A retired physicist, Robert Ehrlich, from George Mason University, claims that the neutrino travels faster-than-light and is very likely a tachyon – any hypothetical particle that always travels faster than the speed of light. His finding was recently accepted by the journal Astroparticle Physics.

Earlier OPERA experiment conducted back in 2011 claimed that the speed of neutrinos travelled a little faster-than-light, however, when their speed was measured again using new measuring technique, known as a liquid argon time projection chamber, the result was found to be error.

Ehrlich uses imaginary mass of the neutrinos to measure their speed which is much more sensitive than measuring their speed, so the result of his measurement strictly relies on tachyons having an imaginary mass, or a negative mass squared. Imaginary mass particles speed up as they lose energy.

Neutrino Is Likely A Faster-Than-Light Particle

According to Ehrlich, the magnitude of the neutrino’s imaginary mass is 0.33 electron volts, or 2/3 of a millionth that of an electron. He deduces this value from six different observations based on data from areas including cosmic background radiation fluctuations, gravitational lensing, cosmic ray spectra, neutrino oscillations, and 0ν double beta decay; and all yield this same value within their margin of error.

A 1962 article by George Sudarshan and his colleagues Bilaniuk and Deshpande suggested the idea of faster-than light as a kind of loophole in relativity. Even Albert Einstein had it shown that it is impossible for particles (or space ships) to outmatch the speed of light because for a particle to accelerate beyond the speed of light, it will required infinite energy.

However, Sudarshan and his colleagues proposed that if particles were created initially with faster-than-light speed in particle collisions, no acceleration or infinite energy would be necessary, which unfortunately is not possible for space ships. So cynicism of tachyons often cite conflicts with relativity theory.

Decades after tachyons were first proposed, three theorists Chodos, Hauser, and Kostelecky suggested in 1985 that they might be hiding in plain sight – specifically that neutrinos are tachyons. This idea led them to propose that protons should beta decay when they travel at sufficiently high-speed towards us.

The process of protons beta decay is forbidden because it could not conserve energy, but that changes if neutrinos are tachyons, energy can be negative in certain reference frames – in effect negative energy tachyons travel backwards in time.

The proposal of Chodos-Hauser-Kostelecky is what triggered Robert Ehrlich to take up the hunt in 1999 when he claimed support for neutrinos being tachyons based on several cosmic ray studies. Ehrlich’s new result relies on data from four other areas besides cosmic rays, and is therefore more robust.

Robert Ehrlich’s claim of neutrinos travel faster-than-light, however, has not been concluded to be correct because some phenomena are yet to be observed. A check on his claim could come from the experiment known as KATRIN (Karlsruhe Tritium Neutrino Experiment), which should start taking data in 2015. This experiment could reveal the mass of the neutrino by looking at the shape of the spectrum in the beta decay of tritium, the heaviest isotope of hydrogen; and if luck favors, another test based on high energy cosmic rays could be made using existing data.