More details on the "faster than the speed of light" neutrinos

[jayfish]

http://arstechnica.com/science/news/2011/09/neutrino-results-depend-on-exquisite-measurements-of-time-space.ars

Last night, in response to a worldwide surge in interest, the OPERA experiment released a paper that describes the experiments that appear to show neutrinos traveling faster than the speed of light. And today, CERN broadcast a live seminar in which one of the work's authors described the content of the paper. Both of those emphasized the point of our initial coverage: figuring out whether anything is traveling beyond the speed of light requires incredibly accurate measurements of time and distance, and the OPERA team has made an extensive effort to make its work as accurate as possible.

As a spokesperson for the MINOS neutrino experiment told Ars yesterday, there are three potential sources of error in the timing measurements: distance errors, time-of-flight errors, and errors in the timing of neutrino production. The vast majority of both the paper and the lecture were dedicated to discussing how these errors were reduced (the actual detection of the neutrinos was only a small portion of the paper).

The end result is that the OPERA team doesn't see any obvious problems in its measurements. All of the errors, when added up, shouldn't be able to account for anything close to the 60ns gap between the neutrinos' arrival and the speed of light. The difference between their speed and that of light is very statistically significant, and the neutrino data itself looks excellent. The team has recorded over 16,000 events now, and the profile of events over time very closely matches the structure of the proton bunches that created them.

But that doesn't mean that this presentation is the last word on the topic. There are a lot of potential sources of error they know about—the paper's table lists a dozen of them. Small errors in each of these could add up to something more significant than their total error. Then there are the classic unknown unknowns. The authors have tried to think of everything, but it's not clear that they can.

[MineralMan]

1. It's a very interesting story, and will be worth following.

The key will be duplicating the results. If they can do that, then they'll have something to begin studying. High energy particle physics is fascinating, if hard for the layperson to understand.

[Rabblevox]

2. I'll admit that I don't understand, but it's still fascinating to follow...

what I haven't seen though, is how MUCH faster than light speed these neutrinos were. 60 nanoseconds over 400 miles is WAY too difficult for me to do the math.

[MineralMan]

4. It's actually quite a bit, considering that the speed of light is about

186,000 miles per second. I understand it conceptually, but can't do the math at that level. So, I read second-hand reports and suss it all out from there.

[jberryhill]

6. 1 nanosecond = about 12 inches of light travel /nt

[pokerfan]

9. google concurs!

Actually I knew it already (pretty much have to as part of my job) but I just love playing with the google calculator.

[jberryhill]

5. Think of it this way

Light travels about 30 centimeters in a nanosecond.

That's 11.8 inches - about a foot.

Go find a 12 inch ruler - that's how far light travels in a nanosecond.

If you had a race between light and these neutrinos from Geneva to the detector in Northern Italy (not that far through the Alps, really), the neutrinos would win the race by about 60 feet.

[valerief]

3. Now can we do time travel and undo NAFTA and undo Gramm-Leach-Bliley

and undo Bush 2000?

[nadinbrzezinski]

7. And for nerd humor

https://mobile.twitter.com/#!/search/%23mundaneneutrinoexplanations

Hilarious.

[pokerfan]

10. and more nerd humor

[nadinbrzezinski]

11. Thanks, saved it

[bananas]

8. It's actually consistent with previous experiments

"Curiously, when taken at the face value, all results point to a negative mass squared"

http://cupp.oulu.fi/neutrino/nd-mass.html

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Measurements for electron neutrino mass

The mass of electron neutrinos is measured in tritium beta decay experiments. The decay results in a 3-helium, electron and an electron antineutrino. If neutrinos have non-zero mass, the spectrum of the electrons is deformed at the high energy part, i.e. the neutrino mass determines the maximum energy of emitted electrons.

To be excact, the experiments measure the neutrino mass squared. Curiously, when taken at the face value, all results point to a negative mass squared, particularly the oldest experiment. This is probably due to a systematic error, and actually two running experiments, Mainz and Troitsk, have been able to measure physically acceptable values.

Experiment measured mass squared formal limit C.L. Year
Mainz -1.6 ± 2.5 ± 2.1 2.2 95 % 2000
Troitsk -1.0 ± 3.0 ± 2.1 (**) 2.5 95 % 2000
Zürich -24 ± 48 ± 61 11.7 95 % 1992
Tokyo INS - 65 ± 85 ± 65 13.1 95% 1991
Los Alamos - 147 ± 68 ± 41 9.3 95% 1991
Livermore - 130 ± 20 ± 15 7.0 95% 1995
China - 31 ± 75 ± 48 12.4 95% 1995
Average of PDG (98) -27 ± 20 15 95 % 1998

Masses in units of eV.

<snip>