FTL Neutrinos, Part 2: What They Don’t Mean

That faster-than-light neutrino still refuses to go away.

Granted, this latest experiment doesn’t prove that it really is going faster than c; all that it does is disprove one proposed source of error; it is still entirely possible that some future experiment, taking something else into account, will get rid of the anomaly.

Personally, every time I read about this neutrino, I feel like an adult staying up late on Christmas Eve to wrap presents, only to look up and see Santa Claus alive and real, standing in my fireplace with a bag of toys for everybody. It’s fantastic, it’s magical, it answers a childhood dream long dismissed as impossible…and it is, almost certainly, all too good to be true.

But if, however, it is true, then all manner of things long dismissed as mere science fiction are suddenly back on the table; the deep places in the universe are suddenly (at least in principle) accessible to us- so too (again, at least in principle) is the past. Indeed, if true then we may be forced to dispose of our notions of causality altogether, just as Special Relativity forced us to dispose of our notions of simultaneity.

That said, I have been noticing a number of misconceptions about the significance of this finding eminating, in particular, from nonscientists, so I would like to use this space to clear a few of them up. First of all…

1) This finding proves that special relativity is wrong!

Yes, but there are degrees of wrongness. Special relativity is a very successful theory, experimentally tested in many different ways and truly impressive in its predictive and explanatory power. It is the basis upon which quantum electrodynamics is constructed, and that is arguably the best-verified theory in the history of physics. So, no: regardless of how fast that neutrino is going, the entire edifice of special relativity is not about to be sent crumbling into dust. It may need to be modified in some limit to account for this phenomenon (just as Isaac Newton’s physics had to be modified to account for the constancy of the speed of light).

Moreover, it might not even be necessary to modify special relativity- just start taking seriously things which were previously imagined to be non-physical results. The reason that we’ve all been told that travelling faster than the speed of light is impossible is that it takes an infinite amount of energy to accelerate a massive particle to the speed of light. However; a particle already travelling faster than the speed of light has a finite energy; it just so happens that, if we want this energy to be real, the particle’s mass must be imaginary. I admit, that it is not easy to square the idea of a particle with imaginary mass into our conception of the real world (pun intended), but if these results keep getting confirmed, then it will be time for us to start taking this possibility seriously.

2) These particles should be travelling backwards in time!

How do you know that they aren’t?

Yes from our perspective it looks like the signal has been recieved after the transmission was sent (that is to say that  the usual order of cause and effect appears to be maintained), but that’s only in our frame of reference. Nothing in SR says that particles travelling faster than light must be travelling backwards in time in all reference frames- just that it should be possible to define some (sublight) reference frame in which the usual relationship between cause and effect is reversed. Stop privileging your own reference frame!

3) Light is much more interactive than neutrinos; how do we know that they weren’t able to reach OPERA first just because the light was being refracted by the matter in the Earth?

The researchers didn’t race a photon againt a neutrino from CERN to Italy; they fired off a neutrino, measured it’s observed speed, and compared it to the (constant) speed of light in vacuum.

4) Could the Heisenberg Uncertainty Principle account for us being unable to localize the speed of the neutrino some some value less than light?

No; this is based on a misinterpreting the UP to mean that a particle’s velocity cannot be known specifically within a certain range of position, when in fact it is the momentum to which this applies. Classically, momentum is proportional to velocity, so its not usually a problem, but at very high energies, the momentum asymptotes towards the speed of light. Thus, no matter values momentum is allowed to range between, the corresponding values of velocity will always be less than c.

5) What is what we call “c” is actually the speed of the neutrinos and photons actually move slightly slower?

In the context of special relativity, “c” is probably best defined as the speed at which massless particles travel in a vacuum; as far as anyone knows, photons are massless. There have actually been a great many experimental tests of this claim and so far no evidence of mass has come-up, which means that, if they do have mass, it is very, very small, indeed, smaller than the observed masses of neutrinos (although I should say that mass is not actually super well-defined insofar as neutrinos are concerned, particularly not tau neutrinos).

6) If science is wrong about nothing travelling faster than the speed of light, it means that it could be wrong about Global Warming/Evolution/the Vaccine-Autism link/Dowsing/Bigfoot/My personal woo of choice!


This is not an intellectually honest argument, and I suspect that at some level, anyone who advances it knows it. First of all, see point one: even if special relativity is, in some sense wrong, there are degrees of wrongness.  To quote Isaac Asimov, “When people thought the earth was flat, they were wrong. When people thought the earth was spherical, they were wrong. But if you think that thinking the earth is spherical is just as wrong as thinking the earth is flat, then your view is wronger than both of them put together.” Science is always changing, but science will never change in such a way as to validate a view that has already been proven false. Moreover, if science was wrong in this case, how did we just learn about it? By doing more science! This does nothing to invalidate science as a discipline; if anything, it shores up the validity of science. To say nothing of just how incredibly dubious it is for someone to suggest that a finding an anomaly in high-energy physics somehow invalidates completely unrelated findings in completely different sciences. Indeed, this argument is so ridiculously bad that you may well think I’m advancing it as a strawman; if this is the case, I urge you to look at the comments thread following almost any mass media story on the subject.


About thevenerablecorvex

I have the heart of a poet, the brain of a theoretical physicist, and the wingspan of an albatross. I am also notable for my humility.
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