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Faster-than-light neutrinos could be proof of extra dimensions

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The recent announcement that neutrinos had been observed seemingly going faster than the speed of light sent shockwaves through the physics community. But there's one possible explanation that could keep Einstein's relativity intact and open up a whole new cosmos.

It should be stressed that we're still far from a confirmed result for these faster-than-light neutrinos. The findings from Italy's OPERA detector have stood up decently well to initial scrutiny, and a lot of the more obvious objections have been answered, at least for the time being. But there's still every chance this is some sort of systematic error, and we won't be able to declare this an actual discovery until the results can be replicated elsewhere, with many other teams already beginning their own experiments. This is still a crazy result, and our first, second, and third reactions should all be deeply skeptical.


Still, while it shouldn't yet be considered the most likely possibility, let's imagine for a moment that these results stand up and it turns out the neutrinos really did arrive at their destination 60 nanoseconds faster than the speed of light would allow. What then? While it might seem that such a discovery would invalidate Albert Einstein's theory of special relativity - which takes it as a given that the speed of light is the absolute limit - there may be a way to reconcile the theory with the results.


The idea is that the speed of light does remain the fastest possible speed in the three spatial dimensions we're familiar with - but that the neutrinos aren't just traveling in those dimensions. Instead, they could take a shortcut through a theoretical fourth spatial dimension, which would provide a shorter distance between two points than would be possible in the normal three dimensions. The neutrinos still aren't exceeding the speed of light in this scenario. And yes, that is basically the particle physics equivalent of doing the Kessel Run in twelve parsecs.

Anyway, the larger idea here is that the three spatial dimensions and one temporal dimension we're familiar with are what make up a four-dimensional membrane, known as the brane. However, this brane "floats" in a larger reality known as the bulk. While in the ordinary course of things it would be impossible to leave the universe - to leave the brane - at incredibly high energies it might be possible for particles to temporarily break free and zip through the bulk.


This may be all getting a bit metaphysical, but a lot of these ideas are crucial to string theory, which takes extra hidden dimensions as one of its central features. Until now, string theory has remained an elegant theory that is completely beyond the bounds of experimentation. If - and, again, this is one gargantuan if - the OPERA results hold up, that could represent the first tangible evidence for string theory.

Basically, it's possible for Einstein to still be right and the speed of light to remain inviolate even if this result turns out to be a genuine discovery - his theory might just prove to be somewhat incomplete. And, if that's the case, then we're on the verge of some seriously exotic new realms of physics. It's a little too early for that much optimism...but it's still an extremely intriguing thought.


Read more at New Scientist. Image of OPERA detector via.