Particles recorded moving faster than light

[starslayer]

They wouldn't be announcing this at all unless they had at least a 5-sigma detection, so I imagine they have a very statistically significant result. Given how ghostly neutrinos are, I'm not sure how they're able to get that kind of significance, but I'll wait for either a summary to be slapped up on the ArXiv or someone to come forward saying they found the (likely) systematic error.

[Anacronian]

Just a question from a layman here.

If we assume that the tested neutrinos actually moved faster than light could that be because neutrinos actually have rest mass(unlike photons) and that mass got accelerated by Earth's gravity instead of just blueshifting like photons??

[Bakustra]

Just a question from a layman here.

If we assume that the tested neutrinos actually moved faster than light could that be because neutrinos actually have rest mass(unlike photons) and that mass got accelerated by Earth's gravity instead of just blueshifting like photons??

No, because acceleration in relativity is asymptomatic at the speed of light. It takes infinite energy to accelerate to the speed of light, and so you cannot ever reach it through ordinary acceleration, let alone exceed it.

[Anacronian]

Just a question from a layman here.

If we assume that the tested neutrinos actually moved faster than light could that be because neutrinos actually have rest mass(unlike photons) and that mass got accelerated by Earth's gravity instead of just blueshifting like photons??

No, because acceleration in relativity is asymptomatic at the speed of light. It takes infinite energy to accelerate to the speed of light, and so you cannot ever reach it through ordinary acceleration, let alone exceed it.

Oh well then i'll just stick to my first thought then..*They shouldn't have sent them to Italy, Nothing there ever sticks to the speed limits.*

[Batman]

Well there's laws of physics saying FTL travel is impossible.

And that's it-they're laws. Nobody enacts laws that forbid the impossible, there'd be no point. If it's impossible, it's impossible. I thereby posit that it is possible to travel faster than light, Nature just really doesn't want us to

[SpaceMarine93]

When situations like this happens, there's usually either a human error, an unforeseen complication e.g. natural neutrinos going in at that random moment, or some new discovery.

The scientists probably needs to do more testing before they could confirm whether the discovery contradicts current model of physics. Even if it contradicts the current understanding of physics, big deal! This is good news in the fact that we probably just found the holy grail of telecommunication: if these FTL neutrinos could be applied to practical use, this would guarantee almost instantaneous communication across the planet.

But then again, it could just be some form of error. Let's wait for further news.

[SilverWingedSeraph]

When situations like this happens, there's usually either a human error, an unforeseen complication e.g. natural neutrinos going in at that random moment, or some new discovery.

Three years. 15,000 different tests. Hell yes there's totally a possibility for errors that might have turned up, most likely they'll be errors in methodology or technical ones, but I highly doubt natural neutrinos going through at a random moment are responsible. Random isn't that reliable.

The scientists probably needs to do more testing before they could confirm whether the discovery contradicts current model of physics. Even if it contradicts the current understanding of physics, big deal!

No, see, this is actually a big deal if it's true. Particles with non-zero mass traveling faster than c pretty much blows relativity to pieces. We'll need to invent completely new physics to explain how the fuck that happens. That's a major fucking deal.

This is good news in the fact that we probably just found the holy grail of telecommunication: if these FTL neutrinos could be applied to practical use, this would guarantee almost instantaneous communication across the planet.

1) No it wouldn't. For one, the neutrinos were only measured as nanoseconds faster than light in a vacuum. Even if that turns out to be correct, they'd be useless for telecomminications.

2) Our current communications systems are more or less light speed. They're constrained by technology, but radio waves, electical impulses, all that noice, all travel at the speed of light. Less than 0.001% faster than c would make no difference.

3) Using neutrinos for telecommunications would make a huge difference though, because it means you'd likely only get a tiny fraction of whatever was being sent to you, because detecting neutrinos is hard as fuck.

[Surlethe]

They wouldn't be announcing this at all unless they had at least a 5-sigma detection, so I imagine they have a very statistically significant result.

I've heard it's a six-sigma result.

[Kuroneko]

It is indeed a six-sigma result [arXiv:1109.4897].

[Lord Baal]

Another layman question. How can they be sure the neutrinos detected are the ones they emitted? I mean, they have to do it someway, how?

[SilverWingedSeraph]

Another layman question. How can they be sure the neutrinos detected are the ones they emitted? I mean, they have to do it someway, how?

Well, repeating the test 15,000 times can effectively rule out any stray neutrinos and render them statistically irrelevant, and I'm sure they likely had other methods of ruling out stray neutrinos as well. Any stray neutrinos would be coming from the sun, and would have significantly different trajectories from the ones being shot at the detectors, which would probably be noticable. That's one possibility that comes to mind, anyway.

[VarrusTheEthical]

Assuming that the claim of neutrinos being slightly faster than light is true, would it therefore be prudent for other scientists to attempt the same experiment but over a longer distance so that the apparent gap between the speed of a neutrino and the speed of light are more apparent?

[Skgoa]

Intuition says its probably a) going to be harder to pull off and thus take more time/money and give less conclussive results or b) the exact distance doesn't even matter as much as the infrastructure at the two locations.

[VarrusTheEthical]

Yeah, I thought as much. Perhaps given enough time, if those results are replicated on a small scale, it may justify the cost of a large scale experiment. If it is concluded that the Neutrino is faster than light, and not just the result of faulty equipment or methodology, the next step would be to determine exactly how fast a neutrino is and if that speed is affected by medium.

[Ted C]

From what I heard about this in the news, the scientists published largely because they're skeptical of their own results, and they want to see if other researchers can duplicate them. They suspect there may be something wrong with the design of their test that is causing the discrepancy.

[Sriad]

It is indeed a six-sigma result [arXiv:1109.4897].

Glad we've finally got it, now we can talk more exactly.

The paper rules out all of our (frankly too obvious) objections. They've got the distance measurement exact with an error window of 20cm, timing measured at each end with matched atomic clocks with an error window that takes into account relativistic effects of transportation, and they use detectors at BOTH ends--the emitted neutrinos pass through a detector to start the timer, then travel 730.085 km to the second detector to get the actual travel time.

Another layman question. How can they be sure the neutrinos detected are the ones they emitted? I mean, they have to do it someway, how?

The neutrinos are emitted in pairs of pulsed bursts: burst one has several peaks 50 nanoseconds apart, then about 50 milliseconds later a second pulse in the same pattern is fired. There is a distinct waveform produced at detector 1 which is closely matched at detector 2, to the limits inherent in neutrino detection. The chances of even one pulse measurement being coincidental is about as likely as a marksmanship contest being misjudged because of stray shots from a different range.

b) the exact distance doesn't even matter as much as the infrastructure at the two locations.

This one. The error window in distance is small enough that the source of problems would be equipment related. 730 km is a happy medium between the logistical difficulty of setting up the experiment and measurable deviation from lightspeed.

[Sriad]

(and again please don't take anything I say as deliberately high-handed; I'm just enthusiastic whenever a subject where I'm relatively knowledgeable comes up.)

[Lord Zentei]

I can see how the time of emission is crucial given such short time intervals, but does the uncertainty in the distance within the 1 km emitter/receiver really make the experiment that inaccurate with such a huge distance (730 km) between the emitter and receiver?

Absolutely. If you detect a neutrino, you don't know exactly where it came from. What you actually want is the distance and duration from the emission event to the detection event; otherwise you can't calculate the speed. So it's not just when and where it was within the detector and emitter, but I think it's probably the largest contributor to error.

Of course, I managed to misread the article after all, and therefore the ~1/730 difference in distance seemed significantly greater than the relative difference in time intervals. But of course, 60 nanoseconds is 1/40000 of the expected interval.

Probably a systematic error.


PS: STFU Sriad!!

[Rassilon]

Yes this is almost certainly an error with the detector and timer.

[Chirios]

Yes this is almost certainly an error with the detector and timer.

Does anyone know how much it would cost to replace this stuff? Because if it turns out that CERN isn't working properly after they spent all those billions to build it that would be bad.

[Surlethe]

I don't think you realize just how many different machines are working at CERN. This is not the same as the LHC, for example. But anyway, the detector is in Italy.

I think the problem's going to be in their data analysis. This isn't like an undergraduate lab; particle physics produces reams of data that require careful, precise statistical analysis. Even if the data are perfectly correct, the slightest misstep during analysis -- statistical or conceptual -- produces wild results.

[starslayer]

The random error on these measurements is probably very well constrained (based on half-remembered papers rumbling around in my head, their error of 10 ns seems reasonable for this type of experiment), and I doubt they ran into any problems there; while error propagation can get be very complicated and fraught with algebra mistakes (among others), everyone on the team's almost certainly checked all that at least 10 times already. Systematic effects have got to be killer, though. I wouldn't be surprised if someone else comes in and they suddenly find that, oops, their clocks were off by 100 ns this whole time or something and nobody noticed.

[weemadando]

Then orders a beer. A neutrino walks into a bar.

Just saw that. Appreciated it.

[Chirios]

http://www.bbc.co.uk/news/science-environment-15034852

^ Brian Cox in the above link explains what the implications would be if it was true.

[Lord Baal]

Thanks a lot my friend! I was looking for something like this!

Does anyone have a link or know something about the last Friday reunion they was going to have with peers?