Re: Left-handed molecules [was Re: SOC: The Monkey God]

From: John Clark (
Date: Sun Jan 23 2000 - 09:20:54 MST

Robert Bradbury <> Wrote:

>My impression was that the favored reason for left-handed molecules
>being dominant is the effects of polarized light in gas clouds.

The polarization of light is indeed slightly rotated when it goes through
a neutral gas, very slightly; think of the angle your hand at a distance
of 600 miles. It's also true that the weak nuclear force causes the
atomic nucleus to slightly attract right handed electrons and slightly
repel left handed ones, thus when the electrons are captured to form
atoms and molecules the two different bonds have very slightly different
energy levels. The lowest energy level of anything is almost always
the most common, so Stephen Mason calculated in 1985 or so that
L amino acids, the sort used by life, should indeed outnumber the
D amino acids. Why has this effect never been observed in the
chemistry lab when amino acids are synthesized? Because they
would be outnumbered by only one part in 10^17.

That's a pretty small effect, I think the true explanation for the domination
of L amino acids may be much simpler, pure blind chance, and the fact
that once a standard is set it's very difficult to change.

     John K Clark

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