Cosmologist Stephen Hawking expands on his changed theory of black holes at the 17th General Relativity Gravitational conference in Dublin, Ireland, July 21, 2004. Hawking, 62, who has a crippling muscle disease, lost one of the most famous bets in scientific history on Wednesday after he conceded that American physicist John Preskill was right to reject the 1975 black hole theory that helped make Hawking's name. REUTERS/Paul McErlane