Where did the elements heavier than hydrogen and helium of the universe come from and how?
Very small amounts of these elements formed out of the primordial plasma, which gave rise to mostly hydrogen, some amount of helium, trace amounts of lithium and beryllium and essentially none of anything else. Most of the lithium and beryllium in existence now, as well as practically all the heavier elements, were formed as a result of fusion processes going on in the cores of giant stars and in the supernova explosions those stars create when they die. Small stars like the Sun only fuse hydrogen to helium during their main sequence lifetimes, but eventually fuse helium into carbon when they die, although almost all of this carbon stays in the white dwarf stellar remnant and is not blown out into space. Larger stars fuse successively higher elements one after the other as they age and their cores become denser, and eventually have several layers in their cores where different kinds of fusion are occurring. Finally the central part of the core has enough energy to fuse iron, which resu
