By Geoff Brumfiel, Nature magazine on September 22, 2011. The difference they found with respect to the speed of light is very small, so some errors in the calulations must have been made. @Sklivvz The mass of the neutrino is so small that it is irrelevant in the argument, if the refraction is of the order of magnitude of the measurement. It seems to indicate that you could transform a matter particle (a neutrino) into an antimatter particle (an antineutrino) simply by changing your motion relative to the neutrino. What should I follow, if two altimeters show different altitudes? A new discovery raises a mystery. MINOS will soon upgrade its equipment with snazzy new atomic clocks, says Rob Plunkett, a Fermilab physicist working on a MINOS experiment. This is a BETA experience. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. If the neutrino always moved at the speed of light, it would be impossible to move faster than the neutrino. It uses an experimental design that was never intended for this purpose, and that is inherently poorly suited to it; the beam pulses were 10,000 ns wide, and the shift they claim to have measured is only 60 ns. It will likely take years for their experiment to yield robust results, but any events at all in excess above the expected background would be groundbreaking. At Japans T2K experiment, where particles travel only 295 kilometers, the speed discrepancy would be smaller and more difficult to observe. Frdric Grosshans links to a nice discussion by Matt Strassler Even though few believe that these results will ultimately hold up, their implications have stirred up quite a fuss. Tunnelling through a brick wall wouldn't actually violate any known law of physics, it's just sufficiently improbable according to those laws that if we ever observed it, we'd consider it more likely that our theories have to be amended than that we just have observed such an unlikely event. Critics of the first report in September had said that the long bunches of neutrinos (tiny particles) used could introduce an error into the test. But for right now, with current technology, the only neutrinos (and antineutrinos) we can detect via their interactions move at speeds indistinguishable from the speed of light. Weve measured neutrinos and antineutrinos produced by cosmic rays that interact with our atmosphere. The Special Theory of Relativity (STR) of Einstein, through the principle of the speed limit, makes the magnetic force come from the electric one and the magnetic force is an electric force, as physicists know; an easy demonstration of that can be found in chapter 3 of my file at the following link (also English inside): http://www.fisicamente.net/FISICA_2/UNIFICAZIONE_GRAVITA_ELETTROMAGNETISMO.pdf. Our mission is to provide accurate, engaging news of science to the public. This means that the shift can only be detected statistically, and it makes the result extremely vulnerable to unanticipated systematic errors, e.g., correlations between the time of emission of the neutrinos and their energy (which strongly affects the efficiency of detection) or the direction of emission. The first announcement of evidently faster-than-light neutrinos caused a stir worldwide; the Opera collaboration is very aware of its implications if eventually proved correct. Unless we could accelerate a modern neutrino detector to speeds extremely close to the speed of light, these low-energy neutrinos, the only ones that should exist at non-relativistic speeds, will remain undetectable. Invest in quality science journalism by donating today. Is there a generic term for these trajectories? I will bet all my beans into the idea that they didn't estimate the spacetime curvature inside the earth well and over the beam trajectory, and what they actually discovered is a great way to measure space-time inside the Earth. I was quite surprised to read this all over the news today: Elusive, nearly massive subatomic particles called neutrinos appear to travel just faster than light, a team of physicists in Europe reports. And yet neutrinos and antineutrinos, despite appearing to move at the speed of light, must have a non-zero rest mass, otherwise this neutrino oscillation phenomenon would not be possible. To approach a question 400 million years in the making, researchers turned to mudskippers, blinking fish that live partially out of water. It will likely take years for their experiment to yield robust results, but any events at all in excess above the expected background would be groundbreaking. Other neutrino experiments plan to double-check the results. You must convince yourself that the absolute measurements have the same error bars as the relative measurements, and I did not see that in the arxiv paper. By Lisa Grossman. Until i hear or read any counter-claims to that paper, i'll consider this to be a settled matter. Weve measured neutrinos produced by the Sun. It is less important that the rotation of the Earth. We stop timing the neutrino when it arrives in Italy, and calculate that it moves at a speed that's comfortably below the speed of light. All particles show the same speed limit as light, yet neutrinos with a rest mass greater than light possess a larger speed limit? E-mail us atfeedback@sciencenews.org | Reprints FAQ. The results of the neutrino experiment shook the world of physics The head of an experiment that appeared to show subatomic particles travelling faster than the speed WebIn September 2011, OPERA researchers observed muon neutrinos apparently traveling faster than the speed of light. It depends. Neutrinos might have mass, but their mass is so small that of all the ways the Universe has to create them, only the neutrinos made in the Big Bang itself should be moving slow compared to the speed of light today. @nominator: Any relativistic effect cannot make the speed superluminal. It has been posted to the Arxiv repository and submitted to the Journal of High Energy Physics, but has not yet been reviewed by the scientific community. Closing in on the speed of light (Image: Volker Steger/ Science Photo Library) The faster-than-light neutrino saga is officially over. "That doesn't make sense," they say. The wiggles themselves, shown with the non-wiggly part subtracted out (bottom), is dependent on the impact of the cosmic neutrinos theorized to be present by the Big Bang. Neutrino 'faster than light' scientist resigns - BBC News Faster than light? Neutrino finding puzzles scientists Most populous nation: Should India rejoice or panic? Furthermore, the pulses are quite long (10s), so an error in this analysis could easily be of the good order of magnitude. The new setup (3 ns pulses, 20 times shorter than the observed effect) has eliminated the last two points. "That makes sense," we say, and send the start time and the stop time down to our colleagues on Earth, who take one look at our numbers and freak out. Neutrino experiment repeat at Cern finds same result - BBC News The upgraded experiment, which will start in 2013 and last for a year or so, should have uncertainties comparable to OPERAs. Unauthorized use is prohibited. (In fact, five senior members of the collaboration did not put their names on the paper.) 2 hours of sleep? Where do the most energetic neutrinos come from? How this animal can survive is a mystery. Yet another reason for disbelief is that the velocity of propagation of neutrinos has been measured to much higher precision by other techniques, so if you want to believe the OPERA result, you have to posit a very strange energy-dependence of the velocity. Weve observed this process: where a nucleus changes its atomic number by 2, emits 2 electrons, and energy and momentum are both lost, corresponding to the emission of 2 (anti)neutrinos. (I actually had something similar happen to me on an experiment: I had an analog signal splitter "upstairs" that sent a signal echo back to my detectors "downstairs", and a runty little echoed pulse came back upstairs after about a microsecond and got processed like another event. Weve measured neutrinos produced by the closest supernova to occur in the past century: SN 1987A. Update: Rumors seems to tell that the boring explanation is the good one. That's why everyone is so excited about it. All experimental measures of |v-c|/c are within this limit. Heres where the disconnect between theory and experiment lies. (another interesting file, also related to this subject): http://www.mednat.org/new_scienza/strani_legami_numerici_universo.pdf. Quantum Tunnels Show How Particles Can Break the Speed of Light. By analogy, if Einstein relativised the classical picture, how would this result "relativize" Einstein's theory of gravity? One possibility is that the widespread use of GPS for measurments of earth has redefined the meter. OPERAs neutrinos were born from protons smashed into a chunk of graphite at CERN. Of course the conclusion would be to investigate if there is one circuit running on one clock pulse less than expected by design / testing. @Lagerbaer I think the trajectory is all underground it starts in a deep tunnel at CERN and ends under a mountain at Gran Sasso :-). If confirmed by other experiments, the find could undermine one of the basic principles of modern physics. Scientists around the world reacted with cautious shock on Friday to results from an Italian laboratory that seemed to show that certain subatomic particles can travel faster than light. Usually, you just lose some pulses travelling down the cable. The new findings come from four experiments that study streams of neutrinos sent from CERN in Geneva to the INFN Gran Sasso National Laboratory in Italy. If so, would it be a real violation of Lorentz invariance or an "almost, but not quite" effect. I thought it might be a good idea to list the possible systematic biases which could lead xkcd's character to win his bet. In summary: nothing is wrong with the calculation, the theoretical assumptions, rotation of the Earth, etc A hardware problem caused the 60 ns time gap. So the definition of refractive index might need adjusting, but effectively the vacuum has a non-zero refractive index, or rather the vacuum is not entirely empty. @dmckee: The "partial apology and retraction" is not an apology or a retraction. What are neutrinos? | Space A bad cable connector can take a beautiful digital logic signal and reflect part of it back to the emitter, in a time-dependent way, turning the received signal into an analog mess with a complicated shape. It took more than two decades from when it was first predicted to when it was finally detected, and they came along with a bunch of surprises that make them unique among all the particles that we know of. As a nonprofit news organization, we cannot do it without you. If there were no oscillations due to matter interacting with radiation in the Universe, there would [+] be no scale-dependent wiggles seen in galaxy clustering. it is unlikely that the neutrinos go superluminal or SR is not holding true anymore, it is unlikely that the distance is measured incorreclty, it is unlikely that the GPS setup/usage is incorrect. Edit: The "problem" is solved: it was mainly a problem in the timing chain, due to a badly screwed optical fibre. The same lab that first reported the shocking results last year, which could have upended modern physics, now reports that neutrinos "respect the cosmic speed limit" The final nail in the coffin may have been dealt to the idea that neutrino particles can travel faster than light. Copyright 1996-2015 National Geographic Society, Copyright 2015-2023 National Geographic Partners, LLC. There's no complicated theoretical analysis that needs to be done to determine whether the speed of light was exceeded.
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