3.1. Baryogenesis
The baryon to photon ratio
is determined during
baryogenesis
[3],
[36],
[37].
It is not known when baryogenesis occurred.
Sakharov [38]
noted that three conditions are required:
different interactions for matter and anti-matter (CP violation),
interactions which change the baryon number, and
departure from thermodynamic equilibrium.
This last condition may be satisfied in a first order phase transition,
the GUT transition at 10-35 s,
or perhaps the electroweak transition at 10-11 s.
If baryogenesis occurred at the electroweak scale, then future measurements
may lead to predictions for
, but if,
alternatively, baryogenesis is at the GUT or inflation scale,
it will be very hard to predict
(J. Ellis personal
communication).
The matter/anti-matter asymmetry of the universe (the
value)
is attracting discussion in the popular science press
because of the inauguration of major experiments to study CP violation in
B mesons ([41],
[42];
Economist, May 8 1999, 85-87).