Decoupling of Radiation and Matter
This movie illustrates the decoupling of radiation and matter in the early Universe, which occurred
several hundred thousand years after the big bang when the temperature had dropped to several thousand K.
The decoupling
transition made the Universe transparent for the first time, since photons could now travel long
distances without scattering off free electrons. This transition was also essential to the formation of
structure, since matter coupled to photons could not form structure because of continuous interaction
with the photons in the hot plasma.
Usage:
The beginning of this movie describes the state of the Universe before decoupling of
radiation and matter. Click the "Play" button to see a schematic representation
of this time. Click "Play" again to animate the illustration.
Click "Next" to see a description of the relation between radiation and matter
after decoupling occurs. Clicking "Play" at this point shows an animated
representation of this state.
"Home" returns to the beginning of the movie.