An astronomer is evaluating two historical cosmological models of the Universe: the Big Bang theory and the Steady State theory.
The astronomer writes: 'Both theories are compatible with the cosmological redshift observed in distant galaxies. However, the discovery of the Cosmic Microwave Background (CMB) radiation provides definitive evidence that supports only the Big Bang theory.'
Explain why cosmological redshift supports both theories, whereas the CMB radiation is only consistent with the Big Bang theory.