Right, so last weak I enumerated all of the things that the apparent discovery of superluminal neutrinos definitively did not mean. Now, I will list some of the things which I think that it may mean, based purely on my own speculations and (admittedly imperfect) knowledge of physics (I am currently working on my Master’s in the subject).
First of all, it needs to be said that this discovery easily could mean that some of OPERA’s equipment is malfunctioning, or that there is some sort of systematic error that has so far been overlooked. Now, I know that this isn’t what anyone really wants to hear, but let us pay a tiend to skepticism and to Sagan’s famous dictum about extraordinary claims requiring extraordinary evidence. This still, in my opinion, remains the most likely explanation.
But of course, that’s boring! So let’s assume that these particles really are traveling faster than light. It could (as I touched upon last time) mean that these neutrinos have imaginary masses; this seems like it would be the simplest way to avoid doing much violence to modern physics, but conceptually it is very difficult to grasp. It also has the problem (or so I have read) of being extremely difficult to reconcile with our present understanding of Quantum Field Theory.
In fact, tachyons are so difficult to resolve with Quantum Field Theory that one interesting consequence of assuming an imaginary mass is that all of the extra-dimensions of string theory actually become redundant. Those dimensions were conceived, specifically, in order to get rid of tachyons, so if it turns out that tachyons exist, then it would seem that the swift application of Occam’s razor is in order.
It’s also worthwhile to point out that imaginary mass means negative mass-squared. A black hole’s horizon-area is proportional to it’s mass-squared, so if a FTL-neutrino were to be absorbed by a black hole it would seem like it should actually make the hole smaller. That said, it’s not obvious to me that it even makes sense to think about a superluminal particle becoming trapped in a black hole; indeed, it seems like these things could make it possible, at least in principle, to probe black hole interiors. Speaking of horizons, why stop only at black holes? It seems like superluminal particles could allow disparate regions of the universe to be causally-connected to one another- potentially solving the horizon problem.
There are, of course, other alternatives to the neutrinos being tachyonic. One currently making the rounds through the mass media (on account of how Science Fiction-y it sounds) is that these are just normal particles, travelling at near-lightspeed through an extra-dimension. Personally, I find this explanation to be aesthetically displeasing; it seems a bit of an ad hoc hypothesis, and raises the question of why this extra dimension only appears to be accessible to this one particular species of neutrino; surely other species of neutrinos at comparable energies would exhibit similar behaviour.
That said, none of this should be taken too seriously; all of these are just idle speculations that I am making more-or-less off the top of my head. But if these results do turn out to be true, the world just got a whole lot more interesting.