As part of our joint project with FQXi called Science fiction, science fact, we've been asking you what question on the frontiers of physics you'd like to have answered. The question that topped our first poll was 'What is time?'. We went to ask Paul Davies, a theoretical physicist and cosmologist at Arizona State University and Director of BEYOND: Centre for Fundamental Concepts in Science and here is his answer.
This issue of Plus is a special, marking the occasion of Stephen Hawking's 60th birthday. Plus attended his Birthday Conference in Cambridge, where we interviewed some of the world's most influential mathematicians and physicists.