About the SA Blog Network

Basic Space

Basic Space

Space and astrophysics research made simple
Basic Space Home

Faster-than-light neutrinos show science in action

The views expressed are those of the author and are not necessarily those of Scientific American.

Email   PrintPrint

It may look all serene from this vantage point, but underneath the Gran Sasso mountain is a hive of neutrino-detecting activity. Credit: Wikipedia/w:nl:Gebruiker:Idéfix

Unless you’ve been hiding under a rock for the past 24 hours, you’ve probably heard about the neutrinos that turned up at the Gran Sasso Laboratory in Italy a few nanoseconds earlier than they were supposed to, in a feat that would have required them to travel faster than the speed of light.

The story has been covered by many news outlets already, and, while some headlines may have raised a few eyebrows, most of the coverage has been suitably cautious. Heck, even the Daily Mail has generously thrown a few “ifs” and “mights” into their take on the findings.

The results were first announced, unceremoniously, in a tweet by Reuters Science last night. The tweet linked to a story on that describes how three years worth of measurements show that some neutrinos must have travelled faster than the speed of light.

The neutrinos in question undertook a journey from CERN in Geneva, through the Earth, and finally ended up at the Gran Sasso laboratory deep underneath the mountain of the same name in Italy. The neutrinos were produced by the Super Proton Synchrotron at CERN, along with a lot of other sub-atomic particles. The trick particle physicists use to get a beam of only neutrinos, and the reason the detector for the experiment is located so far away from the source of the beam, is to send the beam of particles off to travel underground for several miles. Neutrinos are the only particles that survive the journey, because they pass through matter completely unscathed whereas the others do not. The now pure neutrino beam takes less than 3 milliseconds to travel the 730km between CERN and Gran Sasso, and the neutrinos are detected by apparatus belonging to the OPERA experiment, consisting of around 150,000 bricks of photographic film interleaved with lead plates.

The neutrinos, says the paper released by the OPERA experiment after the news was first broken, reached the detector 60 nanoseconds before they would have done had they been travelling at the speed of light. The result amounts to a statistical significance of 6-sigma. “Sigma” is shorthand for standard deviation, a statistical tool that can be used to give an estimate of the certainty of a result. Generally, the higher the number of sigma, the more trustworthy the result. A minimum of 5-sigma, equivalent to a one in 1,744,278 chance that the result is a fluke, is normally required to claim a discovery. 6-sigma, equivalent to a one in 506,797,346 chance is even more convincing.

If any other particle physics result had been shown to have a statistical significance of 6-sigma, champagne corks would be popping in laboratories all over the world. But this one is different.

The universal, unwavering, cosmic speed limit — the speed of light — is the most fundamental of constants. Without it, we can wave goodbye to relativity as we know it. Causality — the fundamental relationship between cause and effect — would have to go. As Subir Sakar, head of particle theory at Oxford University put it to the Guardian yesterday: “Cause cannot come after effect and that is absolutely fundamental to our construction of the physical universe. If we do not have causality, we are buggered.”

Aside from being inconsistent with both relativity and causality, the result doesn’t appear consistent with the past behaviour of neutrinos either. I’ve written before about supernova 1987a, whose arrival was heralded by a burst of neutrinos. In this case, the neutrinos, travelling at the speed of light, reached Earth 3 hours before the light did. The light from the supernova was delayed because it had to get through the remnants of the stellar explosion, not because of any sneaky faster-than-light travel on behalf of the neutrinos. Dr Ben Still, a particle physicist working on the T2K neutrino experiment, blogged earlier today about the Opera result and calculated that if the neutrinos from supernova 1987a had exhibited the same odd behaviour as those that are under the spotlight today, they could have arrived 4.14 years before the light did. The neutrinos and light from supernova 1987a are well documented and this does not appear to have been the case.

Of course, there could be some explanation that is able to bring all of the so far seen problems together and solve them in one fell swoop. There could also be mistakes in the paper that have been missed by physicists working for the OPERA experiment. Time will tell.

For what it’s worth, I’d be prepared to put money on Einstein winning this one, but that doesn’t mean that the excitement and interest these results have generated was for nothing. While, arguably, the announcement of the result could have done with a little more careful planning, the OPERA experiment has now got what it needed: lots of pairs of eyes looking over the results, and checking for something everyone else so far might have missed. Looked at in the right way, this episode is the perfect insight into how science really works. Scientists test hypotheses and current theories (yes, even ones as seemingly solid as relativity) and pipe up when they see something out of the ordinary, to allow others in the field to double and triple check their analysis. This is what is happening now.

While scepticism is necessary in situations like this — I’m sure we’re all aware of the famous Carl Sagan quote, “extraordinary claims require extraordinary evidence” — progress is not made by shouting down anything that does not fit within the current status quo. You never know, perhaps this result will be the one that topples relativity. (They probably didn’t, but there’s a chance, however slim, that those neutrinos did travel faster than light — and that’s a very interesting prospect indeed).

In science, when something out of the ordinary appears, the next step is often to repeat the experiment and try to recreate the results. So, if someone could just lend me a particle accelerator, a mountain and a deep underground mine, I’ll get to it…


Now you’ve had my two pence, there’s plenty more speedy neutrino goodness to be had:

My SciAm blogs colleague Caleb Scharf has a post up with lots of links to more coverage on this story. For a great overview of the science I’d particularly recommend Ethan Siegel’s blog post at Starts with a Bang.

At Discover blogs, the Bad Astronomer has his say and Sean Carroll at Cosmic Variance also has his take on the paper.

And finally,Randal Munroe at XKCD was extremely quick of the mark and had a neutrino-themed comic up and ready earlier today.


The OPERA Collaboraton (2011). Measurement of the neutrino velocity with the OPERA detector in the CNGS
beam . arXiv: 1109.4897v1

Kelly Oakes About the Author: Kelly Oakes has a master's in science communication and a physics degree, both from Imperial College London. Now she spends her days writing about science. Follow on Twitter @kahoakes.

The views expressed are those of the author and are not necessarily those of Scientific American.

Previous: An impossible star? More
Basic Space
Next: In praise of the Tevatron

Rights & Permissions

Comments 61 Comments

Add Comment
  1. 1. hollypahl 5:42 am 09/24/2011

    And before looking, perhaps those faster-than-light particles hadn’t existed yet.

    Link to this
  2. 2. Adam_Smith 7:51 am 09/24/2011

    Reportedly, GPS — with much adjusting for various effects and uncertainties — was used to determine the distance from source to detector. I am wondering how they allowed for differences in elevation. What does GPS say about elevation? Any measure of elevation ought not be relative to nominal “sea level”, as that varies by latitude, but relative to the center of the earth, basically defining a precise triangle from center of earth, source and detector. Besides just the geometry, there is a small time dilation effect associated with differing depth within the earth’s gravity well.

    I wish I had the time and expertise to plow through the details myself but, as a dilettante, all I can manage is to put on record my guess where the error might be — along with my very firm, (but not absolute), conviction that there must be an error. There is simply too much well explained by relativity as it stands.

    Link to this
  3. 3. Atomboy 7:54 am 09/24/2011

    Mass differential and interfering mass/energy in the experiment. Just as in the case of 1987a, the light is being slowed by material between the accelerator and the target. Neutrinos, which speed through material seemingly undeterred, aren’t affected. I’d like to see the same experiment performed in a vacuum.

    Link to this
  4. 4. MarkHarrigan 8:15 am 09/24/2011

    Thanks – great summary and it’s a fascinating result and a truly meticulous experiment. Irrespective of the outcomes (my money is still on c being a limit) the scientists involved have acted exactly as they should.

    I gather one issue is that they do not actually measure the departure time of the neutrinos but infer them from detection of the reaction/photon burst from the collision that produces them. Perhaps there is something unanticipated happening there.

    Regardless it is, indeed, an excellent example of science is done.

    If only the climate denialist blogosphere would take heed and stop positing conspiracy theories all the time we might all make some progress.

    Link to this
  5. 5. Torbjörn Larsson, OM 8:36 am 09/24/2011

    Well, I had my say over at your college’s post. It is of course bloody obvious that a non-energy dependent discrepancy (according to the paper) points to a distance or time-of-flight error.

    As Adam_Smith here, I note problems with the GPS. Most glaringly, the mismatch between the GPS system geodetic distance and the travel distance is ~ 22 m for 730 km of Earth curvature. Neutrinos traveling near light speed would then appear to arrive ~ 60 ns early.

    I read their papers, but worryingly doesn’t see the explicit conversion between geodesic and travel distance mentioned. Instead they mention use of a web based GPS system routine, most of which would give geodesic distances I would think. Unlikely goof, but possible.

    Also, they average over particle bunches, so they haven’t measured individual particles (or relativistic information!) yet.

    “We don’t allow FTL neutrinos here”, said the barman. A neutrino walks into a bar.

    [HT Miscience]

    Link to this
  6. 6. grelf 8:59 am 09/24/2011

    Until now it has been assumed that the maximum speed of information propagation (c1) inside subatomic particles is equal to the speed of light in a vacuum (c0) but there has been no means of testing that assumption.
    Photons cannot travel through nuclear particles but neutrinos can, and usually do. So the observed timing may be giving us the first indication of the value of c1. It may be showing that neutrinos move very rapidly across nuclei traversed in rock. We need to know the average proportion of the neutrinos’ paths through the Italian rock that are within nucleons, to see whether this would account for the phenomenon.
    If this is correct our ideas about neutron stars and black holes would need revising but the space-time in which we live remains Einsteinian.

    Link to this
  7. 7. jbairddo 9:56 am 09/24/2011

    “progress is not made by shouting down anything that does not fit within the current status quo.” and yet, try to have an alternative view of climate change than SA’s dogma and see how long it is until it is “shouted down”.

    Link to this
  8. 8. Shoshin 10:14 am 09/24/2011

    You’re spot on. This article outlines how science must be done to be called science. Anything else is unacceptable. I think SCIAM is Bipolar: part of the editorial staff is interested in real science, the other part (anything to do with AGW)only has interest in political dogma.

    Must make for interesting editorial meetings. My money is on the scientists. Scientists keep at it until the burning curiosity is satisfied. The political dogmatics get bored and find a new butterfly to chase.

    Link to this
  9. 9. CezaryPiotrowski 10:49 am 09/24/2011

    What is exactly the speed of neutrinos that exceeds c?

    Link to this
  10. 10. How Science Works in Action | PACTISS – Philosophers and Critical Thinkers in Senior Schools: Resources for Educators 11:37 am 09/24/2011

    [...] Faster-than-light neutrinos show science in action [...]

    Link to this
  11. 11. analyzer 11:51 am 09/24/2011

    A book I wrote “An Investigation into the Origin of Scientific Measurements,Formulas,Equations and Their Absolute Numerical Values”, which I had copyrighted with the Library of Congress on 6/14/99 Registration Number TCX5-036-717
    Chapter 9 of the book is call the Velocity of Light. In simple arithmetics I illustrated that the velocity of light is not a natural law but a human created one, based actually on the human visual senses. This is what the breakdown of the research on the velocity of light showed.

    It than became the standard associated with all electro-magnetic equipment, and also acting like a governor limiting the velocity in the electrical and communication fields.

    If you are interested to know more contact me at: josephschuman@sbcglobal

    Link to this
  12. 12. analyzer 11:55 am 09/24/2011

    A book I wrote “An Investigation into the Origin of Scientific Measurements,Formulas,Equations and Their Absolute Numerical Values”, which I had copyrighted with the Library of Congress on 6/14/99 Registration Number TCX5-036-717
    Chapter 9 of the book is called the Velocity of Light. In simple arithmetics I illustrated that the velocity of light is not a natural law but a human created one, based actually on the human visual senses. This is what the breakdown of the research on the velocity of light showed.

    It than became the standard associated with all electro-magnetic equipment, and also acting like a governor limiting the velocity in the electrical and communication fields.

    If you are interested to know more contact me at:

    Link to this
  13. 13. Leroy 1:29 pm 09/24/2011

    @jbairddo & Shoshin – You show me a 6-sigma study that says CO2 isn’t a greenhouse gas and we’ll take you very seriously.

    Link to this
  14. 14. bartonlp 4:46 pm 09/24/2011

    So what’s new? The starship Enterprise on Star Trek has been going faster than light for over 20 years now. Even Klingons can go it. I guess our 21st century science is just catching up.

    Link to this
  15. 15. knightshold 5:24 pm 09/24/2011

    If neutrinos travel in a space of more than 3 dimensions, it is easy to appear to be traveling faster than the speed of light if light is constrained to travel in 3 dimensions. Take the case of a two dimensional world lie a sheet of paper. If that paper was rolled in the third dimension, no 2d dwellers would know it. The distance between two points could be far shorter in 3 dimensions than it is in 2 dimensions. Perhaps neutrinos never condensed down to 3 dimensions after the superexpansion near the beginning of the universe. Likewise, this reminds us how the universe could expand faster than the speed of light during the superexpansion.

    Link to this
  16. 16. HowardB 6:11 pm 09/24/2011

    “The story has been covered by many news outlets already, and, while some headlines may have raised a few eyebrows, most of the coverage has been suitably cautious. ”

    I beg to differ – it has been completely OTT and out of control.

    It’s like deja vous with cold fusion and arsenic bacteria … how long before the expose.

    Link to this
  17. 17. Relatively funny « the.soft.anonymous 6:31 pm 09/24/2011

    [...] been a lot of talk on the blogosphere about this discovery, its potential implications for Einstein’s [...]

    Link to this
  18. 18. Steve Wise 6:46 pm 09/24/2011

    So the neutrinos are found to be barreling along faster than light travels in a vacuum. Is that a reason to abandon Einstein? We already know that light slows down drastically when it is passing through solid matter. So isn’t it more likely that this result simply reveals that the speed of light in a vacuum is not the fundamental constant that Einstein postulated, but rather a lower speed at which light propagates when it is impeded only by the local density of dark matter? It may well be that neutrinos are also retarded by dark matter, but not quite as much.

    Link to this
  19. 19. wizgeezer 8:55 pm 09/24/2011

    I’m missing something here – will someone kindly elucidate.

    “The OPERA experiment, consisting of around 150,000 bricks of photographic film interleaved with lead plates” describes a very crude but serviceable neutrino detector. How does this detector time stamp events with NANOSECOND resolution?

    Link to this
  20. 20. Speaker to Wolves 9:47 pm 09/24/2011

    You ask: “How does this detector time stamp events with NANOSECOND resolution?”

    From the paper: “Each section is a succession of walls filled with emulsion film/lead units interleaved with pairs of 6.7 × 6.7 m2 planes of 256 horizontal and vertical scintillator strips composing the Target Tracker (TT). The TT allows the location of neutrino interactions in the target. This detector is also used to measure the arrival time of neutrinos. The scintillating strips are read out on both sides through WLS Kuraray Y11 fibres coupled to 64-channel Hamamatsu H7546 photomultipliers [8].”

    So timestamped events are coming from the “Time Tracker” scintillator-strip detector grids, not the emulsion film layers.

    The two detector systems complement each other. The layers of emulsion film provide precise position data for the event tracks, but they have no time resolution capability. The scintillator strips provide precise time data, but have a much poorer spatial resolution than the emulsion-film layers.

    Recall the the primary purpose of this experiment was to observe conversions of muon neutrinos to tau neutrinos as they passed through the intervening ~732 km of rock, which requires precise measurement of particle tracks through the detector to distinguish between the muons and taus produced when a neutrino interacts with one of the lead bricks. The time-of-flight measurement was just a “piggyback” side-analysis.

    Link to this
  21. 21. Kannin 1:15 am 09/25/2011

    According to Einstein, a particle that has mass becomes heavier the faster it goes. As it approaches the speed of light, that additional mass means it takes more energy to accelerate it to even higher speed. At the speed of light the particle would have infinite mass and therefore it would have taken an infinite amount energy to get it there. That is why a particle that has mass can’t be accelerated to the speed of light. And it is also why the speed of light is considered a “speed limit.”
    But what about a particle that doesn’t have mass, like a photon? If you solve the equations for a zero-mass particle, you find that it must travel at the speed of light.
    So the speed at which a particle can travel is very much dependent on its mass. In electronics and other areas, many quantities must be expressed as complex numbers. Those are just numbers that have a component that is a multiple of the square root of minus one. If you were to solve the relativity equations for a particle traveling at twice the speed of light, you would find that its mass at that speed is equal to its rest mass times the square root of -3. A bit odd, perhaps, but not impossible.
    Thus, finding a particle traveling faster than light is not a violation of Relativity, it just has some interesting implications for the mass of that particle.

    Link to this
  22. 22. DavidLJ 4:00 am 09/25/2011

    I’m waiting for them to find the yard long piece of pipe that got logged in at a meter some place on the drawings.



    Link to this
  23. 23. jtdwyer 5:50 am 09/25/2011

    And I agree with Torbjörn Larsson, OM, Adam_Smith and others elsewhere that the GPS distance estimation, and especially its use in estimating the reference time of flight for light, is an extremely likely source of error, especially if a radial distance along along the surface of an idealized reference ellipsoid returned by standard software was used as Torbjörn suggests.

    Whatever method was used to determine the reference time of flight at c, that is meaningless unless the actual flight path of detected neutrinos can be definitively determined – however, it cannot. It almost certainly was not a radial distance, but it also might not have been even an ideal linear path, and might possibly have produced some relativistic contraction of spacetime owing to its velocity and mass.

    Moreover, neutrinos’ gravitational interaction with Earth’s mass should also have some effect on their flight path through the Earth.

    Whatever the actual flight path taken by detected neutrinos, their propagation would be effected to some extent by the Mikheyev-Smirnov-Wolfenstein effect, which alters neutrinos oscillation between neutrino flavors (each with its own specific assigned mass) – varying their effect mass. That might account for some of any difference between neutrino propagation through interstellar space, depending on particle energies.

    Kannin – While I think the question of flight paths and distance for the reference time of flight for light and the indeterminable actual distance traversed by detected neutrinos likely produced an erroneous neutrino velocity result, the oscillation of neutrinos between their three flavors of differing tiny masses could be considered as your “interesting implications for the mass of that particle”…

    Link to this
  24. 24. jtdwyer 6:34 am 09/25/2011

    Kannin – Perhaps I should better explain my meaning.
    You stated:
    “If you were to solve the relativity equations for a particle traveling at twice the speed of light, you would find that its mass at that speed is equal to its rest mass times the square root of -3. A bit odd, perhaps, but not impossible.
    Thus, finding a particle traveling faster than light is not a violation of Relativity, it just has some interesting implications for the mass of that particle.”

    I have no idea, but must wonder: what is a nutrino’s mass as it oscillates from a <0.17 MeV muon neutrino to a <2.2 eV electron neutrino – perhaps it also must accelerate?

    Link to this
  25. 25. Adam_Smith 9:09 am 09/25/2011

    “When an experiment finds an apparently unbelievable result and can find no artifact of the measurement to account for it, it’s normal procedure to invite broader scrutiny, and this is exactly what the OPERA collaboration is doing, it’s good scientific practice,” said CERN Research Director Sergio Bertolucci.

    There must have been similar reactions to the “apparently unbelievable” Michelson-Morley experimental result, (although at that time there was a theoretical prediction of a sort in that the speed of light entered Maxwell’s equations as a constant). I wonder if I had lived then, back in 1879, if I would have been among the skeptics of Michelson-Morley. Relying upon the demonstrated success of the physics of Newton and Galileo, I probably would have been. I would have been guessing wrong about the eventual conclusion but, at least, I would have been consistent with “good scientific practice”.

    Link to this
  26. 26. jtdwyer 11:43 am 09/25/2011

    I am compelled to comment on another, somewhat similar discovery that what not approached with such open self appraisal.

    If in fact the FTL status of neutrinos was derived from their time of flight traversing a rather linear distance in comparison to a reference calculation of light’s time of flight over a longer, more curved distance as Torbjörn Larsson, OM has suggested, the OPERA collaboration will have done a great service to science by not convincing science (and the public) of a conclusion based on a misconception.

    I must say that the establishment of galactic dark matter some 30-40 years ago was based on a similar referential discrepancy – that galactic rotation was not consistent with the Keplerian rotational curves illustrating the laws of planetary motion. Those ‘laws’ were empirically established by observation of the special conditions of the Solar system (where 99.86% of total mass is contained within the Sun), to infer the existence of galactic dark matter.

    For many decades no one has questioned that the laws of planetary motion might simply not apply to spiral galaxies, even though Newton had centuries ago proved that Kepler’s laws applied only to the Solar system’s special conditions of mass distribution.

    The OPERA collaboration’s approach may save science decades of wasted effort.

    Link to this
  27. 27. Kannin 12:58 pm 09/25/2011

    jtdwyer – I think you are on to something! You stated “I have no idea, but must wonder: what is a nutrino’s mass as it oscillates from a <0.17 MeV muon neutrino to a <2.2 eV electron neutrino – perhaps it also must accelerate?" Your idea may be mathematically testable: If we express the mass of the particle as a complex number, and make the assumption that it represents a closed system during its time-of-flight; then its total mass-energy should not change. We can see if the "missing mass" corresponds to the measured discrepancy in its speed. Let me think about this for a bit…

    Link to this
  28. 28. Luis Gonzalez-Mestres 1:19 pm 09/25/2011

    This is a very strong effect, but it may be compatible with a very week mixing between neutrinos and superbradyons. Superbradyons are particles with positive mass and energy, and a critical speed in vacuum much larger than the speed of light, that I introduced in 1995 : . The basic idea is that the light would just be the critical speed of the excitations of a phase of matter (the vacuum of our universe), just as the sound speed is the critical speed of phonons in condensed matter. Then, more fundamental particles may have a much larger critical speed.

    For a recent review, see : . This 2010 paper, updated last week, also discusses a possible spinorial description of space-time that I suggested in 1997 : . In this geometry, the cosmic time is the modulus of the cosmic spinorial position. Then, space translations are SU(2) tranformations and form therefore a compact group easier to mix with the so-called “internal symmetries”. The anomaly of the neutrino speed can then be assimilated to a symmetry breaking within this description.

    Best regards
    Luis Gonzalez-Mestres
    CNRS, France

    Link to this
  29. 29. Luis Gonzalez-Mestres 1:34 pm 09/25/2011

    Sorry, please read “a very weak mixing” and “the speed of light would just…”.

    Superbradyons are also possible dark matter candidates, see for instance : . They may be the ultimate constituents of standard matter, but also be present in our Universe as free particles just as light can cross transparent media. Contrary to tachyons, they would strongly violate Lorentz symmetry. In our Universe, superbradyons would spontaneously decay by emitting standard particles until they are slowed to a speed close to the speed of light. They can then form a cosmological sea. See also : and, about the mixing between superbradyons and standard matter :

    The reason to consider superbradyons is, in particular, that any standard extrapolation of Lorentz symmetry violation from Planck scale fails by orders of magnitude to reproduce the effect claimed by OPERA (and previously by MINOS but with much less precision).

    Best regards
    Luis Gonzalez-Mestres

    Link to this
  30. 30. jtdwyer 2:46 pm 09/25/2011

    Kannin – That’d be great! However, you’ll have to do all the math.

    That does makes sense to me: that the mass-energy should not change, especially since it will (as I understand) oscillate back to a muon neutrino, etc.

    As I understand, though, there is some thought that neutrinos might combine in some way, but then they rarely interact with each other or any other matter. Certainly the oscillation of mass might be related to velocity. Please let me know if I can be of help in some non-mathematical way!

    Link to this
  31. 31. Kannin 3:29 pm 09/25/2011

    jtdwyer – OK, I’ve been doing some research. Let me synopsize for you:
    1. Our (your) hypothesis that the neutrino may oscillate through a form that has a rest mass in the form m = iz (where i^2 = −1)may be original and plausible. (It is the oscillation part that may be original – the idea that a particle with imaginary rest mass *must* be superluminal, is not.)
    2. A clever mathematical manipulation to Einstein’s energy-momentum relation has already been done that avoids any necessity for imaginary masses, sidestepping the problem of interpreting exactly what a complex-valued mass may physically mean.
    3.In 1985 it was proposed by Chodos et al. that neutrinos can have a tachyonic nature. In this framework, neutrinos experience Lorentz-violating oscillations and can travel faster than light at high energies. On the other hand, that proposal was strongly criticized by some researchers. I suspect that Chodos beat us to it and that it is his theory that needs to be dusted off.
    4. My proposed derivation won’t work. We end up with one more unknown than we have equations for. That is, if we specify the fraction of time that the neutrino spends in its tachyonic state, we can calculate its velocity, and vice-versa. We just can’t calculate both simultaneously. Sorry :-(

    Link to this
  32. 32. Kelly Oakes in reply to Kelly Oakes 4:50 pm 09/25/2011

    @ Luis Gonzalez-Mestres

    Your comments got stuck in moderation because of the links — please accept my apologies for the delay in posting!

    Link to this
  33. 33. Shoshin 4:50 pm 09/25/2011


    Your comment is a perfect example of the non-discriminatory scientifically illiterate mind at work. No one says that CO2 is not able to trap heat; the debate is whether the amount is significant or not.

    Your appeal to authority is also unscientific.

    So, in summary, in one sentence, you provided two examples of how science should not be done.

    Link to this
  34. 34. Kelly Oakes in reply to Kelly Oakes 4:59 pm 09/25/2011


    The amount of coverage may be over the top, but what is written in the articles and blog posts is quite measured — no one (that I’ve seen) is actually claiming that Einstein has been proved wrong, just that this phenomenon (the FTL neutrinos) may have been seen.

    The difference between this and arsenic bacteria is that the scientists from OPERA are not really claiming anything, just opening up the floor to comments. They say this at the end of the paper:

    Despite the large significance of the measurement reported here and the stability of the analysis, the potentially great impact of the result motivates the continuation of our studies in order to investigate possible still unknown systematic effects that could explain the observed anomaly. We deliberately do not attempt any theoretical or phenomenological interpretation of the results.

    Link to this
  35. 35. Kelly Oakes in reply to Kelly Oakes 5:08 pm 09/25/2011

    @jbairddo & Shoshin:

    I have to say, I’m impressed that you’ve managed to bring an article on particle physics round to climate change. Next time though, shall we try to stay on topic?

    Link to this
  36. 36. jtdwyer 7:31 pm 09/25/2011

    Kannin – Thanks very much for investigating. I did find what might be a further development of Chodos’ proposal (below), but it’s likely going nowhere also. You might find it interesting – I can’t assess. In my simplistic reasoning their seems to be a fundamental question that remains: where does the mass go (and come from) in neutrino oscillations? It seems certain to me that neutrinos do not propagate like photons. BTW – I have no theory here – just an idle thought. Please feel free to continue any related investigation on your own – I appreciate your consideration!

    Teoretycznej et al., (1995), “Are neutrinos spinorial tachyons?”,
    “A particular case of the helicity… is investigated in detail and a corresponding consistent field theory is proposed. In particular, it is shown that the Dirac-like equation proposed by Chodos et al., inconsistent in the standard formulation of QFT, can be consistently quantized in the presented framework. This allows us to treat more seriously possibility that neutrinos can be fermionic tachyons as it is suggested by the present experimental data about neutrino masses.”

    Link to this
  37. 37. Shoshin 7:45 pm 09/25/2011

    The article also expounded on “how science should be done”. In this vein, this article and the comments the follow serve as an excellent example of the discussion, and methodology of science. My only wish is that this type of discussion and level of understanding of science would filter into the man made global warming debate.

    Link to this
  38. 38. Paul Duffy 8:51 pm 09/25/2011

    Could soild matter speed the travel of nurtinoes? Could nurtinoes be hitching a ride in solid matter? If so, this could explain their arrival 3 hours faster than light in 1987. (Is it more likely that the light and nurtinoes were created at the same time?) The nurtinoes arrived earlier because they were accelerated through matter? The nurtinoes from CERN traveled through rock.

    Link to this
  39. 39. Skyview1 11:25 pm 09/25/2011

    Paul Duffy’s idea that neutrinos speed up slightly in solid matter might not be so far fetched. If they were similarly speeded up by passing through the dense shell of matter surrounding Supernovae 1987a, it would only subtract 60 micro-seconds from their flight time to Earth, assuming they traversed about 1000 times as much matter as the Grand Sasso neutrinos. That would be virtually unnoticable.

    Am experimenting with superconductors to look for previously reported acceleration signals, when the superconductor is bodily accelerated, or zapped with high voltage. Assuming there’s any validity to these reports, it could be connected to the strange neutrino results at Grand Sasso. Experiment URL:

    Link to this
  40. 40. jtdwyer 12:26 am 09/26/2011

    Paul Duffy – As the article explains, “The light from the supernova [1987a] was delayed because it had to get through the remnants of the stellar explosion, not because of any sneaky faster-than-light travel on behalf of the neutrinos.” Light can be obstructed by matter; neutrinos effectively pass through matter unobstructed. It’s thought that visible light and neutrinos were simultaneously emitted when the supernova first occurred. The effects produced by neutrinos propagating through matter (which have not been explicitly shown to include velocity) seem to be related to the density of the matter traversed (more below). I guess that they would not be significantly affected passing through disperse supernova remnants.

    Many of the characteristics of neutrinos seem to be still undetermined, but then much that seems to have been determined is beyond my comprehension. As I understand, evidence indicates that neutrinos oscillate between their three flavors at rates that vary in certain conditions. Each flavor is considered to have differing but tiny amounts of mass. Particle propagation velocity is inversely related to its mass. A MSW effect (see below), also known as the ‘matter effect’, can modify the oscillation characteristics of neutrinos in matter.
    I have found some seemingly related discussions in wikipedia.
    “On 31 May 2010, the INFN and CERN announced[2] having observed a tau particle in a muon neutrino beam in the OPERA detector located at Gran Sasso, 730 km away from the neutrino source in Geneva.”
    “Eigenstates with different masses propagate at different speeds. The heavier ones lag behind while the lighter ones pull ahead. Since the mass eigenstates are combinations of flavor eigenstates, this difference in speed causes interference between the corresponding flavor components of each mass eigenstate. Constructive interference causes it to be possible to observe a neutrino created with a given flavor to change its flavor during its propagation.”
    “The presence of electrons in matter changes the energy levels of the propagation eigenstates of neutrinos due to charged current coherent forward scattering of the electron neutrinos (i.e., weak interactions). The coherent forward scattering is analogous to the electromagnetic process leading to the refractive index of light in a medium. This means that neutrinos in matter have a different effective mass than neutrinos in vacuum, and since neutrino oscillations depend upon the squared mass difference of the neutrinos, neutrino oscillations may be different in matter than they are in vacuum.”
    “The MSW effect can also modify neutrino oscillations in the Earth, and future search for new oscillations and/or leptonic CP violation may make use of this property.”
    I hope this helps…

    Link to this
  41. 41. jtdwyer 9:13 am 09/26/2011

    To reiterate and summarize previous comments:

    The reference speed of light Time of Flight (TOF) estimation may have used standard GPS routines to calculate (curved) surface distance.

    Whatever distance was used for the speed of light TOF reference, the actual distance traversed by detected neutrinos cannot be definitively determined. These distances are a likely source of significant error.

    If, as it seems most likely, detected neutrinos traversed a much shorter, nearly linear, flight path than was presumed by the reference speed of light TOF estimate the resulting distance discrepancy may fully account for the apparent FTL neutrino velocity.

    Distance assumptions should be carefully reexamined for potential errors!

    Link to this
  42. 42. Remmert 10:01 am 09/26/2011

    My first thought was if neutrinos could tunnel through a nucleus or experience their travel through the earth as traveling through a medium with a negative index of refraction then they will certainly arrive before light photons.
    A solution to the 60 nanoseconds problem is that neutrinos speed up slightly in solid matter. That can be checked. At least if the time of arrival/detection of a neutrino from the sun is registered with some precision. If the sun sets at the location of the neutrino detector the neutrinos will start to arrive at a slightly faster pace. More will be detected. At sunrise the reverse comes true. So if anyone who has such numbers at his of her disposal this explanation of the 60 nanoseconds problem can be decided upon.
    The number of detected neutrinos from the sun is low. So some corrections will be necessary. At least a correction is necessary for the distance between the neutrino detector and the sun.
    If more neutrinos could be detected this could be used as a means for a rough t0ol for the analysis of the distribution of mass in the earth and the moon.

    Link to this
  43. 43. pbudnik 11:57 am 09/26/2011

    Einstein’s doubt about relativity

    First I want to observe that faster than light travel violates causality only if you assume relativity. Experimental observations that are consistent with relativity are also consistent with the assumption that any inertial frame is the fixed frame of reference and causality is relative to that frame. Faster than light travel is possible within that frame without violating causality.

    The faster than light observations must be decisively confirmed before they are accepted, but it is worth speculating that this is the first glimpse of what Einstein came to suspect may ultimately replace relativity. “I consider it quite possible that physics cannot be based on the field concept, i. e., on continuous structures. In that case nothing remains of my entire castle in the air gravitation theory included, [and of] the rest of modern physics.” — Albert Einstein from Subtle is the Lord p, 467, Abraham Pais.

    I recently published a paper
    ( ) that shows that any fully discretized theory on a topologically regular grid that approximates the wave equation must introduce nonlinearities and must allow some physical effects to propagate faster, perhaps much faster, than the velocity of wave propagation. This opens the possibility that fundamental particles are stable dynamic structures that ordinarily approximate the wave equation to extremely high accuracy but also undergo state transformations that are superluminal and nonlinear. The paper suggests that tests of Bell’s inequality should look for any space time structure to quantum collapse and not focus only on the speed of light.

    Link to this
  44. 44. Kannin 3:54 pm 09/26/2011

    Imagine a near-planar wavefront from a gamma ray burst striking, at a shallow angle, a cold shell of gas from an old supernova. A distant observer would see a pulse of heating sweep through the gas at far greater than the speed of light. There is no violation of causality, though, because no information can be encoded on that superluminal pulse.

    By the same token, a tachyonic neutrino would be regressing to an earlier state, and therefore losing more current information, in direct proportion to its speed above c. So, again, no violation of causality.


    Link to this
  45. 45. Paul Duffy 1:52 am 09/27/2011

    Re ‘Paul Duffy’s idea that neutrinos speed up slightly in solid matter might not be so far fetched’. Yeah – I’m very aware that without some repeat of a faster than light result for neutrinos there is nothing to really talk about. But if the result is verified then we will probably need to look to something ‘far fetched’ for an explanation. (‘Solid’ matter seems to be something that will normally slow things down but if something can pass through it then the result may be different? And of course what could the mechanism be?)

    Link to this
  46. 46. silentcartog 2:17 am 09/27/2011

    Seems a bit premature to be jumping to conclusions. Can this not somehow be explained by warping of space, or relative motions of bodies?

    Link to this
  47. 47. Dileep Sathe 10:35 am 09/27/2011

    It is necessary to wait for details from physicists from CERN, Fermilab etc. But, on the basis of B.Sc. Physics knowledge (which may be considered as the level of a common reader), one “can” expect neutrinos to move with velocity greater than that of light. This is because neutrinos are mass-less and can not face the barrier of relativistic mass increase – set by Albert Einstein.

    Link to this
  48. 48. jtdwyer 4:11 pm 09/27/2011

    Kannin – I vaguely recall reading a research report about a year ago that described emission beams produced by superluminal flows of electrical charge state changes (not flows of electrons). If I understand, I suspect that cloud energy could increase at superluminal rates. as long as no matter was required to move FTL…

    Link to this
  49. 49. jtdwyer 4:23 pm 09/27/2011

    Dileep Sathe – I understand that the standard model of particle physics specifies that neutrinos are massless, but that there is a great deal of experimental and observational evidence that neutrinos have very tiny but non-zero mass. They also come in three flavors, each with a specific rest mass.

    They have also been observed to oscillate between flavors as the they propagate, somehow gaining and losing mass!??! Please see comment #40 above.

    Link to this
  50. 50. Kannin 10:22 pm 09/27/2011

    jtdwyer – Re gaining and losing mass – As it was once said, “I don’t know the answer, but I admire the question.”

    I do have a bit of insight, though, re the non-zero mass of the neutrino: If it is massless, it travels at the speed of light. If it travels at the speed of light, Time dilation is infinite, and no time at all passes for it during its transit. It would, therefore, have no time to change flavor. It does change flavor, therefore, it has mass.

    Link to this
  51. 51. Pranab1 2:48 am 09/28/2011

    Faster then Light particles Tachyons – are these missing neutrinos? OPERA neutrino experiment in 2011at underground Of Gran Sasso Laboratory, measured velocity of neutrinos from CERN protons generated neutrinos beam over a baseline of about 730 km with approximate 16000 neutrino interaction events detected by OPERA at higher accuracy than previous studies conducted with accelerator neutrinos, though the distance was too short. To perform first detection of neutrinos oscillations in direct appearance mode in the vu-v channel. G. R. Kalbfleisch in 1979,[ Phys. Rev. Lett. 43, 1361 (1979); showed the muon neutrino speed |v-c|/c < 4×10-5, at ~30 Gev at high energy, when MINOS experiment reported (v-c)/c = 5.1 ± 2.9×10-5,however at lower neutrinos energy 10 Mev . OPERA experiment was done with only Muon neutrinos generated from hadron. [400 GeV/c with the CERN Super Proton Synchrotron (SPS). was the CNGS beam used here was the purest vu beam with at energy of 17 GeV, optimized for v-v for neutrinos oscillation study. What was about the anti neutrinos contaminations in those tube?. what was the exact place and exact time that the neutrinos were produced if from mesons in figure -5 of OPERA? How much uncertainty remains with neutrinos δt and while commuting δt for photons ? The relative difference of the muon neutrino velocity with respect to the speed of light in OPERA :( v-c)/c = t /(TOF’c - t) = (2.48 ± 0.28 (stat.) ± 0.30 (sys.)) ×10-5, The results of the study indicate for CNGS muon neutrinos with an average energy of 17GeV an early neutrino arrival time with respect to the one computed by assuming the speed of light in vacuum :t = (60.7 ± 6.9 (stat.) ± 7.4 (sys.)) ns

    Question remain whether there is any particle moves faster then speed of photon particles? We authors consider it is possible through another particle called “Tachyons Particles”, detected in 1974 by Roger Clay and Ohilip crouch of Adelaide University in Australia. What were Tachyon particles? Of course, the Super string theories that evolved from spinning string theories, which incorporated supper symmetry and had no Tachyonic ground states. Tachyons are still mathematical quirk of mathematicians with no physical meaning. Can these tachyons be the missing Neutrinos particles with real zero mass? However Einstein’s equation E=mc2 says “that nothing in this observable universe, can cross the speed of photon [light particles]”. But tachyons have probably that curious property of going faster then speed of light, as the particle mast loose energy, unlike other ordinary particles. It is still probably unknown, whether within relativity theory (E=mc2] solutions of Einstein, permit also two families of particles to exist -1) which always have a speed less than light and 2) other which always have speed greater than the light. If it permits the second one, then the later particle must be tachyons or a kind of neutrinos whom we do not know yet or called “missing neutrinos with zero mass”. Physicists till date do not understand how neutrinos behave when they travel an astronomical distances. The neutrinos behave differently than physicists had assumed so far. If tachyons really exist then many of our normal physical laws, laws of this universe are to be reversed.
    The standard description of two families of particles allowed by Einstein equations follows from the requirement that the total energy of a particle is given by a formula —— M0C2(1-(v/c)2)1/2. The key point being that taking the square root (half Power) introduces two families of solutions. For zero velocity, of course the expression reduces to mc2. Square root of negative numbers although allows mathematically , do not have physical significance and obvious interpretations of this expression to give real total energies is the term (1-(v/c)2, must therefore be positive or at least zero, so that “v” is always less than or equal to “c” and particles can never travel faster than light. But there may be other ways to think also. Possibility with, imaginary mass (where I is the square root of -1). In that case the situation will be reversed and in order to obtain a real energy, we must take another square root of a negative number in order that the imaginary . “I”s multiply out to-1. In other words for imaginary masses, “v” must exceed here “c”, so that (i-v/c)2) is always negative. This is the origin of Tachyon
    But suppose, we allow “v” to exceed “c” while maintain the real mass “m”. Now we are taken into very strong realms-the imaginary part of space time. Might we consider a tachyon particle with imaginary zero mass moving through the real part of space time at a speed greater than that of light. Tachyons can then provide the link between past and future and possible time travel.

    Link to this
  52. 52. dantevialetto 4:03 pm 09/29/2011

    I am sure that the calculations were very well made, but since I am not a scientist I ask a stupid question: Is it not possible the curvature of the earth is longer than the straight right path of neutrinos, and this made the apparent difference of speed?

    Link to this
  53. 53. murli 6:39 am 09/30/2011

    OPERA experiment’s finding has evoked exotic thoughts from several that arrow of time would reverse, rules of science would need to be rewritten and so on. I do not think that any of such things is likely to happen. I believe that Special Relativity theory and cosmic speed limit proposed by Einstein revolve around spin 1 particle – photon. I am not sure whether Einstein had evaluated what would happen if spin 1/2 particle has nearly zero mass and travel at speed nearly to that of light. My own hypothesis is that spin 1/2 and 1 particles with nearly zero mass like electron neutrino and photon respectively would not travel exactly in the manner and speed. There is bound to a difference and this is where OPERA experiment, if experimentally proven by other persons or organizations might provide a clue.

    Therefore, we need to focus on establishing whether there is a case to set different cosmic speed limits for spin 1/2 and 1 particles going forward!

    Murli Lohia

    Link to this
  54. 54. Skyview1 10:39 am 09/30/2011

    Not sure this is relevant to the issue at hand, but years ago I had a simple idea to explain the existence of the two higher generations/flavors of neutrinos – muon neutrino, tau neutrino. I wrote a long detailed paper on it, and submitted it to Scientific American. But it was not accepted.

    The gist of the idea is that if you consider that the electron neutrino carrys a fundamental quantum of ‘weak’ charge, just as the electron carries a fundamental quantum of electric charge, then perhaps there could exist weak-magnetic pole charges, just as Dirac proposed the existence of magnetic monopoles to complement electrically charged particles. Thus the existence of two, and only two flavors, of higher generation neutrinos would be explained by a north weak-magnetic pole charge and a south weak-magnetic pole charge, one being the muon neutrino, the other the tau-neutrino. The second and third generations of charged leptons and quarks, would then represent bound states of the electron, and up and down quarks with one of these weak-magnetic pole charges.

    But the idea implicitly required flavor conservation, so when overwhelming evidence for neutrino oscillations arrived, this idea went the way of the Dodo bird.

    Link to this
  55. 55. frank atkinson 3:13 pm 10/2/2011

    Atkinson’s submission.

    I am pleased to be able to report that the CERN – Gran Sasso finding that things (in this case, neutrinos) ] can go faster than ‘c’, confirms the prediction made in the Tempo field theory. That theory shows the requirement in special relativity that the speed of light is a universal constant at 299,792.458 kilometers a second is flawed. It was originally thought that the universal constant was necessary for several reasons but these have proved to be spurious over the years. However, the most important reason was that it was considered to be the only way that clear images could be received at the eye. In other words, to avoid light being all jumbled up at our eyes and to enable us to see clearly, it was assumed to be an essential prerequisite for all rays of light to have the same universal speed. However, this assumption is wrong, the Tempo field theory suggests a much simpler way. This demonstrates that all that is required is for each observer to see all rays of light with a closing speed relative to their individual time dilations. They each have their own constant for the speed of light relative to their time dilation which ensures they receive clear images. The Tempo field theory allows the speed of light to increase as the time of the observer dilates but it does not admit of anything going faster than this increased speed. It is not possible to outrun light but it is possible to go faster than 299,792.458 kilometers a second when the speed is measured from dilated time. This of course, preserves the principle of causality and avoids the difficulty of travelling backwards in time, for which I apologise to all science fiction writers.

    In the case in question, the experiment is timed from a point that is below ground level, that is to say, close to the mass of the Earth and therefore in dilated time. Experiments to try to establish the speed of light have in the past, been carried out above ground level, i.e. at a point more remote from the mass of the Earth and consequently in more contracted time. It can be readily envisaged that the neutrinos will be consequently clocked at a faster speed than that previously attributed to light.

    The scientists who have conducted the experiment have asked for other teams to try to confirm their results by carrying out the experiment at other locations but care must be exercised to exactly mimic the degree of time dilation if the same results are to be obtained. The way to demonstrate that the aberration is due to the variation in time dilation, is to have the neutrinos and photons of light timed over a common course when it will be found that they both travel at the same speed. This has been done in nature by our receiving the neutrinos from distant supernova at approximately the same time as its photons of light.

    The principle that the speed of light varies in proportion to the time dilation of the observer can be proved with the following thought experiment. If we consider a tall skyscraper, it is well established physics that time goes more slowly at the bottom, near to the mass of the Earth than at the top. Using this knowledge, let us carry out a light experiment by placing atomic clocks alongside mirrors at the top and bottom of the skyscraper so that a pulse of light can be bounced from top to bottom of the skyscraper between the mirrors. If this is done a given number of times, the distance travelled by the light is exactly known. The travel time of the pulse of light can then be accurately timed by the atomic clocks. It is now inevitable that as the two clocks are running at different rates they will measure different values for the travel time of the light. This yields the result that the speed of light is faster at the bottom of the skyscraper in dilated time, than at the top in faster contracted time. This is exactly the result that the scientists at Cern and Gran Sasso have accidentally come across. The Tempo field theory can be found on its open access website, where it gives a paradigm for quantum gravity.

    Frank Atkinson

    Link to this
  56. 56. rgclark 8:53 am 10/4/2011

    It should be noted that superluminal speeds need not entail causality violations, that is back in time signaling. What it would require is a preferred frame.
    See here:

    Newsgroups: sci.physics.relativity, sci.physics, sci.astro, sci.math
    From: Robert Clark
    Date: Sun, 2 Oct 2011 06:27:24 -0700 (PDT)
    Subject: On causality and superluminal speeds.

    Bob Clark

    Link to this
  57. 57. billsincl 8:18 pm 10/10/2011

    I am wondering if the photons they compared the neutrinos with were actually travelling at the speed of light.

    If they traveled thru some other medium, not a vacuum, they would be slowed down as a result – For example, the earth’s atmosphere. Were the photons travelling in a straight line? Not if they bounced off the ionosphere.

    So the neutrino arrival time is possibly being compared to something NOT travelling at light speed. That would skew the results.

    Link to this
  58. 58. chokseym 8:16 am 11/5/2011

    Is this something to do with the fact that the eearth rotates, and that ijn effect the source and detector have moved during the course of the experiment?

    Link to this
  59. 59. spazioroby 1:44 am 11/22/2011

    Si tratta di una misura diretta: sorgente – rilevatore su 730 km. Se la nostra galassia si sposta a 1000 km/ qualche direzione potrebbe andare il rilevatore incontro alla sorgente.
    in tal caso nel tempo che un neutrino percorre i suoi 730 km, supposto che abbia la velocità della luce,730/300.000 =24*10^-4 sec la sorgente va verso di esso e compie 1000*24*10^-4= 2,4 km.
    per fare 2,4 km. il neutrino alla velocità della luce
    2,4/300000 =8*10^-5=8000*10^-9sec=8000 nanosecondi
    in tal caso essendo anticipato il suo arrivo di 60 nanosecondi vorrebbe dire che la sua velocità è più bassa della velocità della luce o che la direzione del moto della galassia è un altra.

    Link to this
  60. 60. awkwardmatty 5:25 pm 12/8/2011

    Maybe the time difference is actually down to the fact the Neutrinos traveling through the Earth had only traveled for a short time at that speed and the neutrinos that went through space not only have the distortions of space but we also have no idea of the effects of traveling at the speed of light especially for so long in comparison.Do we even have evidence that Neutrinos all travel at the same speed? The results so far say otherwise.

    Link to this
  61. 61. Thuven 2:50 am 12/28/2011

    The universe is composed of almost 85% of unknown form of matter that has been anonymously called the ‘dark matter’ and scientist do not know what is exactly accelerating the universe. We have known only a scratch of the possible workings in the universe, and to solely depend on Einsteinian law of physics that nothing travels faster than light just based on our knowledge of 5% of the universe is seemingly ‘arrogant’ towards mother nature.Again it all depends on how we define matter, if matter is something that can e visibly seen, than yes probably Einstein theorem holds,but if it includes even ‘matters’ that are not physically conceivable, than it is most prbably a metter of time before this whole theorem falls down.Just like how we have transformed from Biblical Science to Classical Mechanics and now quantum mechanics, there will come a time, when we will need to look at things at totally different perspective to understand greater details..

    Link to this

Add a Comment
You must sign in or register as a member to submit a comment.

More from Scientific American

Email this Article