that we have seen the entire range of chemical elements, we can
reasonably ask where they all came from. Were they all made at once
when the universe was formed, or did they develop gradually? This
is outside the mainstream of chemistry, but is too interesting a
line of thought to pass by.
There are two rival theories for the origin of the universe, the
bigbang and the steady-state theories. Both agree that the red shift
in atomic spectra indicates that the universe is expanding rapidly,
and that the original matter of the universe consisted of hydrogen
gas. The big-bang theory proposes that our material universe started
its odyssey approximately 15 billion years ago in a violent fireball
explosion at a billion degrees. In contrast, the steady-state theory
proposes that new hydrogen gas is being created continuously in
interstellar space to fill the gaps in an expanding but infinitely
old universe. Although the issue is not yet completely settled,
it is beginning to look as if the big-bang theory is correct. For
example, radio astronomers have found that our universe is bathed
in electromagnetic radiation around 1mm in wavelength, possibly
the last traces of the big fireball explosion. Nothing can be said
about the state of the universe before this cataclysmic event. It
could have begun then, or could have gone through an unknown series
of earlier expansions and contractions in a "pulsating universe"
If the original universe were made up of only hydrogen, where did
helium and the heavier elements come from?