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String Theory Put to the Test

ScuttleMonkey posted more than 6 years ago | from the line-em-up-and-shoot-em-down dept.

Math 407

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."

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Flipping Burgers? (1, Interesting)

toonerh (518351) | more than 6 years ago | (#17741036)

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 [imdb.com] . Maybe that's why Peter MacNicol [imdb.com] aka Dr. Larry Fleinhardt bailed to be a heavy on 24 [imdb.com] ?

Anyway, we may see some very smart guys flipping burgers next Christmas...

Re:Flipping Burgers? (5, Informative)

Martin Blank (154261) | more than 6 years ago | (#17741214)

The number of dimensions isn't that high. When all of the string theories are combined into M-theory, the total number of dimensions is eleven, IIRC. Harder to understand? Yes. Impossible to visualize? Yep. But not abhorrently high.

Why not use ten dimensions but make them bigger? (5, Funny)

spun (1352) | more than 6 years ago | (#17741388)

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!

Re:Why not use ten dimensions but make them bigger (0, Offtopic)

TheMadcapZ (868196) | more than 6 years ago | (#17741582)

You forgot "Nigel: Brilliant!!!" and then the Guinness toast!

The trick is projection (5, Funny)

benhocking (724439) | more than 6 years ago | (#17741392)

Impossible to visualize? Yep.

Not at all. You merely have to project one of the dimensions down so that you're only considering a 10-dimensional space.

Re:Flipping Burgers? (2, Informative)

scoopr (849708) | more than 6 years ago | (#17741774)

Harder to understand? Yes. Impossible to visualize? Yep.
Quite. Found some help for understanding from here [tenthdimension.com] .

Re:Flipping Burgers? (3, Funny)

kfg (145172) | more than 6 years ago | (#17741216)

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.

And the essential problem in trying to falsify it is that it's so bad it's not even wrong.

KFG

Re:Flipping Burgers? (0)

Anonymous Coward | more than 6 years ago | (#17741302)

This is not wikipedia. There is no reason to link to everything that can also be explained somewhere else in your post especially when you chose to ignore linking to information on string theory and unified field theory when those are what the article was about, not actors and tv shows.

Bravo on your first post though!

Re:Flipping Burgers? (1)

jacekm (895699) | more than 6 years ago | (#17741446)

As long as it is not related to God, Occham razor doesn't apply to science anymore. JAM

Re:Flipping Burgers? (5, Informative)

Ambitwistor (1041236) | more than 6 years ago | (#17741480)

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.
Actually, it's the simplest known way of creating a unified field theory.

It's been known since the 1920s that adding extra spacetime dimensions allows you to unify forces; Kaluza and Klein successfully unified classical electromagnetism and gravity that way, with a theory in 5 spacetime dimensions. Unfortunately, this idea can't be readily extended to all the forces in the Standard Model, and the unified theory is at least as difficult to quantize as gravity alone.

From a different perspective, leaving gravity out of it, there are the grand unified theories. They too have "extra dimensions", except that the extra dimensions are not of spacetime, but of an internal "gauge" symmetry space. (Kaluza-Klein theory basically turns these internal gauge dimensions into true space dimensions, paving the way to a gravitational theory.)

String theory also does not add as many "undefinable, physically meaningless constants as possible". Indeed, it has fewer constants than the Standard Model. In fact, it has only one constant, which is certaintly definable: it is the string tension. Furthermore, the dynamics of string theory are unique, unlike the quantum field theories. (You can write down infinitely many different particle physics theories with different particle content and interactions, but all of the string theories are part of the same theory, and all the strings obey the same fundamental laws of interaction.)

In short, string theory is not a totally contrived fudge; pretty much all of the ideas that led to semi-successful unified field theories found their way into string theory in a natural and uniquely determined way.

Re:Flipping Burgers? (4, Insightful)

exp(pi*sqrt(163)) (613870) | more than 6 years ago | (#17741656)

String theory always seemed to be the most complicated mathematical way you could "force" a unified field theory into existence...
On the contrary, it is the simplest. The standard model has an arbitrary set if particles with few principles guiding how they should be chosen, and an arbitrary set of interactions that can take place between particles. It doesn't even single out 4 dimensions as special in any way - the choice of 4D is completely arbitrary. The choice of 30 or so constants defining the interaction strengths is also arbitrary.

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.

You can't prove a theory (5, Informative)

hypnagogue (700024) | more than 6 years ago | (#17741060)

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.

Re:You can't prove a theory (3, Interesting)

stevesliva (648202) | more than 6 years ago | (#17741176)

Welcome to slashdot; here's your junk science for the day.
Welcome to Slashdot; here's your whining about semantics for the day. Pretty soon you're going to tell me that "subatomic particles" aren't actually particles, per se.

Proofs are for mathematics (4, Insightful)

rumblin'rabbit (711865) | more than 6 years ago | (#17741398)

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.

Re:Proofs are for mathematics (2, Funny)

stevesliva (648202) | more than 6 years ago | (#17741732)

How often have we heard someone claim that we shouldn't allow something because it has never been proven to be safe?
Indeed, especially with regard to GMOs. Safety is a testable theory though, and "proven safe" is generally the third option of "lies, damn lies, and statistics."

Re:You can't prove a theory (-1, Offtopic)

Anonymous Coward | more than 6 years ago | (#17741536)

hehe, while we're at it, why not discuss the term "atom" (the greek word átomos means "indivisible").

Re:You can't prove a theory (1)

Ithika (703697) | more than 6 years ago | (#17741588)

Well, have you ever tried splitting one?

Last time I took a knife to an atom the damn thing blew up in my face! Got a nice head on my beer though....

Re:You can't prove a theory (5, Insightful)

Bastian (66383) | more than 6 years ago | (#17741238)

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."

Re:You can't prove a theory (1)

kyliaar (192847) | more than 6 years ago | (#17741602)

I wouldn't call that junk science so much as failure to make a pedantic distinction.
So, the Scientific Method is pendantic now? I see.

Re:You can't prove a theory (3, Funny)

giminy (94188) | more than 6 years ago | (#17741292)

Thank you.

Please vote to give this article the scientificmethodcantproveonlydisprove tag :).

Cheers,
Reid

Re:You can't prove a theory (2, Funny)

truthsearch (249536) | more than 6 years ago | (#17741426)

Please vote to give this comment the concatenated-words-need-hyphens-to-be-readable mod :).

Bah (4, Informative)

Phanatic1a (413374) | more than 6 years ago | (#17741066)

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.

Re:Bah (4, Funny)

Bluesman (104513) | more than 6 years ago | (#17741276)

Actually, ALL of the experimental data in the universe could do that.

Re:Bah (2, Insightful)

Sunburnt (890890) | more than 6 years ago | (#17741436)

Actually, ALL of the experimental data in the universe could do that.

Of course, how would one know when they got there?

Re:Bah (4, Insightful)

alienmole (15522) | more than 6 years ago | (#17741474)

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.

Re:Bah (1)

maxume (22995) | more than 6 years ago | (#17741846)

Once you had accounted for all the possible parallel universes, you would still have to prove that there wasn't another reality somewhere else with another set of all possible parallel universes.

Data that contains itself (1)

rumblin'rabbit (711865) | more than 6 years ago | (#17741580)

Unfortunately that collection of data would have to part of the data itself, since it's part of the universe. And the part of the collection of data that represented the thing that collected data would have to be part of both the original collection, and part of the collection that represented the collection of data. And so on.


Enough to give Bertrand Russell a splitting headache, who's memory would also be part of the collection.

Re:Bah (1)

AndyG314 (760442) | more than 6 years ago | (#17741572)

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.
No theory can ever be compleatly proven. We can simply test it's predictions with experements. After a while, when we have tested a theory many times, we figure it's good enough to use. Eventually however we come up with a prediction of the theory not suported by an experement. Then we go back and start to refine the theory or come up with a new one. Any theory, even a well established one, can be disproven by an experement. However even a disproven theory can be very usuful and still make accurate predictions in certin circumstances.

Well... (0)

Anonymous Coward | more than 6 years ago | (#17741668)

I'm getting "error establishing a database connection" errors trying to connect to the site, but here's what the article has to say about that:

It is with this accelerator, that will allow researchers to begin observing the scattering of W bosons, an elementary particle that is one of the four fundamental interactions of nature and required in 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.

"Our work shows that, in principle, string theory can be tested in a non-trivial way," said Ira Rothstein, co-author of the paper and professor of physics at Carnegie Mellon.

"The beauty of our test is the simplicity of its assumptions," said Benjamin Grinstein, a professor of physics at the University of California "The canonical forms of string theory include three mathematical assumptions--Lorentz invariance, analyticity and unitarity. Our test sets bounds on these assumptions."

Grinstein also noted that if their test does not substantiate what the theory predicts, one of the key mathematical assumptions about the current string theory would be incorrect.

Re:Bah (4, Informative)

radtea (464814) | more than 6 years ago | (#17741852)

The tests proposed would not "prove" string theory. They are only testing some of the fundemental assumptions on which string theory is based.

The assumptions are:

1) Lorentz invariance
2) Analyticity
3) Unitarity

The problem is that these are not exactly assumptions but rather desirable characteristics of any good theory in this domain, period. If anyone comes up with an alternative to string theory that is even remotely within the bounds of conventional physics, it will also have these chracteristics.

Lorentz invariance means that the theory is consistent with special relativity. Since our universe is manifestly correctly described by SR to a very high degree of accuracy, this is a desirable property of any theory of everything.

Analyticity (am I spelling that right?) means that the theory is mathematically continuous, which is again something that seems to be highly desirable as our universe contains very few (probably no) formal sigularities. One major goal for theories of everything is to show that the singularities in general relativity are smoothed away at small enough scales.

Unitarity means that the propogator conserves what is being propogated, so spontaneous creation or destruction of stuff doesn't just happen. Again, this is considered a generally desirable property, to the extent that any theory that lacked any of these three properties would be considered a very bad theory. The creator of such a theory would have to give some account as to why it was ok for their theory to not be Lorentz invariant, analytic or unitary.

So this is not so much "testing string theory" as "testing some very basic assumptions about the constraints any good theory should fulfill." This is a good and worthy goal, but it is a very weird bit of marketing to advertise it as "testing string theory" rather than putting it in its more fundamental context.

Flexible Theory (1, Funny)

Lucan Varo (974578) | more than 6 years ago | (#17741084)

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?

Re:Flexible Theory (0)

Anonymous Coward | more than 6 years ago | (#17741664)

Huh?

C is one of the simplest programming languages around. K&R C has only something like 35 reserved words!

Don't they want string theory to succeed? (1)

Philomathie (937829) | more than 6 years ago | (#17741086)

"planning a definitive test with the future launch of the Large Hadron Collider in Switzerland that could disprove the current theory." 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.

Re:Don't they want string theory to succeed? (1)

P3NIS_CLEAVER (860022) | more than 6 years ago | (#17741286)

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.

Re:Don't they want string theory to succeed? (2, Informative)

alienmole (15522) | more than 6 years ago | (#17741408)

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...

Re:Don't they want string theory to succeed? (5, Insightful)

kfg (145172) | more than 6 years ago | (#17741448)

From the wording in the article it sounds like they actually want string theory to fail. . .

A test in which a theory fails is the most useful sort of test.

. . .despite the fact that we have few alternatives so far.

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

Re:Don't they want string theory to succeed? (2, Informative)

terrymr (316118) | more than 6 years ago | (#17741646)

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.

Wrong place, mate. (1, Insightful)

Anonymous Coward | more than 6 years ago | (#17741778)

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.

Thank God (1)

pln2bz (449850) | more than 6 years ago | (#17741088)

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.

Somewhat innaccurate title (3, Insightful)

ThinkFr33ly (902481) | more than 6 years ago | (#17741092)

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.

Re:Somewhat innaccurate title (1)

MollyB (162595) | more than 6 years ago | (#17741544)

This whole article appears misleading, although IANAS(cientist). I believe the next energy level at which experimetation takes place may turn out to reveal the so-called "Higgs boson" which is the particle/field that gives the other subatomic particles their particular masses. If they find it, it will help support, Not Prove that sting theory (now morphing to M-Theory) is possibly valid.

We run up against an inconvenient idea called the Anthropic Principle which basically says that the universe is the way it is or we wouldn't be here to wonder about it, since the Constants we observe are so exquisitely tuned to form a world like the one we see and sense. String theory has the albatross around its neck of explaining why there are so many (squillions of trillions) solutions to the theory, each representing a possible universe, and why we live in the one we do.

It is pretty hard to posit (but not demonstrate) an infinity of parallel universes along side our own, especially if the energy needed to explore Planck-length dimensions is beyond our theoretical grasp at the moment. String theory exhibits mathematical elegance, but it has a lot of 'splaining to do.

Large what collider? (5, Funny)

elliott666 (447115) | more than 6 years ago | (#17741128)

Oh...Large Hadron Collider. If it was in the Castro district I would really be suspicious.

Hmm... (1)

rewt66 (738525) | more than 6 years ago | (#17741146)

Grinstein also noted that if their test does not substantiate what the theory predicts, one of the key mathematical assumptions about the current string theory would be incorrect.

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.

Re:Hmm... (1)

pln2bz (449850) | more than 6 years ago | (#17741352)

Sounds like the physicists want to try to tweak it rather than junk it, even if it fails the experiment.

"The peer review system is satisfactory during quiescent times, but not during a revolution in a discipline such as astrophysics, when the establishment seeks to preserve the status quo."
-- Hannes Alfven

Epicycles redux? (4, Insightful)

sjbe (173966) | more than 6 years ago | (#17741154)

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.

Re:Epicycles redux? (2, Informative)

stevesliva (648202) | more than 6 years ago | (#17741270)

String theory has always struck me as a modern day version of epicycles before it was realized that planets follow ellipses instead of circles
Epicycles were a way to explain why planets that were orbiting the earth apparently reversed their direction in our sky for certain periods of time.

Re:Epicycles redux? (1)

Legendre (634519) | more than 6 years ago | (#17741608)

It's even worse than epicycles. Although the model was wrong, epicycles actually churned out the correct numerical answers. String theory can't even spit out a single number that we can compare with experiment. The original article is about putting supersymmetry to the test, which is but ONE assumption of string theory.

Re:Epicycles redux? (5, Interesting)

Ambitwistor (1041236) | more than 6 years ago | (#17741634)

Everyone always seems eager to compare to epicycles any modern physics theory they don't care for. String theory, dark matter, what have you...

Physicists were led to string theory in a search for a consistent theory of quantum gravity, not in a search to make up the most complicated theory possible to fudge arbitrary data. For more on why string theory should be taken seriously as a solution to this problem, you can read a long analysis in a previous post of mine here [slashdot.org] . String theory itself cannot be modified to "fit" to a model; it is a unique theory with no adjustable parameters or interactions. However, you can construct various string models to fit observations, as you can presently using quantum field theory models like the Standard Model.

It is also not correct that string theory doesn't make testable predictions. This whole story is about testing predictions of certain string models. However, we can't presently test predictions of all string models at once, and thus rule out all of string theory. But then, the same is true of quantum field theory models as well; there are infinitely many such models that could be true but which we can't yet test.

Re:Epicycles redux? (4, Insightful)

alienmole (15522) | more than 6 years ago | (#17741654)

I think you're quite right. The problem, though, is that we really don't know how else to do this kind of science at this point. We've reached the edges of our ability to test theories, not just for want of bigger particle accelerators, but also because of more fundamental issues -- we're inside the universe, and there's no fundamental reason that we should be able to figure out exactly how it universe works, from the inside, any more than a creature inhabiting the two-dimensional surface of a balloon can figure out that the balloon's surface is supported by air pressure in a three-dimensional space.

So in a sense, string theory is just the cover story that scientists use to continue conducting research. It's something to focus energy around, like the space program was for 1960's America. Eventually maybe we'll hit on some experimental data or a less unconstrained idea which gives us a clue as to how to proceed.

Re:Epicycles redux? (-1, Troll)

PCM2 (4486) | more than 6 years ago | (#17741950)

I am an engineer who has taken a LOT of physics classes over the years and I'm not completely ignorant either ... 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.

That's OK, though. You're forgiven for thinking like an engineer. This is science -- or at least higher math -- not industry. We're talking about thinking here, not producing a product. If these smart guys believe they're getting somewhere with all that thinking, then by all means let them. If, at some point down the line, some practical application of what they're talking about turns up, then the engineers can get excited about it, too.

The LHC is at CERN (5, Interesting)

Anonymous Coward | more than 6 years ago | (#17741182)

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?

Cool.... Sweet.... Awsum.... (0)

Anonymous Coward | more than 6 years ago | (#17741194)

Just one question: How is building this techo gadget going to prove / disprove string theory?

Nothing new (3, Informative)

forand (530402) | more than 6 years ago | (#17741200)

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.

No Crying In Baseball / No Proof In Science (1)

localman (111171) | more than 6 years ago | (#17741254)

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.

Black holes? (2, Interesting)

egrinake (308662) | more than 6 years ago | (#17741274)

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 :)

Why we musn't fear microscopic black holes (5, Informative)

benhocking (724439) | more than 6 years ago | (#17741500)

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.

Re:Why we musn't fear microscopic black holes (1)

Impy the Impiuos Imp (442658) | more than 6 years ago | (#17741832)

I read somewhere that scientists estimate a black hole dropped into the Earth would have to be on the order of a centimeter or larger before it would grow faster than it would evaporate away.

And that much would probably require a few full-sized mountains to create, if not more. A few dozen atoms' worth of mass ain't gonna cut it.

Re:Black holes? (1)

David_Shultz (750615) | more than 6 years ago | (#17741596)

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 :)

First of all the black holes being created by the LHC are not intentionally being created -they are a predicted (by some) consequence of smashing together protons at such high velocities (read 99.99999% the speed of light). The real purpose of the LHC is to attempt to create conditions where we can observe the predicted but as yet unobserved Higgs-Boson particle.

Second of all, a miniature black hole, even if it didn't dissipate due to Hawking radiation, wouldn't gobble up the Earth. It would still have the gravity of a mere two protons, since that is what constitutes its mass. Furthermore, it would be only a tiny, tiny, fraction of the size of a proton -remember, in order to be a black hole, you must exceed a certain mass:size ratio, thus, for two protons to become a black hole you must have a very small size indeed. This black hole would be so tiny it would miss practically everything (remember that the subatomic world is mostly empty space.) At that size, I doubt it would be able to "gobble up" any detectable chunk of the Earth before our sun dies out. But, I haven't done the math so who knows.

Re:Black holes? (3, Insightful)

vondo (303621) | more than 6 years ago | (#17741766)

Second of all, a miniature black hole, even if it didn't dissipate due to Hawking radiation, wouldn't gobble up the Earth. It would still have the gravity of a mere two protons, since that is what constitutes its mass.
Not quite. The theorized micro-black-holes would have masses of about 1000 protons, the amount of energy available in the collision.

Re:Black holes? (1)

David_Shultz (750615) | more than 6 years ago | (#17741908)

The theorized micro-black-holes would have masses of about 1000 protons, the amount of energy available in the collision. That's a neat trick -but it makes sense. Thanks.

Damn, what a useless blurb (0, Flamebait)

frankie (91710) | more than 6 years ago | (#17741300)

Secretsather managed to pick a quote from the article that (except for the liquid helium bit) describes the operations of ANY large synchrotron (aka circular particle accelerator). Of course, that might be a good thing, because it means that only people who know particle physics and/or have read the article will be able to post a comment with anything close to relevance.

Re:Damn, what a useless blurb (4, Informative)

frankie (91710) | more than 6 years ago | (#17741620)

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 [google.com] reveals much more informative articles [physorg.com] , which allows one to find the original journal article [aip.org] . Here's the abstract...

We show that the coefficients of operators in the electroweak chiral Lagrangian can be bounded if the underlying theory obeys the usual assumptions of Lorentz invariance, analyticity, unitarity, and crossing to arbitrarily short distances. Violations of these bounds can be explained by either the existence of new physics below the naive cutoff of the effective theory, or by the breakdown of one of these assumptions in the short distance theory. As a corollary, if no light resonances are found, then a measured violation of the bound would falsify generic models of string theory.

...most of which is beyond grasp of what I remember from 200-level college physics. Would a domain expert care to jump in now?

The project is described as (0)

Anonymous Coward | more than 6 years ago | (#17741304)

nonexistent?

Assumptions Tested (0)

Anonymous Coward | more than 6 years ago | (#17741306)

First of all, the article is very poorly written. The description: "They then introduce a new particle into the accelerator, which collides with the existing ones" is grossly inaccurate.

But most importantly they imply that this can have some baring on the standing of string theory. In reality the assumptions they are testing are the fundamentals of all physics. Whether they are confirmed or not has no baring on how string theory compares with the standard model.

IANA Theoretical Physisist, but.... (3, Interesting)

hhr (909621) | more than 6 years ago | (#17741312)

"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?

Re:IANA Theoretical Physisist, but.... (3, Informative)

Ambitwistor (1041236) | more than 6 years ago | (#17741684)

Yes, those assumptions are also shared by standard quantum field theory. (You can write down Lorentz-violating quantum field theories though.) So you're right, if those turn out to be wrong it's a bigger deal than just ruining string theory.

Bye, everyone! (3, Funny)

Rob T Firefly (844560) | more than 6 years ago | (#17741324)

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?

debate still rages? (5, Funny)

mugnyte (203225) | more than 6 years ago | (#17741342)


  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...

Re:debate still rages? (0)

Anonymous Coward | more than 6 years ago | (#17741826)

Sorry, wrong string theory.

I think this is the one about never having any string when you need it. I mean, serisouly, who keeps string lying around? Heck, where can I even buy some?

largest, and highest energy particle accelerator (1)

demonbug (309515) | more than 6 years ago | (#17741356)

I'm not real keen on this; I've already got one, you see.

It's very nice-a.

Rubbish (1)

Darktachyon (984691) | more than 6 years ago | (#17741368)

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.

Re:Rubbish (0)

Anonymous Coward | more than 6 years ago | (#17741428)

I believe in string theory too.

Wrong--Not About String Theory at All (1)

adavies42 (746183) | more than 6 years ago | (#17741430)

If this is the same story referenced here [ucsd.edu] , it's bogus [columbia.edu] . To quote Not Even Wrong [columbia.edu] ,

It is based on a paper which has nothing to with string theory and doesn't do a string theory calculation at all. The paper first appeared on the arXiv last April with the title Falsifying String Theory Through WW Scattering, and was extensively discussed here. In October a new version of the paper was put on the arXiv, with a changed title Falsifying Models of New Physics via WW Scattering (and this was discussed here). I'm guessing that the removal of the claims about string theory from the title was due to a referee at PRL not being willing to go along with such a title [...].

High-energy physics - fun, fun, fun! (2, Funny)

TheWoozle (984500) | more than 6 years ago | (#17741476)

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! ;-)

Yeah..... (0)

Anonymous Coward | more than 6 years ago | (#17741734)

And how exactly do you think the theory of the atom, and quantum mechanics came about? Given that those comprise the basis for a fantastic amount of human industry, and pretty much all the valuable ones, was that a good investment?

Re:High-energy physics - fun, fun, fun! (1)

Quiet_Desperation (858215) | more than 6 years ago | (#17741746)

"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."

Other than the speed of light part, most anyone who ever worked on a military weapons contract.

old prediction, new way to prove it? (1)

krotkruton (967718) | more than 6 years ago | (#17741604)

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.

Proven String Theory (3, Funny)

WED Fan (911325) | more than 6 years ago | (#17741628)

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.

Re:Proven String Theory (1)

Dachannien (617929) | more than 6 years ago | (#17741926)

If people would quit stretching their damn strings when they cut them, we wouldn't have this problem.

Imaginary Universe. (1)

ZwJGR (1014973) | more than 6 years ago | (#17741642)

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.

Re:Imaginary Universe. (1)

exp(pi*sqrt(163)) (613870) | more than 6 years ago | (#17741770)

String theory describes very neatly and elegantly, using complex multidimensional mathematics, an imaginary universe.
Just for the record I thought I'd add that the classical mechanics of Newton (as well as Quantum Mechanics, Quantum Field Theory, Special Relativity, General Relativity, and just about every other physical theory) also "describes very neatly and elegantly, using complex multidimensional mathematics, an imaginary universe", so your statement has a fairly low information content.

Inventing ideas using a pencil, paper and supercomputer are no match for measuring first and then performing a detailed analysis
This is like telling a golfer that it helps to put the ball somewhere near the little hole. Why not say something that has content rather than recycle truisms?

Some questions: (2, Insightful)

Quiet_Desperation (858215) | more than 6 years ago | (#17741708)

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?

 

Re:Some questions: (4, Informative)

Ambitwistor (1041236) | more than 6 years ago | (#17741882)

Which string theory? There's a few. Anyone who says "M-Theory" will get slapped.
All of them. (And "M-theory" is a perfectly legitimate answer; you can't escape the fact that all the string "theories" are really just different regions of solution space of the same theory.)

What predictions does the string theory in question make?
In this case, unitarity, analyticity, Lorentz invariance, and crossing. (Or rather, that all those properties are obeyed to arbitrarily high energies.)

Are the predictions unique to string theory?
No, they're also axioms of standard relativistic quantum field theories.

From the author (1)

Ambitwistor (1041236) | more than 6 years ago | (#17741742)

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 [utexas.edu] and here [utexas.edu] .

Mythbusters (4, Funny)

Cervantes (612861) | more than 6 years ago | (#17741936)

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...
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