Guido D'Amico

Right after its birth, the Universe wasn't just expanding: it was inflating at an unimaginable pace. This stage, called inflation, was proposed by Alan Guth. New models compare the process to inflating a balloon with quick, jerky pumps.

Light from the very beginning of the cosmos has been traveling toward us for 13.8 billion years. During that time, its polarization, the direction of its oscillations, might have been twisted, like a compass needle that someone quietly nudged. Physicists call this phenomenon cosmic birefringence.