SETI & Technosignatures

Constraining the Lifespan of Intelligent Technological Civilization in the Galaxy

By Keith Cowing
Status Report
astro-ph.GA
February 27, 2026
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Constraining the Lifespan of Intelligent Technological Civilization in the Galaxy
Constraint on the lifetime 𝐿 = 10𝑛 of intelligent technological civilizations derived from the Fermi paradox. The expected number of coexisting civilizations 𝑁 is shown as a function of the civilization lifetime for different assumptions about the probability 𝑓 that a habitable planet produces a technological civilization. The shaded region corresponds to values for which 𝑁 ≫ 1, which are observationally excluded by the absence of detected extraterrestrial civilizations. The dashed line indicates the boundary 𝑁 = 1 and is shown for reference. — astro-ph.GA

In this work, we explore constraints on the emergence and longevity of technologically intelligent civilizations in our Galaxy, considering the Fermi paradox.

We argue that under optimistic assumptions about the probability of life and intelligence emerging on Earth-like planets, the absence of contact with extraterrestrial civilizations imposes limits on their lifespan.

Our analysis suggests that if intelligent life is common, technological civilizations must be relatively short-lived, with lifetimes constrained to ≲5Γ—103 years under our most optimistic scenario.

Considering electromagnetic communication, we note that our current light cone encompasses the entire Galactic history over the past ∼105 years, making the lack of detected signals particularly puzzling for long-lived civilizations. We emphasize that these results should be interpreted as upper bounds derived from the Fermi paradox, not as predictions of actual lifespans.

Sohrab Rahvar, Shahin Rouhani

Comments: 4 pages, 1 figure, accepted in MNRAS Letters
Subjects: Astrophysics of Galaxies (astro-ph.GA); Earth and Planetary Astrophysics (astro-ph.EP); Popular Physics (physics.pop-ph)
Cite as: arXiv:2602.22252 [astro-ph.GA] (or arXiv:2602.22252v1 [astro-ph.GA] for this version)
https://doi.org/10.48550/arXiv.2602.22252
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Submission history
From: Sohrab Rahvar
[v1] Tue, 24 Feb 2026 20:57:21 UTC (90 KB)
https://arxiv.org/abs/2602.22252
Astrobiology

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) πŸ––πŸ»