What did the cosmic microwave background tell cosmologists about the early universe?
A) Nothing; it is a product of the black hole in the center of our own Galaxy.
B) The horizon problem, in that the microwave background is almost too isotropic
C) The discovery of dark energy and its role in accelerating the universe
D) The discovery of relativistic redshifts and the Big Bang
E) The dark matter in the universe is mostly baryonic in nature, for a closed Big Bang.

Question

Quizplus · Accepted Answer

The almost perfect isotropy of the cosmic microwave background raises the horizon problem, which asks why parts of the universe that were never in contact have the same temperature. This led to the development of the theory of cosmic inflation to explain this phenomenon, as well as other features of the early universe.

What Did the Cosmic Microwave Background Tell Cosmologists About the Early