String Theory Tested, Fails Black Hole Predictions

eldavojohn writes "Back in 2006 there was a lot of talk of testing String Theory. Well, today CERN has released a statement for the Compact Muon Solenoid Experiment. The short of it is simply that as far as they could tell, 'No experimental evidence for microscopic black holes has been found.' The long statement indicates that since the highly precise CMS detector found no spray of sub-atomic particles of normal matter while LHC smashed particles together, the hypothesis by String Theory that micro black holes would be formed and quickly evaporated in this experiment was incorrect. These tests have given the team confidence to say that they can exclude a 'variety of theoretical models' for the cases of black holes with a mass of 3.5-4.5 TeV (1012 electron volts). Not Even Wrong points us to the arxiv prepublication for those of you well versed in Greek. While you may not be able to run around claiming that String Theory is dead and disproved, evidently there are some adjustments that need to be made."

Comments

Simple

[ledow]

Simple. The Creator obviously didn't NULL-terminate. Hence his strings have no black hole at the end.

The story of string theory

[Pojut]

One day, Bob the Scientist was puffing on some buddha. He smoked and smoked, and smoked some more. Suddenly, Bob the scientist looked down: the lines between the tiles on the floor started to wiggle this way and that, giving the tiles the impression that they were vibrating. Bob the Scientist blinked his eyes twice, only to see the lines still wiggling, enticing them with their random, chaotic dance.

"That's it!" Bob shouted. "That's the answer, man!"

Bob the Scientist went and grabbed Bill the Scientist. He pointed at the floor, saying over and over again "The lines, man! Look at the lines! Wooooooaaaaaahhhhh."

Bill the Scientist sniffed, and said to Bob "Bob...have you been smoking that crazy ganja again?"

"Yes, but so what? Duuuuude...the liinnnes...their taaaalking to meeeee..."

"Give me some of that shit." Bill the Scientist took a big drag, looked down at the floor, and they both stared. "Woooooaaaaaaah...we better write this down, so we don't forget!"

And thus, string theory was born.

Re:The story of string theory

[Pojut]

The whole "vibrating line" thing is based off an optical illusion that affects even sober people, which pot can exacerbate. If it was LSD, the tiles would have been floating slightly above the ground and shifting colors, rather than something as simple as stationary lines showing trail-like vibrations.

I've been called many things, but never a square :p

Re:The story of string theory

[Pojut]

They're called tracers and it's not common at all for users of pot. In fact, pot 'hallucinations' are most likely a placebo effect in 99% of cases. Sleep depravation is more likely to cause them.

Look at a tile floor in a bathroom when you're stone-cold sober. Stare between the tiles, allow your eyes to lose focus, and tell me that after 15 seconds or so you don't see the lines start to dance.

Floating slightly above the ground and shifting colors? Please. What textbook did you read that out of?

My own experience, actually.

Maybe you should actually try a hallucinogen (a real one: acid, 'shrooms; not a 'classified' one: pot) before pretending to be an authority on the matter.

Between the ages of 19 and 23 (I'm 26 now), I tried the following "real" hallucinogens: LSD, LSA, mushrooms, salvia, DMT, and DXM. Before taking each one for the first time, I did extensive research by talking to people who had taken them AND taking the time to read up on them, using erowid.org and other online resources. I paid paritcular attention to their expected effects, what other substances could safely and couldn't safely be mixed with them, what to do in case of an accidental overdose/"bad" experience, what kind of food should be eaten 24 hours before ingestion, and suggestions for environmental factors such as lighting, entertainment, and topics to think/talk/write about. I took LSD, LSA, Mushrooms, and DXM numerous times, while the others I only took once or twice.

I wouldn't say I'm an authority on the matter, but I have a lot of calculated, measured experience with them.

When enough LSD is taken, you can't just characterize the hallucinations as one way or another. Things don't necessarily float or shift colors. It's an ineffable experience, but it starts with tracers -- your "vibrating lines."

And not everyone has the same reaction to the same substance, asshat. If I had never done any of these things, I would have said something about gnomes jumping around, the walls melting, or seeing my dead grandmother...all common "hallucinations" assigned to things like LSD by people who have never done them.

It's blatant mischaracterizations of marijuana such as your original post that make it remain taboo and illegal.

Fuck you very much. I fully support the legalization of marijuana, and actively try to inform people about its relative safety, especially when compared to legal substances like nicotine, caffeine, and alcohol.

The post actually would have been unwittingly funny if you had said acid rather than pot, because many hippy-geeks really do view acid-tracers as a metaphor for string theory. But a lot of nonsensical stuff seems enlightening on acid. Pot just makes you relaxed and hungry.

Then you haven't been doing the right things while under the influence of pot.

Re:Unobservable

[vadim_t]

Does it matter if something inobservable exists? If you posit the existence of something that can't be observed, how do you verify that hypothesis? What are the applications for a theory that doesn't suggest effects we can detect and verify?

adjustments

[Tom]

While you may not be able to run around claiming that String Theory is dead and disproved, evidently there are some adjustments that need to be made."

...again

String theory is one of those theories that get changed around every time they run into trouble. I can't imagine what it would take to have it go away, aside from a paradigm change.

Re:adjustments

[TheRaven64]

String theory is one of those theories

No it isn't. 'String theory' is an informal term used to describe a collection of theories with some common principles. Not all of them make the same predictions. It works as a pretty good filter when reading scientific journalism. Any article that contains the phrase 'string theory says' is almost certainly written by someone who doesn't know what they are talking about.

that get changed around every time they run into trouble

Uh, that's how science works. You observe, hypothesise, test, and then refine the hypothesis. Sometimes it takes a lot of testing before you find a case where the hypothesis makes predictions that are wrong (e.g. Newtonian gravity), sometimes it takes very little. If a theory is sufficiently high profile, a lot of effort (e.g. building the LHC) will go into testing it, so hopefully you'll find errors quickly.

Very occasionally, someone will come up with a completely new theory that makes the same predictions as an existing one (or more accurate ones) but is simpler. When this happens, it generally displaces the old theory, but it's very rare.

Re:adjustments

[Dr. Spork]

Good, I'm glad someone said this so I don't have to. As it happens, the very fact that there are so many string theories available is my #1 reason for being disillusioned with the theory. Not only does this data slow down any string theory research program, but they have not even described any possible data that could. String theories (or I should say M-theory) is so empirically slippery that it serves more as an explanatory framework and less a scientific theory.

An explanatory framework is a normative constraint on how we should interpret the world, not a set of statements that entails to observational predictions that can be falsified. The Enlightenment view that "the universe is a clocklike mechanism" is clearly not a scientific theory, but it sort of provides a framework for things that are. They basically said "we don't want to hear any theories that don't represent the universe as a clock-like mechanism." That's why I said "normative." M-theory evangelists are best understood as people who try to commit us to a new normative framework ("we only want theories that can be expressed in 'elegant' M-theory math'), rather than to a scientific theory.

Re:adjustments

[sjames]

The problem is that the wrong field is studying string theory. It's more a toolbag of high end mathematics than a physics theory at this point. Like many things in math, it may or may not be about anything that actually exists. You can write out a bazillion arbitrary equations and use amazingly advanced techniques to solve them, but they might not mean anything.

There are so many variations and so many "knobs" that can be adjusted that as it stands, string theory has no predictive power at all. Any result can be accommodated by making the right adjustments. Worse, having made the adjustments, any future result can still be accommodated by making further adjustments. A real theory would say "the knobs must be set this way and only this way because..." and that would yield specific predictions that could be tested.

Consider a world where we have "polynomial theory" and we wish to discover the laws of radioactive decay. We make measurements of the intervals between decay events and plot them on a graph. With each result, we add another term to our "god polynomial" so that it fits. Provably, we can go on doing that forever and make it fit. However, at no point do we know what term comes next, so we can never actually predict an atomic decay event.

I think it's good either way

[line-bundle]

It shows string theory is testable after all.

Even failing still sheds light on what is wrong with our theory (or reality if you're an economist :-).

Re:I think it's good either way

[KiwiCanuck]

"I haven't failed, I've found 10000 ways that don't work."-Thomas Alva Edison.

Re:I think it's good either way

[dkleinsc]

The same is not true for economics

And there's an easy answer as to why: False theories in economics can be very profitable, and where there is large profit to be made there will be somebody trying to make it (that's one of the few settled theories of economics).

For instance, the Laffer Curve has been consistently demonstrated to be absolutely nothing like what Arthur Laffer postulated it would be (namely, a smooth parabola) when tax rates are anywhere in between about 10% and 90%. But the Laffer Curve also motivates politicians to cut taxes, which for people who pay a lot of taxes is very profitable. So if I'm an economically rational wealthy guy who normally pays $1 million in taxes, and I can pay somebody $30,000 to tout the Laffer Curve to help convince politicians to cut my taxes by 5% (thus with a potential savings of $50,000), I'm going to do just that.

Re:fail

[Jeremiah Cornelius]

Then how DO you explain these infinite number of parallel universes? There must be some experimental rationale for the overwhelming evidence of these!

Signed, Arthur XXII, King of Britain and Jupiter.

Dangerous Ground!

[eldavojohn]

How can we be sure that the black holes were not created?

As one might suspect, the very opening to the paper in the arxiv explains this. After lengthy explanation of several peer reviewed papers that have been widely accepted on detection of black holes, they state:

The microscopic black holes produced at the LHC would be distinguished by high multiplicity, democratic, and highly isotropic decays with the final-state particles carrying hundreds of GeV of energy. Most of these particles would be reconstructed as jets of hadrons. Observation of such spectacular signatures would provide direct information on the nature of black holes as well as the structure and dimensionality of space-time [1]. Microscopic black hole properties are reviewed in more detail in [15, 16].

Now, as you can see by the [1], [15] and [16] references, each of these claims will lead you to a further longer paper on the concept of black holes themselves. Is it possible this method is flawed? I'm not a particle physicist so I'm not authorized to answer that. But I will say that this experiment has been a long time coming and I'm certain the authors of this paper were very careful in all their statements about String Theory.

String theory posits that there exist physical dimensions outside of our 4 dimensional universe, in fact that these are part and parcel of our universe. However, given our tools are all limited to 4 dimensions, it makes sense that there could be phenomena that is unobservable in our universe yet occurring in those other unexperienceable dimensions.

I know what you're saying but String Theory turns a lot of people off when its nature seems to be "unobservable" as you so put it. You'd have just as easy a time proving God exists as you would proving String Theory. The joke about String Theory is that it is conceived to make it untestable so it can never be wrong. This is dangerous ground and whenever a prediction is made by the theory that can be tested, it must be taken seriously. "Unexperienceable dimension?" Ahhh, I wouldn't go around talking to scientists about 'unexperienceable' things. I do not believe the scientific process looks kindly on such things.

I agree with the summary, this isn't the defeat of String Theory. It is a chance to refine and improve it.

I am the submitter, I don't think I said anything too far one way or the other. Usually Not Even Wrong points me in the correct direction but they gave this paper an unusually short nod with little correspondence or refutation. I think this is a good indication that everyone is waiting for the real scientists (not my lame armchair ass) to look this over and weigh in. You know, if you make predictions and they're wrong and you stretch your model to always avoid any sort of direct contradiction but you never get anything correct, then you look more like a fortune teller than a theoretical physicist. They should have the option to revise but my prediction is that this result will lose them a large amount of support in the community. It doesn't outright disqualify them but it sure is a vote of no confidence in a lot of the popular String Theory models.

Re:Dangerous Ground!

[mangu]

From the Wikipedia article on Michelson-Morley,

The constancy of the speed of light was postulated by Albert Einstein in 1905, motivated by Maxwell's theory of electromagnetism and the lack of evidence for the luminiferous ether but not, contrary to widespread belief, the null result of the Michelson-Morley experiment.

Ah, the dangers of Wikipedia! That citation is from a footnote in a book mentioning what someone said Einstein told him. Polanyi wrote in a footnote that Balzas told him that Einstein said that it was not the Michelson-Morley experiment that motivated the special theory of relativity.

The truth is that when Maxwell published his equations they were obviously right according to everything that was known about electromagnetism, but they were logically flawed according to classical mechanics.

When you see two electric charges moving side by side, for instance, electric current in parallel wires, there is a magnetic force between them, in addition to the electrostatic force. However, if you are moving along with the charges, then you should observe no magnetic force, since both charges aren't moving with respect to you. That was a paradox of Maxwell's equations and something that seemed to demonstrate that Maxwell was wrong, but magnetism exists and no one could explain why.

The Michelson-Morley experiment presented another mystery, that the speed of light seemed constant and did not depend on the speed of either the emitter or the receiver of the light. Another paradox that no one could explain yet was demonstrated in practice by experiment.

Einstein was the first person to create a theory that explained both of these results. He showed that an always constant speed of light could explain magnetic force if one applied a Lorenz contraction to moving electric charges. The magnetic force between two moving charges is equal to the difference between the electrostatic force of the charges while standing still and the electrostatic force reduced by a Lorenz contraction due to the speed.

In that way both the observer that's standing still and the observer that's moving along with the charges will measure the same force between the charges, only one of them will see a pure electrostatic force and the other one will see an electrostatic force between two slightly larger electric charges plus a magnetic force.

In conclusion, Maxwell was right, but without the Michelson-Morley experiment he would be only empirically right. And even the general theory of relativity wasn't fully proved from an experimental point of view until the Moessbauer effect was discovered.

Re:Unobservable

[NEDHead]

God, for example?

In case you want to know from a physicist

[Anonymous Coward]

I happen to be an actual theoretical particle physicist. The headline and summary are completely misleading/sensationalist and this has essentially nothing to do with string theory. If I hadn't seen the string-theory connection here on slashdot, "string theory" would not even have crossed my mind reading this. If you happen to actual read the so-called "long statement" (which is only half a page really) you would have noticed that it doesn't say anything about string theory. What this measurement has ruled out are certain theories that have some small extra dimensions that would predict these tiny black holes. Those theories don't really have anything to do with string theory per se. The only conceived connection is that string theory also has more than 4 spacetime dimensions.

Calling this "string theory tested, fails prediction" is close to the following analogy: Someone comes up with a crazy theory according to which once a while (say 1 in 100) an apple that gets detached from a tree should rise into the sky (say by using complex numbers to cleverly generate a minus sign in Newton's laws). After having observed sufficiently many apples all fall down, we can now say with confidence that apples don't rise but in fact always fall. The slashdot headline would be: "Complex numbers tested, fail apple prediction."

So rest assured, no string theorist will have a sleepless night and none of them will make any adjustments whatsoever. The main reaction in the particle physics world to this will be a lunch conversation along the lines of: "Told you so, this whole idea about mini-blackholes was ridiculous in the first place, in any case, glad they rule it out, so hopefully this will quiet down this whole black-hole circus now."

Re:Nerdrage at incongruence in TFS

[Sockatume]

I suspect a carat or other symbol was dropped by the slashcode, and it used to read "TeV (10 *to the* 12 electron volts)".

Re:Unobservable

[DragonWriter]

Wrong. A layman would tell you that 1 + 1 = 2. Layman means someone who understands a subject and can even work with it to some extent, but is NOT an expert.

No, "layman" doesn't mean "someone who understands a subject and can even work with it to some extent but is NOT an expert." It means simply "someone who is not a member of a particular profession", full stop. (That's actually the second, but relevant, definition, which evolved from the earlier and still primary definition, which is specifically someone who is not a member of the clergy.)

"Layman" is sometimes prefixed with an adjective like "experienced", and so modified may mean something like what you suggest, but that isn't what it means on its own.

summary is completely incorrect

[bcrowell]

The summary is completely incorrect. Whoever wrote the summary simply didn't understand the paper. String theory does not predict the production of microscopic black holes at LHC eneries. The paper's abstract says, "Limits on the minimum black hole mass are set, in the range 3.5 -- 4.5 TeV, for a variety of parameters in a model with large extra dimensions, along with model-independent limits on new physics in these final states." Note that phrase "large extra dimensions." Here is the WP article on large extra dimensions. String theory has *small* extra dimensions: extra dimensions that wrap around on themselves at the Planck scale. The LHC doesn't probe the Planck scale. Theories with large extra dimensions have, er, *large* extra dimensions. This experiment falsifies those theories, not string theory.

Re:Unobservable

[Anonymous Coward]

Probably, but the number of tests that string theory failed is by now quite a few. Lots of incidents. But every time they "made adjustments" to the hypothesis. One might think this is all very well but there's a bit of a problem :

theorists : string theory "predicts" A
-> experimenters : we searched ... no A
theorists: string theory's still valid because we modified it to predict B
-> experimenters : we searched ... no B
theorists: string theory's still valid because ... we modified it again to predict C
-> experimenters : we searched ... no C

The problem is what the modifications prove : that string theory can predict all kinds of stuff. String theory is a model that is "too general". It's like answering the question of "what are the laws of physics" by saying "math", or "english".

The issue is also not that the laws of physics can't be expressed as mathematical equations, or can't be explained in english. But it is not an answer to the question at all. It's a bit like a customer came to the university for a voip installation and they give him a C compiler. Sure it's a tool that can be used to build what he needs, but it's a bit of a stretch to say it answers any question for real.

In reality we're barely a step further than when the standard model was finalized. Sure lots of mathematics were researched to get to "string theory", but none of it proved valuable in analyzing the real world (like climate theory, we're certainly not lacking in theories, or even proof that theories hold perfectly for some small subset of the problem, but when a prediction is made, they just don't match up to reality).

We're back in 1910. Quantum theory is very wrong. Relativity theory is very wrong (we've found experiments that violate both theories, and in any case, there are many real-world things they don't touch (quantum theory can't explain anything "big" and relativity can't explain anything "small"). The only attempts at finding alternatives have ... well ... they've basically failed. That also means that many "accepted" facts, like the many-worlds hypothesis are ... well there just isn't any proof for them, so actually they should be treated like the average star trek episode, a firm "FICTION" label applied to them.

Like in 1910, the conclusion should simply be : we need some new ridiculously simple idea, because we're stuck in a dead end with the theories we have.

The problem is string theory is firmly entrenched in universities, produces papers like Obama produces debt, and ... well ... even without those arguments there's the saying "paradigms change one funeral at a time". Lots of funerals need to happen before an alternative to string theory can be given real academic resources.

Re:Unobservable

[jfengel]

It's not a bad analogy. But it's also important to realize that the geocentric model is a GOOD model. Navigators used it long after Copernicus and Galileo, and if it's going by the wayside there, it's only because GPS really is geocentric.

The key to heliocentrism isn't changing the center, but changing the shape of the orbit. If you think of the sun as the center of the universe but are still trying to force things into circular motion, you end up with as many correction factors as geocentrism does. Galileo and Copernicus were well aware of the mathematical difficulties. It wasn't until Kepler that they finally had a solution.

The problem with the analogy is that it's not string theory that's equivalent to geocentrism, it's quantum mechanics, quantum field theory, and general relativity. These are excellent theories that still have problems in that they disagree with each other. String theory is the epicycle tacked on to try to account for the differences.

That's still not quite apt, since the failure modes are different. Geocentric theory failed because data contradicted it without awkward modifications. Quantum and relativistic theories agree with the data, but disagree with each other under circumstances that are difficult to produce experimentally. So string theory is useful theory with no data, and epicycles were a good way to deal with the data but with poor theoretical support.

Some scientists are aggrieved that a theory with no data, and none forthcoming, should receive so much attention. Disproving it would actually be a great advance, and would actually reflect well on the people studying it. Unfortunately, the import of the experiment in this article is exaggerated.