Does anti-matter exist in a different time stream?

Question

according to Richard Feynmann

Answer 1

A different time stream?  What does that mean?

When the universe was created there could have been exactly equal amounts of matter and antimatter created.  If that were the case then the brand new universe would annihilate itself in a burst of energy.

But there is a probability (based on quantum mechanics) that there will be a slight difference in the amount of matter and antimatter, say 51 percent matter and 49 percent antimatter.  In such a universe 49 percent of the matter will be annihilated by coming into contact with antimatter, leaving 2 percent matter.  That remaining matter would make up a universe like ours.

Small amounts of antimatter are produced continuously during nuclear decay (positrons) but they don't get far before running into electrons which results in annihilation and a burst of gamma rays.