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
Perhaps, when the particle is small enough for its wave function not to collapse and its velocity is large enough, it tunnels through space; traversing in a higher dimension.
Extraordinary claims don’t require extraordinary evidence. It is the facts of the experiment that require an explanation. The explanation of these facts is that the particles are traveling faster than light. Or that there is an error in this theory. But they are unable to find the error. Subsequent experiments may unearth the error. But if the error is not found then does that mean the FTL theory is correct? NO. It just means an error in the theory hasn’t been found. What is required is not just another experiment (which might unearth an error in the theory) but an elaboration of the theory itself – how their FTL theory works – how it explains the facts. At the moment their theory is so vague as to be completely useless.
The reaction of many physics folks reminds me of the reaction of people in my profession (Aerospace Engineering) in the 1930’s and 40’s. Due to the Prandl-Glaurette compressibility expressions that were denominated in terms of the speed of sound drag appeared to increase asymptotically as v approached mach = 1. Obviously since we have rockets and supersonic vehicles this limitation was theoretical not practical. Clearly we haven’t observed (or known we’d observed) as many violations of this rule but the logic seems to flow.
I certainly hope that the people at CERN did not make the mistake Torbjorn Larsson outlined in comment No.22 – that would be bad, but I do like the calculation, it’s of just the size to set things right. However, let’s assume CERN got it right; let’s assume those muon neutrinos really are moving faster than light. In the spirit of Jimthompson’s comment No.20 I propose the following:
1) The electron-neutrino, like the photon, has zero rest mass. The muon and tau neutrinos have small (non-zero) rest mass.
2) Mass increases with velocity as specified by m = m_o/(1-(v/c)^2)^1/2 but deviates from the Einstein equation at high energy such that as v goes to c mass is a high, but finite, multiple of the rest mass. In other words FTL velocities are possible – given enough energy. (Sorry AL, but you had a good run for 106 years).
Given these assumptions we would expect the following:
1) Electron-neutrinos from Super-Nova 1987A would arrive along with the photons from the explosion – just as was observed – because both the electron-neutrinos and the photons truly have zero rest mass and travel at c upon formation. Oh, and for those of you who insist on neutrino oscillation, the neutrinos (be they electron, muon or tau) produced by SN 1987A only had an energy of 10 MeV – not enough for FTL (see below).
2) CERN’s 17 GeV FTL muon-neutrinos have enough energy (i.e. a high enough multiple of their rest mass) such that their velocity is greater than c (if only by a little).
3) Given enough energy, not just muon-neutrinos, but electrons, protons and everything else with non-zero rest mass can be accelerated to v greater than c.
Indeed, if we knew the rest mass of the muon-neutrino (which, sadly, we do not) we could derive a light-speed transition energy factor that we could apply to all matter. For example, if the muon-neutrino had a rest mass of say 1 KeV and assuming CERN’s 17 GeV transition to FTL, we would have a light-speed transition energy factor of 17 GeV/1 KeV = 1.7×10^7. It would then take 5.11×10^5 eV (1.7×10^7) = 8.7×10^12 eV = 8.7 TeV to accelerate an electron beyond c, and 1.6×10^16 = 16 PeV to accelerate a proton beyond c. These particle energies are beyond our current means, but this would explain why we have not observed FTL effects with these particles – we have not yet pumped enough energy into them.
Before anyone is continuing to speculate over superliminal velocities, I would like to point
out something interesting…
Determination of the CNGS global geodesy
http://operaweb.lngs.infn.it/Opera/publicnotes/note132.pdf
To get the exact point on the surface of earth, we need to know the position
of the GPS satellites for a given time and their distance from us. No problem so far,
GPS is able to provide us with that information.
The authors used the Bernese software which is available under
http://www.bernese.unibe.ch/
There are some kinds of problems which will be further points of investigation
if my first suspicion is incorrect.
One problem: You will normally compile Bernese yourself and it is a known problem
that FORTRAN compilers are very different in their quality to numerical
problems. The second problem is that FORTRAN constants are stored in REAL
precision (6-7 digits) if you are not declaring them. Anyway…
Lets imagine a programmer did the marginal error of not using the correct
reference ellipsoid value of 6 378 137 m, but the abbreviated version
6 378 000 m.
What will be the influence on the GPS precision ? Practically *NOTHING* because
the satellites are symmetrically around the earth and position accuracy is very insensitive against
height changes if the distance between sender and receiver is long enough.
For example, to get a 18 m change for a distance of 730 km you need a height difference of
5 km !
So the values are in fact accurate concerning the position and noone will see a problem,
the software is reliable.
But what if you want to know the *distance* between two points on earth ? Having a slightly
smaller value has the effect that the calculated distance is smaller than the actual distance.
How much ?
730534.610 km * ( (6 378 137 /6 378 000)-1.0) = 15.7 m
15.7 m / 299 792 458 m/s = 52.3 ns
Opera difference: 53.1 and 67.1 ns
Strange coincidence, isnt it ?
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.
http://groups.google.com/group/sci.physics.relativity/msg/675fa9a3cca68825?hl=en
Bob Clark
Consider this possibility: The OPERA experiment is correct given their false assumption about GPS calibration. The OPERA experimenters ignored what I call the Rañada-Milgrom effect.
According to Rañada, the Rañada effect (as I call it), if it exists, “would imply that all the clocks would be changing with a constant acceleration or, in other words, there would be a nonuniformity of time.” My qualitative understanding of Rañada’s basic idea is as follows: In Rañada’s theory, the interaction of dark energy with the background gravitational potential produces a distortion in Einstein’s field equations. In order to mathematically model this distortion, Rañada distinguishes “the proper speed of light” from the “non-proper speed of light” (which is a result of the dark energy distortion underlying the Pioneer anomaly). The “proper speed of light” remains constant as the universe expands. The “non-proper speed of light” increases slightly as the universe expands due to the interaction of dark energy with the background gravitational potential. The “non-proper speed of light” is a book-keeping device to allow Rañada’s quantitative theory to predict the anomalous acceleration of clocks due to the Rañada effect. The non-proper acceleration due to the dark energy distortion in the background gravitational potential implies a blue shift of light with respect to the proper speed of light. “This means that an adiabatic non-proper acceleration of light has the same radio signature as a blue shift of the emitter, although a peculiar blue shift with no change of the wavelength (i.e. all the increase in velocity is used to increase the frequency).” (See page 9 of Rañada’s 2005 paper on the Pioneer anomaly.)
http://arxiv.org/pdf/gr-qc/0410084v2 A. F. Rañada’s “The Pioneer anomaly as acceleration of the clocks” Found. Phys. (2005)
http://en.wikipedia.org/wiki/Pioneer_anomaly
In Rañada’s theory, the anomalous acceleration of clocks is a result of how dark energy interacts with the background gravitational potential. In my physical interpretation of Seiberg-Witten M-theory with neutralino physics, the anomalous acceleration of clocks is a result of the weak interactivity of neutralinos and also how D-brane force interacts with neutralinos; the anomalous acceleration of clocks is an apparent effect because neutralinos are not detected — in other words, spacetime appears to get a slight extra redshift from the undetected neutralinos. When gravity attracts neutralinos, then D-brane force mysteriously and 11-dimensionally seems to cancel the inertial-mass energy of the neutralinos. I claim that Rañada-Milgrom real-or-apparent effect has a model consisting of replacing the -1/2 in the standard form of Einstein’s field equations by -1/2 + dark-matter-compensation-constant, where this constant is roughly equal to sqrt(15) * 10**-5.
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My long experience with measurements inclines me to say that systematic errors, the ones which affect accuracy, are often very difficult to assess, especially with absolute measurements like the Opera’s. One has to sift through hints and clues often scattered among a myriad of data, while stirring immagination in order to arrive at verifiable hypotheses.
The problem is one needs to be determined like some investigators typical of some detective story. Several times it happened to me to be looked at as the “bad one” because of my resolution to track down possible sources of systematic errors.
Perhaps someone already knows who could be the “bad” detectives by both CERN and INFN this time. They are strongly needed, I think.
Very interesting discussion… how about revisiting Inflation Theory. The violation of c here is tiny, Inflation was huge, perhaps due to the energy differences. This will be worth investigating when all systematic measurements are vetted out. If relativity were not involved this would be just another odd result.
first of all scientist should check the speed of neutrinos in vacuum that decide the difference between the neutrinos & photons.higgs-bosson particle should be discovered by detecing it presence in sunlight & the rays coming out from the sun because it give an idea which particle is present in higgs-bosson which helps further in getting an idea from which particle our universe is created & which particle was emit first &which particle is fast.scientist can also find the higgs__bosson in recent developing solar system & can also find the origin of second recent developiing solar systemv
scientist should discover second recently developing solar system which particle makes the universe
Check out this paper: http://arxiv.org/ftp/arxiv/papers/1110/1110.2832.pdf
I particularly like the abstract.
Another favourite of mine is by Max Tegmark, the famous poet: http://adsabs.harvard.edu/abs/1996ApJ…470L..81T
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Ironically, the suggestion that neutrinos take shortcuts in higher dimensions has actually been suggested as far back as 2005:
http://arxiv.org/abs/hep-ph/0504096
and that neutrinos could even travel backwards in time using said shortcuts:
http://arxiv.org/abs/gr-qc/0603045
by oscillating into sterile neutrinos, travelling through the extra dimension, and re-entering normal space then oscillating back into one of the 3 known flavors of neutrino.
What is far more interesting though, is that these papers also state that gravity, being comprised of closed strings, like sterile neutrinos, could also take the same shortcuts. This might lead to interesting testable cosmological phenomena regarding gravity travelling faster than light as well.
Also, this does raise a question in the back of my mind Sean, does this leave the door open for certain phenomena regarded as pseudo-scientific to have a basis in physics? Namely, I’m thinking that the flow of information either faster than light or backwards in time, might be possible if one embedded said information on a gravity wave or neutrino beam, meaning in future, a form of precognition or telepathy might be possible, if it isn’t naturally so already in a very weak form. (I’m actually a skeptic of psychic phenomena, but if faster than light travel of matter or information is allowed in physics, it does raise the question about what sort of phenomena might have to be re-examined simply to shut up the woo contingent.)
“It is a miracle that curiosity survives formal education.” – Albert Einstein
I’d like to believe that Einstein himself would be open to, and fascinated by the possibility, and wouldn’t be so arrogant to rule things out in order to protect his theories.
People are often limited only by their own doing, hence they don’t even know they only think within a box!
In all honesty I know nothing, but it’s all very interesting to me, whether or not OPERA’s findings stands the test of time!
…..By chance I happened to watch a documentary on these findings the other day (on BBC2 I think!). I believe the that the media publicizing the astonishing findings of the OPERA experiment have failed to convey the mood of those conducting the experiment regarding the findings.
The physicists explained on the documentary that they themselves find the results nearly impossible to digest and feel uncomfortable with accepting them. They have looked for every possible flaw in the experiment themselves.
After thorough scrutiny, and no way to disprove their findings, they took the brave decision to release the results to the wider scientific community, to see if someone outside the OPERA group can find the flaw.
They have not approached this like they are confident in their findings. They merely want to understand where they might have gone wrong. It was apparent to me that the OPERA scientists are in greater disbelief than you, me and everyone that refuses to believe.
Speed of thought is instant… in a sense that- If telepathy is possible- thought would travel faster than the speed of light. I know it’s just my mystified opinion, but some phenomena that are now proven and completely ‘normal’ were magical, when they were first encountered.
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