Faster-Than-Light Neutrinos Confirmed? In One Way, Yes; In Another, No

By Amir Aczel | November 22, 2011 5:21 pm

In a previous post, I reported on the baffling new finding that neutrinos appear to travel faster than light. The stuff of science fiction…travel to the past…weird science…Einstein rolling in his grave. (Except that faster-than-light doesn’t necessarily imply the possibility of time travel, and superluminal neutrinos might not violate relativity if they were the hypothetical tachyons.) The result was met with widespread skepticism in the world of physics, and the skepticism still continues. But just as the furor was beginning to die down, the OPERA (Oscillation Project with Emulsion tRacking Apparatus) consortium that runs the neutrino experiment at the Gran Sasso laboratory deep in the Apennine Mountains of central Italy, using neutrinos created 732 kilometers away at CERN, near Geneva, reported an experimental confirmation of their own earth-shattering results.

Originally, the pulses of protons that CERN used to generate the neutrinos through collisions with a stationary target were relatively long, and some critics have claimed that the long pulses, lasting 10.5 microseconds, could have introduced some uncertainty into the process. The OPERA scientists therefore asked CERN to shorten the pulses, and the new pulses have been only three nanoseconds (billionths of a second) long. The original result had been that the neutrinos traveled from CERN to Gran Sasso 60 nanoseconds faster than light would have taken for the same 732 kilometers, with a statistical standard error that was one-sixth as large (hence the result was statistically significant at “six-sigma,” which is extremely significant and its probability of being a fluke was therefore less than one in 3.5 million). The much shorter pulses make the pulse length fall within the standard error, and not a contributor to a possible false finding. Significantly, the new results, based on 20 detected neutrinos from the new and ultrashort pulses, replicated the earlier OPERA finding: The neutrinos still appear to travel faster than light.

What lies ahead? The OPERA scientists are obviously more confident of their results than they had been before. And there appear to be no obvious flaws in their research. At a recent conference at MIT, one of the physicists described the OPERA team as consisting of “Germans, Swiss, and clocks”—accuracy doesn’t get much better. Early concerns that the extremely accurate atomic clocks and GPS used by OPERA were somehow misread or misinterpreted have been easily overturned. But what the world of physics now seeks is a confirmation or refutation of the OPERA results by other research teams.

I just discussed this further work with Professor Stan Wojcicki of Stanford University, one of the founders of the MINOS (Main Injector Neutrino Oscillation Search) project in the United States, which gets its neutrinos from Fermilab, near Batavia, Illinois. Wojcicki told me that the MINOS physicists are now looking through the voluminous data set on neutrino velocities they had accumulated over many years of research. This group did not use a GPS as accurate as that used by OPERA, but the time and space accuracy attained by the group—and their immensely large data set—should still be useful in confirming or challenging the results from Gran Sasso. It is important to note that early analyses of the MINOS data set has indeed indicated that the neutrinos may well travel at speeds higher than that of light. But these results lacked statistical significance (they did not meet the two-sigma, 95% probability standard of proof). It will be fascinating to see what MINOS and other research teams discover over the next few months, and whether we may be forced to update our understanding of Einstein’s special theory of relativity.



Amir D. Aczel is a researcher at the Center for the Philosophy and History of Science at Boston University and the author of 18 books about mathematics and physics, as well as numerous research articles. He is a Guggenheim Fellow and a frequent commentator on science in the media. See more at his website or follow him on Twitter: @adaczel.

  • Joe

    Here is a little neutrino humor:

  • James Ph. Kotaybar

    — James Ph. Kotsybar

    Oh, little neutral one of tiny mass,
    Who flies anomolously from the sun,
    you zip through matter photons cannot pass:
    Could this explain the races you have won?

    From Einstein, few believe that it could be
    that any mass can go as fast as light —
    it’s deemed complete impossibility,
    assuming Relativity is right.

    If true, the implications terrible,
    will give complacent physicists a scare.
    In terms that twist the ancient parable
    It’s you that’s tortoise; the photon’s the hare.

    It seems, though steady, light can’t keep up pace.
    You oscillate, and yet you win the race.

  • Bob Hamilton

    If anyone is still confused, let me help. The first result was wrong. Any tests confirming the first result are also wrong. Glad to help.

  • cbunix23

    C as the speed limit applies in a vacuum and in a straight line, right?

    Is the CERN apparatus a perfect vacuum? Maybe there is enough matter in the apparatus to slow down photons more than neutrinos?

    How much of an effect does going around the track itself have on photos vs. neutrinos?

    Best regards,


  • Rich Borutta

    Dr. Aczel,

    The results of the OPERA measurements are encouraging to me in that they tend to support the methodology I have adopted in my own research in another field. They can be interpreted as a result of attempting to apply a precise specification of the time and place of a particle (neutrino) that is a very weakly interacting entity and therefore has no precise space-time coordinate.

    The theorectical basis for this can be found in W. Schommers, “Symbols, Pictures and Quantum Reality” in which he couples the Energy-Momentum configuration space with our natural Space-Time and develops a picture of quantum reality from that. His theories how that the time parameter for a system depends on the strength of the interations between the particles or components of the system. It is not a classical variable in this situation.

    I’ve used some of these ideas in publications and presentations explaining changes in awareness during Near Death Experiences for the Acedemy of spirituality and paranormal studies since 2008.

    A related topic is the phenomena of the gamma ray measurements which reveal that lower energy gamma radiation from cosmic sources propogates faster than high energy gamma radiation from the same sources. The principle of using the Energy-Momentum factor in Double Speccial Relativity was used by researchers at the Perimenter Institute
    to account for this.
    In the OPERA experiment they use a small volume detector to measure the particles in the beam which forces the shift in time to occur.

    Rich Borutta

  • Alexander W.

    Well, my thoughts about paradoxes are if possible it would have happened in the past, the distant past is has diffrent locialization time Symetry breaking is possible within a small periods of earth’s localized cardinalty can be resolved.

    Other then that it requires new form of vector aligned parity in some quanta of energy. And complete knowlege of: unified theory, and dimensional entanglement and the relationships they share.

  • Alexander W.

    Oh yeah, the events measured on Earth, could be super laminal, but we are only seeing secondary events long after the event is over….

  • Arahan

    Hi! Your blog on the experiment regarding the velocity of the neutrinos was quite pertaining. But it did leave an obvious curiosity to me regarding the inertial mass of the neutrinos. How does the Einstein’s relativistic principle copes up to the change in the inertial mass of the neutrinos which at the speed higher than that of the light? I think it will provide us with more insights if you could put that also in the account.
    Thank you

  • Uncle Al

    The universe does not tolerate contradiction. As with negative temperatures kelvin (lasers, NMR, MRI, EPR… population inversions) there is assuredly a footnote. The neutrino case may be akin to staring down the barrel of a relativistic jet in astronomy. Distortion of spacetime gives a distinct FTL Euclidean projection – except the geometry is not Euclidean and there is no FTL anything.
    “Hubble Space Telescope Observations of Superluminal Motion in the M87 Jet” Astrophys. J. 520(2) 621 (1999)

    Neutrinos have rest mass. Launch an FTL neutrino from here to there. First, as gravitation propagates no faster than lightspeed, you have just created mass out of nothing by having one neutrino’s gravitation appear sourced in two places at once by a distant observer. Second, the detector detects SOP. How does that happen? Third, if the FTL neutrino is observed as an SOP neutrino, and it passed through the lightspeed singularity, then its mass went infinite and time locally stood still. Messy. Negative temps kelvin cool to positive temps kelvin along a path that does not include zero kelvins. It is clever but not paradigm-shifting.

  • JaberwokWSA

    So why isn’t the experiment being done again with a different source or destination? For example CERN to the Super-Kamiokande: Neutrino Detector in Japan?

    If the same setup over a distance twice as far gives the same 60 nanoseconds, then that would imply there is a definite problem with measuring the time. If, however, the neutrinos arrive twice as early for twice the distance, then that would imply that the speed is probably the actual cause of the measurement.

    And @ #4 cbunix23, the experiment is not solely at CERN. CERN is used just to generate the neutrino beam, which is pointed at the Gran Sasso laboratory, 732 kilometers away in a straight line through solid rock. There are no photons making that journey; only neutrinos. The speed the photons would theoretically make over that distance is the compared value, as it can be determined from the distance (which takes into account the curvature of the Earth, differences in X, Y, and Z coordinates, etc) and the speed of light. It turns out that the neutrinos are getting there 60 ns sooner than they should

  • MrTemple

    @cbunix23: “C as the speed limit applies in a vacuum and in a straight line, right?
    Is the CERN apparatus a perfect vacuum? Maybe there is enough matter in the apparatus to slow down photons more than neutrinos?”

    All good questions. c is commonly thought of as the ‘speed of light’ or the ‘speed that light travels’, but it isn’t quite the same. Which light and c are very tightly tied, c applies to things other than light.

    In this experiment, neutrinos weren’t racing light (they went through hundreds of kilometers of bedrock, which neutrinos happily do as if it were a vacuum, but which light obviously cannot do.

    There are a great number things which might explain the apparent faster than light neutrinos. Neutrinos are a very tricky species. It’s all but impossible to detect a single neutrino. One will happily travel through a light-year of lead with only a 50-50 chance of hitting *anything* at all! The only way to detect a neutrino is to fire billions and billions of them at the detector, and hope that just one hits!

    c is a constant which actually pops out of some fairly fundamental equations on electro-magnetism. Maxwell discovered these equations over a century ago, and much of modern physics (including Relativity) is based on mathematical manipulations of these equations. Maxwell’s equations and their derivatives have been so thoroughly tested and verified, that we’re very creatain they aren’t ‘wrong’, they may be incomplete certainly, but they will never be outright wrong.

    The rub is that for speeds greater than c, Maxwell’s equations and their derivatives simply break horribly. It’s hard to imagine how perfectly well the equations work to predict some very widely varied and also very unintuitive realities of the universe, and yet be fundamentally broken with regard to c.

    While this experiment is exciting and tantalizing, a healthy dose of skepticism is warranted. Especially with an apparent speed for these neutrinos being so very, very close to the *exact* value of c that we predict, it seems far more likely that there’s something wrong with the very complicated experiment. Indeed those running the experiment agree with this, and this is why they’re seeking outside help, trying to find any issues.

    The smart money is on sub-light neutrinos, but I, along with all physicists would dearly love to lose that bet.

    I wrote more about it here, if interested:
    Point-Five Past Lightspeed | is this your homework?

  • Arahan

    Hey can anyone please help me explain the relativistic change in the mass of the neutrinos in accourdance to the Einstein’s principle of relativity. It has become a paradox to me. Does this experiment some how contradicts the Principles of Relativity?

  • Mephane

    @11 MrTemple: “Is the CERN apparatus a perfect vacuum? Maybe there is enough matter in the apparatus to slow down photons more than neutrinos?”

    This misconception is being repeated far too often. There never was a light beam sent alongside the neutrinos as if to have them race against each other, so it does not matter at all whether photons would locally have been slower somewhere down the trip. Also, the neutrinos had to go through solid matter, right through the Earth, which they can only do because unlike photons, they interact with matter only very very rarely.

  • MrTemple

    @13 Mephane: That was a quote of somebody else asking that. My post was an explanation to that question much the same as yours.

  • Amir D. Aczel

    Hi, Thank you so much for all your thoughtful comments!! We live in interesting times, in which fascinating results are found…time will tell which ones are real–and will surprise us, I am sure.

  • Chris H

    Imagine what our physics would read like if we only had ears. It would take us a very long time to devise and appreciate an experiment that showed anything faster than sound waves. Recall experiments over hills with early experiments flashing light to attempt to measure its speed. Now consider the makeup of every instrument we have and all the sensors we have. Are we reaching a point were we can see a hint of things faster than our instruments limitations. Are we just developing eyes?

  • David Brown

    “… MINOS … did not use a GPS as accurate as that of OPERA …” Is the GPS timing the key to understanding the OPERA neutrino anomaly?
    Is Mordehai Milgrom’s theory of Modified Newtonian Dynamics (MOND) as fundamental as Alfred Wegener’s theory of continental drift?
    According to Wikipedia, “Alfred Lothar Wegener … is most notable for his theory of continental drift, proposed in 1912, which hypothesized that the continents were slowly drifting around the Earth. However, his hypothesis was not accepted until the 1950s, when numerous discoveries such as palaeomagnetism confirmed his hypothesis of continental drift.”
    Is the OPERA neutrino anomaly merely another confirmation of MOND? The MOND pages (McGaugh) Pavel Kroupa: Dark Matter, Cosmology and Progress

  • Ian

    I am not sure why the clocks in the 2 locations have to be scrutinized for perfect synchronization.

    My thought: If you send a pulse of light beam across the path to measure its speed and then repeat the same test for the neutrinos, they would be experiencing the same time error due to the clock sync. So if you compare their measured speeds from the experiment, you can still determine which one is faster. Only if you need to find out the exact speed of neutrinos then you would require “perfect” timing.

    I don’t know much about quantum physics and I wish someone would explain to me.

  • Pete

    Strange hypothesis. I would assume they would simply calculate the speed of limit from those two distances. It doesn’t make logical sense to send a beam of light to measure it when we know the exact speed of light.

  • Chris

    @Uncle Al
    > if the FTL neutrino is observed as an SOP neutrino, and it passed through the lightspeed singularity, then its mass went infinite and time locally stood still. Messy.

    I don’t know what it means to have infinite mass for zero time. This is the problem with singularities. :)

    It occurs to me, that if neutrinos can change flavor in transit, to one of three known neutrino flavors, then perhaps some of the neutrinos are transforming briefly into symmetric neutrino flavors that go faster than light, i.e. a tachyon-neutrino.

    That would require new science, but if so what an exciting time!

  • clifford Wright

    As a mere retired electronics engineer I was hesitant about addding a post here. But the obvious lack of experimental technique shown by some posters has given me confidence.
    The whole point of using GPS is to accurately fix the neutrino path length. This is now probably known within centimetres. Obviously light cannot travel through the Earth but knowing the distance with great accuracy a simple calculation gives the expected arrival time.
    The “signal” involved (60 nsecs) is VERY large by modern standards. Most home computers could perform hundreds of operations in that time.
    I have seen postings of the “it can’t be right, I won’t believe it” from apparent real Physicists!
    Well I can only suggest that if the results are confirmed they should change to Theology where they would be more at home.
    Is it not ironical that in the same short time we have and apparent detection of the Higgs boson.
    (pro relativity we are told) and the FTL neutrino (seriously questioning relativity).
    I do have one serious point to make however.
    Looking at the real world is not the whole idea of time travel to the past ridiculous.
    In fact I philosophically doubt that you could have any kind of stable reality if it could occur.


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About Amir Aczel

Amir D. Aczel studied mathematics and physics at the University of California at Berkeley, where he was fortunate to meet quantum pioneer Werner Heisenberg. He also holds a Ph.D. in mathematical statistics. Aczel is a Guggenheim Fellow, a Sloan Foundation Fellow, and was a visiting scholar at Harvard in 2005-2007. He is the author of 18 critically acclaimed books on mathematics and science, several of which have been international bestsellers, including Fermat's Last Theorem, which was nominated for a Los Angeles Times Book Award in 1996 and translated into 31 languages. In his latest book, "Why Science Does Not Disprove God," Aczel takes issue with cosmologist Lawrence M. Krauss's theory that the universe emerged out of sheer "nothingness," countering the arguments using results from physics, cosmology, and the abstract mathematics of set theory.


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