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On Neutrinos and the Speed of Light

If you’re tracking the interesting news from CERN on neutrinos moving slightly faster than the speed of light, be advised that there is an upcoming CERN webcast on the matter at 1400 UTC later today (the 23rd). Meanwhile, evidence that the story is making waves is not hard to find. I woke up to find that my local newspaper had a headline — “Scientists Find Signs of Particles Faster than Light” — on the front page. This was Dennis Overbye’s story, which originally ran in the New York Times, but everyone from the BBC to Science Now is hot on the trail of this one.

The basics are these: A team of European physicists has measured neutrinos moving between the particle accelerator at CERN to the facility beneath the Gran Sasso in Italy — about 725 kilometers — at a speed about 60 nanoseconds faster that it would have taken light to make the journey. The measurement is about 0.0025 percent (2.5 parts in a hundred thousand) greater than the speed of light, a tiny deviation, but one of obvious significance if confirmed. The results are being reported by OPERA (Oscillation Project with Emulsion-Tracking Apparatus), a group led by physicist Antonio Ereditato (University of Bern).

Neutrinos are nearly massless subatomic particles that definitely should not, according to Einstein’s theory of special relativity, be able to travel faster than light, which accounts for the explosion of interest. According to this account in Science Now, the OPERA team measured roughly 16,000 neutrinos that made the trip from CERN to the detector, and Ereditato is quoted as saying that the measurement itself is straightforward: “We measure the distance and we measure the time, and we take the ratio to get the velocity, just as you learned to do in high school.” The measurement has an uncertainty of 10 nanoseconds.

It’s hard to do any better than Ereditato himself when bringing caution to these findings. Let me quote the Science Now story again:

…even Ereditato says it’s way too early to declare relativity wrong. “I would never say that,” he says. Rather, OPERA researchers are simply presenting a curious result that they cannot explain and asking the community to scrutinize it. “We are forced to say something,” he says. “We could not sweep it under the carpet because that would be dishonest.”

And the BBC quotes Ereditato to this effect: “My dream would be that another, independent experiment finds the same thing. Then I would be relieved.” One reason for the relief would be that other attempts to measure neutrino speeds have come up with results consistent with the speed of light. Is it possible there was a systematic error in the OPERA analysis that gives the appearance of neutrinos moving faster than light? The timing is obviously exquisitely precise and critical for these results, and a host of possibilities will now be investigated.

This paragraph from a NatureNews story is to the point:

At least one other experiment has seen a similar effect before, albeit with a much lower confidence level. In 2007, the Main Injector Neutrino Oscillation Search (MINOS) experiment in Minnesota saw neutrinos from the particle-physics facility Fermilab in Illinois arriving slightly ahead of schedule. At the time, the MINOS team downplayed the result, in part because there was too much uncertainty in the detector’s exact position to be sure of its significance, says Jenny Thomas, a spokeswoman for the experiment. Thomas says that MINOS was already planning more accurate follow-up experiments before the latest OPERA result. “I’m hoping that we could get that going and make a measurement in a year or two,” she says.

Unusual results are wonderful things, particularly when handled responsibly. The OPERA team is making no extravagant claims. It is simply putting before the scientific community a finding that even Ereditato calls a ‘crazy result,’ the idea being that the community can bring further resources to bear to figure out whether this result can be confirmed. Both the currently inactive T2K experiment in Japan, which directs neutrinos from its facility to a detector 295 kilometers away, and a neutrino experiment at Fermilab may be able to run tests to confirm or reject OPERA’s result. A confirmation would be, as CERN physicist Alvaro de Rujula says, ‘flabbergasting,’ but one way or another, going to work on these findings is going to take time, and patience.

The paper “Measurement of the neutrino velocity with the OPERA detector in the CNGS beam” is now up on the arXiv server (preprint).

Addendum: For an excellent backgrounder on neutrino detection and the latest measurements, replete with useful visuals, see Starts With a Bang. Thanks to @caleb_scharf for the tip.

And this comment from a new Athena Andreadis post is quite interesting:

If it proves true, it won’t give us hyperdrives nor invalidate relativity. What it will do is place relativity in an even larger frame, as Eisteinian theory did to its Newtonian counterpart. It may also (finally!) give us a way to experimentally test string theory… and, just maybe, open the path to creating a fast information transmitter like the Hainish ansible, proving that “soft” SF writers like Le Guin may be better predictors of the future than the sciency practitioners of “hard” SF.


Comments on this entry are closed.

  • Martin J Sallberg September 23, 2011, 9:03

    There is a theory of variable speed of light. Maybe the speed of light recently made a slight increase. Other possibilities is that a wormhole-shortcut formed or that the neutrino quantum-tunneled at some point. Or it may indeed be a new class of tachyonic particles.

  • Alex Tolley September 23, 2011, 9:46

    I’d be willing to bet that the results are due to mismeasurement rather than new physics. If the distance between the 2 sites was incorrectly determined, that could account for the finding.

    One way to test this might be to have both neutrinos and light travel the same journey and therefore eliminate some distance measurement error by direct determination of the time of flight.

  • Steven Rappolee September 23, 2011, 9:52

    I am assuming they took into account the tidal bulges in the earths crust from lunar and solar gravity?

  • henk September 23, 2011, 10:44

    Martin J Sallberg

    a wormhole-shortcut. Are you joking, but if its was a wormhole. Why did those Neutrinos not vanish somewhere else in space. That mean a wormhole was created for a tiny distance just to make a illusion that it goes faster than ligh.

  • Martin J Sallberg September 23, 2011, 11:07

    @Steven Rappolee
    That may actually be an error source. They have got wrong results because they ignored lunar gravity before, but I thought they had fixed it. But it will be investigated, we will soon see. Such a big discovery will of course be rigorously tested. Ignoring lunar gravity TWICE would be really, really embarrasing for the accelerator scientists!

  • Alex McLin September 23, 2011, 11:23

    Sterile neutrinos is also one possible explanation for the speed difference if it does get confirmed.

  • Richard Burke-Ward September 23, 2011, 11:28

    I could be wrong here, but isn’t the absoluteness of the speed of light an assumption rather than something that has ever been proved? I thought relativity explored what would happen *if* the speed of light in a vacuum is absolute…

    I know that a century of experiments have failed to disprove that assumption (perhaps until now). And I know that the predictions of relativity have have so far conformed with pretty much every observation ever made…

    But there’s still some theoretical wriggle room there.

    Or do I have this wrong?

  • JohnQ September 23, 2011, 11:41

    Here is a link from 1986 that refers to a possible theoretical justification for neutrinos going FTL: http://adsabs.harvard.edu/abs/1986PhLB..178..115G

    Obviously, I haven’t read the paper and have no comment on it, but I would be curious if anyone is aware of these studies.

    My own thought is that even if confirmed this may not be that big of a deal for the physics of the universe (though obviously the theoritical community would be excited). The question is: can these supposedly FTL neutrinons be used for signalling? My guess is no, they cannot. Relativity theory and QM allow for all kinds of FTL slight-of-hand, as long as no information is exchanged. In other words, if causality is preserved, there is nothing to disturb Einstein’s slumber.

  • Mike Lockmoore September 23, 2011, 12:09

    I think the distance measurement is probably pretty accurate. But how do you ensure the timing is accurate? If the particles traverse a one-way flight, do they use two clocks, one at the start, and one at the end? How were they synchronized? How was the synchronization verified? Or is there some kind of electromagnetic signal that travels in parallel to the neutrinos? If the neutrinos fly through solid rock while the timing pulse went “the long way” over the air or a cable or something, you could easily have a time difference. But with all the publicity this will now get, the results will be thoroughly scrutinized.

    But of course, I hope this result is verified. Like many here, I’ve been hoping some unexpected new physics would appear and help us find a path around the seeming limitations we have known so long.

  • Bob September 23, 2011, 12:59

    What strikes me is that if one really thinks about it, the speed of light is so blasted slow when compared to the scale of the universe. It would take on the order of a day at light speed just to circumnavigate the solar system let alone years to the nearest stars. This is not a physics statement but I just have an intuitive feeling (or rather, hope) that some underlying structure may allow an almost instantaneous connection.

  • Tom Baty September 23, 2011, 13:26

    Alex, I am with you, some error was made in the calculations or as Steve suggested something else was not taken into consideration. With all due respect your test with using light and neutrinos would not be able to be done at CERN as the facility is underground.


  • ljk September 23, 2011, 13:31

    This post on the subject at Bad Astronomy also has a link to the ArXiv paper:


    I would presume the scientists in question have already taken into consideration the distance between the two facilities and measured them as accurately as possible. But mistakes do happen.

    My other question is, if this is for real, how exactly are we going to harness this effect to make FTL travel possible? Neutrinos are slippery little suckers, to quote Julia Roberts’ character in the film Pretty Woman.

  • Skeptic Tim September 23, 2011, 13:39

    An interesting coincidence: My “back of the envelope” calculation indicates that the travel time at c difference between a chord through the earth between the detector and the source (the expected neutrino travel path) and the same distance measured along a geodetic (that given by GPS) is almost exactly 60ns. I have not yet read their paper but I’m sure, however, that these investigators have compensated for this difference.

  • jkittle September 23, 2011, 13:53

    Obviously extraordinary claims require extraordinary evidence so all of the comments on the need for accuracy are well founded. I assume the team is very careful about the more obvious ones. Also – the measured differences are only slightly faster… we are not ready to ride to a distant star on a ship made of neutrinos. While the project to build the Warp-drive FTL ship is not exactly “shovel ready ” it is an interesting time to be alive. We may see some new physics come out of this..
    For me, the most easy way to understand the significance is to try to calculate the mass of a particle approaching then exceeding the speed of light. the mass is dependent on the rest mass divided by the square root of ( 1 minus the square of the ration of (velocity over the speed of light). [Hard to write as text]. in any case the mass of a moving object starts to increase as it approaches the speed of light, then at the speed of light approaches infinity and beyond the speed of light is described by an imaginary number! so.. the physics would definitely need to be different. This increase in apparent mass of an object as it reaches relativistic speeds is VERY well established, and is one of the reasons why it is so hard to consider building a star ship traveling near the velocity of light.
    IF this holds up , then perhaps we can eventually learn to cheat on the fabric of normal space time. I do not hold about a lot of hope, but please recall how quickly progress was made on nuclear energy once the neutron was discovered in 1932, or the wholesale changes in biologic sciences brought about by the discovery of DNA and subsequent gene sequencing technology- all in the lifetime of the James Watson!

  • Tom Louden September 23, 2011, 15:04

    Lunar effects are effectively ruled out, the measurements were taken over a 3 year period, no modulation from tides were detected (although an earthquake in 2009 and continental drift are visible in the signal!) and 2 independent measurements of the distance between the two sites were done a year apart, and were consistent to within 1 cm. A 60 ns delay implies a 20 cm error, which there is not an easy way to account for.

    I’m fairly confident this will turn out to be in error somehow, but the OPERA team have been extremely thorough in ruling out the obvious ones, i’ll be interested to see how this plays out!

  • davethebald September 23, 2011, 15:23

    As an enthusiastic amateur, I am not even remotely qualified to comment on the technical aspects of this announcement, but I offer a few thoughts:

    1. I am delighted at how humble the CERN scientists are. Every quote I have read can be translated into “We have something here that we cannot explain, please help”. Wouldn’t it be be nice if politicians could learn to question themselves?

    2. How exciting! At least for the moment, everything is up in the air. Although my money is still on Einstein, the possibilities are fun to think about.

    3. What a wonderful lesson this can be for students. At least in science, everything is always up for review. If some phenomenon is not studied anymore, it is only due to a lack of resources and a need to allocate what we have to where it seems to have a reasonable chance of success. But that is not because settled issues are unworthy of review.

    Can’t wait to see how it come out.

  • Dave Moore September 23, 2011, 15:26

    I seem to remember a set science column articles in Analog SF dealing with evidence pointing to Neutrinos having an imaginary mass and therefore being a form of Tachyon. This was before the mass of a neutrino was nailed down.

    Neutrinos appear to resonate between their various forms. If there was a tacyonic form, which it became, then this would account for the results.

  • Bob September 23, 2011, 15:39

    “extraordinary claims require extraordinary evidence”

    I never liked that statement.

    Actually, what is ordinary and what is extraordinary is determined by our bias and on the history of discoveries or their contexts or interpretations and thus is kind of subjective. The same solid evidence for an ordinary claim is just as good for an “extraordinary” claim. Evidence is evidence.

  • Zarpaulus September 23, 2011, 15:44

    I wonder.

    Is the difference between the speed of the neutrinos and light in this experiment equivalent to the difference in speed between light in vacuum and light in air by any chance?

  • Athena Andreadis September 23, 2011, 16:42

    Thanks for the signal boost, Paul!

    I wanted to comment on the CD entries about Kepler 16 (including the point of one of the commentators about crowdsourcing of data crunching) but my reply got article-long and the CERN results showed up, so I put it up on my blog.

  • Rob Henry September 23, 2011, 16:54

    I am interested to find from the link in Paul’s addendum that the detected part of this beam is of muon neutrinos. I thought that explaining how this could be a tachyon in terms of string theory was harder than doing the same for an electron neutrino.

    Another puzzle, from that addendum link is why its author thinks there is a discrepancy between this speed and SN 1987a data. I thought that neutrinos had been shown to oscillate between their 3 types, and the tau neutrino would surely be a tardyon wouldn’t it??

    For that matter, how were all the experiments giving the electron neutrino a negative squared mass explained in the end, and what’s the fundamental problem with an uncharged particle being a tachyon?

    I am a mighty confused outsider, and it would be great if any of you could help me with any of this, but I must say that I think Bob was spot on about extraordinary claims. What that saying means in practice is that scientists shouldn’t bother to spend much time investigating postulates that don’t fit the current paradigm unless they are really forced to. That mindset must slow progress a bit.

  • time_bandit September 23, 2011, 17:30

    If SR requires that a mass’s clock slows down as it approaches light speed (and starts going backwards above LS?), then wouldn’t the neutrino have traveled back in time in some sense, if this result is really legitimate? Or is that just a paradox used to make the theoretical case for Special Relativity, which is out the window if this result holds up?

  • David September 23, 2011, 17:36

    I agree with the scientists that discovered this -Lets not jump to Good advice. I alos agree with Bob. That line is overused.
    I diagree with the claim that this could make string theory testable or there wont be warp drives because I dont know what it means and I dont think we can say yet.
    From a Popperean point of view however I would say if it holds …something might have been falsified here…..especially since the energy did not become infinite at the spped of light.

  • ljk September 23, 2011, 18:00

    Some relevant links I found:

    One Way Light Velocity Toward Gran Sasso

    By Sascha Vongehr | September 23rd 2011 04:38 AM


    To quote:

    The people with the atom smashers, especially the ones at Opera (Oscillation Project with E-tR Apparatus) in Italy’s Gran Sasso, today announced to likely have a whopping ten nano second systematic error with some neutrino experiments that have according to insiders about only 60 nano seconds of accuracy anyway, but it makes for much better news to question Einstein.

    The scientists blame journalists for the hype, but of course they prepared everything just so that the press has no reason not to go ahead and make an Einstein spectacle out of it – the BBC promptly obliged.

    It is the usual ‘claim-to-be-fundamental-strategy’ as done with the God particle and all the other blown out of proportion humps-on-bumps, and I note that Wired Science and SciAm for example go along with this worse than the BBC. Supposed to be the other way around? What does this tell us about science(media)?

    When the speed of light is involved, especially much nonsense comes shooting from all sides, not only from those with revolutionary claims, but often particularly from those who defend that this cannot possibly be because XYZ. Overwhelmingly, XYZ turns out to be nonsense.

    Faster-Than-Light Neutrinos?

    by Sean Carrol of Cosmic Variance, 9-23-2011


    Neutrinos exceed the speed of light?

    From Jerry Coyne’s Why Evolution is True blog for Sept. 23, 2011


    To quote:

    Now how could this happen? Wormholes!

    John Learned, a neutrino astronomer at the University of Hawaii, said that if the results of the Opera researchers turned out to be true, it could be the first hint that neutrinos can take a shortcut through space, through extra dimensions. Joe Lykken of Fermilab said, “Special relativity only holds in flat space, so if there is a warped fifth dimension, it is possible that on other slices of it, the speed of light is different.”

    Now I’m no physicist, but if neutrinos can go through wormholes, then information can be transmitted faster than the speed of light, which would truly be a monumental finding.

    If another intelligence were trying to get someone’s attention, might not playing with some fundamental forces of physics be one way? It’s still a cool idea, regardless. :^) Perhaps we all better read Einstein’s Bridge.

  • Paul Gilster September 23, 2011, 18:01

    Athena Andreadis writes:

    I wanted to comment on the CD entries about Kepler 16 (including the point of one of the commentators about crowdsourcing of data crunching) but my reply got article-long and the CERN results showed up, so I put it up on my blog.

    It’s an excellent blog entry, and in fact your thoughts on crowd-sourcing more or less parallel my own. I’ll be talking a bit about this in my comments in Orlando — it’s not a major part of the talk, but where crowd-sourcing does and does not work seems like an unexplored frontier these days, except for your online thoughts as linked to in the entry above.

  • Chris T September 23, 2011, 18:17

    Bob – The saying is justified in this instance. Nearly a century’s worth of data and theory strongly back c as a fundamental limit. The claim that these neutrinos are somehow exempt is pretty extraordinary.

  • Athena Andreadis September 23, 2011, 18:28

    Paul, I look forward to the conference with great anticipation! If nothing else, I’ll get to meet you and a few others in person.

    David, warp drives are not FTL; they’re predicated on other types of (so far totally hypothetical) energy. Even if neutrinos are proven to exceed light speed, they would exceed it by such a miniscule amount that the distances to other stars would remain daunting — even if we made starships from neutrinos, which gives new meaning to the term “gossamer” (as Larry pointed out in an earlier comment in this thread).

  • Last Hussar September 23, 2011, 19:16

    re all the above possible explanations: They have spent 3 years re doing this, trying to prove they were wrong. After all that they have thrown it out to the scientific community. As I said to my step-son, this must have made for some pretty interesting conversations with the financial backers. “So, found anything yet” “err, we’ve definitely not broken any fundamentals – promise!”

  • bigdan201 September 23, 2011, 19:23

    I’m strongly leaning towards this being an error. Neutrinos are strange particles for sure, but we’ll need exhaustive study to ensure that these results are correct. If they are, it’d be great – it would open a door to experiment on the more exotic theoretical physics. However, the limit of c is a strong one, given its relationship to relativity, so we must proceed with caution. In any case, it must be thoroughly proven in order to use it as a foundation for future experimentation.

    “extraordinary claims require extraordinary evidence”

    I never liked that statement.

    Actually, what is ordinary and what is extraordinary is determined by our bias and on the history of discoveries or their contexts or interpretations and thus is kind of subjective. The same solid evidence for an ordinary claim is just as good for an “extraordinary” claim. Evidence is evidence.

    I have to respectfully disagree here. I’ve always liked that phrase. If you’re starting out, evidence is evidence. However, once you have a tested framework of how the world works, it is foolish to toss out your reliable knowledge base over one new piece of evidence. Anything can be considered, but a result with sweeping ramifications does need stronger evidence than a result that neatly fits into the existing puzzle. The more evidence you have that is consistent, the more you need to question something that challenges it. I’m not emphasizing intellectual xenophobism – but it’s a principle that will save you quite a bit of trouble.

    What strikes me is that if one really thinks about it, the speed of light is so blasted slow when compared to the scale of the universe. It would take on the order of a day at light speed just to circumnavigate the solar system let alone years to the nearest stars. This is not a physics statement but I just have an intuitive feeling (or rather, hope) that some underlying structure may allow an almost instantaneous connection.

    Indeed. Foldspace and wormholes are two favored possibilities. The Alcubierre bubble could also work, although I’m not sure if it would be feasible.

  • Ron S September 23, 2011, 20:56

    Richard Burke-Ward: “I could be wrong here, but isn’t the absoluteness of the speed of light an assumption rather than something that has ever been proved?”

    It is not the speed of light that is absolute but that the local “measurement” of light speed is c. That’s no assumption.

    Bob: “It would take on the order of a day at light speed just to circumnavigate the solar system let alone years to the nearest stars.”

    Sorry, that’s wrong. The real answer is that your trip would be far, far faster than that.

    Skeptic Tim: Your comment is strikingly similar to this one — are you a meta-pseudonym?:

    jkittle: “…mass of a moving object starts to increase as it approaches the speed of light…”

    The mass is constant. It’s the momentum that increases at a higher rate than predicted by Newtonian dynamics.

    Zarpaulus: “Is the difference between the speed of the neutrinos and light in this experiment equivalent to the difference in speed between light in vacuum and light in air by any chance?”

    I’m afraid not. The neutrinos are effectively in free space; they do not interact with the intervening matter. Also, photons are always measured at c, while light (as waves, not as individual photons) have a net speed loss in a non-vacuum medium.

    time_bandit: “If SR requires that a mass’s clock slows down as it approaches light speed…”

    No, its clock does not slow down. It is an observer with a non-zero relative velocity that observes a drift in clock synchronization. Each of us always travels at a 4-velocity of 1 second per second.

    My preferred perspective: http://xkcd.com/955/

  • David September 23, 2011, 21:18

    Warp Drives are based on the idea that space can move fatser than light as opposed to these neutrinos that are objects in space that are moving faster than light.
    If the measurement is correct this should be a real problem for relativity and in that case I have no idea what that will mean.

    I am just guessing here but sine the neutrinos are in a measuring device that the fact they are a quantum sized object would not have anything to do with this. Also no other quantum sized object has done this except in entanglement

  • Adam September 23, 2011, 21:58

    Hi All
    John Cramer has discussed tachyonic neutrinos over the years in his “Alternate View” column for “Analog”. This latest sighting of such isn’t the first such claim, but it might well be the best measurement so far. Cramer’s AV essay on tachyon rockets is well worth a read too – no, they don’t let you go FTL, but they do allow some other interesting applications. In the early 1970s tachyons were a hot-topic too, based on Gerald Feinberg’s theoretical work in the 1960s, and tachyon rockets turned up in a bunch of SF stories, notably Joe Haldeman’s “The Forever War”. The effects of “imaginary mass” are interesting, to say the least.

  • Eniac September 23, 2011, 22:51

    I have to side with Chris and bigdan. An “extraordinary finding” is one which contradicts heaps of evidence previously assembled, and has nothing going for it except your one experiment. You darn well need better evidence to back it up than you need for a “boring finding”, which is consistent with all the prior evidence.

  • djlactin September 24, 2011, 1:17

    I’d guess that the source-target distance was incorrect. The stated distance was “about 750 km”; a 0.0025 % (25 ppm) error amounts to about 19 m. This is comparable to GPS accuracy: “…Noise can create an error between 1 to 10 meters and results from static or interference from something near the receiver or something on the same frequency. Objects such a mountains or buildings between the satellite and the receiver can also produce error, sometimes up to 30 meters . The most accurate determination of position occurs when the satellite and receiver have a clear view of each other and no other objects interfere.”
    (http://www.maps-gps-info.com/gps-accuracy.html) (emphasis added.)

    p.s.: I tried to access the preprint and got a ‘document not found’ response.

  • djlactin September 24, 2011, 1:41

    OK, I accessed the article using the link in “Startswithabang”. It states that the distance is known to within 2 cm.

  • Joy September 24, 2011, 4:14

    I read quickly, but 28 comments and I don’t think anybody mentioned SN 1987a! Maybe it is because I can see the LMC every clear dark night here, and was already a fully grown astronomy enthusiast in 1987, but it was pretty obvious to me, and (independently) to Nicole Bell in Melbourne:

    “Explosive astronomical evidence

    Nicole Bell, a senior lecturer in theoretical particle physics at the University of Melbourne in Australia, pointed to an example from astronomy that seems to refute the latest results.

    It comes from a star that went supernova in 1987 within the Large Magellanic Cloud galaxy.

    Supernovae are formed when stars explode as they get too large or reach the end of their lives. As part of the radiation emitted when they do this, they release neutrinos and light.

    The Kamioka Nucleon Decay Experiment detector in Japan picked up neutrinos from the explosion three hours before light from supernova event reached Earth.

    “However, this does not mean the neutrinos travelled faster than the speed of light. It just means that the neutrinos left the supernova first, while the light was trapped in the supernova for longer before it could get out,” said Bell.

    If the neutrinos from the explosion actually had been travelling faster than the speed of light, like the CERN experiment suggests, they would have reached Earth years, rather than hours, before the light did, explained Bell.

    “In a way, you can regard the supernova observation as an independent experiment result which refutes the OPERA measurement.”


    QED! Seriously folks, SN 1987a was a natural neutrino velocity experiment four orders of magnitude tighter than this accelerator experiment. The explosion released 10^58 neutrinos at a distance if 168,000 LY. If neutrinos traveled 20 ppm faster than light, the neutrino burst would have arrived more than 3 years before the visible light, and they didn’t. Until we get another SN in the Milky Way, this is the gold standard of measurement of the speed of neutrinos in vacuum across cosmic distances.

    There are three possibilities here:
    1) there is a flaw in the accelerator data (very likely)
    2) neutrinos can travel slightly faster through condensed matter than vacuum, and I can’t even speculate why that would be true

    Finally, the politician/science managers at CERN (a multi-billion euro complex hosting the LHC, which was marketed as a machine for finding the Higgs boson or maybe supersymmetric particles) are staring down a public relations disaster by New Year’s, when they will likely have to admit the Higgs is just not there and SUSY isn’t home either. So they are holding press conferences to hype flaky preliminary data in search of a new mission for CERN. If that sounds far fetched, well the EU has some very serious financial issues, and CERN would be tempting to axe. The US axed the SSC in 1993 following a recession less serious than the current sovereign debt crisis. There are 2400 employees at CERN plus almost 8000 visiting scientists in fear for their jobs and grants. Of note the neutrino beam was not produced by the LHC, but by the SPS/CNGS. So messing around with neutrino measurements could employ a lot of people even if the LHC was retired.

  • Sean M. Brooks September 24, 2011, 4:27

    I am by NO means a scientist or astronomer, just interested. I’ll simply say I hope CERN’s experimental results are confirmed. Because that will then make it slightly more possible that a way around the light speed barrier might be found. It is my firm belief that the true future of mankind lies in getting OFF Earth and settling other worls, preferably both in the Solar System and on planets orbiting other stars.

    I do wish Poul Anderson, the spiritual father of Tau Zero/Centauri Dreams, could have lived to see this day.

    Sean M. Brooks

  • Avatar2.0 September 24, 2011, 6:50

    About neutrinos exceeding the speed of light being an experimental error:
    The teams conducting the experiment tried for 3 years to find such an error. If it exists, it’s not something simple/obvious such as the distance not being correctly measured or the clocks not being properly synchronised.

    If superluminal neutrinos are NOT an experimental error:
    Most likely (aka the explanation that best fits the known principles of physics) is that neutrinos generate a small negative curvature in space-time – which explains their larger than c speed from our external perspective.
    The Shapiro time delay effect is the opposite phenomenon (and it’s experimentally verified) – near a positive curvature of space-time (generated by anything that has mass – except, perhaps, neutrinos), the speed of light (and of everything else) seems to slow down – from an external perspective.

    This would mean that now, we finally know from where to get the amount of negative energy needed to create and maintain stable wormholes (and other such constructs).
    Fingers crossed.

  • Avatar2.0 September 24, 2011, 6:56

    Also, if neutrinos really do generate a negative space-time curvature, they may play a larger role in the existence of the mysterious dark energy than anyone suspected.

  • A. A. Jackson September 24, 2011, 7:36

    As usual the press goes goofy about what this means.
    Einstein Wrong!
    Well no, Special Relativity is still valid.
    I don’t know how much Einstein emphasized it during his life time but later it was recognized what Classical Special Relativity said was that there be a finite speed with which information is transmitted. Causality being the important concept that Einstein introduced, that is cause must precede its effect according to all inertial observers.
    So as long as information is not transmitted instantaneously classical Special Relativity holds and Einstein is still right.
    (I exclude all the strange effects of the quantum world which are still not firmly understood.)

  • lorq September 24, 2011, 8:28

    Ron S: “It is not the speed of light that is absolute but that the local ‘measurement’ of light speed is c. That’s no assumption.”

    Yes, it is. Perhaps more accurate to call it a postulate, one of two major postulates of the Special Theory.

    I wonder if the fact that the neutrino beam passes under an arc of the earth might cause the beam to be affected by the earth’s gravitational field (or, more precisely, by the change in the beam’s relationship to the earth’s center of gravity as it traverses the arc). (Which would bring the General Theory into the mix…)

  • djlactin September 24, 2011, 8:30

    Perhaps the answer is that c IN A VACUUM is 25 ppm (~7500 m/s) faster than thought. In what (VERY little) I have read on this subject, measurements assumed that space is a perfect vacuum, but it is not. A deviation of 25 ppm from the expected value of c suggests that “space” has a refractive index (v/c) 0f 0.999975, not 1.

  • djlactin September 24, 2011, 9:39

    Tests of my hypothesis:
    (1) measure the refractive index of space (to much less than 25 ppm).
    (2) measure c (with exquisite precision) over a large range of “vacuum pressures”; extrapolate the asymptote.

  • Ron S September 24, 2011, 11:12

    lorq, c is a measurement. Einstein used its constancy as a postulate.

    More generally, the team appears to have accounted for all external effects in their calculations, so the difficulty, if there is one, may be deeper; that is, either a systematic error in the experiment or a statistical error. The latter is important since the error bars in each detection are a couple of orders of magnitude greater than the estimated effect. They have to do some intensive statistical analysis of the data to pull a signal out of the much larger noise. That is a part of the analysis that requires scrutiny.

    It’s a little early to go nuts about new physics. The less on SN1987A is that one should not cherry pick experimental results simply because they seem attractive. One experiment does not make all the others wrong. As pointed out in the Cosmic Variance article ljk references, it is possible, though unlikely, that the energy and noise background differences between this latest result and that from SN1987A could indicate an energy-dependent velocity difference. We’ll see.

    I am also amused by the charges being made against the CERN team for publicizing their results. Just how else does anyone imagine they can invite the scrutiny of those outside their team? They appear to be acting most responsibly (as Paul emphasizes in his more recent article).

  • Skeptic Tim September 24, 2011, 12:44

    @Ron S
    Hi. I’m not a “meta-pseudonym” of Torbjörn Larsson, who’s comments I enjoy very much and often learn from. In this case however, I simply did a quick calculation using the mean radius of the earth obtained from an old geophysics text and a simple chord distance formula while trying to demonstrate the usefulness of geometry to a young friend. Sometime later I read Torbjörn Larsson’s comment and was pleased to see that he got a similar result hopefully saving me from having to explain away some obvious arithmetic error to my young friend. (I don’t know, however, weather or not Mr. Larsson’s methodology was different from mine).

  • Ron S September 24, 2011, 13:45

    Thanks for the clarification, Skeptic Tim. I did have to wonder when I saw the same use of certain words along with the calculation result. Perhaps I should have held my tongue.

  • John Freeman September 24, 2011, 18:03

    Time will tell…. I agree if it is an error it wil be something subtle and easily missed. And I’d like to join with others in praising the CERN team for their humble and pragmatic attitude; ‘we have an anomaly we cannot explain, and we appeal to others for help’ as opossed to ‘we’ve cracked lightspeed!’

  • ljk September 24, 2011, 18:21
  • Bob September 24, 2011, 18:22

    Bob: “It would take on the order of a day at light speed just to circumnavigate the solar system let alone years to the nearest stars.”

    Ron S. “Sorry, that’s wrong. The real answer is that your trip would be far, far faster than that.”

    You may have thought I was thinking of relativistic ship time but I just meant the speed of a beam of light. If we use about 40 AU for the distance to Pluto, the distance of a circular loop at that radius is simply 2 Pi 40AU. Divide that by the speed of light which is about 1AU/8 minutes and we get about 2011 minutes which is about 33.5 hours. Of course we would need one heck of a black hole to pull light into an orbit at that distance…

    Shockingly slow isn’t it.

  • Adam September 24, 2011, 22:24

    SN1987 neutrino timing isn’t inconsistent with tachyonic neutrinos because their energy was much, much higher than the neutrinos observed by OPERA. Tachyons travel slower at higher energies.