Podcast
Calculating the multiverse
If there's a multiverse, then how many of its component universes are like our own?
How big is the Universe? Where did it come from and where is it going? Why is it the way it is? These are just some of the questions cosmologists study.
Why does time only ever move in one direction? We talk to philosophers of physics Jeremy Butterfield and David Wallace, as well as the eminent Roger Penrose about the puzzle time poses to physicists and what it has to do with the Big Bang and the second law of thermodynamics.