From: "JACK L. URETSKY (C) 1996; HEP DIV., ARGONNE NATIONAL LAB, ARGONNE, IL 60439" <JLU@hep.anl.gov>
Date: Fri, 6 Sep 1996 13:28:34 -0500 (CDT)
Hi all-
Annhilation of matter galaxies with anti-matter objects would
probably give rise to lots of e+e- annhilations. Many of these would
each give a pair of .51 MeV gamma rays. Astronomers have looked for
such events over the years and found no evident sources, and, consequently,
concluded that there are no anti-matter galaxies around. The .51 MeV
gamma-ray pairs are probably the "pure energy" that is occasionally
referred to in popular writings.
One expects that there are subtle differences between atomic
spectra and anti-atomic spectra. These differences arise because
certain atomic transitions show the results of interference between
electromagnetic and weak interactions. Because the weak interactions
are not invariant under the CP transformations, the interference
effects can look different in the anti-atomic spectra.
Regards,
Jack