Probably not. But maybe! Or in other words: science as usual.
For the three of you reading this who haven’t yet heard about it, the OPERA experiment in Italy recently announced a genuinely surprising result. They create a beam of muon neutrinos at CERN in Geneva, point them under the Alps (through which they zip largely unimpeded, because that’s what neutrinos do), and then detect a few of them in the Gran Sasso underground laboratory 732 kilometers away. The whole thing is timed by stopwatch (or the modern high-tech version thereof, using GPS-synchronized clocks), and you solve for the velocity by dividing distance by time. And the answer they get is: just a teensy bit faster than the speed of light, by about a factor of 10-5. Here’s the technical paper, which already lists 20 links to blogs and news reports.
The things you need to know about this result are:
- It’s enormously interesting if it’s right.
- It’s probably not right.
By the latter point I don’t mean to impugn the abilities or honesty of the experimenters, who are by all accounts top-notch people trying to do something very difficult. It’s just a very difficult experiment, and given that the result is so completely contrary to our expectations, it’s much easier at this point to believe there is a hidden glitch than to take it at face value. All that would instantly change, of course, if it were independently verified by another experiment; at that point the gleeful jumping up and down will justifiably commence.
This isn’t one of those annoying “three-sigma” results that sits at the tantalizing boundary of statistical significance. The OPERA folks are claiming a six-sigma deviation from the speed of light. But that doesn’t mean it’s overwhelmingly likely that the result is real; it just means it’s overwhelmingly unlikely that the result is simply a statistical fluctuation. There is another looming source of possible error: a “systematic effect,” i.e. some unknown miscalibration somewhere in the experiment or analysis pipeline. (If you are measuring something incorrectly, it doesn’t matter that you measure it very carefully.) In particular, the mismatch between the expected and observed timing amounts to tens of nanoseconds; but any individual “event” takes the form of a pulse that is spread out over thousands of nanoseconds. Extracting the signal is a matter of using statistics over many such events — a tricky business.
The experimenters and their colleagues at other experiments know this perfectly well, of course. As Adrian Cho reports in Science, OPERA’s spokesperson Antonio Ereditato is quick to deny that they have overturned Einstein. “I would never say that… We are forced to say something. We could not sweep it under the carpet because that would be dishonest.” Now there’s a careful and honest scientist for you, I wish we were all so precise and candid. Cho also quotes Chang Kee Jung, a physicist not on the experiment, as saying, “I wouldn’t bet my wife and kids [that the result will go away] because they’d get mad. But I’d bet my house.” A careful and honest husband and father.
Scientists do difficult experiments all the time, of course, and yet we believe their results. That’s simply because it’s proper to be extra skeptical when the results fly in the face of our expectations: extraordinary claims require extraordinary evidence, as someone once paraphrased Bayes’s Theorem. When the supernova results in 1998 suggested that the universe is accelerating, most cosmologists hopped on board fairly quickly, both because we had a simple theoretical model in hand (the cosmological constant) and because the result helped explain several other nagging observational problems (such as the age of the universe). Here that’s not quite true, although we should at least mention that Fermilab’s MINOS experiment also saw evidence for faster-than-light neutrinos, albeit at a woefully insignificant level. More relevant is the fact that we have completely independent indications that neutrinos do travel at the speed of light, from Supernova 1987A. If the OPERA results are naively taken at face value, the SN 87A should have arrived a couple of years before we saw the explosion using good old-fashioned photons. But perhaps we should resist being naive; the SN 87A events were electron neutrinos, not muon neutrinos, and they were at substantially lower energies. If neutrinos do violate the light barrier, it’s completely consistent to imagine that they do so in an energy-dependent way, so the comparison is subtle.
Which brings up a crucial point: if this result is true (which is always a possibility), it is much more surprising than the acceleration of the universe, but it’s not as if we don’t already have ways to explain it. The most straightforward idea is to violate Lorentz invariance, a strategy of which I’m quite personally fond (although I’ve never applied the idea to neutrino physics). Lorentz invariance says that everyone measures the speed of light to be the same; if you violate it, it’s easy enough to imagine that someone (like, say, a neutrino) measures something different. Once you buy into that idea, neutrinos are an interesting place to apply the idea, since our constraints on their properties are relatively weak. It’s an interesting enough topic that there are review articles, and even a Wikipedia page on the idea.
And there are more way-out possibilities. Graininess in spacetime from quantum gravity might affect the propagation of nearly-massless particles; extra dimensions might provide a shortcut through space. This experimental result will probably give a boost to theorists thinking about these kinds of things, as well it should — there’s nothing disreputable about trying to come up with models that fit new data. But it’s still a long shot at this time. I hate to keep saying it over and over in this era of tantalizing-but-not-yet-definitive experimental results, but: stay tuned.
A few of the countless good blog posts on this topic:
- Matt Strassler (two, three)
- Philip Gibbs
- Ben Still
- Aidan Randle-Conde liveblogs the OPERA seminar at CERN
The information I have gathered from my physicist friends is that previous neutrino experiments had measured faster than light results, but were not used because of measurement uncertainties. Also, isn’t it only the tau-neutrino that is registering faster than light results (please let me know if I am mistaken)? If it were some kind of mistake or anomaly, wouldn’t other neutrinos measure faster than light results as well? Something very interesting is happening, and while I am skeptical, I can’t help but be very excited as well. I am holding my breath until the results are back from the Fermi Lab experiments.
One more question, has it been explained yet how a neutrino can go the speed of light or near speed of light considering that it has mass, unlike had been previously thought?
Also, to those physicists who are reacting to these results dismissively, that kind of response is just as damaging to good science as readily accepting the results as proof-positive. Be skeptical, not dismissive.
I am not a physicist and greatly appreciate the informed discussions. This is all very exciting.
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As we know that if a particle moves in a resisting medium , its resistance increases with velocity “v”.but the character of atmospheric resistance is difference .there is no such rule for this case.experiments results give us that 1. a particle moving with velocity less than 800ft/sec.resistance is varies approximately the square of velocity.
2. when the velocity approaches the speed of sound the resistance varies as the cube or higher power of velocity but 3. if the particle moves higher than 1350ft/sec or greater that speed of sound again the resistance varies as the square of velocity . neutrino have tiny mass so it may be act like this when it moves faster than light, may be in the resisting medium it behave like this.
or
may be when the particle moves at the speed of light it converts into into energy and this energy is actually the millions of neutrinos which can able to move faster than light and it is the smallest unit particle.
but i have a question
that is it possible to get the neutrinos with out fission and fusion ?
I wonder if the neutrino beam is changing in some subtle way over the length of the 10 usec spill. For example, maybe the proton/secondaries beam is inducing currents in structure of the target, causing the particles to diverge slightly more, or maybe the graphite is expanding slightly due to heating, reducing the number of interactions.
About your experiment concerning the speed of light:
All constants with units are in fact variables. And so the speed of light varies. Only those functions that originate outside the universe appear in the universe as true constants such as pi are without units, which transcend.
All functions in the universe are products of velocity and time
E^(i*pi) = -1 = -D = Velocity x Time is the big bang
All functions are products of the following equations
Phi + phihat = 1 = D = time + velocity is the template for all quadratic and polynomial forms
Phi x phiat = -1 = -D = time x velocity are single inertial fields or proper systems
Einstein cosmological constant is equivalent 2 and 2 pi is the fine structure constant.
2 represents (v+v)/v, the ratio of scalar and proper velocities, which is also the wave and particle duality.
George James Ducas
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“The most straightforward idea is to violate Lorentz invariance, a strategy of which I’m quite personally fond”
A question about this comment by Sean. I was under the impression that most of the time when physicists discuss the possibility of a violation of Lorentz invariance, they’re not actually suggesting that the most fundamental laws of physics break Lorentz-symmetry, but rather that spontaneous symmetry breaking shortly after the Big Bang might have left some sort of “relic field” present throughout space that would have its own rest frame, and particles would behave differently depending on their velocity relative to the field. That’s what seems to be suggested by this article for example. If it’s just a matter of a physical field with its own preferred frame, and the most basic laws are still Lorentz-invariant, then it seems to me there would always be at least the theoretical possibility of shifting the field’s rest frame (say by raising the energy levels to what they were before spontaneous symmetry breaking and thereby restoring the symmetry, then letting energy decrease so the symmetry gets randomly broken again). And if this is a case, it seems to me that any FTL would still at least theoretically allow for causality violation–Alice could send a message to Bob which was FTL in her frame but backwards in time in Bob’s, then something could shift the rest frame of the field between them, making it possible for Bob to send a reply which was FTL in his frame and backwards in time in Alice’s, such that she would receive the reply before she sent the original message. However completely impractical it might be to do this, it seems like at a theoretical level, as long as the most fundamental laws of physics are Lorentz-symmetric, any FTL should lead to the theoretical possibility of causality violations.
OFF THE SCALE
— James Ph. Kotsybar
The young lady known simply as Bright,
who could travel at speeds fast as light,
said, “While I’m never late,
I’m concerned that my weight
goes to infinite mass, though I’m slight.”
I’m not a physicist. And I don’t even play one on TV. But I do try to keep up with the highlights as a layman. And with the understanding that peer review of this experiment has barely gotten started, and will likely turn up some unexpected systemic error…
If it did turn out to be true, and if the neutrinos were taking a shortcut through one or more extra dimensions, could that mean that gravitons might do the same thing, and propogate slightly faster than light? And could it also mean that the surprising weakness of the gravitational force (compared to other forces), and the notoriously weak interactions of neutrinos with other matter, might be related?
I’m not sure if that makes sense at all. I guess gravitons would be gauge bosons. And it’s really the force carrying gauge boson for gravity that is hypothesized to possibly dissipate into extra dimensions to explain gravity’s apparently weak force. And not any sort of fermion, like the neutrino.
I just happened to notice the similarity between those two “remarkably weaks” in relation to the talk about extra dimensions being a possible explanation for these allegedly FTL neutrinos, and thought, “hmmm…”.
-Steve Bergman
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Einstein did not really get it in the end. http://bit.ly/qsvnNe
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If the scientists are right that neutrinos are faster than light, then contrary to what most experts believe in, neutrinos do not have any mass. And since they do not interact or interact as strongly as photons to the numerous types of particles, antiparticles, matter, dark matter and gravity in a vacuum, they are not slowed down by these entities as in the case of light. Therefore they should be able to move faster than light. The C in Einstein’s equation should be the speed of neutrinos in a vacuum!
Actually, the particle or entitiy that has no mass, no charge and absolutely do not react or interact with anything in this universe should hold the ultimate speed record. Unfortunately, it is by definition impossible to detect.
Alternatively, if neutrinos do have a tiny mass, then the speed of light in an absolute vacuum where there are none of those numerous types of energy, particles, matter, gravity etc. is in fact much higher than the 300,006 km/sec of the speed of the measured neutrinos. In other words, C > 300,006 km/sec and the neutrinos has not exceeded the real unimpeded speed of light. The speed of light that we have been measuring is not the maximum speed that light is capable of if it is not slowed down by the numerous “things” that really exist in a so called vacuum.
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If this results turns out to be real… I was wondering if the differences in speeds between light and muonic neutrinos are because the light weakly interacts with some sort of field that permeates the universe. Will the number resemble in order of magnitude to the one expected from a weak interaction with dark energy?
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Here’s a thought: What if neutrinos are slightly tachyonic only when moving through solid matter, and move at c in vacuum? In that case the speed of neutrinos from supernova 1987a would not be distinguishable from c. Assuming the superluminal departure from light speed for neutrinos is roughly proportional to the amount of matter they traverse, the arrival time of the 1987a neutrinos would be advanced by only a small fraction of a second. For example, if the amount of matter the 1987a neutrinos had to traverse was equivalent to 1000 times the distance in the Gran Sasso experiment, then these neutrinos would have arrived about 6 microseconds earlier than expected. That would have been completely unnoticeable.
Something that might also be relevant: A team, led by Martin Tajmar, at the Austrian Research Center, reported acceleration pulses emanating from a rapidly spun-up, ring-shaped superconductor (2003-2007). These were tens of magnitudes larger than allowed by General Relativity. Perhaps there’s a connection to the strange neutrino results. As a garage tinkerer, I’m actually trying to replicate their experiment at: http://starflight1.freeyellow.com/index.html#dbw
I am an engineer, not a physicist. Speed = distance over time. If the distance is wrong – the speed is incorrect. If we know the correct speed, we can calculate the correct distance???
Puny Brains! Y’all think that by using @ 5-6% of your brain you know anything for sure?
It will be proven that FTL particles do and have existed; whether it’s from this current experiment or others in the future. Another surprise… Duh.
Airplanes won’t not fly ’cause they’re heavier than air… Infinity. What does that mean?
Please, know one thing for sure: you don’t!
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Undoubtably The LHC team will getting a letter of no- no from the
Einstein Family .At c mass becomes infinite and the force required to
becomes infinit fintithe s
foi
Undoubtably The LHC team will getting a no-no letter from the
Einstein Family .At c mass becomes infinite and the force required is the same.
We await peer review .