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:adjustments (Score:5, Interesting)
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:Dangerous Ground! (Score:4, Interesting)
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 [wikipedia.org] was discovered.