The Doomsday Argument in Many Worlds
  You and I are highly unlikely to exist in a civilization that has produced
only 70 billion people, yet we find ourselves in just such a civilization. Our
circumstance, which seems difficult to explain, is easily accounted for if (1)
many other civilizations exist and if (2) nearly all of these civilizations
(including our own) die out sooner than usually thought, i.e., before trillions
of people are produced. Because the combination of (1) and (2) make our
situation likely and alternatives do not, we should drastically increase our
belief that (1) and (2) are true. These results follow immediately when
considering a many worlds version of the "Doomsday Argument" and are immune to
the main criticism of the original Doomsday Argument.
