Interplanetary collision hazards in many planetary systems force civilizations to become spacefaring or extinct. This selection pressure apparently acts on a timescale of 10(sup 5) years on Earth's current human civilization, but may act on shorter or longer timescales elsewhere.
Cosmic Collisions and the Longevity of Non-Spacefaring Galactic Civilizations
1998-05-01
Preprint
Keine Angabe
Englisch
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