Astrobiological Phase Transition: Towards Resolution of Fermi’s Paradox

Abstract

Can astrophysics explain Fermi's paradox or the "Great Silence" problem? If available, such explanation would be advantageous over most of those suggested in literature which rely on unverifiable cultural and/or sociological assumptions. We suggest, instead, a general astrobiological paradigm which might offer a physical and empirically testable paradox resolution. Based on the idea of James Annis, we develop a model of an astrobiological phase transition of the Milky Way, based on the concept of the global regulation mechanism(s). The dominant regulation mechanisms, arguably, are gamma-ray bursts, whose properties and cosmological evolution are becoming well-understood. Secular evolution of regulation mechanisms leads to the brief epoch of phase transition: from an essentially dead place, with pockets of low-complexity life restricted to planetary surfaces, it will, on a short (Fermi-Hart) timescale, become filled with high-complexity life. An observation selection effect explains why we are not, in spite of the very small prior probability, to be surprised at being located in that brief phase of disequilibrium. In addition, we show that, although the phase-transition model may explain the "Great Silence", it is not supportive of the "contact pessimist" position. To the contrary, the phase-transition model offers a rational motivation for continuation and extension of our present-day Search for ExtraTerrestrial Intelligence (SETI) endeavours. Some of the unequivocal and testable predictions of our model include the decrease of extinction risk in the history of terrestrial life, the absence of any traces of Galactic societies significantly older than human society, complete lack of any extragalactic intelligent signals or phenomena, and the presence of ubiquitous low-complexity life in the Milky Way.

Population growth, energy use, and the implications for the search for extraterrestrial intelligence

“…In that case, we may not even have to worry about the kinds of "doomsdays" documented here! Alternatively, perhaps the Milky Way is undergoing a phase transition in habitability allowing civilizations to emerge now (Ćirković & Vukotić 2008). There are no shortage of possible solutions to the Fermi paradox (see Ćirković 2009 for a review).…”

Astrobiological landscape: a platform for the neo-Copernican synthesis?

“…Of course, in practical terms it is the Galactic astrobiological landscape that is of foremost interest for research. 3 In theory, we can imagine zooming out & Vukotić 2008. ) so much that we include galaxies located at cosmological distances, which are impossible to observe except in very early stages in their evolution; this is, of course, purely abstract point, since nobody really expects to have anything but the Dead space zero level at cosmologically early epochs.…”

Anthropic Shadow: Observation Selection Effects and Human Extinction Risks

“…The degree of importance of these explosive processes for the emergence and evolution of life has been the subject of considerable research in recent decades. ( 22‐32 ) Fragmentary geochemical traces of such events in the past could be found in the terrestrial record, especially ice cores. ( 33 ) The same applies to a lesser degree to giant solar flares.…”