Tests of Big Bang Cosmology

The Big Bang Model is supported by a number of important observations, each of which are described in more detail on separate pages:

The expansion of the universe

Edwin Hubble's 1929 observation that galaxies were generally receding from us provided the first clue that the Big Bang theory might be right.

The abundance of the light elements H, He, Li

The Big Bang theory predicts that these light elements should have been fused from protons and neutrons in the first few minutes after the Big Bang.

The cosmic microwave background (CMB) radiation

The early universe should have been very hot. The cosmic microwave background radiation is the remnant heat leftover from the Big Bang.

These three measurable signatures strongly support the notion that the universe evolved from a dense, nearly featureless hot gas, just as the Big Bang model predicts.