The ascent of parity-violation: exochirality in the solar system and beyond
We review recent developments stemming from Stephen Mason's work on the origin of homochirality, focusing in particular on the parity-violating energy difference (PVED) between enantiomers. We summarize results of calculations of the PVED--both our own and those of other groups--which show that the natural enantiomers are indeed favoured by the weak force in most cases. The PVED has become important not only to explain the selection of the L-amino acids in the origin of life, but also as a "molecular footprint" of fundamental physics, leading to proposals to derive values of the Weinberg angle from future spectroscopic measurements of the PVED. The new field of exochirality--chirality outside the Earth--is now taking off, with reports of excesses of L-amino acids in meteorites, and proposals to look for homochirality as a signature of life on other planets and even in other solar systems. If it was indeed the PVED that determined life's handedness, we would expect to find L-amino acids rather than D everywhere in the universe.
MacDermott
AJ
Department of Chemistry, Wake Forest University, Winston-Salem, NC 27109-7486, USA. ajm58@cus.cam.ac.uk