In Einstein's universe, spacetime is supposed to be some crazy rubber sheet full of folds and bends. But the idea of curved space is not the most intuitive in the world. And what does light have to do with any of this? In this week's Ask a Physicist, we'll find out.
For the last few weeks, we've been running a contest to answer some of the most interesting questions about the cosmos. This week's winner is RT who should shoot me an email to get a free signed copy of my new book. He/she asks: