* Astronomy

Title: Universal Doomsday: Analyzing Our Prospects for Survival
Authors: Austin Gerig, Ken D. Olum, Alexander Vilenkin

Given a sufficiently large universe, numerous civilisations almost surely exist. Some of these civilisations 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 colonising their galaxy and becoming enormous in size. What fraction of civilisations in the universe are long-lived? The "universal doomsday" argument states that long-lived civilisations must be rare because if they were not, we should find ourselves living in one. Furthermore, because long-lived civilisations are rare, our civilisation'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.

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