"Alfred A. Aburto Jr." <aaburto@pacbell.net> wrote in message
news:j0TSa.2720$e23.85286069@newssvr21.news.prodigy.com...

Your're not correct about the Moon being responsible for Earths molten

core

(Joseph Lazio commented on this too)--- it does cause tides but Earth's
molten core is due to radioactivity. Venus also has a molten core by the
way, volcanic activity, and plenty of outgasing too ...

Books that talk about the relationship between tectonics and the presence of
life mention not just volcanic activity and outgassing, but also recycling
of carbon materials due to plate subduction (is that the right word? I'm
doing this pre-coffee, so coherence is not guaranteed). Venus may have
volcanoes, but the references I've seen say that there do not appear to be
any actual crustal plates (and therefore no movement, no recycling of the
surface).

And BTW, you are claiming by inference (even if you don't realize it) that
Earth has plenty of internal radioactives, but not Venus or Mars. Why would
this be? Sounds like a violation of Mediocrity again. More on this below.

I don't think you're arguments can be generalized as making a case for a
requirement for life ... too many factors at play ... on Earth though the
right factors came together ... how rare is that? ... no one really knows
for sure now ... but I "estimate" :) we'll find plenty of Earth like

planets

in the future ... with life too no doubt ...

True, but it may not be a case of yes/no requirements. It might be that life
can develop anywhere, but that in order to thrive and evolve, or even
survive long-term, certain factors will improve the odds. If a molten core,
tectonics, a large satellite, a distance from the sun suitable for liquid
water, are all factors that affect the chances of life, then the Earth may
be rare in that it has enough of these factors going for it.

The current most accepted theory for the existance of the moon is a
platenary impact that shredded off part of the early Earth. Maybe that's
where the radioactives came from (but if so, why was the impactor so
blessed? This just moves the question back one step). In this case, maybe
the moon is not a cause, but a result of the same event that made life on
Earth possible.

There are other factors that might come into play as well. A recent
Scientific American issue had an article that suggested that terrestrial
planets may only be able to develop in a doughnut-shaped subsection of the
galaxy (with our system in it, of course).

 In other words, the Fermi equation may not have enough of the important
factors built in. It may be that the chances of intelligent life are
actually much lower than most people have calculated. If you get the
probability down low enough, then things like planet-busting comets and
nearby novas become significant in wiping things out.

Let's face it - we haven't detected other civilizations, and if they're out
there, we should have. So the possible explanations are:

1) God really did create the universe just for us
2) Life is very rare, and / or intelligent life is even more rare
3) We just happen to be in a part of the galaxy where there are no other
civilizations.

There are other possibilities but they generally have problems.

I won't even bother discussing the problems with #1. Leave that to
sci.skeptic. #3 just exchanges one unlikely event for another, without
really explaning anything. #2 Seems to me to be the most likely, and the
only remaining question is: what factors make the Earth so unusual that
intelligent (?) life evolved here?