[extropy-chat] Scientists Confront 'Weird Life' on Other Worlds

[BillK]

On Thu May 13 20:14:25 MDT 2004 Mike Lorrey wrote:
> And carbon can form what? 8 or 12 bonds? That's a good reason right
> there: you get more diversity in possible bonds, thus a more complex
> chemistry capable of interacting in exponentially greater numbers of
> ways.

NASA seems to agree with you, Mike.
<http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/980221b.html>
Scientists have occasionally speculated that life could be based on an
element other than carbon. Silicon, being the lightest element with an
electronic structure analogous to that of carbon (having a half-filled
outer shell with 4 unpaired electrons), is the most likely candidate
mentioned. However, carbon's tendency to form the long chains and rings
that form the basis for organic compounds that at some level of
complexity begin to self-replicate is unique. Also, because older stars
naturally produce carbon, along with nitrogen and oxygen (its neighbors
on the periodic table), it is relatively abundant in the universe.

Also space.com
<http://www.space.com/searchforlife/seti_carbon_040415.html>
Silicon may be carbon’s chemical cousin, but it’s a poor relation.
Because the silicon atom is larger, its bonds with other elements are
weaker. While carbon hooks up with two oxygen atoms to make carbon
dioxide, a nice waste product for both humans and SUV’s, the silicon
equivalent, silicon dioxide, quickly assembles itself into a crystalline
lattice. It’s better known as sand, and would make exhaling a gritty
experience. The weaker bonds of silicon also preclude the easy formation
of those long, same-atom molecular chains that underlie many biological
compounds. A slew of complex carbon-based molecules are easily produced
in comets, interstellar dust, and university glassware. But if you check
out nature’s chemistry lab for silicon (consider volcanic lava), the
products are far less interesting.


Non-carbon based life-forms seem to be mainly sf speculation in order to
make a good story. Possible life on the surface of a sun? Life which
creates an atomic reactor inside it's body for energy? Yea, sure.

BillK