Wednesday, October 26, 2011

Superluminal Neutrinos

I mentioned this case about the OPERA neutrinos experiment yesterday in class. Here's the original news report from Nature. It seems to me revealing of a lot of different ideas we talked about: most clearly, the resilience of well established theories being resilient in the face of apparent falsification. Think of how many people reacted to the apparent falsification of special relativity with a "ho hum: there must be something wrong with the experiment or their calculations" (without even knowing anything about the experiment). (Compare our reaction to the "pigheaded" opponents of Galileo.)

One of the most telling problems with the hypothesis that neutrinos go faster than light is that we would have noticed this before. From the news report above:
"Ellis, however, remains sceptical. Many experiments have looked for particles travelling faster than light speed in the past and have come up empty-handed, he says. Most troubling for OPERA is a separate analysis of a pulse of neutrinos from a nearby supernova known as 1987a. If the speeds seen by OPERA were achievable by all neutrinos, then the pulse from the supernova would have shown up years earlier than the exploding star's flash of light; instead, they arrived within hours of each other. "It's difficult to reconcile with what OPERA is seeing," Ellis says."
Follow-up reports offer some interesting suggestions about how the study might have gone wrong:
"Faster-than-light neutrinos face time trial" (Nature)
"Finding puts brakes on faster-than-light neutrinos" (Nature)
"Faster-than-Light Neutrino Puzzle Claimed Solved by Special Relativity" (Technology Review)
"Particles Faster Than the Speed of Light? Not So Fast, Some Say" (New York Times)
The comments on many of these posts are sociologically interesting too (I tell myself never to read comments on blogs/news sites, lest I lose faith in humanity; but sometimes I can't resist).

Note one extremely interesting aspect of many of these explanations: what is doing the explaining away of the OPERA results? Relativity. What is the theory that would be "falsified" by the OPERA results? Relativity. So relativity is apparently testifying on its own behalf! On its face, this looks like a problem. Is it? (You can replace a SWA question with your answer.)

Here's XKCD's suggestion of how to monetize skepticism about skepticism:

Also: check out the abstract to this article: "Can apparent superluminal neutrino speeds be explained as a quantum weak measurement?". It has my vote for best abstract to an academic paper for 2011.

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