In the past several billion years the rate of expansion of the universe has
A) been constant.
B) decreased.
C) increased.
D) varied irregularly.

Question

Quizplus · Accepted Answer

Observations of distant supernovae and the cosmic microwave background radiation indicate that the rate of expansion of the universe has increased over time, which suggests the presence of a mysterious force called dark energy.

In the Past Several Billion Years the Rate of Expansion