What if the world of dark matter was a mirror of our own, just with a broken set of rules? That might explain why dark matter appears to be so abundant yet invisible, a new theory suggests.
The researchers posited that for every physical interaction in normal matter, there's a mirror of it in the world of dark matter. This would be a new kind of symmetry in nature, connecting the normal and dark matter worlds, the researchers said. In the paper, the researchers point out another strange coincidence. In the physics of normal matter, a neutron and proton have almost exactly the same mass, which enables them to bind together and form stable atoms. If a proton was just a little bit heavier, it would be totally unstable and decay in only a few minutes, making the formation of atoms impossible. In this imaginary scenario, the universe would be left with a sea of free-floating neutrons.