Einstein's theory of relativity passes crucial test

Washington, Oct 16 : Albert Einstein's theory of relativity has survived a neutrino test, which was conducted by physicists trying to disprove the premise.

The physicists were 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.

The test of Lorentz invariance, conducted by MINOS Experiment scientists, 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," he added.

The neutrinos are aimed at two detectors: one at Fermilab (the near detector) and another in the Soudan Mine in northern Minnesota (the far detector).

To produce the neutrinos, the MINOS scientists point a proton beam at a carbon target. The interaction causes a spray of pions (or pi mesons, a type of subatomic particle), some of which decay into muon neutrinos in the direction of the detector.

Neutrinos travel at close to the speed of light, are unaffected by gravitational and magnetic fields, and because of their peculiar properties, can travel right through the crust of the Earth unaffected.

The notion of a Lorentz-violating field has become popular among theoretical physicists.

Known physical rules do not do a very good job of explaining the cataclysmically chaotic moments immediately following the Big Bang, so some physicists are developing new theories to sort out the mess.

The possibility that some of these new theories violate relativity was proposed by Mufson's colleague Alan Kostelecky, distinguished professor of physics at IU Bloomington.

Kostelecky's "Standard-Model Extension" describes the most general possible Lorentz-violating fields that could arise in the universe's beginnings and also ties together Einstein's relativity rules and post-Einsteinian quantum mechanics.

One of the implications of Kostelecky's ideas is that the Lorentz-violating field could have been very strong during the mind-numbingly brief first moments of our universe. ow that the universe has expanded to considerable size, however, the strength of the Lorentz violating field may be severely reduced, making its existence hard to detect, if it is, indeed, actually there.

"Every experiment so far has not found violations of Lorentz invariance," Mufson said. "That doesn't mean we'll stop looking," he added.

ANI