Talk:Galactic habitable zone

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Habitability[edit]

We have, self-evidently, experience of life on only one planet - our own. There is no reason at all to suppose that life must necessarily depend on water, or oxygen, or what we consider to be equable temperatures. Life as we know it, yes, but life as we do not know it could as far as we know, take virtually any form at all and have virtually any kind of metabolism. --Anthony Bradbury"talk" 17:10, 16 May 2013 (UTC)

This is very true. However, there are many reasons why carbon-based life forms like ourselves are preferred to other alternative biochemistries-from the abundance of carbon, hydrogen, oxygen, nitrogen, and others in the Universe to the chemistry of carbon. Of course, there may be somewhere, some life based on alternate biochemistry. But carbon-based life is most likely. I will update this message later. Wer900talk 18:21, 16 May 2013 (UTC)
I agree. But as it now appears that many G, F and K type stars (at least) have planets, and as the number of stars just in this galaxy is, as you clearly know, very large, there is at least in theory room for almost infinite variety. And even if we discount the possibility of silicon-based life, there is surely scope for carbon-based life not dependent or water or oxygen? Only speculating.--Anthony Bradbury"talk" 20:32, 16 May 2013 (UTC)
I'm not denying the possibility of alternative biochemistry. However, the galactic habitable zone would still hold in many cases; you need a high-mass planet to maintain an atmosphere, and you need abundant heavy elements for that. At the same time, you cannot be so close that sterilization would happen at the galactic center. These requirements apply to any life, whether or not carbon-based. Wer900talk 23:46, 16 May 2013 (UTC)