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

[Eugen Leitl]

On Sat, May 15, 2004 at 10:50:15AM -0700, Mike Lorrey wrote:
> http://www.daviddarling.info/encyclopedia/A/ammonialife.html
> 
> David is pretty smart here. I'd sooner believe in ammonia replacing
> water on a high pressure planet than I would living silicon rocks.

In regards to alternative chemistries, consider this: all congealed star drek
is roughly the same in element abundancy (there are some minor variations in
the processing degree).

In regards to silicon, if you have enough of it you're up to your gills up in
silicates. Silicates are very stable, have lots of structural diversity, and
can even act as precursors/catalysts of life, but not much further.

Life's CHNOPS (it does use other elements, Si include, though), and 
there's a reason for that.

Silanes are much too unstable in wet environments. They're lousy at chains
and cages, anyway. As Alejandro (?) has said, they don't do chains very well.
Carbon is unique in that it does very stable pure-C polymers, and
heteropolymers with lots of other elements.

In closing, I suggest we hang on for chemistry date from Titan and
Jovian/Saturnian system in general. These large-scale alternative-chemistry
reactors are pretty unique, and protolife had plenty of opportunities to
adapt to new substrate via very frequent material transfer through impact
ejecta crosscontamination.

In regards to solvent, it has to be polar, and has to show large area in
phase diagram in liquid under native conditions, and if it does phase changes
under native conditions the solid should be less dense than liquid so it
should float.

You might notice that water over ammonia over hydrogendisulfide has very
interesting properties. By virtue of abundancy water should win hand-down
anyway.

So I will eat this keyboard if you will fetch me a native life based on
anything other than carbon, based on anything other than water (maybe -- just
maybe -- ammonia).

-- 
Eugen* Leitl <a href="http://leitl.org">leitl</a>
______________________________________________________________
ICBM: 48.07078, 11.61144            http://www.leitl.org
8B29F6BE: 099D 78BA 2FD3 B014 B08A  7779 75B0 2443 8B29 F6BE
http://moleculardevices.org         http://nanomachines.net
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 198 bytes
Desc: not available
URL: <http://lists.extropy.org/pipermail/extropy-chat/attachments/20040515/3ca99688/attachment.bin>