Friday, September 23, 2011

Do Neutrinos Travel Faster than Light?

Today the media published preliminary reports (here is one) that neutrinos generated at CERN are being detected 450 miles away at the Gran Sasso Laboratory  in Italy 60 nanoseconds sooner than they would be expected to arrive if they traveled at the speed of light.

If this result is upheld through further experiment, it will be revolutionary (and very exciting!) within Physics as Einstein's Theory of Special Relatively (which is very well established) postulates that no particle can travel faster than the speed of light.

It is noteworthy that neutrinos travel in a straight line, and a straight line between Geneva and Rome is underground (but neutrinos can travel through rock essentially unhindered).

I've asked students in my classes at FSU, for up to 5 points of extra-credit, to answer the following questions.

How many nanoseconds would neutrinos take to make this flight at the speed of light?

What is the percentage difference between the expected and the observed travel time? Hint, you should use scientific notation to express this result.

If the experimental error is 10 ns as expected, what is the probability that the experimental error can explain this discrepancy? Hint, divide the discrepancy by the expected error, and then integrate the Chi-square distribution from this number of standard deviations (6) to infinity (you should get 2E-9).

What other errors might explain this? Hint, Google unrecognized systematic error.


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