Elementary...

I dropped science early at school and never got to grips with the periodic table. Poul Anderson gives us some information in "Lodestar" and repeats it in Mirkheim.

Creation began with the primordial element, hydrogen-1, the smallest atom, a single electron orbiting a single proton. The primordial fireball fused some hydrogen into helium which, I gather, comprises two electrons orbiting two positrons and usually also two neutrons. (See here.) Heavier elements are fused by adding protons to a nucleus. Hydrogen condensed into stars which fused elements heavier than helium. The shedding of gas by red giants and the explosion of stars as either novae or supernovae spread heavier elements through space where they condensed into a second generation of stars and of planets bearing life. Proteins use carbon; bones use calcium; animals breathe oxygen.

Although small stars fuse no element heavier than iron, supernovae fuse copper, gold and uranium. Too many protons in a nucleus generate repulsive forces counteracting attraction and destabilizing the nucleus. However, for some reason that is unexplained, nine elements with atomic numbers 114 to 122 are stable, only weakly radioactive and highly valuable as catalysts, conductors and components in strong alloys.

Observations

Since "...to this day [hydrogen-1] comprises the overwhelming bulk of matter in the universe...," ("Lodestar," p. 388) many more universes can be created from existing materials.

Empirical scientists have achieved what rationalist philosophers attempted, discovered the components of reality.