Text 266, 77 rader
Skriven 2004-10-02 06:07:00 av Brett Aubrey (1:278/230)
Ärende: Re: Different Forms of Li
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"TomHendricks474" <tomhendricks474@cs.com> wrote in message
news:cjk7g1$hfk$1@darwin.ediacara.org...
> >No.  I don't think a similar-sized sun would be a necessity, unless
you're
> >being *very, very* lax with "similar", nor a "orbit sized" life zone.
Just
> >the temperature zone is likely, such that liquid water needs to exist
> >somewhere on the planet.  Of course, I don't *absolutely* rule out
> >some sort of different life form in other unknowable environments,
> >but that would be far less likely, IMHO.   Regards, Brett.
>
> Well lets go further.  The strength of UV varies.Certain distances
> between the star and its planet may be too weak to break the
> bonds or form the monomers, etc. that seem to lead to the
> origin, while certain shorter distance may be too strong.
> This is something that would be an important aspect, IF I am correct in
> suggesting that the sun/UV cycle initiated the origin and powered it
> through every step.  It also would further restrict size, distance etc.
>
> Overall I would say this - the fit between star and planet must be such
that
> there is a reasonably constant cyclic temperature zone that allows for
liquid
> water, and a similar reducing atmosphere as earth probably had.
> Its size probably has to allow for volcanic activity - the source of
> earth's water,  atmosphere etc.

I'll agree, for the sake of ending the thread.  (In reality, I think OOL
might possibly occur without volcanism, and think cylic is uneccessary if
you're talking seasonal.  I'm not sure about "similar" reducing atmosphere.
And as to your initial point, I would *not* rule out other life forms based
on your arguments.)  I'd also say that the above paragraph is considerably
more relaxed that your initial "same-sized" planet and sun.

> (And PERHAPS having a Moon that is more nearly the size of earth than any
> planet/moon in the system, is an important fact too. Its close proximity
after
> the planetoid collision that formed it; set up a much shorter day of
something
> like 5 hours of sun, then 5 hours of night. Perhaps a spin that is much
less is
> too slow to
> power the necessary steps of life, and a spin too fast is much more than
that
> necessary to form and support life.
>
> And lets' add this point. IF the star is much much bigger
> than the sun, it will burn out as quickly as in a billion years. Even if
life
> began on a planet - it is highly unlikely that it would  progress beyond
a
> simple bacteria like single cell life form. So even if there is life, it
would
> never have the chance to be intelligent life (and we may have had to have
> that coment taking out the dinos before we tree swingers had a chance)

Intelligent life isn't relevant to the thread.  Your initial post only
affirmed that you didn't think different life forms were possible, IIRC.
Come to think of it, maybe that *does* apply ;-)

> More and more restrictions to consider in the origin.

I think we've beat this to death.  But will respond if required.  Regards,
Brett.

> Tom

Regards, Brett
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