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

[Robert J. Bradbury]

On Sat, 15 May 2004, BillK wrote:

> That space.com article was a quite brief response from SETI written by
> Seth Shostak. He is Senior Astronomer with SETI.
[snip]
> In his defense I would say that Seth was not writing a technical
> treatise on why alien life would almost certainly be carbon-based. [snip]

I've heard Seth speak and may have even exchanged an email or two
with him.  Seth is a good scientist but it is important to remember
he is an astronomer, not a geologist or a geophysicist.  [I on the
other hand spent many of my childhood and teenage weekends hunting
for interesting rocks in New England and scattered areas around the
U.S. due to my parents interest in the topic.  During that time
I picked up a fair amount of minerology and underlying chemistry.]

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

I know of David's work as well -- he tends to take a more open
minded perspective.  But still he is dealing with sources where
most of the work is focused on the concept that "life" must be
liquid water based.

> 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.

Ok, I will have to review this (and some of the other references).

> 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>

I would be interested in seeing what "natural conditions" are involved.
I have yet to see a discussion of a planet with liquid silicon oceans.
There has been a lot of astronomy discovery lately regarding "hot jupiters".
On these planets most of the lighter elements (including carbon) will be
boiled off -- there has been very little discussion with respect to the
compositionial/geological/"biological" capabilities of such planets.

Only recently there was a proposal that some of the radar reflectivity
anomolous regions on Venus may be due to pools of liquid bismuth or lead.
What kind of "life" could they support?

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

he he he...  I would if I could.  But I think we are going to need a *lot*
more work on what can and cannot be constructed and would constitute "life".
Even after we get through with the various temperature realms we are going
to have to expand that work in multiple directions based on pressures under
which life might be possible.

Robert