How far are extraterrestrial life and intelligence after Kepler?

Abstract

The Kepler mission has shown that a significant fraction of all stars may have an Earth-size habitable planet. A dramatic support was the recent detection of Proxima Centauri b. Using a Drake-equation like formalism I derive an equation for the abundance of biotic planets as a function of the relatively modest uncertainty in the astronomical data and of the (yet unknown) probability for the evolution of biotic life, F b . I suggest that F b may be estimated by future spectral observations of exoplanet biomarkers. It follows that if F b is not very small, then a biotic planet may be expected within about 10 light years from Earth. Extending this analyses to advanced life, I derive expressions for the distance to putative civilizations in terms of two additional Drake parameters -the probability for evolution of a civilization, F c , and its average longevity. Assuming "optimistic" values for the Drake parameters, (F b~Fc~1 ), and a broadcasting duration of a few thousand years, the likely distance to the nearest civilizations detectable by SETI is of the order of a few thousand light years. Finally I calculate the distance and probability of detecting intelligent signals with present and future radio telescopes such as Arecibo and SKA and how it could constrain the Drake parameters.

On the Biohabitability of M-dwarf Planets

“…Recent data of the Kepler mission show that 10-50% of the M-dwarfs have small planets orbiting within their habitable zone (Batalha et al 2013;Dressing and Charbonneau, 2015), which implies that such planets could be found within less than 10 light years from Earth (Wandel, 2015;2017a). A high abundance of Earth-size volatile-rich planets close to low mass M-stars is also supported by theoretical arguments and planetary formation models (Alibert and Benz 2017).…”

The bio-habitable zone and atmospheric properties for planets of red dwarfs

“…With this assumption the average distance db between biotic neighbor planets can be shown to be (Wandel 2015;2017) db ~ 3 (n* FsFEHZ Fb) -1/3 pc (14) where n* is the stellar number-density in the solar neighborhood.…”

“…While some authors point out some disadvantages for the evolution of life on planets orbiting M-type stars, such as high levels of XUV radiation and stellar winds, which may cause atmosphere erosion (Heller, Leconte and Barnes 2011;Leconte, Wu, Menou and Murray 2015, Lingam and Loeb 2017, Tilley et al, 2019, other works argue that such planets may nevertheless host life as we know it (e.g. Tarter et al, 2007, Gale andWandel 2017). They point out that the impact of the high XUV flux received by planets orbiting in the habitable zone of young M-type hosts may be less important for aquatic life.…”

Will recent advances in AI result in a paradigm shift in Astrobiology and SETI?

“…These parameters, are now believed to be of order unity (e.g. Batalha et al 2013;Dressing and Charbonneau, 2015;Wandel 2017). Our main ignorance remains in the last three terms: (i) the chances for the evolution of biological life; (ii) the probability of intelligence; and (iii) the lifespan of a technological communicating civilization.…”