From: "JACK L. URETSKY (C)1998; HEP DIVISION, ARGONNE NATIONAL LAB ARGONNE, IL 60439" <JLU@HEP.ANL.GOV>
Date: Fri, 5 Feb 1999 13:47:26 -0600
In quantum mechanics, fields interact non-linearly. A famous
experiment lets photons hit the coulomb field of a nucleus to produce
neutral pions. This is the time reversed decay of the pi-0 into 2
gammas.
Regards,
Jack
"I scored the next great triumph for science myself,
to wit, how the milk gets into the cow. Both of us
had marveled over that mystery a long time. We had
followed the cows around for years - that is, in the
daytime - but had never caught them drinking fluid of
that color."
Mark Twain, Extract from Eve's
Autobiography