Warp schrieb:
>   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.

You're forgetting lithium, which - along with hydrogen and helium 
(though at a different isotope relation) - is primordial.


> 
>   Coincidentally, the next chemical element a star produces is, surprise
> surprise, carbon.

Strictly speaking, beryllium is produced first; but only few of it ends 
up outside the star, as it will readily be processed further into carbon 
even while it is being "bred".

As another "surprise, surprise", part of the carbon is also processed 
further already, into - guess what - oxygen!


 > 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.)

Not precisely: The breeding of some elements as heavy as iron happens 
earlier already.


>   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.

While there's some reasonable point to that, the argumentation is 
flawed, missing out the fact that during the formation of planets (and 
even stellar systems as a whole) the relation of elements is subject to 
additional pyhsical influences, resulting in much different relations 
between elements in regions accessible to life. For instance, carbon 
makes up for only 0.03% of the mass in earth's crust and atmosphere, 
while silicon accounts for some whopping 25% - only surpassed by oxygen 
(about 50%).

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