All our atoms are as old as the universe. (Matter cannot be created nor destroyed - elementary Physics)
Afterglow of the Big Bang. That is, if you accept the theory.
“volume of a sugar cube.” How big would the sugar cube be if you took out all the ‘space’ between the atoms?
Golly gee whiz! go easy on the revelations here, my feeble brain might get overwhelmed.
Matter can be converted to pure energy and vice-versa - quantum (non-elementary) physics.
Not all of our atoms are as old as the universe, because some of the heavier atoms in our bodies formed in stars younger than the universe, mostly iron and other heavy elements. However, it is true that all the *matter* in our bodies is as old as the universe.
matter can be changed into energy, though, E=MC2 (squared). Atoms can be split, resulting in two new atoms. Atoms can be fused, resulting in one new atom. An atom's electron can be lost or gained, resulting in an ion. Does this count? We'll let that one go.