Novelist/playwright Michael Frayn’s new book “Celia’s Secret” is a literary practical joke: a story of how, during the run of his play “Copenhagen,” he received letters that seemed to shed new light on the nuclear physicists Werner Heisenberg and Niels Bohr (whose mysterious meeting in 1941 is the subject of the play). The letters, of course, soon turn out to be fakes, forged by one of his actors. – The Independent (UK)