Lizard Breath writes:
Sylas writes:
Evolution leads to organisms that are finely adapted for their environment. If the environment was different, then life would be different as well. You can take that as saying life as we know it would be impossible if you like.
So it is entirely possible that every other planet in every solar system in the universe does have life on it but because of the different enviorments, it is impossible for us to catalog it as life because of our exclusive familiarity of our own enviorment.
Boggle. That is nothing like what I was saying.
It is not remotely plausible that every other planet has life; and the question is not one of cataloging or classifying.
We don't know nearly enough about life to tell how common it is in the universe, or what forms it may take. The question of whether there is life on any other planets in our solar system is an open one. If I had to put money on it, I'd suggest most likely not. Plausible candidates are Mars and Europa. Neither is particularly likely, I would guess, but it is well worth looking for it.
The question is whether or not anything exists which is analogous to life on earth. Certainly, if it exists, it would be very different to life on Earth. That is not a problem; we don't have a prior classification that requires life to be exactly what we know already.
The issue you raised originally was one fine tuning of life to circumstances on Earth. That is an inevitable consequence of evolution, and there is no basis for inferring that life is impossible under all other circumstances.
As an even more minor aside, you can't have a closer moon leading by a fixed number of degrees. The orbital periods would be different.
Would it be possible if the further moon had a faster orbital speed which kept it at the same distance from the inner moon?
No. Moons don't stay equidistant from each other. Does it matter? Just propose another Moon; and speculate on what differences that might make. More interesting (IMO) is speculation about no Moon at all. Were tides important in biogenesis? Does a large Moon help keep Earth geologically active, and is that important for life? I don't know.
(Added in edit: JonF has pointed out the Lagrange solution to the 3 body problem; but that does not involve an "inner" moon. I believe it is stable only if the third body is very small. This solution involves exactly the same orbital period and orbital distance for the extra tiny moon as for the existing moon; and the moons are equidistant from each other. The notion of a planet opposite the earth and behind the sun is unstable.)
Cheers -- Sylas
[This message has been edited by Sylas, 02-23-2004]
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