We Have No Idea: A Guide to the Unknown Universe

by Jorge Cham

If dark matter has some way of interacting with itself, then dark matter particles could collide and turn into particles of normal matter, just as two normal matter particles can collide to create dark matter.

This is puzzling. The presumption here is that if you can make one thing out of two other things, then you can make this first thing out of these new other things. It may well be the case and the law on the particle level, however, in my experience you can't turn orange juice back into an orange.

things that are far apart will eventually be expanding away from one another faster than the speed of light.

Wouldn't it be, like, illegal from the laws of physics' standpoint?..

Yet you only need three of those twelve to make up everything around you: the up quark, the down quark, and the electron (one of the leptons). Remember that with the up and down quarks, you can make protons and neutrons, and together with the electron, you can make any atom. So what are the other nine particles for? Why are they there? We have no idea.