State two characteristics of the cosmic microwave background (CMB) radiation.

1.

2.

Explain how CMB radiation is evidence for the Big Bang model of an expanding universe.

electromagnetic radiation in the microwave region;

black body radiation (at a temperature of about 3 K);

(almost) isotropic/uniform radiation;

radiation that fills the universe/exists everywhere/has no obvious point of origin;

CMB radiation was a prediction of the Big Bang model;

CMB “temperature” is consistent with a universe that has cooled from an initial hot state;

CMB wavelength is consistent with a universe that has expanded from an initial hot, dense state;

CMB isotropy/uniformity is consistent with its origin in the very early universe;