nemesis <nam### [at] nospam-gmailcom> wrote:
> Warp wrote:
> > nemesis <nam### [at] gmailcom> wrote:
> >> carbon-based life.
> > 
> >   Has any form of (intelligent) complex life which is not based on chemistry
> > similar to our own, and/or which is not heavily dependent on water, been
> > even seriously conjectured?
> > 
> >   Complex life (ie. anything more complicated than something resembling a
> > virus) requires certain molecular structures, which in turn require certain
> > chemistry and certain chemical elements to appear in certain proportions.

> Carbon-based complex life certainly. ;)

  Matter-based complex life in general. Complex life requires complex
molecules, and you can't have complex molecules made purely from the first
few elements a star produces, ie. hydrogen and helium.

  Coincidentally, the next chemical element a star produces is, surprise
surprise, carbon. After that it only gets more complicated. Carbon is a
rather versatile molecule, besides being abundant in more developed star
systems, which is probably the reason why we are based on it.

  (The elements in-between those are not formed in the core of the star at
all, but in supernova explosions, which means that any of the more complex
chemical elements must come from remnants of old supernovas (which might in
turn have been formed from remnants of even older supernovas, and so on).
AFAIK these stars don't tend to form at the edges of galaxies.)

  I'd say that if you want complex life which is not carbon-based, the
conditions must be even more ideal than for us, so it's not like it makes
things simpler, but on the contrary, it probably makes life even less
likely.

> >   For example, anything even remotely resembling proteins requires molecules
> > with certain structures and certain elements to be stable and feasible. If
> > these elements are not abundant enough, such complex molecules simply cannot
> > form.

> Reality is quite different inside neutron stars.

  It's hard to imagine any kind of life (much less intelligent life) forming
on or in a neutron star. Matter density is way too high for any kind of
regular chemical reactions to happen. Molecules cannot form. Heck, even
atoms cannot form (due to temperature and pressure).

-- 
                                                          - Warp

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