18 ms·
Neutrino experiment affirms faster-than-light claim
- breadbox 15y agoTo be precise, this latest experiment only ruled out one possible source of error (namely, bias in the detection of arriving neutrinos causing it to preferentially detect neutrinos at the forefront of the pulse). This doesn't affirm that the neutrinos actually exceeded light-speed. But it is an important step towards understanding what's happening, and it's great that the OPERA group were able to put together this followup experiment so quickly.
- jessriedel 15y ago> This doesn't affirm that the neutrinos actually exceeded light-speed. You might be thinking of "confirm". This certainly is an example of the OPERA group affirming their results. > Affirm. v. 1. State as a fact; assert strongly and publicly. 2. Declare one's support for; uphold or defend.
- compman775 15y agoTake a look at definition 1 in your post.
- ars 15y agoAffirm means to say it [again] (without adding any more information). It basically means "Yes I really did/do mean it". Confirm means to check again.
- burgerbrain 15y agoThe way English works, not all of the dictionary definitions for a word need to apply to any particular usage.
- topbanana 15y agoI think all dictionaries work in this way, not just English ones
- sidcool 15y agoOops...I just posted this link on my Facebook account with the sensational heading "Foundations of physics shaken again". I will remove it.
- espinchi 15y agoIndeed, as stated by the internal communication note: This test confirms the accuracy of OPERA's timing measurement, ruling out one potential source of systematic error. The new measurements do not change the initial conclusion. Nevertheless, the observed anomaly in the neutrinos' time of flight from CERN to Gran Sasso still needs further scrutiny and independent measurement before it can be refuted or confirmed.
- lwat 15y agoSo we're left with what, GPS errors? I've gone through their experimental setup and the timing looks foolproof. The only options left in my mind are 1) The distance between the labs is smaller than they think 2) Tachyonic neutrinos (not likely)
- glimcat 15y agoIt's usually best to leave off the "look guys, I broke physics" until human error has been well and thoroughly ruled out.
- rubidium 15y agoSure, I don't think anyone has suggested otherwise. However, the OPERA collaboration has done a heroic job checking everything they could think of. Thus the continued interest. Physics, as I'm sure you know, has undergone many revolutions in its understanding of the world. This could be the start of a new one, or it could fizzle and be a quirky measurement error. In either case, highly worth following to see what happens.
- glimcat 15y agoIf it's not a bit of partially-digested cheese, it might have to do with the interface between relativity and QED. But while it's not unthinkable that relativity requires revision under some circumstances, it's one of the most thoroughly and repeatedly proven tenets of modern physics. It's going to require something much more definitive and reproducible to overturn that mountain. I wouldn't expect a positive answer to this inside ten years, but a negative answer could turn up any time since it depends on someone finds the bug in the gears.
- lwat 15y agoIf another lab using different equipment were to reproduce this result, that would give a positive result in less then 10 years?
- jarin 15y agoI seriously cannot wait for the MINOS experiment :)
- maeon3 15y agoWhat is the difference between neutrinos and regular light photons? Do Neutrinos also exhibit the wave particle duality? Does this mean Albert Einstein was wrong, after all these years of assuming his "biggest blunder" was right?
- fleitz 15y agoPhotons interact much more easily with matter. Photons are massless whereas neutrinos are believed to have mass. Also, photons mediate the electromagnetic force where as neutrinos only interact with the weak subatomic force.
- neutronicus 15y agoPhotons are spin one, and mediate the electromagnetic interaction. They have zero mass and propagate at c. There are actually three types of neutrino (and they spontaneously change from one type to another), they are all spin-one-half, and they interact with other matter only via the weak nuclear force, which has a much smaller effective distance than the electromagnetic force, so they don't interact very often. They have non-zero mass, but it is so small that we don't actually know what it is. Everything in the universe exhibits the wave-particle duality.
- archgoon 15y ago>"biggest blunder" Einstein's self professed "biggest blunder" was the cosmological constant. That term has never referred to the assumption of lorentz invariance.
- deleted 15y ago[deleted]
- davidjohnstone 15y agoThe last thing I heard about this was that the results could be explained by the researchers overlooking the relativistic motion of the GPS clocks, and when corrected for it, the results were actually another confirmation of special relativity. See http://www.technologyreview.com/blog/arxiv/27260/ http://www.technologyreview.com/blog/arxiv/27260/ That said, a brief search turned up this paper ( https://facultystaff.richmond.edu/~ebunn/vanelburg.pdf https://facultystaff.richmond.edu/~ebunn/vanelburg.pdf ) which argues that that explanation is faulty (i.e., the paper made a mistake, and when corrected, the original researchers' results stand). (Disclaimer: although I once read a book on this stuff, I shouldn't be confused with an expert, and I have no idea who's right and who's wrong. But it is exciting.)
- sliverstorm 15y agoI seem to remember when that theory was discussed, it was explained that GPS clocks already take into account relativistic motion. Or something like that, don't quote me, I'm not a physicist.
- nobody31415926 15y agoGPS onboard clock is corrected for relativity due to it's orbit height and speed so it's clock time is approximately correct But measuring the simultaneity of an event between two different points with a moving clock is a lot trick.
- bermanoid 15y agoThat might have been an issue if they were measuring anything with the satellite clocks. But they weren't. By my understanding, they were merely using the satellite signals to synchronize the ground clocks in the ground frame, and after that was done, the satellite's were never heard from again.
- nobody31415926 15y agoSynchronizing two clocks in different positions is very difficult since relativity always comes in as you are moving a third clock between them. It's essentially impossible if you don't know the gravity field encountered by the moving clock.
- sliverstorm 15y agoI am hoping against hope...
- rorrr 15y agoThe worst kinds of bugs are the ones that only happen in production, when you have some crazy set up with a load balancer, a CDN and/or Varnish, and a few app servers, high traffic, middle of the day, and a bunch of executives hovering. I have seen a crazy bug that happened only on one of the identical app servers. Turns out SVN export didn't perform correctly (still don't know why), and one of the files was messed up. That was not easy to find. I have seen Apache ignore updated PHP files, and serving old code, which should never happen. This a real bitch to debug.
- omarchowdhury 15y agoCool story, bro.
- sfaruque 15y agoI think you posted in the wrong comment thread...
- deleted 15y ago[deleted]
- EREFUNDO 15y agoWill this widen the gap between relativity and quantum mechanics? or will it actually help in finally resolving the disconnect between these two greatest and well tested theories? Particles defying general relativity is well known, but defying special relativity? I can see it going both ways.
- hugh3 15y agoOn the offchance that it turns out to be really true, it will certainly point us in the direction of some interesting new physics, so it'll be a step in the right direction. I'm still trying to keep my expectations down for now, though.
- csomar 15y agoI have very basic physic knowledge, and little time. I'm quite interested, however, to know how they synchronized their timers since the Neutrino speed is faster than light. Anyone has a short explanation or an article for that?
- copper 15y agoRoughly, they used gps signals to synchronize two accurate clocks, one each at the source and the destination. For what it's worth, this part of the first paper is pretty accessible - at least, as to how they did it - it's more difficult to poke holes in how accurate it was :)
- shin_lao 15y agoIt's more likely they found a particle that travels back in time than a particle that goes faster than light.
- moomin 15y agoI think that's the same thing.
- deleted 15y ago[deleted]
- JonnieCache 15y agoYep. Relativity says they are exactly the same thing.
- shin_lao 15y agoAFAIK the special relativity says than traveling faster than light will make you go back in time, but if a particle goes back in time it does not mean it goes faster than light.
- JonnieCache 15y agoFair point, I may have over-egged it a bit with "exactly."
- ck2 15y agoIf quantum entanglement "pissed off" Einstein, I can only imagine his reaction to this.
- loup-vaillant 15y agoIf I recall correctly, Einstein was pissed of by the so called "spooky action at a distance", namely non-local interaction. Note however that a many-world interpretation gets rid of that. Now we have neutrinos that may travel faster than light. That would throw Special Relativity out the window, sure, but not the locality principle: those neutrino do not show infinite speed, unlike quantum entanglement under the Copenhagen interpretation.
- ck2 15y agoHe was also upset that it appeared to violate relativity. To his deathbed he believed in his alternate explanation that the particles were set opposite "at birth" and initiated that way until observation (if I understand that correctly). So now we have at least TWO phenomena that appear to be "faster than light" - so get cracking scientists (and engineers) on a practical application for communications to probes that are light-hours or light-years away.
- dodo53 15y agoI think generally the current theory is that quantum entanglement doesn't allow you to transmit information faster than the speed of light as you can't choose which state your local particle collapses into (although there's some disagreement about whether communication could be achieved with groups of entangled particles) http://en.wikipedia.org/wiki/No-communication_theorem http://en.wikipedia.org/wiki/No-communication_theorem http://en.wikipedia.org/wiki/Faster-than-light http://en.wikipedia.org/wiki/Faster-than-light (Quantum mechanics section)
- lobo_tuerto 15y agoI wonder if us realizing speed of light isn't the cosmic limit for everything are like us again at realizing Earth isn't flat.
- jgrahamc 15y agoI wrote to the lead author asking them to release the source code of the software that they used for the data analysis. I have yet to receive a reply, but it's pretty important to eliminate a programming error from this. For example, there were small errors in the Met Office's climate change software that I detected. The scientific papers were correct, but the translation into code was not. This could have happened here and it would be better if they released the code. http://blog.jgc.org/2010/02/something-odd-in-crutem3-station-errors.html http://blog.jgc.org/2010/02/something-odd-in-crutem3-station...
- JonnieCache 15y agoI find it very strange that the source code is not routinely released in these circumstances. What possible reason is there for not doing so? The code and the ideas within have no direct commercial value, surely? At the very least it should be as available as the papers themselves.
- jamesrom 15y agoThe only advantage I can see is that when the theory, formulas and algorithms are published, not the specific implementation itself, it forces people who want to who want to verify your work to write their own implementation. It kind of makes sure that a bug in your own implementation doesn't pollute the results of those trying to verify your work.
- jonhendry 15y agoExactly. It shouldn't matter if Lab A implemented the algorithm in Matlab and Lab B implemented the algorithm in NumPy. Take the data, apply the described algorithms, get the same result. If Lab B doesn't get the same result, and Lab B has confidence in their implementation, then there's probably something funny with Lab A's code or data. Reusing Lab A's code on Lab A's data just reproduces Lab A's errors, if any.
- JonnieCache 15y ago
- dean 15y agoPutting my tester's cap on, would it be feasible to have OPERA repeat the experiment with photons, instead of neutrinos? Presumably, if that experiment showed that photons travel faster than light (i.e., light travels faster than light), it would prove that there had to be an error in the experiment.