2011/04/04 by Adrian Kent, Kent, Adrian
Physics and Astronomy · #FOS: Physical sciences #Popular Physics (physics.pop-ph) #Space Physics (physics.space-ph) #Space Science and Extraterrestrial Life
paper · pdf · doi:10.48550/arxiv.1104.0624
openalex publication_date 2011/04/04 · openalex created_date 2022/10/03 · openalex updated_date 2026/07/28
It is often suggested that extraterrestial life sufficiently advanced to be capable of interstellar travel or communication must be rare, since otherwise we would have seen evidence of it by now. This in turn is sometimes taken as indirect evidence for the improbability of life evolving at all in our universe. A couple of other possibilities seem worth considering. One is that life capable of evidencing itself on interstellar scales has evolved in many places but that evolutionary selection, acting on a cosmic scale, tends to extinguish species which conspicuously advertise themselves and their habitats. The other is that -- whatever the true situation -- intelligent species might reasonably worry about the possible dangers of self-advertisement and hence incline towards discretion. These possibilities are discussed here, and some counter-arguments and complicating factors are also considered.