CERN >c result - eliminating the errors
I was just thinking that it would be helpful to list the possible experimental errors and eliminate them as it is shown that they have already been accounted for. (See
http://www.universetoday.com/89191/faster-than-the-speed-of-light-opera-update/ for some comments from the GSL people re their metrological accuracy.)
In broad terms there are at least the following possible types of errors:
wrong timing (at either end)
wrong distance (between CERN and the Gran Sasso Laboratory (GSL))
wrong neutrinos (ie they just happened to pick up stray neutrinos and misattributed them)
wrong calculation
wrong equipment
if there are other broad types of errors, point them out.
Wrong timing errors
To get an accurate timing, the clocks at CERN and GSL would need to be well synchronised and running at the same rate - what are the relative positions of the two facilities? An image of GSL seems to show that it is up in the mountains, and if I recall correctly, CERN is buried - do their clocks take this into account? Would an error in the difference in altitude be in the right order? Did the work carried out by CERN and GSL take this into account?
Could the measurement process have affected the measurement? (That is, are we looking at a sort of Heisenberg effect, where our observation of the neutrinos is somehow affecting timing in a way that we haven't figured out?)
I'm assuming that any systematic errors in measuring the emission times and arrival times would have been identified and eliminated quite early in the investigations.
Any other possible timing errors?
Wrong distance errors
As pointed out elsewhere, the 60ns that is involved translates to 10m. An error in measuring the distance between the transmitter (CERN) and the receiver (OPERA at GSL). The update article, however, did state that "the measurements of the initial source of the neutrino beam and OPERA has an uncertainty value of 20 cm over the 730 km. The neutrino flight time has an accuracy of less than 10 nanoseconds, and was confirmed through the use of highly regarded GPS equipment and an atomic clock. Every care was given to ensure precision". So 10m is well outside of their uncertainty value, as is 60ns.
The only questionable part of this is that they measured the distance between two points using GPS, rather than the measuring the path that light would take between the points.
Personally, I think this is where the error is. The path that would be taken by light between "the initial source of the neutrino beam and OPERA", if light could take that path without being absorbed/deflected by the chunk of the Earth in between, could possibly be shorter than the distance calculated to lie between the two points. This would not be in contravention of relativity, but might require a slight reinterpretation. I'll go into more depth in a follow up post.
The use of GPS eliminates one of the obvious errors, in that the surface distance between points is not the shortest distance between them. In any event, the chord between 732km of arc of the Earth's radius is something like 730km and such a miscalculation would result in an error in the order of milliseconds, not nanoseconds.
Any other distance errors?
Wrong neutrino errors
Included for completeness. If the experiment was done once, then it could be possible (but highly unlikely) that stray neutrinos could have been picked up 60+ns before the expected neutrinos. Even so, the expected neutrinos should have been picked up 60+ns later (unless the experimental equipment was arranged so that they were ignored).
However, the experiment was repeated. I strongly doubt that this is the error.
Wrong calculation errors
Included for completeness. Calculating a speed is so simple that the possibility of an undetected error in calculation is remote. Once the timings and distances are correct, the error would have to be a repeated misentering of data, and that is probably automated anyway.
If it's automated, then I'd assume that the figures would have been crunched by hand as well (I know I would).
Wrong equipment errors
Included for completeness. Basically they are measuring three things, the emission time, the arrival time and the distance between emitter and receiver. Wrong equipment will just affect their timing and distance.
However, I did think of a possible equipment error that would lead to timing issues. Transmission lag. Presumably, the CERN clock is not right on top of the emitter. Therefore information from the emitter would have to be sent to the clock, saying something like "neutrinos emitted now". At the other end, it would be the same, with information being sent to a clock saying "neutrino(s) detected now". Was this taken into account and eliminated?
Although I only included them for completeness, what other possible wrong neutrino, wrong calculation or wrong equipment errors are there?
neopolitan