(Submitted March 03, 1999)
My question is, since the amount of matter and anti-matter is equal,
why there is a such big different in the ratio of these two things?
You are correct in that we do believe that equal amounts of matter and
anti-matter were created in the big bang. However today we see no strong
evidence for anti-stars or anti-galaxies. When matter and anti-matter meet
they turn into energy, and we know what range of energy this energy
should be seen. Although some anti-matter events are seen, they are not
enough to assume that half the cosmos is anti-matter. The amount of
anti-matter observed can be explained by processes that have occurred
since the big bang.
So where is the anti-matter? There is no reason to think that they could
have/would have separated at the time of the Big Bang, like you suggested.
One theory states that anti-matter decays slightly faster than matter.
Before the matter and anti-matter had a chance to recombine, some of the
anti-matter decayed. So when they recombined, there was some matter left
over which formed our universe.
Hope this helps,
Allie Hajian and John Cannizzo
for Ask an Astrophysicist