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.

*Plus* is very proud to present **Professor Stephen Hawking**'s own Birthday Symposium address.

Astronomer Royal **Sir Martin Rees** gives *Plus* a whistlestop tour of some of the more extraordinary features of our cosmos, and explains how lucky we are that the universe is the way it is.

Nobel Prizewinning Physicist **Professor Gerardus 't Hooft** has always been fascinated by the mathematical mysteries of nature. He tells *Plus* about his early life, and what our Universe might really be like.

Will we ever be able to make computers that think and feel? If not, why not? And what has all this got to do with tiles? *Plus* talks to **Sir Roger Penrose** about all this and more.

What happens when one black hole meets another? **Professor Kip Thorne** shows us how to eavesdrop on these cosmic events by watching for telltale gravitational waves.