Physicists working at the Large Hadron Collider report that after a series of tests, they have not seen any mini black holes, to the chagrin of string theorists and the relief of disaster theorists.
Researchers working on the Compact Muon Solenoid team have been crunching numbers to test a form of string theory that calls for the creation and instant evaporation of miniature black holes. They report that the telltale signs of these black holes are disappointingly absent, however.
String theory is the most widely accepted attempt to unify the two major fields of physics, quantum mechanics and relativity. It holds that electrons and quarks are not objects, but one-dimensional strings whose oscillation gives them their observed qualities. It also says the universe has about a dozen dimensions, rather than the usual four (length, width, height and time).
In one version of string theory, if these dimensions exist, gravitons — hypothetical particles that transmit gravity — would leak into them, explaining why gravity is so much weaker than the other forces, as New Scientist explains it. It’s not really weaker, it just seems weaker, because some of its particles are in another dimension we can’t see. Happily, it takes a lot less energy to test this than it would to actually unify all the forces, and it just so happens it’s is in the energy range that the LHC, the world’s most powerful particle accelerator, is capable of testing.
If this is all true, particles that collided at energies beyond this graviton-leaking energy cutoff would get so close together that gravity would take over, and they would merge to form a tiny black hole. The black holes would instantly decay, so there would be no danger of Earth being swallowed whole, and the decay would be visible as jets of particles. But the researchers have so far seen no jets.
This doesn’t disprove string theory — it just proves that mini black holes can’t be produced at energies between 3.5 and 4.5 trillion electron volts. But they could still theoretically be produced at higher energies, so when the LHC fully fires up in 2013, string theorists will be holding their breath.
Meanwhile, the tests show the LHC is performing supremely well, so physicists aim to keep it running through 2012. This means they might be able to find the elusive Higgs boson sooner than expected.