The speed of light in a vacuum is the ultimate cosmic speed limit. Just getting close to it causes problems: the weird distortions of Einstein’s relativity kick in, so time slows down, lengths go up, masses balloon and everything you thought was fixed changes. Only things that have no mass in the first place can reach light speed – photons of light being the classic example. Absolutely nothing can exceed this cosmic max.We have known about the special nature of light speed since an experiment by US physicists Albert Michelson and Edward Morley in the 1880s. They set two beams...
