String theorist Edward Witten gives prize lecture

The king of string theory visited London earlier this month to accept the Newton medal at the Institute of Physics. His full lecture is now online

"We know a lot of things, but what we don't know is a lot more." So said Edward Witten, one of the world's most prominent theoretical physicists, when I interviewed him recently during his visit to London to receive the Isaac Newton medal at the Institute of Physics.

The medal is awarded each year to international scientists for outstanding contributions to physics. Last year, it was picked up by MIT's Alan Guth, who gave a brilliant lecture on the inflationary universe. The full video of Witten's lecture has just been posted.

Witten is a great speaker and manages to make clear that no matter how much he understands, we have so much more to learn about the nature of matter and the universe, the subjects that dominate his work.

He describes the history of string theory and the bizarre world it paints. That world might well be ours, but it might too be any of the countless others that could be going about their business, beyond our perception in the multiverse. If there's a multiverse, why are we living in this particular region? Witten has the answer.

Witten is something of a phenomenon. He started out, academically, studying history at Brandeis University, then dabbled with economics and politics before returning to university, this time in Princeton, where he studied applied mathematics under David Gross, a Nobel laureate. He is now at the Institute for Advanced Study, also in Princeton, and the former workplace of Albert Einstein.

String theory comes in for its fair share of criticism, but Witten is clear as to why he devotes his time and considerable efforts to it. "I think it's the most interesting avenue we have for trying to go beyond the laws of nature as we currently understand them," he says.

My interview with Witten is here.