Eternity in six hours: Intergalactic spreading of intelligent life (2013)

Eternity in six hours: intergalactic spreading of intelligent life. Stuart Armstrong and Anders Sandberg from the Future of Humanity Institute, Oxford University, explore the Fermi Paradox—the discrepancy between the high probability of intelligent life emerging and the lack of visible evidence. They argue that launching a colonization project for the entire reachable universe is a relatively simple task for a star-spanning civilization, requiring modest amounts of energy and resources. Specifically, they demonstrate that about six hours of the sun’s energy is needed to commence the colonization of the entire universe using self-replicating probes. This results in a considerable sharpening of the Fermi Paradox: if such expansion is physically feasible and energy-efficient, why do we see no evidence of it? The paper uses exploratory engineering to show that these designs are compatible with known physics, suggesting that either intelligent life is exceptionally rare or that civilizations face a 'Great Filter' that prevents them from becoming spacefaring.