Cosmic Infection Model Tightens Bounds on Alien Civilizations
David Kipping’s cosmological infection model for ETIs uses a three-parameter framework (emergence rate, propagation speed, start time) that factors in cosmic expansion. If infections arise frequently, most galaxies would be infected long ago; to align with the absence of detectable technosignatures, the spawn rate must be vanishingly small (roughly less than 1 in 10^16 star systems, or about 1 in a million galaxies over cosmic history). This tightens SETI constraints beyond the Milky Way and keeps the question open, offering explanations like Rare Earth or Zoo hypotheses as possible but imperfect resolutions while underscoring the non-definitive nature of the data.