In a manner of speaking, the physicists came to the wrong book. It is interesting to note that for the most part they have little to say about the other scientists in this book, and, similarly, the other people do not comment on their work. This may have to do with the fact that the language of physics is mathematics; it may also be that ideas about complexity and evolution have not had the same relevance for cosmology and physics as they have for biology and computer science. Astronomers have studied the spectra of light emitted by distant stars billions of years ago, and have so far found no indication that the laws of physics have changed over this epoch.