(Note: This is not new information, just a reiteration of a point in the debate between randomness and determinism.)
Fusion is the process in which light elements fuse together to form heavier elements in the cores of stars. Hydrogens (the lightest element) smash together to form helium (the second lightest element), and the process continues all the way up until iron can be formed. This ends up releasing a lot of energy, which is how a star is fueled. But how does this process actually go down?