by CHARLES Q. CHOI
Fast and elusive? Observations of supernova 1987A indicated that photons and neutrinos obey the same speed laws. But neutrinos might still have some tricks up their sleeve. IMAGE/NASA/ESA/P. Challis and R. Kirshner/Harvard-Smithsonian Center for Astrophysics
One explanation that a number of researchers have proposed is that the neutrinos might be traversing extra dimensions of reality beyond the familiar three of space and one of time. As such, they would only appear to be traveling faster than light from our perspective. This idea would keep Einstein’s theory of relativity intact and help end decades of debate over whether extra dimensions actually exist.
“However, these models have other potential problems,” says Hannestad, a researcher with a potential extradimensional explanation for the neutrino results. For instance, he notes, the neutrino pulses predicted to emerge from a trip through extra dimensions may differ in their attributes from the pulses the OPERA researchers actually detected.
Another notion is that neutrinos may travel faster through Earth than through empty space, with Earth essentially acting like a lens, says theoretical physicist Dmitri Semikoz of University of Paris Diderot in France. “Several checks of our proposal can be performed,” he adds. “In particular, it predicts that the effect is proportional to the intensity of the neutrino wave. This can be checked experimentally by the OPERA and MINOS collaborations with data they already have.” (MINOS, the Main Injector Neutrino Oscillation Search, is a competing neutrino experiment in the U.S.)
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