How do we Know That Half of the Galaxies are not Anti-matter?
Most recent answer: 07/07/2016
- Joe Lozowski (age 55)
South Lake Tahoe, CA USA
Good question. Astronomers now search the skies for all kinds of signals, microwaves, x-rays, light, at all kinds of different wavelengths and frequencies. Now if there were an anti-galaxy it would very likely have an ordinary-matter galaxy neighbor. At the boundary between these two there should be annihilation radiation which results from matter -- anti-matter collisions. No particular radiation of this type has been seen.
The reason why there seems to be only matter and not much anti-matter in the observable universe is a complete mystery. The laws of physics as we know them look almost completely symmetric between the two. Maybe we will figure it out some day.
(published on 07/07/2016)