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 Discovered! Most Earth-Like Alien Planet & 2 Other Possibly Habitable Worlds
(04-20-2013, 04:45 AM)stevebowers Wrote: I would note, by the way, that 'habitable' in this context seems to mean 'a potentially life-bearing world'. There is no guarantee that these worlds do have life, and it seems quite unlikely that many of these worlds would be able to support unmodified human life.

This is something a lot of science fiction ignores. The odds that a very earth-like planet, even one that is earth-like enough to support complex life, would be a 'shirtsleeves' environment for baseline humans is probably very, very small. To take just one factor, our own planet is near the inner edge of the habitable zone, and so has a very, very low percentage of carbon dioxide in the atmosphere. A planet otherwise just like earth but elsewhere in the habitable zone would have much more, perhaps up to a bar or more of atmospheric pressure, just to maintain liquid water at the surface (something that would happen more or less automatically, given the way the carbon cycle works, on an earth-like planet). That would be fatal to most air-breathing vertebrates, including humans, because of the way our physiology works.

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RE: Discovered! Most Earth-Like Alien Planet & 2 Other Possibly Habitable Worlds - by Matterplay1 - 04-20-2013, 06:56 AM

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