The Limits of the "Cosmic Speed Limit"

No doubt you've seen the news of the reported observation of neutrinos traveling faster than the speed of light. Aside from throwing out a century-old law of physics, it sounds like a credible result. Of course, the result will have to be duplicated by other groups before we count it confirmed.

Luboš Motl explores some possible measuring errors. I myself am rather doubtful that there's a problem with GPS. After all it's the military that put it up and for these guys accuracy is a matter of life and death. On the other hand, the military could for security purposes be leaving in some consistent errors in the interpretation of GPS for us civilians (a natural analog of the "GPS blurring" they removed some years ago).

For my part, I don't have expertise to evaluate their experimental procedure or analysis, but I can communicate some pointers about what it might mean.

First, it would likely be good news, because it means new physics. The Standard Model of particle physics works, but there's widespread dissatisfaction with it. It produces all the right numbers, but it fails to provide a deeper understanding, or at least the unification that physicists have come to associate with it. (Observed by Lee Smolin in The Trouble with Physics, but it's hardly unique to him—we physicists are always seeking after the new.)

Second, to understand what this result could mean, it helps to step back and examine the terms that we use. Notice that what we mean by such concepts as "distance" and "speed" are purely electromagnetic (EM). Phenomenally, it's through our knowledge of the hard surfaces of solid bodies we establish distance and even the passage of time. And of course, another unquestioned assumption is that light is a "thing" or body, in the exact same sense as other bodies. People have lost sight of the fact (no pun intended) that light is that by which we see, not that which we see, except in a different sense of the word.

We have no direct experience of strong and weak nuclear forces; our experiences of these are mediated by electromagnetic interactions. We do experience gravity directly, but would have no notion of space to be aware of it, were it not for EM. There's no way to shield gravity or to create zones of gravitational neutrality, because there is no second gravitational "charge." In fact the entirety of what we mean by force (from Newton's Laws of Motion) as such is entirely EM.

Neutrinos, while not vector bosons, in some sense carry the weak force, that is, they only interact weakly. The weak force is supposed to have been unified with EM, but meanwhile previous results from CERN seem to be endangering the plausibility of that argument.

It could be that the "speed of light" only applies to electromagnetism. Regardless of the durability of the OPERA result, it's good to remember how small our universe of experience actually is, even augmented by scientific apparatus.

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Geoff Brumfiel, "Particles break light-speed limit: Neutrino results challenge cornerstone of modern physics," Nature (22 September 2011).

The OPERA Collaboraton, "Measurement of the neutrino velocity with the OPERA detector in the CNGS beam" Arxive (22 Sep 2011) arXiv:1109.4897v1 [hep-ex].