Observations have led to the conclusion that the Universe contains dark matter, a form of matter that has mass and therefore gravity, but apparently doesn't interact otherwise with 'normal' matter. It's existence is unexplained. Then there is the puzzle of antimatter, a form of baryonic normal matter with charges reversed. The Universe has basically no antimatter, although insignificant quantities can be produced by nuclear reactions. The big bang should have produced equal amounts of matter and antimatter but it didn't; there was enough of an excess of normal matter so that stars and galaxies could form eventually. It's tempting to draw the conclusion that the presence of dark matter and the absence of antimatter are related. I am sure i am not the first to be tempted by that idea. What relevant research does anyone know of. This is not a personal theory by the way, I will be very happy to be told that there cannot possibly be any connection.