[Slick]

Here are some neat things:

There is a theory that even protons are unstable and will decay over time. The postulated half-life is on the order of the age of the universe. There have been experiments to look for a decaying proton, but none have been observed. Would be interesting if true. And would play a part in the ultimate fate of the universe.

If another galaxy were made entirely of anti-matter, we would not be able to tell. Light given off from stars burning anti-Hydrogen and anti-Helium would give the same spectra. Most all of chemistry and physics would work in a similar manner (there would be some minor differences). If there were sentient life there, they would think that the entire universe was made of antimatter for the same reasons. There is a small minority of astrophysicists that are trying to prove this one way or another. The reason that it is even postulated in the first place is that equal amounts of matter and anti-matter should have been produced in the big bang, but as far as we can tell, everything that we can see is matter. Where did all the anti-matter go? If there were a slight imbalance of matter over anti-matter and the rest anihilated, the mass/energy state of the observable universe doesn't add up. Certainly an interesting question.

For SE4 purposes an antimatter race could be made. An antimatter race would have trouble colonizing a planet made of matter, though.

Slick. (casual reader of astronomy stuff)