Slashdot is powered by your submissions, so send in your scoop

 



Forgot your password?
typodupeerror
Science

OPERA Group Repeats Faster-Than-Light Neutrino Results 442

Posted by Soulskill
from the looking-for-mistakes dept.
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."
This discussion has been archived. No new comments can be posted.

OPERA Group Repeats Faster-Than-Light Neutrino Results

Comments Filter:
  • More tests please. (Score:2, Informative)

    by nelson.milum (2494144) on Friday November 18, 2011 @08:57AM (#38097452) Homepage
    Of course, there is good reason to be skeptical of this claim. A post from Universe Today (http://www.universetoday.com/89933/special-relativity-may-answer-faster-than-light-neutrino-mystery/), seems to indicate that OPERA may not have taken certain things into account in their measurements. Something about the relativistic motion of the GPS clocks. I'm not a Physicist, so I won't claim to understand fully all of the data. but I agree that independent checks are crucial.
  • Re:Supernovas (Score:5, Informative)

    by boristhespider (1678416) on Friday November 18, 2011 @09:07AM (#38097542)

    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.

  • Re:Supernovas (Score:5, Informative)

    by Dog-Cow (21281) on Friday November 18, 2011 @09:14AM (#38097614)

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

  • Re:Supernovas (Score:5, Informative)

    by TWX (665546) on Friday November 18, 2011 @09:15AM (#38097622)

    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.

  • Re:Supernovas (Score:5, Informative)

    by PvtVoid (1252388) on Friday November 18, 2011 @09:20AM (#38097676)
    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.
  • Not Unique (Score:5, Informative)

    by PvtVoid (1252388) on Friday November 18, 2011 @09:23AM (#38097714)

    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 [fnal.gov].

  • Re:Supernovas (Score:3, Informative)

    by blind biker (1066130) on Friday November 18, 2011 @09:25AM (#38097740) Journal

    Uhmmm. how the fuck am I talking about philosophy? I am saying that this is an experiment that is much harder to refute [blogspot.com] and that it trumps OPERA.

  • Re:Supernovas (Score:5, Informative)

    by arcctgx (607542) on Friday November 18, 2011 @09:30AM (#38097792)

    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 [lanl.gov]

  • Re:Supernovas (Score:5, Informative)

    by Baloroth (2370816) on Friday November 18, 2011 @09:32AM (#38097824)

    The theory is that neutrinos are massless, and massless energy particles always travel at the speed of light (things like light and gravity. And neutrinos). Why is a slightly harder question, but essentially it comes down to "because they can."

  • Re:Supernovas (Score:5, Informative)

    by boristhespider (1678416) on Friday November 18, 2011 @09:34AM (#38097854)

    A supernova explodes from the inside - so the initial burst of photons and neutrinos from the supernova is shielded behind the rest of the neutron star. Light gets blocked, but neutrinos don't, so they get out first.

  • Re:Supernovas (Score:5, Informative)

    by forand (530402) on Friday November 18, 2011 @09:35AM (#38097868) Homepage
    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 [arxiv.org]
    Superluminal neutrinos must have energy dependent velocities.
  • Re:Supernovas (Score:5, Informative)

    by chocapix (1595613) on Friday November 18, 2011 @09:38AM (#38097914)
    No need to know the distance, what was measured was the delay between the neutrino burst and the light burst.
  • by Baloroth (2370816) on Friday November 18, 2011 @09:39AM (#38097920)
    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 [arstechnica.com] 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.)
  • by Chris Mattern (191822) on Friday November 18, 2011 @09:44AM (#38097998)

    Nobody's going to can relativity on the basis of one experiement done at one facility, even if it's consistently repeatable. There's just too much chance that you overlooked something, no matter how careful you are (and OPERA, to their credit, have apparently been *very* careful). The problem is that there's no other facility that can do this experiment at the required precision, and with no idea as to what we're actually seeing, there's no way to design another experiment to get another look at it. The next big news will be when MINOS's upgrades come on line in 2012. Then we'll have independent confirmation (or not).

  • Re:Supernovas (Score:5, Informative)

    by morgauxo (974071) on Friday November 18, 2011 @10:25AM (#38098556)
    No. He put one set of observed data before another. If he didn't have the reference to 1987a then I would agree with you. He is simply saying that these two sets of observed data seem to conflict and he believes that the data from the 1987a supernova is more reliable.
  • by TheTurtlesMoves (1442727) on Friday November 18, 2011 @10:28AM (#38098602)
    Not really. Assuming an average of 1 proton per m^3 for the interstellar medium all the way, its less than 2.5*10^-6 kg/m^2. But then of course the interstellar medium may be quite a bit more dense. Even 6 orders of magnitude gives us only 1kg/m^2 of mass over the 168 000 ly.
  • Re:Supernovas (Score:4, Informative)

    by dmatos (232892) on Friday November 18, 2011 @10:46AM (#38098844)

    I'm pretty sure that neutrino flavour oscillations (which have been observed - taus changing into muons and electrons) are only explainable within the current frame of particle physics if they do have mass.

  • Re:Supernovas (Score:5, Informative)

    by UnknowingFool (672806) on Friday November 18, 2011 @10:57AM (#38099018)
    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 [wikipedia.org] could only detect 1/3 of the neutrinos predicted by the Standard Model. This lead to a puzzle known as the solar neutrino problem [wikipedia.org] 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 [wikipedia.org] 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.
  • Re:Supernovas (Score:5, Informative)

    by NeutronCowboy (896098) on Friday November 18, 2011 @11:26AM (#38099470)

    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.

    For God's sake (har), no. That's not what the initial post was doing.

    Not all data is equal. I can set up an experiment where the data collected conclusively shows that gravity repeals two objects rather than attracts. It will be rightfully so met with incredulity, with most people choosing to ignore it outright. Why? Because I'm a nobody in the field of gravitational research, and it is far more likely that I screwed up my experiment than that I found a new interaction mode for gravity. In this case, a bad grounding caused my metal balls to be electrically charged with the same polarity. My data might be right, but the conclusion is still wrong.

    Even superstars in applied Physics can screw up their experiments. What we're currently seeing is Science in action: one group publishes an experiment, and people are disagreeing with it, dissecting it, creating their own versions of the experiment, with everything being very noisy. People are drawing on past experiments with well verified data to figure out what the current experiment means, how it can be refined, changed and prodded at to confirm or refute the initial conclusion. When the dust has settled, a consensus will emerge that either yes, the experiment's data was not influenced by systemic factors outside of the proposed theory, and that yes, the new theory does a better job explaining the entire set of accumulated data and our general understanding of the universe, or it doesn't.

    New experiments should never, ever be taken either at face value, or outside the context of the current knowledge of Physics. One of the fundamental axioms of Physics is that at the core, the laws of Physics don't change on us. Constants are constant. F=MA doesn't undergo decay. This means that if a new experiment contradicts the results of an existing, well-established experiment, it is absolutely right to first look for problems in the methodology and setup of the new experiment. Otherwise, you'd try to rediscover all rules of the new universe with each experiment.

    TLDR:
    Not all data is created equal, and not all theories are created equal. Ergo, not all data gets the same attention, nor should it.

  • Re:Years. (Score:5, Informative)

    by NeutronCowboy (896098) on Friday November 18, 2011 @11:30AM (#38099514)

    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.

10.0 times 0.1 is hardly ever 1.0.

Working...