The newborn universe may have glowed with light beams moving much faster than they do today, according to a theory that overturns Einstein’s century-old claim that the speed of light is a constant.
João Magueijo, of Imperial College London, and Niayesh Afshordi, of the University of Waterloo in Canada, propose that light tore along at infinite speed at the birth of the universe when the temperature of the cosmos was a staggering ten thousand trillion trillion celsius.
Magueijo and Afshordi came up with their theory to explain why the cosmos looks much the same over vast distances. To be so uniform, light rays must have reached every corner of the cosmos, otherwise some regions would be cooler and more dense than others. But even moving at 1bn km/h, light was not travelling fast enough to spread so far and even out the universe’s temperature differences.
To overcome the conundrum, cosmologists including Stephen Hawking have proposed a theory called inflation, in which the fledgling universe underwent the briefest spell of the most tremendous expansion. According to inflation, the temperature of the cosmos evened out before it exploded to an enormous size. But there is no solid proof that inflation is right, and if so, what sparked such a massive period of expansion, and what brought it to an end.