Universal Doomsday: Analyzing Our Prospects for Survival
  Given a sufficiently large universe, numerous civilizations almost surely
exist. Some of these civilizations will be short-lived and die out relatively
early in their development, i.e., before having the chance to spread to other
planets. Others will be long-lived, potentially colonizing their galaxy and
becoming enormous in size. What fraction of civilizations in the universe are
long-lived? The "universal doomsday" argument states that long-lived
civilizations must be rare because if they were not, we should find ourselves
living in one. Furthermore, because long-lived civilizations are rare, our
civilization's prospects for long-term survival are poor. Here, we develop the
formalism required for universal doomsday calculations and show that while the
argument has some force, our future is not as gloomy as the traditional
doomsday argument would suggest, at least when the number of early existential
threats is small.
