Can’t take a breath this week without stumbling over another particle physics result of note. (It isn’t usually like this, folks — this year has been very odd.) OPERA (the experiment that claims their neutrinos travel faster than light does, which if true would require some kind of modification of Einstein’s relativity principles) is back, and they’ve done a very important cross-check many of us were hoping they would do, which is very good news indeed. Since they say that it confirms their previous result, the plot now thickens considerably; the experiment’s technique is now harder to question, and the long list of possible sources of problems with the experiment is considerably shorter. Obviously this news deserves a long post, explaining exactly what they did and why it is such an improvement. I’ll produce one for you before the weekend is over, possibly as soon as tomorrow. Watch this space!
In the meantime, here’s a guide to past posts, which cover most of what you need to know:
- a catalogue of my several early posts (and a Q&A) on the OPERA experiment, including how you make a neutrino beam and how you detect neutrinos, are here,
- articles that discuss why, if the experiment is correct, certain effects similar to Cerenkov radiation must somehow be shut off, are here, here and here.
- the article that explained that OPERA would be doing this cross-check, and why I thought it was a very good thing, appeared here.
And here’s the key new plot from the OPERA experiment, showing the 20 measured neutrinos arriving 61 ns early, with a spread that is consistent with the uncertainties of the measurement, and not necessarily to be interpreted as the neutrinos having different velocities…