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OPERA Group Repeats Faster-Than-Light Neutrino Results

gbrumfiel writes "Earlier this year, the OPERA experiment made the extraordinary claim that they had seen neutrinos traveling faster than the speed of light. The experiment, located at Gran Sasso in Italy, saw neutrinos arrive 60 nanoseconds earlier than expected from their starting point at CERN in Switzerland. Others have doubted OPERA's claim, but in a new paper, the group reaffirms its commitment to the measurement. 'It's slightly better than the previous result,' OPERA's physics coordinator Dario Autiero told Nature News. Most members of the collaboration who didn't sign the original paper out of skepticism have now come on board. But scientists outside the group still aren't sure. 'Independent checks are the way to go,' says Rob Plunkett, co-spokesman of a rival experiment called MINOS."

36 of 442 comments (clear)

  1. Tachyon pulses into shield grids by masternerdguy · · Score: 5, Funny

    They make you reset the shield harmonics

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  2. Supernovas by GlobalEcho · · Score: 5, Interesting

    As others here noted last time this result came around, if neutrinos really travel that much faster than the speed of light, then we would have expected the neutrino burst from the 1987a supernova to arrive months, rather than hours, before the light came. Thus, I am skeptical.

    1. Re:Supernovas by Gr33nJ3ll0 · · Score: 5, Insightful

      Seems even the OPERA people who first ran the test are skeptical, so you're in good company. :) I think everybody is doing a we're not sure what we've got, but SOMETHING is happening, lets figure it out.

    2. Re:Supernovas by boristhespider · · Score: 5, Informative

      Not in a supernova burst. The initial implosion is deep inside the neutron star, and there's a lot of matter shielding it. Light interacts with matter, so it gets delayed on its way out, but the neutrino burst from that initial implosion doesn't. The predicted delay was of the same order of magnitude as the delay seen in SN1987a.

    3. Re:Supernovas by Tatarize · · Score: 5, Interesting

      And how much of a vacuum can you really get in this universe? With all the virtual particles popping in and out all the time. It seems you'd need to be as weakly interactive as a neutrino to avoid being slowed down just by spacetime and all it's particles kicking up all the time. Considering vacuum space is going to have something in it, I wouldn't be that amazed if neutrinos just travel at closer to actual C than light does.

      --

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    4. Re:Supernovas by Dog-Cow · · Score: 5, Informative

      The Bible does not list an age for the Universe, nor even for planet Earth.

    5. Re:Supernovas by TWX · · Score: 5, Informative

      Or maybe some as-yet-undiscovered property of spacetime or the universe at the quantum level delays neutrinos over vast distances...

      Unfortunately for us, replicating the experiment with a second team in a second location entirely from scratch will be extremely expensive, given that this CERN location used for the experiment is unique.

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    6. Re:Supernovas by goodmanj · · Score: 5, Insightful

      Oh, come on, seriously? You're going to insist that we watch 5000 supernovas before you'll accept this as a valid point? A single carefully measured *truly independent* data point is more valuable than a thousand repetitions of the same experiment.

      Or to put it another way: say you measure the voltage of a battery 100 times with a voltmeter, and measure 0 volts every time. I hook it to a light bulb and the bulb lights up. Are you going to insist that my single observation is useless, or is it possible your voltmeter is broken?

    7. Re:Supernovas by PvtVoid · · Score: 5, Informative

      The new measurement is much more convincing than the previous one. The difference is the size of the proton bunches used to produce the neutrinos at CERN: in original measurement, the proton bunches where huge (milliseconds) compared to the claimed offset in the neutrino pulse (60 nanoseconds). This required a lot of knowledge about the shape of the proton bunches, and a lot of statistical fitting. The new analysis includes a special run with nanosecond-width proton bunches, widely separated from one another, so that each neutrino can be definitely associated with a particular proton bunch at CERN, with knowledge of the production time at the nanosecond level.

      Personally, I'll still be skeptical until it's confirmed by an independent group, but the result is a lot more believable now.

    8. Re:Supernovas by Hentes · · Score: 5, Interesting

      OPERA measures muon neutrinos, not electron neutrinos. It's possible that only one kind travels faster than light.

    9. Re:Supernovas by Richard_J_N · · Score: 5, Interesting

      Yes... but maybe we missed them. Neutrinos are really hard to detect, let alone identify the source direction. Given a non-directional, not-very-strong pulse, possibly widely distributed in time, an unknown amount of time before the supernova, which we weren't expecting, would it really be surprising to have missed it?

    10. Re:Supernovas by goodmanj · · Score: 5, Insightful

      His point (which should be modded up) is that God or no God, the essential difference between religion and science is that religion puts articles of faith before observed data. Which is exactly what the post he was responding to was doing.

      Don't get me wrong: I think the OPERA experiment will turn out to be wrong. But neutrinos are so poorly-understood and poorly-observed that any blanket dismissal of OPERA's results counts as an act of faith.

    11. Re:Supernovas by arcctgx · · Score: 5, Informative

      Simply put, the neutrino emission starts before the emission of light. This article has details: http://library.lanl.gov/cgi-bin/getfile?25-14.pdf

    12. Re:Supernovas by forand · · Score: 5, Informative

      This is addressed in the paper. The 1987a neutrinos have energies in the 1-20 MeV range while the OPERA result is for neutrinos in the 3-100 GeV range. That is around three orders of magnitude higher than the 1987a result. Page 3 section 1 paragraph 3 covers this (for some reason Slashdot won't let me block quote it):
      http://arxiv.org/pdf/1109.4897v2
      Superluminal neutrinos must have energy dependent velocities.

    13. Re:Supernovas by Freddybear · · Score: 5, Insightful

      You can't tell anything to those guys.

    14. Re:Supernovas by ArsonSmith · · Score: 5, Funny

      Light travels at C, Neutrinos travel at C++

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    15. Re:Supernovas by niftydude · · Score: 5, Insightful

      Not necessarily - travelling through vacuum, and travelling through densely packed matter in a gravitational field might possibly make all the difference.

      If real, qualified physicists are pondering this issue, it is a bit early for us mere mortals be openly dismissive.

      --
      You can never know everything, and part of what you do know will always be wrong. Perhaps even the most important part.
    16. Re:Supernovas by Alphathon · · Score: 5, Insightful

      I believe the word you are looking for is dogma, not religion. It is quite possible to be dogmatic about completely secular things; doing so is misguided but certainly not religious.

    17. Re:Supernovas by pavon · · Score: 5, Insightful

      There have already been four credible ideas posted in this discussion as to why the measurements we are seeing could differ from prior ones, without either being wrong. Different energies, different neutron flavors, interactions with gravity, interactions with mass, etc. Neutrons are still not completely understood, and since their predictions/discovery we have had to change the standard model twice (that I am aware of) to match new observations, and we will likely have to again in light of growing evidence of flavor oscillations. Non-baryonic matter is very much at the ragged edge of what experimental physics can observe, and finding unexpected things should be expected.

      I'm skeptical of their results, and think that there is probably something that hasn't been accounted for in their timing. But if you flat-out dismiss new evidence because it doesn't agree with your models based on past evidence, then you have crossed the bounds from scientific skepticism to personal belief.

    18. Re:Supernovas by UnknowingFool · · Score: 5, Informative

      I'm not an expert on theoretical physics but according to the Standrad Model, neutrinos were originally thought to be mass-less. But the in trying to detect solar neutrinos, Raymond Davis could only detect 1/3 of the neutrinos predicted by the Standard Model. This lead to a puzzle known as the solar neutrino problem as no one could find a fault with his experiments but they couldn't explain his curious results either. It wasn't until Masatoshi Koshiba verified the same effect in a different experiment that scientists began to believe his results. The problem was the Standard Model was wrong. Neutrinos because they were massless should also be stateless. Subsequent experiments showed that solar neutrinos were not stateless as they oscillate into different types of neutrinos. Thus they could not be massless. Davis and Koshiba shared part of the 2002 Nobel Prize for this discovery.

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    19. Re:Supernovas by Khyber · · Score: 5, Interesting

      That experiment you link to doesn't even have a five-sigma degree of certainty.

      OPERA is more reliable as it does have at least a five-sigma degree of certainty.

      You are indeed speaking out like a religious zealot.

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    20. Re:Supernovas by geekoid · · Score: 5, Insightful

      Stop being closed minded. Lets look at the science.

      1) They got a result that defies are current understanding
      2) The people performing the tests assume it's an experiment error, but can't find it
      3) The people performing the tests were like " Hey scientific community*, we know this can't be right, but we can't find out where the error is, how about a little help?
      4) The scinetific community is like " what about this this and this
      5) Those are great. we checked and no, no and no? here is the results
      6) Well, ceck all youtr quipement and try again
      7) OK, oh look the same result just better refined.

      So keep an open mind. Not a 'Hey man, anything is possible." open mind, but a mind that looks at the actual evidence.

      Remember, about 125 year ago, someone came up with ideas that where complete outside out understanding of the universe as we know it. If everyone just dismissed bohr, then where would we be?

      Whether or not this is true, it is a great example of science and it' workings.

      For the record, I am skeptical of the findings, but I expected the community to have found something wrong.

      Neutrinos change around for reason we don't know either. So it's not like we complete understand them.

      *Scientific community: The proper experts in the proper fields.

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    21. Re:Supernovas by mr_gorkajuice · · Score: 5, Insightful

      He said: "I am not just sceptical but quite openly dismissive"
      Indeed, new experiments should not be taken at face value. This is why skepticism is encouraged. Dismissal, not so much.

  3. Re:More tests please. by Metabolife · · Score: 5, Funny

    They're probably still trying to sync with time.windows.com. It's a common mistake.

  4. Might the time of day have an effect here? by Anonymous Coward · · Score: 5, Funny

    I notice that lunch-time definitely passes faster than any other time.

  5. Spacetime curvature by mangu · · Score: 5, Interesting

    if there's an effect here, it should probably be related to neutrinos-through-matter vs neutrinos-through-vacuum

    That, or interaction with the gravitational field. Neutrinos from the supernova traveled through essentially flat spacetime, far from any masses.

  6. General Relativity is Wrong by invid · · Score: 5, Interesting

    General Relativity is a classical theory, but the underlying nature of reality is quantum. So General Relativity, like Newton's theory of gravity, is an approximation of reality. Now, I'm not saying that the neutrinos went faster than light, however, perhaps this experiment has finally revealed a hole in General Relativity in the way the equations are applied to the timing of the event.

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    1. Re:General Relativity is Wrong by boristhespider · · Score: 5, Interesting

      Yes, maybe. My (more or less) professional opinion is that the experiment almost certainly hasn't shown this, and instead it will either turn out to be experimental error or a *demonstration* of relativity (either special or general; both affect clock rates in ways that can be significant for this experiment), but yes, it could finally be some experimental evidence against relativity. And since you're quite right in saying that general relativity is definitely "wrong" in that it's not a fundamental theory and cannot be treated as such, this shouldn't be terrifying - just very exciting.

      But I'll withhold judgment for a while - I'm very sceptical about these results.

  7. Light refracting from dark matter hypothesis by LeDopore · · Score: 5, Interesting

    (Near re-post of http://slashdot.org/comments.pl?sid=2507746&cid=37936976)

    OPERA shows light travels little bit slower than the fastest objects we've measured. A little while ago we heard that in galaxies far, far away, either the electric charge is larger, Plank's constant is smaller or the speed of light is smaller (http://slashdot.org/comments.pl?sid=2507746). If it's the speed of light that's smaller, the required slow-down is of the same order of magnitude as the factor by which photons are slower than neutrinos as observed by OPERA.

    Here's my take. There's a field of undetected particles (dark matter?) that refract light a tiny bit, and this field was denser in the early universe. This field would not affect the apparent speed of light as an observer moves through it, just as (ignoring dispersion) light traveling through moving glass doesn't pick up the glass' motion vector (i.e. this wouldn't manifest itself as the Luminiferous aether, which is experimentally disproved). Light from the 1987A supernova would not be delayed too much relative to the neutrinos because most of the journey was through regions of space with low dark matter density.

    There: three mysteries (dark matter, OPERA neutrinos and the fine structure "constant") all tied together with a bow on top. If you know more physics than I (honours undergrad) and you think I've missed something, please tear into this hypothesis, either here or on my blog: http://many-ideas.blogspot.com/2011/11/ftl-neutrinos-and-fine-structure.html. I look forward to hearing from you!

    Best,

    LeDopore

    --
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  8. Re:how does this fit? by boristhespider · · Score: 5, Interesting

    1) Yes, it could, they've attempted to take that into account. The main error would be in the length of the neutrino pulse; a long pulse is easier to detect (I think ~2000 neutrinos, or perhaps even more) but it's hard to pin down a precise time. The repeat experiment used very short pulses, which are harder to detect (~20 neutrinos) but which yield much more precise timings.

    2) All observations so far are suggesting that neutrinos have a positive mass (or, to be more picky, that at least two of the neutrino species have a positive mass) of the order of a tenth of an electron volt or less. (Also, I think it would involve an imaginary mass to move faster than light, at least if you want to stick within current relativity - this result would suggest we might not want to do that, though.)

    3) Yes. For instance, if we're confined to a 3-brane -- basically, a three-dimensional sheet that we and everything around us is trapped on -- and neutrinos are allowed to leak slightly from the brane then little kinks and ripples in the brane will let them take short-cuts through the other seven spatial dimensions. Gravity can do the same, but the idea is that neutrinos would be more tightly trapped to the brane, while gravitons can roam freely.

  9. Not Unique by PvtVoid · · Score: 5, Informative

    Unfortunately for us, replicating the experiment with a second team in a second location entirely from scratch will be extremely expensive, given that this CERN location used for the experiment is unique.

    There are other long-baseline neutrino experiments out there, such as MINOS.

    1. Re:Not Unique by budgenator · · Score: 5, Interesting

      MINOS as it now exists can only check the 730 km trip from CERN to Italy, not the 18-metre (60-light-nanosecond) trip across the iron "hadron stop" at the end of the decay tunnel at CERN, which may be at the heart of the result. This is because MINOS uses a matched near detector / far detector layout, whereas OPERA measures from the original protons (which are "upstream" from the hadron stop).

      Posted by: John Costella | November 18, 2011 01:37 AM, Neutrino experiment affirms faster-than-light claim - November 18, 2011

      The 60 LnS thick hadron stop, and neutrinos getting to a detector 60 nS too soon is just plain suspicious.

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  10. Re:More tests please. by Baloroth · · Score: 5, Informative

    Ummm, no? They didn't just use GPS clocks, they physically carried atomic clocks from one location to the other. Look up the actual science behind what they did, it's pretty interesting. Oh, and relativistic factors of GPS systems is pretty standard learning in basic science. Maybe there was a compounding effect that they missed... but I doubt it. That article is 100% pure speculation. And it's bullshit, quite frankly. Check out this: Ars article for what the team did. (They also ran photons between the sites to check the time, in addition to GPS and portable atomic clocks.)

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  11. Re:More tests please. by nashv · · Score: 5, Insightful

    Whatever it is, I give them props for trying to solve this in the most honest, transparent way possible and remaining open to being wrong. They're exemplifying "good" scientific method and that makes them more credible to begin with.

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  12. bring back Mussolini by goombah99 · · Score: 5, Funny

    In Italy, at least the Tachyon's run on time.

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  13. Re:Years. by NeutronCowboy · · Score: 5, Informative

    Uh, just to be specific, you're talking about the chirality of neutrinos. The way you phrase it, it sounds like an electron is a type of neutrino. It isn't. There are electron neutrinos, but they have no charge. They are merely part of the same family of leptons as the electron, hence the name. You probably knew that, but I had to do a re-read to figure out that that's not necessarily what you meant.

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