daniel_the_smith wrote:I think the discrepancy almost certainly is not caused by the neutrinos going faster than light, definitely not by a percentage. There was a supernova observed a few years ago. If neutrinos go faster than light by the percent claimed, they would have arrived ~4 years before the light. Instead, they arrived 3 hours before the light, which is the amount of time it was expected for the light to take to get through the outer layers of the star. The new scientist article goes into more detail.
IIRC the neutrinos in the CERN experiment are orders of magnitude more energetic, so the comparison is not entirely convincing.
I (and most other physicists) think it's extremely unlikely this result is correct. I would estimate that you could probably get 100 to 1 odds in most physics departments that this won't hold up. But it's the kind of result that is potentially so important it needs to be checked by somebody else with a different experimental setup. The odds-on likely explanation is that OPERA doesn't understand something about their own experimental setup or some gory detail of GPS. In fact, I bet that very few of the people on OPERA believe this result themselves.
The argument from the SN1987A neutrinos is a very strong one, but there are some ways around it. The obvious one is that the SN neutrinos were very much lower energy than the OPERA ones, so it could be an energy dependent effect.
It's important to point out that OPERA are behaving very responsibly here, and doing -exactly- what you are supposed to do with a result like this. You try to figure out what is going on, and if you can't find anything wrong, you publish a paper so that others can look over your analysis and try to replicate it. Note they waited to put out the press release until they had a paper available, rather than doing 'science by press-release' like, say, the cold-fusion cranks.
Even if it does turn out their result is wrong, they aren't likely to retract the paper. At least in high-energy physics, retracting a paper is more a sign of either fraud or a really boneheaded mistake, both of which are incredibly unlikely here. It's probably a much more subtle, interesting mistake, and so hence worth preserving in the literature.
MINOS (the Fermilab experiment) is already rushing to check this. Unfortunately, we will have to wait a while for T2K to check this (the neutrino experiment in Japan, which is in Tokai, not Tokyo) because they were damaged by the earthquake and aren't back online yet.
@Bobc & Edlee: Probably it makes a difference whether the Italian scientist is educated before or under the present Italian minister of Education. In the link you find her claiming that Italians built a 700 km neutrino tunnel.
@Daniel: Maybe in vacuum the neutrino's cannot travel faster than c. But maybe in matter they arrive earlier than expected, maybe because they travel faster, maybe because spacetime is affected in a yet unknow way. The results you mentioned don't exclude this possibility.
@aconley: In a previous MINOS experiment ( USA ) they detected the same phenomenon but the accuracy was less so they didn't consider it significant. Here v exceeded c by 1.8 standard deviation. To me this is still a respectable result that makes the Opera result much more believable. edit: Well, I admit I expressed myself a bit too strongly here.
Last edited by cyclops on Tue Sep 27, 2011 8:18 am, edited 1 time in total.
1.8 sigma is not considered evidence for anything in physics -- especially an a posteri 1.8 sigma! If you test 100 things in your experiment, looking for something odd, then you will probably find at least one 3 sigma result that isn't real. MINOS was checking all sorts of things, and found one 1.8 sigma discrepancy, which is hardly surprising. So no scientist would regard the MINOS result as significant in any way. The usual standard for a posteri significance is more like 5 sigma -- which OPERA satisfies. That's why you probably never heard about the MINOS result until now.
CSamurai wrote:I'm expecting this to be an explainable result which does not obviate all of physics. What that explanation is, I do not know. I lack [edit] the hard science background [/edit] to truly analyze the study. But I feel pretty confident that the science behind my stuff will not fail to work tomorrow.
And, that's the point. Relativity and Quantum Mechanics won't stop working just because of this result. However, this phenomena, may lead us to a result that combines the two theories. If this result holds up, I predict that it splits the physics community in two groups: One group that dismisses the result, and another that accepts and tries to explain the result. Either way, it's the type of result that is so polarizing.
They are, indeed, handling it correctly. They found something that is highly significant and relatively unexpected, so they have to be careful.
In a simple model the earth crust is represented by average nuclei with average mass and average volume located on the lattice points of a cubical lattice. We can draw a line through nuclei parallel to one of the axes of the lattice. Of this line the fraction that passes through nuclei is easily calculated from the average density of the nuclei and the average density of the earth crust. It turns out to be approximately 1/42000. This is remarkably close to the fraction that neutrinos are found to exceed the speed of light ( 1/40000 ) in the earth crust. It only needs the bold assumption that the neutrinos don’t experirience any temporal delay inside nuclei to account for the exceptional measurements of Gran Sasso. Perhaps only the theory of high energy particles in high density material needs to be rewritten.
mass nucleus / A ...... 1,67E-27........kg ............ 1) radius nucleus / A^1/3. 1,25E-15....... m ............. 2) nuclear density ....... 2,04E+17 ...... kgm^-3 crust density ......... 2850 .......... kgm^-3 ........ 3) ratio ................. 1,39E-14 ...... Spatial emptiness third root ............ 2,41E-05 ...... Linear emptiness
cyclops wrote:It only needs the bold assumption that the neutrinos don’t experirience any temporal delay inside nuclei to account for the exceptional measurements of Gran Sasso.
Given that the measurement had the neutrinos going faster than the speed of light, it would require that the neutrinos speed up significantly (double their speed) while inside nuclei.
Doubling wouldn't be enough according my calculations above. Pls correct them if they are wrong. I prefer to see the nucleus as a black box for the time being as far as fast neutrino's are concerned. Physics including space and time need to be reconsidered inside it. I propose the neutrino's to reach the other side of the nucleus in ( almost ) no time.
