Getting Here from There
Speaking in very broad and loose
terms, after the light elements had been produced in the first
three minutes, there are only about
four key events leading to our present Universe. The first is the transition from
radiation dominated to matter (and dark energy)
dominated evolution. The second
is the recombination transition that produced
the first atoms and decoupled matter from light.
The third is the beginning of structure formation in the new Universe. The fourth is the
production of stars as a consequence of the structure formation,
which then provides a mechanism
for the Universe to produce all the heavier elements.