From: Spike Jones (spike66@attglobal.net)
Date: Thu Jul 05 2001 - 21:26:19 MDT

 I am endebted to Anders Sandberg for this idea.

 The air we breathe consists of about 0.2 atmospheres
 of oxygen and about 0.8 atmospheres nitrogen. Divers
 have shown that helium can be substituted for the nitrogen,
 since the body does not use either substance. Helium
 actually works better for high pressure applications, since it is
 a noble gas, and so does not react with or dissolve in the
 bloodstream like nitrogen will do under sufficient pressure.
 In a diving bell, oxygen can be held at .2 atmospheres and
 helium added with no apparent harm or discomfort to the

 The noble gas xenon is chemically similar to helium,
 except for being nearly 33 times denser. If a person
 were to be placed in a pressure chamber with oxygen held at
 0.2 atmospheres, then xenon added until the total pressure came
 up to about 190 atmospheres, the density of the gas mixture
 in the chamber would be about equal to that of water. The
 person would then float. It would simulate weightlessness
 better than being in water, since the xenonaut could breathe the
 medium in which she was floating.

 The partial pressure of oxygen would need to be increased
 somewhat to counteract the tendency of the oxygen to
 float to the top, however there is no reason to doubt that
 humans could swim in xenon. The experience would not
 be exactly the same as floating in your living room however,
 for the pitch of the voice varies as the inverse square root
 of the density of the medium. The xenon swimmer's voice
 would be lowered by nearly 4 octaves, causing her to talk
 like Lurch the butler.

 It would take no extraordinary engineering of pressure vessels
 to accommodate 190 atmospheres. In fact even a relatively
 thin walled container would do fine, if one could arrange to lower
 it into the sea as the pressure is raised. Alternately, the chamber
 could be placed at the bottom of a mile-deep shaft and water could
 be allowed to flow in as the pressure is raised, then drained
 as the pressure is lowered. Even if the pressure needed to be
 dropped quickly, this should not present a problem, since it has
 been pointed out that the solubility of xenon is negligible. The worst
 possible effect would be the expanding xenon would escape from
 the bodily orifices into which it has been forced during the
 pressurization, perhaps creating embarrassing noises.

 The one killer app for weightlessness that eeeeveryone wants
 to try might not work out either, since one likely could not
 breathe fast enough. The dense column of xenon would resist
 changing direction quickly, so the participants could scarcely
 get their breathing rate much above 1 Hz, insuffient for this
 kind of activity. Then there's the problem of sounding like
 Jabba the Hut and Mrs. Hut on their honeymoon, which might
 in itself spoil the mood. Other than that, one could put together
 a really cool sensory deprivation chamber. spike

This archive was generated by hypermail 2b30 : Fri Oct 12 2001 - 14:39:42 MDT