Dale Purves is not musical by nature. He's been trying to play the guitar for forty years-with limited success. He has no formal training and, if presented with a sheet of music, can't tell an F-sharp from a B-flat.

The search for the true nature of light goes back centuries and includes contributions from some of the most illustrious scientists in history.

 A few months ago, Harry Potter was all over thenews again, and not because his creator, J.K. Rowling, had completed her final book about the boy wizard and his friends.