptions than the other, Occam's Razor suggests that the former is probably better than the latter, but you can't take this as "proof" -- at best, it lets you make a better educated guess about which avenue is likely to be more fruitful to continue exploring.
David Gould
main(i){putchar(340056100>>(i-1)*5&31|!!(i<6)<< 6)&&main(++i);}
String theory has one particle - the string. It has one force which emerges from the very simple dynamics put into it at the outset. A wide spectrum of particles and interactions emerges from it in a natural way. There is little choice for the dimension of spacetime - the theory locks it down from the beginning. Gravity emerges from it naturally - something that doesn't even get mentioned in the standard model. There are close to zero arbitrary constants. And at bottom, the initial assumptions of String Theory are really simple. Simpler than other quantum field theories.
I think much of the debate over string theory is, at heart, irrational. Some people are attracted to its beauty and elegance, while others find it so elegant that it is therefore suspect. (I.e., the subluminiferous aether was actually pretty beautiful as a theory in a certain way, too, as were epicycles, crystal spheres, and any number of now-disregarded theories; some people would hold that string theory is suspiciously similar to other elegant ideas which have ended up on the scrap heap.)
In some ways, the debate is less of a purely scientific one than an ideological battle between idealists and cynics; lacking experimental evidence, the community seems split mostly between idealists who support string theory, in all its theoretical elegance, while on the other side are cynics who think the whole thing is just too cute to be true, and that it owes itself more to wishful thinking than actual physics.
This is to be expected; until someone can come up with an experiment that will disprove part or all of string theory (or until the theoreticians can find some prediction made by string theory which differs materially from that made by a competing theory), it's an un-winnable argument. There really is little besides "gut reaction" (and other not-quite-rational factors, like the reputations of various people who have already taken sides) to pick sides based on.
"Ladies and gentlemen, my killbot features Lotus Notes and a machine gun. It is the finest available."
Then just project that down so you're only considering a 8-dimensional space. Easy.
Methematical theories are the only ones that can be "proved", but theoretical physics can take a very critical turn in the next century or so if mathematical models are the purposed output, not just attempts at describing phenomena as we know them by using a model. I am not in this field, but I see no way for the universe to be explained - in a completely athiest manner - without the universe and all its characteristics, particles, and forces being a mathematical necessity. Yes, very "abstract", but the universe is very real. "Why" is the question that needs to be be answered.
I do not believe there is anyone today who can give us satisfactory answers.
Then just project that down so you're only considering a 7-dimensional space. Easy.
Then just project that down so you're only considering a 5-dimensional space. Easy.
Assuming I'm reading it correctly, if the Bosons don't bounce the right way, it means that string theory (as currently formulated) violates one of the fundamental assumptions (Lorenz invariance, analyticity or unitarity). If the string predicted scattering doesn't match the experimental observations, then string theory (in its current form) is "impossible" and at the very least "would have to be reshaped in a highly nontrivial way."
If the Bosons bounce within predicted limits, then string theory still isn't proven - it just survived this elimination round and moves on to next week's physical challenge...
Of course you can project down 4D objects to 3D in several ways, and thus get some feeling about them. But our perception always keeps those images at 3D, so in our brain it's just a 3D image with mentally attached info, unlike in the 3D->2D projected case, where or brain manages to re-create the 3d image without problems. You simply cannot visualize four straight lines staying perpendicular to each other, no matter how hard you try. You can visualize four lines in 3D-space, and can mentally attach the info "that line actually goes to 4th dimension, but was projected here", but that's it. Our mental images are restricted almost the same way the perceptions of real images are. E.g. another thing you just can't do is to visualize a body cell with all its structure in its natural size. You can visualize its structure enlarged (such as you see it in a microscope, or pictured in a book), and mentally attach "like this, but much smaller", or you can mentally shrink it, but then eventually you'll end up in your imagination with a structureless point.
The Tao of math: The numbers you can count are not the real numbers.
It's not a great description. Its branching thing isn't really a 2D surface, it constantly appeals to lower dimensions as things that need to be embedded in higher dimensions in order to curve (not true), and it starts going badly wrong from there on (e.g., the fifth dimension in string theory is just a spatial dimension, not some set of personal quantum histories; likewise the sixth dimension is not a set of disconnected personal histories, it's just yet another a spatial dimension). I stopped watching at the seventh dimension, which was similarly unrelated to the dimensions of string theory.
Not actually. There were quite a large number of particles around before Gell-mann came up with the Eightfold Way or Path or whatever. They didn't even have much of any way of classifying them (which is why the nomenclature for hadrons is so screwy today). There were certainly not any models predicting the nucleus before Rutherford hit on it, at least not any that carried much weight. Quantum mechanics kind of grew weirdly from various models like the Bohr model of the atom which were entirely based on experiment.
Even string theory has experiment backing it up. No, really, it does. Everyone talks all the time about how string theory has no experimental evidence. Well, no, it has just does not have any predictions which are currently testable which differ from leading other non-string theories. But, think about it. Other, leading, non-string theories don't have any predictions which are currently testable which differ from string theory! That puts it in the same boat as the standard model and friends.
Furthermore, string theory in its original incarnation was motivated by experiment. It was first developed as a rival to QCD. I don't think that any theory ever (with any kind of success) has been just dreamed up in an experimental vaccuum. Certainly not quantum mechanics. Certainly not string theory. Certainly not thermodynamics, nor Newtonian mechanics. Certainly not relativity, either general or special. All have been motivated by some kind of observations. Later, many of them were found to have predictions that were more far-reaching than what had been observed so far.
SIGSEGV caught, terminating
wait... not that kind of sig.