Neocatastrophism

Neocatastrophism is the hypothesis that life-exterminating events such as gamma-ray bursts have acted as a galactic regulation mechanism in the Milky Way upon the emergence of complex life in its habitable zone.

[1][2][3] It is one of several proposed solutions to the Fermi paradox since it provides a mechanism which would have delayed the advent of intelligent beings in local galaxies near Earth.

It is estimated that Earth-like planets in the Milky Way started forming 9 billion years ago, and that their median age is 6.4 ± 0.7 Ga.[4] Moreover, 75% of stars in the galactic habitable zone are older than the Sun.

"[7] The hypothesis posits that astrobiological evolution is subject to regulation mechanisms that arrest or postpone the advent of complex creatures capable of interstellar communication and traveling technology.

[1][2][3] Part of the neocatastrophism hypothesis is that stellar evolution produces a decreasing frequency of such catastrophic events increasing the length of the "window" in which intelligent life might arise as galaxies age.