Well the laws of physics don't change, not at least in the visible universe, there are black-holes of course but they governed by rules we do not yet understand rather than the lack of them.
The atoms making up the molecules and cells in your body will disperse over time and eventually be part of other organisms. Then after the sun expands and basically vaporizes the earth sending everything along with its own outer layers on a trajectory into deep space, perhaps to form gas clouds and collapse forming new stars.
A calming thought, basically every atom in your body and our planet, apart from hydrogen and helium most likely formed in cores of supermassive stars that went supernovae billions of years ago. So you're pretty much made from star dust.
