Planet Formation and Panspermia. Группа авторов

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Planet Formation and Panspermia - Группа авторов

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discussions of the relevant technical and bioethical topics.

      The other key input is the rate of habitat formation in the course of the Galactic history. The pioneer study of Charles Lineweaver [3.42]—and the subsequent improvements by [3.9, 3.43, 3.64]—indicates that the median age of Earth-like planets in the Galaxy is

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      which is significantly greater than the Earth/Solar System age. Since roughly that epoch, the rate of formation of terrestrial planets in the Milky Way has steadily decreased. While this can be used to strengthen Fermi’s Paradox (as argued at length in [3.14]), there are other interesting speculative applications of the Lineweaver timescale.

      Notably, this timescale justifies our previous conclusion that we are living in an early epoch of evolution of our own brand of intelligent observers. The fact that we have discovered these timescales now and have our, even very crude and simplistic, models of the relevant processes implies that older and more advanced civilizations have much better and precise insight into the same. Thus, a Kardashev’s Type 2.x civilization is likely to be able not only to survey all sites for abiogenesis in the Galaxy but is likely to be able to predict the emergence of future habitable sites. Moreover, an implication of the research of Lineweaver and others is that, as far as terrestrial planet formation is concerned, the Milky Way is past its prime: the rate of such habitat formation already decreased and will continue to decrease in the future. A clear implication is that the rate of local occurrences of abiogenesis is decreasing and will continue to decrease.

      Of course, we need to keep in mind the point emphasized by Freeman Dyson (e.g., [3.24, 3.25]) that not all potential habitats are Earth-like planets; however, formation rates of other potential habitats generally follow the same pattern, which follows from the general chemodynamical evolution of the Milky Way. This was valid for the Galactic past, on which our evidence is based. Therefore, we are justified in using Earth-like planets as synonymous with habitats for origination and evolution of life and intelligence so far. Why is the temporal qualification important here? This is the key point here: because directed panspermia, in contrast to other processes leading to the expansion of life, is not bound by a narrow class of Earth-like planetary habitats.

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