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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."
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 :-).
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.
My work here is dung.
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.
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