What do astronomers believe is currently having the largest effect on the change in the expansion rate of the present-day universe?
A) dark matter
B) baryonic (normal) matter
C) dark energy
D) radiation pressure
E) gravity

Question

Quizplus · Accepted Answer

Astronomers believe that dark energy is currently having the largest effect on the change in the expansion rate of the present-day universe. This is based on observations of distant supernovae, cosmic microwave background radiation, and large-scale structure of the universe. Dark energy is a theoretical form of energy that is thought to be responsible for the accelerating expansion of the universe.

What Do Astronomers Believe Is Currently Having the Largest Effect