The isotropy of the cosmic microwave background radiation (same temperature in all directions) indicates that
A) the universe had an early period of inflation in which regions initially in equilibrium were carried to huge separations from each other.
B) the universe did not begin to expand significantly until after the era of recombination.
C) regions that appear to observers to be on opposite sides of the visible universe are in fact in close contact with each other.
D) the universe has always been dominated by matter.

Question

Quizplus · Accepted Answer

The isotropy of the cosmic microwave background radiation suggests that the early universe underwent a period of rapid expansion, known as inflation. This expansion would have stretched regions that were once in thermal equilibrium to vast distances across the universe, explaining the uniform temperature observed today.

The Isotropy of the Cosmic Microwave Background Radiation (Same Temperature