String Theory Tested, Fails Black Hole Predictions 307
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."
Re:Unobservable (Score:4, Insightful)
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 (Score:5, Insightful)
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.
I think it's good either way (Score:5, Insightful)
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 :-).
Dangerous Ground! (Score:5, Insightful)
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:Unobservable (Score:3, Insightful)
Re:adjustments (Score:5, Insightful)
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:Simple (Score:1, Insightful)
Or perhaps the FSM is simply changing the results to make us THINK that string theory is false, to test our faith.
Re:Unobservable (Score:1, Insightful)
You would detect it indirectly through observing its effects on objects we can observe.
Re:Unobservable (Score:3, Insightful)
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. Most if not all of us are medical laymen for example. We can apply a band aid, apply CPR, know how to take a pulse and if one is not evident that a person is dead. But we wouldn't be the one to go to, to perform a complex diagnosis or prescribe medicine or perform an operation... because we are laymen. Laymen can know enough on a subject to sound like they know what they are talking about, and drive experts crazy. Now I am waiting for real language experts to go ballistic on me. [grin]
Re:Unobservable (Score:4, Insightful)
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 ... no A ... no B ... we modified it again to predict C ... no C
-> experimenters : we searched
theorists: string theory's still valid because we modified it to predict B
-> experimenters : we searched
theorists: string theory's still valid because
-> experimenters : we searched
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:The story of string theory (Score:2, Insightful)
This was awesome. Whether it is recreation drugs or anything else people can become expert in, I've noticed the following levels of expertise: Novice, journeyman, and guru. The novices, clearly know nothing. The Gurus know everything. The moderately skilled journeymen know just enough to think they know everything, but often they do not know as much as they think and sometimes can't tell the difference between an novice and guru.
Re:adjustments (Score:5, Insightful)
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.