Distance/velocity relationship: distant galaxies are moving away from
us, with speeds which increase linearly with distance
Chemistry: the universe is almost entirely hydrogen and helium, in a
mixture of roughly 12 H atoms to 1 He atom
Cosmic Microwave Background: no matter where we look in the universe, we
see radio waves which look like those radiated by a blackbody at about 2.7
degrees above absolute zero. There are tiny (one part in 10,000) variations
in the brightness of this radiation on scales of a degree or so
Is there any way to tie all these pieces of data together? Yes! One model
which can explain them all is called the Big Bang model. The name was
coined by a scientist who didn't like the theory and tried to make it sound
silly.
