Why would we expect the rate of expansion of the universe to be slowing down?
A) The gravitational pull of all objects in the universe on each other would lead to slowdown.
B) All expansions after explosions naturally slow down with time.
C) Galaxies feel a kind of friction as they move through space, which slows them down.
D) The greater the distance between two objects (such as galaxies or superclusters), the harder it is to push them farther apart.

Question

Quizplus · Accepted Answer

The gravitational pull of all objects in the universe on each other would lead to a slowdown. As the universe expands, galaxies and other celestial bodies move away from each other, but the gravitational force between them tries to pull them back together, resulting in a gradual deceleration of expansion.

Why Would We Expect the Rate of Expansion of the Universe