Why is cosmic background radiation used as evidence of the big bang theory of the origin of the universe? A. It corresponds to the temperature predicted by the big bang theory. B. It is emitted from a black hole at the center of the universe. C. Its wavelength is getting shorter, so it must be very old. D. It is not very common, so it must be running out.

Answer 1

The correct answer is A. It corresponds to the temperature predicted by the big bang theory.

Cosmic background radiation, specifically the Cosmic Microwave Background (CMB), is the remnant radiation from the hot, dense state of the early universe. The properties of this radiation, such as its uniform temperature of about 2.7 Kelvin and its spectrum, match the predictions made by the Big Bang theory. This serves as strong evidence that the universe underwent a hot and dense beginning before expanding and cooling over time.