In a recent issue of the Atlantic Monthly, Cullen Murphy wrote that "It is always a little disconcerting when audacious scientific theories come a cropper." In this case, he was speaking of Stephen Hawking's now self-repudiated idea that information swallowed by cosmic black holes might be escaping into "baby universes." John Losee looks at the subject of rejected scientific theories through an analysis of case studies from more than two centuries...