THE long-standing mystery about how life came to be left-handed may finally
have been solved.
Many molecules have alternate forms that are mirror images, like our left and
right hands. Yet all life on Earth uses only left-handed amino acids to make
proteins.
It had been suggested that polarised light was to blame, because left
and right-handed molecules absorb polarised light differently. In some reactions
driven by light, this causes one form to break down faster, leaving a larger
proportion of the other. But sources of polarised light in the Universe are rare
(Â鶹´«Ã½, 27 November 1999, p 20).…
