| The article does ask this: "Why not faster? Why not slower?" Certainly a lot of physicists are content with leaving it at "because it is." They're not searching for purpose, they're searching for explanation. The article doesn't just ask the question either, it explores a possible avenue for seeking the answer. Experiments over the past few years seem to indicate that the speed of light can be derived by measuring electric and magnetic properties of the vacuum. This leads to the question: is it possible that the speed of light is the value it is because the vacuum restricts it to this value? This would mean the speed of light is not a fundamental constant, but an observable parameter of the vacuum. The article is light on links, but here is a paper that I think the article was referring to, by Marcel Urban and colleagues at the University of Paris-Sud: http://arxiv.org/abs/1302.6165 From the paper: "When a real photon propagates in vacuum, it interacts
with and is temporarily captured by an ephemeral pair.
As soon as the pair disappears, it releases the photon to
its initial energy and momentum state. The photon continues to propagate with an infinite bare velocity. Then the photon interacts again with another ephemeral pair and so on. The delay on the photon propagation produced by these successive interactions implies a renormalisation of this bare velocity to a finite value. This “leapfrog” propagation of photons, with instantaneous leaps between pairs, seems natural since the only length and time scales in vacuum come from fermion pair lifetimes and Compton lengths." The paper claims that the speed of light might fluctuate as a consequence, and proposes possible experiments to test this. "The propagation of a photon being a statistical
process, we predict fluctuations of its time of flight of the order of 0.05fs/√m. This could be within the grasp of
modern experimental techniques and we plan to assemble
such an experiment." This could answer the question, why is light so slow? |