[downquark1]

Originally Posted by Sephiroth

If the elementary particles that are generated by collisions in supernovae (or something) create replacement matter, which is one of the theories going round somewhere, then we have the answer.

I don't think that's such a big "if". Neutron Stars, for example, when they explode, Neutrons break apart; particles collide and stuff is formed. Obviously something has to happen when particles collide. Seems logical to me.

Particles are generated in supernova however these are from the energy already existing in the star. Not additional things entering the universe. Or so is understood.