Einstein's Relativity Survives Neutrino Test

Physicists working to disprove "Lorentz invariance" -- Einstein's prediction that matter and massless particles will behave the same no matter how they're turned or how fast they go -- won't get that satisfaction from muon neutrinos, at least for the time being, says a consortium of scientists.

The test of Lorentz invariance, conducted by MINOS Experiment scientists and reported in the Oct. 10 issue of Physical Review Letters, started with a stream of muon neutrinos produced at Fermilab particle accelerator, near Chicago, and ended with a neutrino detector 750 meters away and 103 meters below ground. As the Earth does its daily rotation, the neutrino beam rotates too.

"If there's a field out there that can cause violations of Lorentz invariance, we should be able to see its effects as the beam rotates in space," said Indiana University Bloomington astrophysicist Stuart Mufson, a project leader. "But we did not. Einsteinian relativity lives to see another day."

Mufson is quick to point out that the Physical Review Letters report does not disprove the existence of a Lorentz-violating field. Despite the sophistication and power of MINOS's detector, "It may be that the field's effects are so exceedingly small that you'd need extraordinary tools to detect it," Mufson said. ... - sd