The holy grail for 21st century physics is to produce a unified theory of everything that can describe the world at every level, from the tiniest particles to the largest galaxies. Currently the strongest contender for such a theory is something called M-theory. So what is this supposed mother of all theories all about?

It's been nearly 18 months since the Large Hadron Collider at CERN started up and scientists are eagerly awaiting their first glimpse into the cosmic mysteries it was designed to explore. But when can we realistically expect the first ground-breaking discoveries to come through? Last week, John Ellis, outgoing leader of the theory division at CERN, addressed an audience of physicists at the University of Cambridge to update them on the current state of play. Plus went along and also managed to catch Ellis for a quick interview.

Find out with Martin Rees

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.