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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."
String theory always seemed to be the most complicated mathematical way you could "force" a unified field theory into existence by adding as many dimensions and undefinable, physically meaningless constants as possible. This is stuff for the likes of Dr. Charlie Eppes from the TV show Numb3rs. Maybe that's why Peter MacNicol aka Dr. Larry Fleinhardt bailed to be a heavy on 24?
Anyway, we may see some very smart guys flipping burgers next Christmas...
Welcome to slashdot; here's your junk science for the day.
You can't prove string theory through experimentation, all you can do is attempt to disprove it.
Liberty you never use is liberty you lose.
It can't prove string theory. It can *support* it, or it can disprove it, falsify it, contradict it. But it can't confirm it. All the experimental data in the universe can't do that.
Wasn't string theory compared to C? A horribly complex construct that could be made to match any of the customers problems (test results) no matter how complex?
Maybe we can finally move on. And maybe the physicists can take their field back. Hopefully, they didn't lose the keys to the the labs that have been abandoned for years now.
"A man cannot begin to learn that which he thinks he already knows." --Epictetus, 1st Century A.D.
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.
42.
Did anyone honestly think that the answer would be different?
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I say, kill all the particles and let science sort 'em out...
I hope, when they die, cartoon characters have to answer for their sins.
Oh...Large Hadron Collider. If it was in the Castro district I would really be suspicious.
As opposed to the whole idea being bogus? The difference is whether you go for the New, Improved String Theory, Now With Fewer Bogus Assumptions(TM), or whether you throw the whole thing out. Sounds like the physicists want to try to tweak it rather than junk it, even if it fails the experiment.
Note that "starting over with a major assumption changed" and "throwing it all out" aren't that different, so maybe I'm just ranting. Perhaps the major difference will be whether the new thing is still called string theory.
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 think it's funny how the article forgets to mention that the LH collider is located at the CERN (the European nuclear physics institute). As a matter of fact, it is not only in Switzerland, but extends to France as well. The article only mentions it is similar to the U.S. Fermilab accelerator, but then forgets to add that there are many kinds of accelerators world wide.
Funny, ain't it?
The tests being proposed by the physicists in this blog would not test string theory, in that it does not test any prediction of string theory but the underlying assumptions. The write up is very misleading since Lorentz invariance has been tested throughout the past 80 years and always stood up to the tests. I suspect that someone wants to get more funding and mentioned testing string theory to a funding agency.
All the tests in the world can only do one thing with string theory: show that we haven't found a way to disprove it yet. All scientific theories are open to being disproven, that is the beauty of science, that is why it is not a religion, as much as religious types would like it to be, and despite the fact that many so-called scientists actually use it as a religion. The best one can hope for is that observation continues to bear out the predictive abilities of the theory. And you can consider a well tested theory as being good enough for general use... but you'll never really know for sure. So, I say get used to it. Revel in the fact that we don't know, but can still make amazingly useful predictions about our world.
Speaking of which: lets say that string theory survives this test. How far away are we from making useful predictions with string therory? That is, ones that are meaningfully more precise than quantum mechanics or general relativity? Last time I read about it they seemed nowhere near such a prediction because of the complexity of the mathematics. It seemed almost hopeless that they'd make predictions. Is that still the case? This test seems to say otherwise, but are the predictions notably different from what quantum mechanics predict?
Cheers.
I remember hearing about plans to use the LHC to produce and study miniature black holes. These are supposed to evaporate nearly instantanously due to Hawking radiation, but such radiation is only a theory without any experimental verification, and apparantly quite a few scientists are concerned it will just go ahead and gobble up the earth.
At least it will be quick :)
String theory has wasted a tremendous amount of grant dollars and mind share over the years. It has pretty much paralyzed the physics department at Princeton.
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"The canonical forms of string theory include three mathematical assumptions--Lorentz invariance, analyticity and unitarity. Our test sets bounds on these assumptions." --Benjamin Grinstein
Don't quantum mechanics and GRT also include the above? Meaning if the experements don't confirm the above then more than just string theory is in trouble.
Of course analyticity probably has some very subtle meaning in string theory. Any one here in the know?
November 2007? Sure, what the hell, I've had a good life.
So, who wants to loan me large sums of money? Pay you back in December?
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Here is the mirror.
It thought this was cleared up years ago:
Scanning/Copying based on a terminator byte pattern is fraught with error and is definitely not secure.
Buffer sizes are terribly problematic when left tot he caller to check on overflow. It must be in the methods, and thus part of the data structure. (see point above).
Strings these days are UTF-7 or 8, which makes them an even better candidate for a object-based construct rather than a memory map.
I'd like to point out the....oh, wait...
I'm not real keen on this; I've already got one, you see.
It's very nice-a.
This is quite frankly rubbish. He does not give any links to the exact details of the test, but a lot of waffle hinting something that is known already. The LHC is built to test High energy Physics theories, and some aspects of these theories will influence factors in string theory. So what? This article says nothing of particular consequence. and stop complaining about a 'new improved string theory' - that is the point of science, to come up with better and better theories. Just because one was not discarded but modified, it doesn't invalidate it until disproven. /rant over.
Nigel: As you can see, our theories all go to eleven, right across the board. Look: eleven, eleven, eleven.
Marty: Does that mean it's better? Is it any better?
Nigel, well, it's one more, isn't it? Most blokes, their theories only use ten dimensions. They're at ten, where do they have to go from there? When we need that extra push over the cliff, you know what we do?
Marty: Put it up to eleven?
Nigel: Eleven. Exactly. One more!
- None can love freedom heartily, but good men; the rest love not freedom, but license. -- John Milton
Not at all. You merely have to project one of the dimensions down so that you're only considering a 10-dimensional space.
Ben Hocking
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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.
I haven't RTFA (site is returning a database error), but the biggest criticism of string theory so far has been that there aren't many good ways to falsify it, i.e. disprove it, which makes it somewhat suspect as a scientific theory. Having a way to do a test that could disprove it is, in a sense, very good news for the theory. (Besides, you can't ever prove a scientific theory, you can only support it with evidence and fail to disprove it with tests.)
OTOH, a test that actually does disprove string theory could be very bad news for string theorists. But you can bet there'll be a lot of scrambling to rejigger the theory after a failed test...
...and if it sounds like a banjo, string theory is true?
If this is the same story referenced here, it's bogus. To quote Not Even Wrong,
Media that can be recorded and distributed can be recorded and distributed.
-kfg
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
In what other endeavor can you persuade people to spend hundreds of millions of dollars to build complicated machinery and pay you a salary based on the following (roughly paraphrased) prospectus:
;-)
"You see, what we'll do is accelerate some shit up to within a hairs-breadth of the speed of light then smash it into some other shit and see what happens."
Gotta love those wacky physicists!
Insisting on "correct" English is like saying that there is only one, definitive recipe for chili.
The energies that will be created in the LHC happen on a daily basis in our upper atmosphere. The only difference is that we will have detectors in the immediate vicinity.
Ben Hocking
Need a professional organizer?
http://arxiv.org/abs/hep-ph/0604255
Humourbot: "Then he said, 'meet SuperCollider,' Super collide her?! I just met her"
Enough to give Bertrand Russell a splitting headache, who's memory would also be part of the collection.
In Brian Greene's book The Elegant Universe (1999), he claimed that the LHC would be able to find the existence of superparticles that were predicted by string theory. I'm unable to explain a lot of the details there, but this new article seems pretty similar. 8 years ago we were waiting for the LHC to come along and have a chance of confirming string theory, and now some scientists tell us to wait for the LHC to be able to prove string theory. It's not like we ran out of ways to prove/disprove string theory and that these new guys have had some miraculous insight into the problem (which they may have had anyway); other scientists have just been waiting for the same thing they are waiting for to be able to show it.
And furthermore, now that I have read the "article", it turns out to be a freaking BLOG POST containing nine whole sentences. NINE! Sheesh. Secretsather, you deserve some serious downmods for your laziness and obvious lack of subject knowledge.
A quick news search reveals much more informative articles, which allows one to find the original journal article. Here's the abstract...
...most of which is beyond grasp of what I remember from 200-level college physics. Would a domain expert care to jump in now?
String Theory was proven on July 16, 2003, and confirmed after peer review and over 20 separate duplicated efforts, including a lab in Dallas, Texas.
Proven: When you need a piece of string to tie something up, and you find a piece of string in a junk drawer, it will always be too short for use, or too long and when cut to the appropriate length, the remaining piece will be too short for further use.
A similar, but as yet unproven theory is in testing: When you have a piece of string and measure it by "eyeballing" it will always be too short for actual use.
Politics is the art of looking for trouble, finding it everywhere, diagnosing it incorrectly and applying the wrong fix.
String theory describes very neatly and elegantly, using complex multidimensional mathematics, an imaginary universe. Unfortunately this hypothetical universe of strings does not seem to behave in a similar manner to our own, shown by the unending series of problems and mispredictions of string theory. Attempting to correct these by 'refining' the model, ie, making it unneccesarily complex by adding large numbers of arbitrary terms, dimensions and general gotchas, is a sign of a not particularly robust mathematical hypothesis. Nobody bases their next industrial application or development on string theory as it is simply not reliable, whereas other theories such as quantum theory, theories of electromagnetism, heat, gravity, etc, are.
Trying to fit data to a series of made up equations is simply not the way to go.
Physicists are thinking of turning strings into membranes and adding even more dimensions, to me that is even more improbable and unwealdy.
Inventing ideas using a pencil, paper and supercomputer are no match for measuring first and then performing a detailed analysis.
No doubt the physicists will be 'surprised', 'stumped' or 'shocked' by the results of the experiment, which will require some 'tweaking' of an obviously fundamentally flawed model.
String theory is part of a long list of fictional entities or relationships that have been dreamt up on the spot. String theory, along with a few other miscalleaneous dingbats, has sipmly not yet been disproved and abandoned.
There is no psychiatrist in the world like a puppy licking your face - Ben Williams
That's what experiments are for, you disprove a current theory and then start work on the new theory that fits the observations from the experiment.
Here is the pdf of the paper on arXiv for those interested.
This post climbed Mt. Washington.
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?
If anyone cares to read a highly technical discussion of the paper by its first author (Jacques Distler), you can read his blog entries and the accompanying comments here and here.
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.
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.
This is why the Mythbusters should not be allowed to design scientific equipment. I can picture Adam dancing about in girlish glee even now...
If I knew the wedgies I gave you back in 6th grade would have resulted in this . . . I might have taken a moments pause.
Back when folks were still trying to figure out the Periodic Table of Elements, there was a promising idea which came out of the field of topology. It was based on the topology of knots, such as one could visualize as closed loops of string. It seemed to "predict" chemical properties for elements as heavy as Calcium but broke down beyond that. The similarity of the two patterns turned out to be only a coincidence, so the theory was discarded.
I predict that this new incarnation of "string theory" will be similar. It will seem reasonable for some of the simpler things (if any) but will fail to predict results when applied to more complex things.
Who knows? String theory could be a practical joke perpetrated by frustrated topology dweebs.
We can have a raffle! How will the LHC destroy us? Check one: [ ] Microscopic black holes [ ] Trigger collapse of the false vacuum [ ] Strange matter [ ] Magnetic monopoles [ ] Disruption of the Wigner observer cascade causes a universal system reset [ ] God notices and stuffs us all into Carlsbad Caverns
Sounds painful. Oh, Had-ron... nevermind.
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No experiments can "prove" the stringtheory. As foolish as the stringtheorists are, they probably wouldnt accept anyone disapproving the theory either. Any disapproving the stringtheory would only lead to the stringheorists yet another time ajusting the theory to fit the new data.
One should rather look at stringtheory as a failed tool to getting a greater understanding of how the universe function, microscopically and macroscopically. Common sense suggest that the easy solution is probably the correct one. If one use the paradigm of earth being the center of our solar system and view all of the movements in this system as circular you are able to get a model which works. But this is a very complicated model, and wrong. Putting the sun in the center of our solar system and using elliptic orbits on the other hand makes perfect sense. In this analogy the string theory is the earth-centered theory. Its very complicated, it grows even more complicated with time as you have to add new discoveries and adjust the theory for these anomalies.
Stringtheory equals dingtheory
Clue for the humor-impaired: I was kidding
But, you know...I'm pretty sure that for most of the sub-atmoic particles and all of quantum mechanics, there were mathematical models that predicted them well before there were any experiments that yielded results to support them.
Insisting on "correct" English is like saying that there is only one, definitive recipe for chili.
"String theory is arguably the most popular theory in theoretical physics; that is, it cannot be proven."
... has not been strongly tested" is a sentence I could agree with.
Depending on how you read the intend of this sentence, there are up to three errors. As others have noted, nothing in science can be proven true - they can only be proven false. The word here should be "tested". It is not that it cannot be tested, but that it has been beyond our capability to do so. Even this isn't true - after much effort at developing the theory, it turns out to be compatible with current physics - this is a test, as it might not have happened. One might argue it is not a very arduous test. "String theory
"... the proposed testing of the current string theory. I use "current" because string theory is just that, a theory; and it is constantly changing as more information becomes available."
Argh! The old "just a theory" boggie! "Theory" here means a logical structure which uses a small number of axioms/hypotheses to explain a large and disparate body of observation. It is independent of the level of experimental support the theory has. Newtonian gravity, evolution by natural selection, special relativity and quantum mechanics are all theories with sufficient experimental support to reguard them as fact (within suitable limits - e.g. we know Newtonian gravity fails in relativistic conditions.) General relativity is very nearly there. String theory is still hypothetical.
(Biological note: I'm an ex-astronomy student now doing mathematical evolutionary biology. I've attended string theory talks, and failed to understand them. Take the above with salt added to taste.)
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As other have pointed out the test will not confirm string theory or measure any of its parameters or predictions. The test described in the article says that they are only probing Lorentz invariance, analyticity, and unitarity. These are basic assumptions of String Theory and so if they are found not to be the case then string theory cannot be "correct". What is left out is the fact that these are also the basic assumptions of all modern theories that are quantum mechanical. If you find a problem with one of these principles not only have you killed String Theory but also the Standard Model and most other modern physics theories. Now as I grad student in experimental physics I can't say that I would dread such a discovery. It would open a lot of new avenues for discovery, but a finding described in the paper would be bad for a lot more than just String Theory.
Is this the same device that is suposed to have a mathematically slim chance that it could completly destroy all the matter known to exist in the unverse? If so I think we should assume string thoery is true and move on with researching something less threatening to the fabric of our existence.
You can't "prove" string theory through an experiment. Even if the experiment works exactly as string theory predicts, it doesn't "prove" anything, it merely fails to disprove string theory.
The best outcome would be if the experiment clearly doesn't work like string theory predicts, because in that case, we'd learn the most from it.
So after we prove that the Universe is nothing more than God's big ball of string, then what?
"It's the height of ridiculousness to say for those 9 lines you get hundreds of millions."
Anybody else think that the string theorists will explain away the inevitable unexpected results by coming up with some new crapload of overcomplicated BS that *just happens* to need an even bigger accelerator to test.
People who think they know everything really piss off those of us that actually do.
Wrong. According to string theory, they are all the same, they're just vibrating differently.
Engineering is the art of compromise.
Successes can be useful, too, though less useful than failures. In succeeding, it refutes the notion that string theory is untestable, which is a major reason to go work on something else instead.
As you point out, that's aesthetic rather than factual, but the aesthetics of science aren't arbitrary. They've proven themselves to be a pretty good way of finding out more truth, without getting sidetracked. Simplicity is the ultimate dogma of science, the thing that it believes without proof and without the possibility of proof, but it has nonetheless shown itself to be useful.
(Utility, of course, is yet another aesthetic judgment, and a while separate branch of philosophy, namely the "What are we as humans supposed to DO?" branch. I'm a lot less comfortable in working out that branch, and will content myself with the notion that I do science because it amuses me.)
If that's your goal, then you probably need extra dimensions, string theory or not.
It seems like that's the $6,400 question, then. Are we blinding ourselves in seeking a unified theory, in the same way that Copernicus was blinding himself by looking for a geocentric, circular-orbit model? If you take as an assumption that there must be a unified theory, it may well be that many dimensions fall from it as a necessary consequence. Similarly, if you assume that the planets rotate around the Earth, epicycles are an almost immediately necessary consequence of even the most trivial observations (because the planets seem to change speed and occasionally even direction). I'm sure that Copernicus thought that having a universe centered around the earth was just as necessary and desirable as modern physicist think a unified field theory is; a universe without one would just be so ugly.
It's not my area of physics so I have just decided to not hold an opinion, at least at this point, but it does seem as though we need to be constantly vigilant about the assumptions we make, and the goals we set ourselves. It's pretty easy to laugh at the geocentrists, but logically it's almost certain that we today hold views that in a few centuries, will be just as laughable.
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Simplicity is the ultimate dogma of science, the thing that it believes without proof and without the possibility of proof, but it has nonetheless shown itself to be useful.
Make things as simple as possible, but no simpler.
KFG
While the LHC will be looking for the effects of supersymmetry, the Higgs boson, and extra dimensions, among other effects that would be consistent with string theory, the LHC will never end up definitively testing string theory. That is, the number one problem with string theory in its current young form is that it is not really falsifiable, especially in the energy domains currently possible in modern colliders (including the LHC). That is, there are many SUSY theories that predict supersymmetry, not just string theory, thus discovering it would not prove string theory at all. On the other hand, if supersymmetry isn't observed, string theorists may just argue the collisions were not high enough in energy. The same arguments apply to all of the barely fleshed out predictions in string theory. In that sense, string theory is barely a kosher physical theory. This isn't to say the LHC isn't a huge deal. No matter what they find with the LHC, it'll be exciting. Many physicists are very confident that it'll give us new insight into candidates for dark matter, and certainly confirmation of supersymmetry and the Higgs would be monumental.
This isn't going to prove or disprove anything. The LHC is just looking for the existence of particles theorized to exist with classical high-energy particle physics. The only way string theory could be tested is if it could actually make a prediction that can be put to a test. Unfortunately, it can't predict how fast a ball will fall from the top of the Leaning Tower of Pisa. Kinda sad how a theory that's had tens of thousands of man-hours wasted on it can't predict anything at all, no?
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
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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.
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Obviously a mathematical and legal proof is not the same. The general meaning is "something that convince you that it is true".
In physics the meaning is usually taken to be "an experiment that demonstrates predictive power to a theory that didn't exist without it."
Due to laypeople who confuse physical proofs with other kinds of proofs, we usually say "validate" instead of "prove".
- It's not a theory but a collection of theories. The original five different-but-possibly-dual theories and handwaved 'M-theory', plus different flavours with added restrictions or extensions?
- It's not by any means finished: for instance, finiteness hasn't been proven, and there is no explicit background independent formulation which yields GR spacetime?
- The basic idea may seem simple, but is overlaid by a lot of kludges such as supersymmetry to eliminate tachyons and fluxes to get a positive cosmological constant?
But on the other hand, the topological variations on extra dimensions and fluxes add up to 10^500 different theories with different predictions. How does that make an improvement over the twenty variables of the standard model? Granted, string theory attempts to explain more, but... Really? Which? Does the mythical 'M-theory' exist other than as a big 'Maybe'? What does it look like? What predictions does it make? Substitute 'might be' for 'are' and add a 'conjectured' in front of 'theory'... Perhaps. But there seems to be a lot of contrivance in there.Dammit! You beat me to it. Very nice. :)
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...
Three dimensions plus time will only define an event point in spacetime. It takes another three dimensions to provide orientation. Imagine an arrow. At time t, the arrow will be at (Xt, Yt, Zt), but which way is it facing? North? Up? Towards the target? You will need another three dimensions to specify which way it is pointing. Now, what about spin? Is the arrow spinning? Is it tumbling through the air? Add another three dimensions to capture that. What about the mass? The color? The charge? Dimension. Dimension. Dimension.
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As another poster noted somewhere in the comments, the explanation of dimensions on that site has little to do with dimensions as they are conceived in string theory.
However, Occam's Razor can be formalized. Bayesian Statistics allows us to do this, and furthermore the formalization tells us that one's definition of "simple" is not fixed, and the results of the use of the formal razor depend greatly on one's choice of "simple". From the article:
So, Occam's Razor should be used only where you first state your definition of "simple", or else its use is irrational.
SIGSEGV caught, terminating
wait... not that kind of sig.
What if we actually do learn something from these tests? What if useful information was actually derived and the points which have been difficult to consider with math alone are made less fuzzy, or even more clear? What if the collision of certain particles at certain speeds under other certain conditions revealed a nugget of information that formed the seed of knowledge that allowed some nut job somewhere to do something useful? Wouldn't that just be the worst result possible? I mean, all the cynics on either side would have to accept that there's some use to figuring out how the universe works and whether one particular theory describes it well enough to do us any good. Just know this, when I'm sipping martini's on an inhabited world in another galaxy, I'll be laughing with the green skinned bar-tender about all the arguments sentients have over things they neither know anything about, or really even care about.
Sure. But would it be good science, in this case? There still aren't really any positive indications that string theory (or brane theory, or whatever) is even remotely on the right track. If foundational assumptions turn out to be false, then a more rational approach may be to start looking for different theories, perhaps ones that have, I dunno, some testable connection to observable reality?
All true. And in fact, it's probably naive of me to expect that many physical theories will hold throughout the entire universe for its entire life. Laws would certainly have been different near the time of the big bang, for example.
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 may be that the Standard Model is the epicycle. It works really well for many calculations, but there are problems it doesn't explain, such as the mass of some particles (The Higgs Particle, IIRC) should be way off (hierarchy problems), which is solved by SuperSymmetry but then there are missing Super Partners which should exist but we haven't found them (but should be detectable at this new collider if they can reach 250 GeV (again, IIRC)). Also, gravity doesn't work. But if you lay things out in a braneworld with some kinds of particles sequestered in extra dimensions and the graviton as the particle that can cross the bulk then the math starts to work out.
So, really String Theory is more like the elliptical orbits in that the theory fits the observable data. The question is still whether it's the right theory that fits the observable data, and to test that we need better colliders.
IANAP either, I just like to follow the lay press when I have time.
My God, it's Full of Source!
OUTSIDE_IP=$(dig +short my.ip @outsideip.net)
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
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Uncountably infinite theories, depending on how you compactify the extra dimensions to hide them from us.
Occam's razor states: "It is foolish to do with more that which can be done with less."
It's not about the number of assumptions, or veracity of the theory. It's a fundamental statement that science's job is about predicting results. As long as the predicted results cannot be distinguished, go for the simpler theory. It's why we still teach Newtonian mechanics in schools - 99.9999% of the time, Newton is plenty accurate and far easier to learn and apply.
"The canonical forms of string theory include three mathematical assumptions--Lorentz invariance, analyticity and unitarity. Our test sets bounds on these assumptions."
Uh... can I get back to you on that?
While many people use it in your useage, I don't think it's really with merit as most theories nowadays are extremely complex and since our simplest observation tools are among the first discounted (matter is mostly empty space, yet it looks and feels pretty solid to my eyes and hands) so the simplest theories are seldom the right ones anymore; there's tremendous complexity to our theorizing.
I prefer to look at it this way: it isn't about two competing theories so much as one theory that encompasses each other. So, for example, a theory says "If I do a little dance and then pull the trigger, the bullet will fire." while an experiment shows "If I pull the trigger, the bullet will fire." We can use Occam's Razor to cut away the theory and we can pretty confidently say that dancing had almost nothing to do with the bullet firing. (Unless he was breakdancing--then he needs to be shot.)
This approach makes two different changes: for one thing, by the end, I stopped talking about being "right" and changed it to "useful", partially because simplicity makes things easier to use and partially because two competing models may be equally accurate. For example, while we like Galileo's model nowadays, Tycho Brahe accepted that the planets circled the sun, but he also held that the sun circled the earth. From a certain perspective, they both were "right" but the math involved with Brahe's model was much more complex. Galileo won out because it's just easier to think his way; but the reality is that it's equally valid to compute from the perspective of a still earth with a circling sun. Still, in the Brahe vs. Galileo fight, we used Occam's Razor to cut off those brancehs of Brahe's more complex theory that the earth didn't behave as a planet. (As an aside, at the time there were good reasons to prefer Brahe back then. For one, the problem of parallax. Also, if you drop something from a moving platform like a ship it falls directly down while the ship moves forward but if the platform of the earth moves around the sun then items dropped should similarly drop away from us but this doesn't happen--Galileo's response to these problems were never satisfactory to many of the best scholars of his day).
However, the second change in my formulation is to stengthen the cutting power of the razor almost purely on logical grounds alone. It is in vain to use more when less will do. It becomes a deductive tool rather than a rule of thumb and I can guarantee you that the cuts I make with my razor are never wrong while the cuts made with the "simplicity is best" razor might cut out science and leave only God given the right butcher.
Me lost me cookie at the disco.
Experiments show that a car moves without an invisable pink elephant. Occam's razor says dump the elephant, even though IPE's may move cars, IPE's are not required to move any car known to science.
Occam's razor chooses the simplest explanation between competing theories that give identical results, it does not gaurentee the chosen theory is the simplest explanation possible.
BTW The definition of "simple" is the opposite of complex, AFAIK complexity can be measured in complex ways.
And did you exchange a walk on part in the war for a lead role in a cage? - Pink Floyd.
FOR IMMEDIATE RELEASE
THE PHYSICS TIMES
Princeton, NJ
Ed Witten was seen reading Woit's THE NOT EVEN WRONG while simultaneuosly walking down Nassau Street in an inertial frame, followed by his 137 postdocs, who were chanting in unison, as measured by a stationy observer standing outside of PJ's Pancakes.
Some towards the front of the line started crying first (in the lab frame), as they realized it was the end of a free ride for blind obedience, and that for health benefits, trips to exotic conferences, and summers off, they were going to have to start thinking on their own.
The news spread far and wide. Up in Cambridge Lubos Motl changed his snarky one star amazon review for NEW to a laudatory five star review, so as to secure future NSF funding. And Michio Kaku added Woit as a friend on his myspace page, after a call from his media team.
"I've seen darker days than this," Brian Greene smiled, recalling the bar scene with the hot chick in his PBS mini-series. "I already got my two string theory coffee table books out and am set. I know that I have secured the Nobel--in literature."
Witten said, "It is time to make peace. The most important thing that we ST, LQGers, and Not Even Wrongers must do is continue to oppose physical theories, which unify disparate physical phenomena in the same physical framework. Otherwise mathematical masturbation will fall out of favor, and we will have to join the proletariat in working for a living and taking what they're giving."
I wish Woit would have talked more about his views on the future of physics. For it is not enough to criticize, and I would hate to see the future of physics dominated by those untying the knots of String Theory.
ST hath failed. Utterly and completely. It could not have failed more with twice as much NSF fundining.
String Theory was the only game in town, and now there are two--ST & deconstructing ST.
But there is another that actually unifies QM & SR & GR with a physical model: MDT--it's physics!
Moving Dimensions Theory is in complete agreement with all experimental tests and phenomena associated with special and general relativity. MDT is in complete agreement with all physical phenomena as predicted by quantum mechanics and demonstrated in extensive experiments. The genius and novelty of MDT is that it presents a common physical model which shows that phenomena from both relativity and quantum mechanics derive from the same fundamental physical reality.
Nowhere does String Theory nor Loop Quantum Gravity account for quantum entanglement nor relativistic time dilation. MDT shows these derive from the same underlying physical reality. Nowhere does ST nor LQG account for wave-particle duality nor relativistic length contraction. MDT shows these derive from the same underlying physical reality. Nowhere does ST nor LQG account for the constant speed of light, nor the independence of the speed of light on the velocity of the source, nor entropy, nor time's arrow. MDT shows these derive from the same underlying physical reality. Nowhere does String Theory nor Loop Quantum Gravity resolve the paradox of Godel's Block Universe which troubled Eisntein. MDT resolves this paradox.
Simply put, MDT replaces the contemporary none-theories with a physical theory, complete with a simple postulate that unifies formerly disparate phenomena within a simple context.
THE GENERAL POSTULATE
OF DYNAMIC DIMENSIONS THEORY
The fourth dimension is expanding relative to the three spatial dimensions.
If at first the idea is not absurd, then there is no hope for it.
-Albert Einstein
But after thirty years of the absurdity of String Theory, millions of dollars from the NSF, and billions of complementary dollars from tax and tuition and endowments spent on killing physics and indie physicists, perhaps it's time for something that makes sense-for a physical theory that actually accounts for a deeper reality from which both Relativity and Quantum Mechanics, from wh
Who cares how many dimensions? who says that Occam's selection is valid? Science and, yes, physics is only the practice of coming up with working models of what we can observe. If you want to worry about something, try and prove that "natural laws" are time-invariant. Might they even be discontinuous? What about Gödel's incompleteness theorem? Is mathematics even a valid means of modeling "Reality?" Hmmm...
Be as you would have the world become.
WHAT is your favorite DIMENSION?!?!
"10... no, wait 11!.... AUUUUGGGGHHH"
I hold very few opinions. I hold information based on observation and fact. If you wish to disagree, please use facts.
Cripes, better make sure they don't use Dobly.
You don't do high energy physics in Dobly do you.
In the free world the media isn't government run; the government is media run.
Einstein was kind of unique in that way. He certainly was concerned with experiment, but it played unusually little role in the development of any of his ideas. String theory comes closest to approaching that (which isn't really a good thing), in that the modern string theory in its "theory of everything" form spent much of its development motivated reasons of pure mathematical consistency.
You can argue, though, that mathematical consistency is still at least indirectly connected to experiment since you're trying to be consistent with other theories which have been experimentally verified.
But we *can* think of causes for them to change. Local differences in the curvature or geometry of the universe, for example, which we might have inadvertently built into our theories. For all we know, something like that could explain dark energy and/or dark matter. Assuming laws are constant throughout the universe is understandable, but we shouldn't forget that it might not actually be valid.
Not only little to do with string theory, that site has nothing whatsoever to do with string theory.
unzip; strip; touch; finger; mount; fsck; more; yes; unmount; sleep
As with its hose, cable, shoelace and little daughter's hair relatives, they are a form of life, sentient enough to tangle when you need them straight.
I'm not qualified to answer that question. And almost all the people who are qualified have a vested interest one way or the other, so it's very hard to tell.
But yes, as far as relationship to experiment is a sliding scale, Einstein and the string theorists have been perhaps farther from experiment than anyone else. At any rate, anyone else with any success...
SIGSEGV caught, terminating
wait... not that kind of sig.
String theory may turn out to be crap, or it may turn out to be prescient. But until experimental physics makes a few more strides forwards, trying to say one way or the other seems to be fruitless. Of course, it's worth continuing with string theory, if only for the advances it has brought in mathematics and for the lessons it may teach us about what a unified field theory has to be. Every unified field theory that fails teaches us one more way to not construct a theory. And were string theory to fail, I think physicists would probably be able to glean a great deal of insight from how it failed.