Black Holes and the Information Paradox; The Edge of Physics; Special Editions; by Leonard Susskind; 6 Page(s)

SOMEWHERE in outer space, Professor Windbag's time capsule has been sabotaged by his rival, Professor Goulash. The capsule contains a mathematical formula vital to future generations. But Goulash's diabolical scheme to plant a bomb on board has succeeded. Bang! The formula is vaporized into a cloud of electrons, nucleons, photons and an occasional neutrino. Windbag is distraught. He has no record of the formula and cannot remember its derivation.

Later, in court, Windbag charges that Goulash has sinned irrevocably: "What that fool has done is irreversible. Off with his tenure!" "Nonsense," says an unflustered Goulash. "Information can never be destroyed. It's just your laziness, Windbag. All you have to do is go and find each particle in the debris and reverse its motion. The laws of nature are time symmetric, so on reversing everything, your stupid formula will be reassembled. That proves, beyond a shadow of a doubt, that I could never have destroyed your precious information." Goulash wins the case.