What is time? Newton thought it was absolute, Einstein thought it was relative, and today some people think it doesn't exist at all. This package, which is part of our Science fiction, science fact project brings you articles and podcasts exploring the nature of time.
According to Einstein, the past, present and future have exactly the same character - so why do we feel that there is a particular moment we call "now"? The physicist George Ellis looks for an answer in the curious laws of quantum mechanics.
One of the many strange ideas from quantum mechanics is that space isn't continuous but consists of tiny chunks. Ordinary geometry is useless when it comes to dealing with such a space, but algebra makes it possible to come up with a model of spacetime that might do the trick. And it can all be tested by a satellite. Shahn Majid met up with Plus to explain.