Pulsars and Extreme Physics

Pulsars were discovered some 40 years ago. What do we know about them now and what have they taught us about the extremes of physics? With an average density comparable to that of the nucleus, magnetic fields of around 100 000 000 T and speeds close to c, they have stretched our understanding of the behavior of matter. They serve as extremely accurate clocks with which to carry out precision experiments in relativity. Pulsar research continues to deliver exciting, startling and almost unbelievable results.