Re: Shuttle lift-off questions

In article <44aed1e4.970809816@xxxxxxxxxxxxxxxx>, kmuldrezw@xxxxxxxxxxxx (Ken Muldrew) writes:
mmeron@xxxxxxxxxxxxxxxxxx wrote:

In article <44aea1c4.958500411@xxxxxxxxxxxxxxxx>, kmuldrezw@xxxxxxxxxxxx (Ken Muldrew) writes:
mmeron@xxxxxxxxxxxxxxxxxx wrote:

In article <e8lb1h$8qk_001@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx>, jmfbahciv@xxxxxxx writes:

Does this have anything to do with Ken's comment about
biology is all about surfaces? I'm still thinking about that one.

This one is more complex. But, in a nut shell, biology is about
structures in liquid. and stuff is happening on the surfaces of the
structures. But it could've been a different liquid than water.

Just to push the "nut shell" analogy a bit further, because of the
hydrogen bonding of water (which is also responsible for its freezing
behavior), long chain aliphatic compounds (oils) are not soluble. But
if you make a molecule with one part that hydrogen bonds and the other
part a hydrocarbon tail, then you can make bilayer membranes. These
are the structures that provide the surfaces for biology.

Now, what could play same role in a different working liquid (say,
ammonia)?

Hmmm...ammonia has weaker hydrogen bonding than water so you might
think that the same amphipathic molecules would work. But to form
stable membranes and vesicles, it should take at least 10kT to disrupt
the structures and I don't think ammonia will do it. I suppose the
temperature could be lowered but then the oils become waxy and you
lose the liquid properties that are necessary for movement within the
membrane. If you shorten the aliphatic tails then they become more
fluid but once again you lose stability by lessening the amount of
solvent that is displaced by the oil-phase of the membrane.

Do you have something in mind?

Nothing special, really, I just recall some science fiction discussion
from many years ago about possible alternatives to water based life
and I remember ammonia being mentioned. But the details are very hazy
by now.

Mati Meron | "When you argue with a fool,
meron@xxxxxxxxxxxxxxxxx | chances are he is doing just the same"
.

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