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

[BillK]

On Fri May 14 14:55:21 MDT 2004 Robert J. Bradbury wrote:
> And you might want to leave out the space.com
> references since we can assume from the above THAT THEY HAVEN'T DONE
> THEIR HOMEWORK...

That space.com article was a quite brief response from SETI written by
Seth Shostak. He is Senior Astronomer with SETI.
Bio:
Seth is an astronomer involved with Project Phoenix, and has a BA in
physics from Princeton and a PhD in astronomy from Caltech. But he's
also responsible for much of the outreach activities of the Institute.
He edits the newsletter, gives talks and writes magazine articles (and
books) about SETI. He also teaches a half-dozen informal education
classes on astronomy and other topics in the Bay Area.


In his defense I would say that Seth was not writing a technical
treatise on why alien life would almost certainly be carbon-based. He
just, rather humorously, gave a few reasons to effectively say that
non-carbon-based life is very unlikely, though not necessarily
impossible, considering the size of the universe.

One good resource is:
The Encyclopedia of Astrobiology, Astronomy, and Spaceflight
<http://www.daviddarling.info/encyclopedia/ETEmain.html>

Silicon-based life is discussed here:
<http://www.daviddarling.info/encyclopedia/S/siliconlife.html>
This gives a more technical description of the problems involved in
using silicon to support life.

The NASA Astrobiology Institute has more info:
<http://nai.arc.nasa.gov/index.cfm>

Here NAI Astrobiologist Ben Clark says much the same:
<http://nai.arc.nasa.gov/astrobio/feat_questions/silicon_life.cfm>

Scientific American got Raymond Dessy, a professor of Chemistry at
Virginia Polytechnic Institute and State University in Blacksburg, Va.
to write a similar response:
<http://www.sciam.com/askexpert_question.cfm?articleID=0004212F-7B73-1C72-9EB7809EC588F2D7&pageNumber=1&catID=3>

There is a research paper online showing that:
"Silicon simply cannot form as diverse a range of molecules as carbon
under natural conditions; however silicon does have unique properties
which carbon does not possess, such as a high affinity for oxygen and
the ability to form zeolitic mineral structures."
<http://www.cmste.uncc.edu/papers/Can%20Silicon%20Based%20Life%20Exist.doc>


None of the above however, prove that silicon-based life is absolutely
impossible under all conditions. After all it is very difficult to prove
a negative (as all UFO believers know). But it does indicate that
silicon-based life at best will be very much rarer than carbon-based
life.

Show me a living rock, even one above ~2504 deg K - that's all.  ;)

BillK