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The 'habitable zone' is overly simplistic in general. Look at Europa - it's nowhere near the habitable zone, but is one of the most Earth-like plants in our Sol

by davedx 15y ago

The 'habitable zone' is overly simplistic in general. Look at Europa - it's nowhere near the habitable zone, but is one of the most Earth-like plants in our Solar System. That's just inside the one Solar System we have a fairly complete planetary record of! It also assumes that liquid water and an oxygen atmosphere are prerequisites for life. Extremophiles [1] living on our own planet prove that this is not so. [1] http://en.wikipedia.org/wiki/Extremophile http://en.wikipedia.org/wiki/Extremophile

CWuestefeld 15y ago
It also assumes that liquid water and an oxygen atmosphere are prerequisites for life. Extremophiles living on our own planet prove that this is not so. Maybe this is splitting hairs, but we have evidence that life can exist in such extreme condition. We have no evidence that life can arise under those conditions. I think it's perfectly plausible that it's path-dependent: life needs the friendlier conditions to first develop; once it's up and running with a means of evolving, it's able to acclimatize gradually to the extremes. If I'm right, then it's still correct to exclude worlds that could never have had the "correct" conditions.
- eric-hu 15y ago
  Adding onto this thought, even if life can arise under extreme conditions, the probability of necessary events could still be far lower than the probability of necessary events for life to arise under earth-like conditions. Thus, the habitable zone criteria is simply narrowing the search space to planets with a high(er) probability of developing and supporting life--while discarding planets with a low(er) probability (though some discarded may indeed have life). It seems reasonable to me in this light, as well.
  - majmun 15y ago
    there is probably more chance of finding intelligent life on planet that is not habitable and can't originate life. because once life becomes "intelligent" it will probably try to colonize more than one "uninhabitable" planet by intelligent machines designed for specific environment.
- keys1234 15y ago
  life needs the friendlier conditions to first develop. Primitive Life on earth developed on not so friendly environment with poisonous gas (No Oxygen - Oxygen is a byproduct primitive living things created), regular meteor showers and boiling hot waters. If Life evolved here under these conditions, it can evolve anywhere with such conditions
- deleted 15y ago
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polyfractal 15y ago
While I agree "habitable zone" is a bit of a simplification, it really just serves as a starting point for exploration of the galaxy. If we can find thousands of "theoretically habitable" planets, we can pretty much guarantee there are hundreds of thousands of "uniquely habitable planets" like Europa, which we most likely can't detect using our telescopes. Low hanging fruit first.

by davedx 15y ago

CWuestefeld 15y ago

It also assumes that liquid water and an oxygen atmosphere are prerequisites for life. Extremophiles living on our own planet prove that this is not so. Maybe this is splitting hairs, but we have evidence that life can exist in such extreme condition. We have no evidence that life can arise under those conditions. I think it's perfectly plausible that it's path-dependent: life needs the friendlier conditions to first develop; once it's up and running with a means of evolving, it's able to acclimatize gradually to the extremes. If I'm right, then it's still correct to exclude worlds that could never have had the "correct" conditions.

eric-hu 15y ago
Adding onto this thought, even if life can arise under extreme conditions, the probability of necessary events could still be far lower than the probability of necessary events for life to arise under earth-like conditions. Thus, the habitable zone criteria is simply narrowing the search space to planets with a high(er) probability of developing and supporting life--while discarding planets with a low(er) probability (though some discarded may indeed have life). It seems reasonable to me in this light, as well.
- majmun 15y ago
  there is probably more chance of finding intelligent life on planet that is not habitable and can't originate life. because once life becomes "intelligent" it will probably try to colonize more than one "uninhabitable" planet by intelligent machines designed for specific environment.
keys1234 15y ago
life needs the friendlier conditions to first develop. Primitive Life on earth developed on not so friendly environment with poisonous gas (No Oxygen - Oxygen is a byproduct primitive living things created), regular meteor showers and boiling hot waters. If Life evolved here under these conditions, it can evolve anywhere with such conditions
deleted 15y ago
[deleted]

polyfractal 15y ago

While I agree "habitable zone" is a bit of a simplification, it really just serves as a starting point for exploration of the galaxy. If we can find thousands of "theoretically habitable" planets, we can pretty much guarantee there are hundreds of thousands of "uniquely habitable planets" like Europa, which we most likely can't detect using our telescopes. Low hanging fruit first.