Why is flatness a problem in cosmology?
A) The total amount of known matter (even if dark matter is included) is not enough to make the universe flat.
B) The universe appears to be flat to within observational error, yet the universe is expanding, and it is impossible for an expanding universe to be flat.
C) The universe appears to have a hyperbolic geometry to within observational error, yet the universe is expanding, and expanding universes have to be flat.
D) Matter is known to create bumps in the geometry of spacetime; therefore, the universe cannot be flat.

Question

Quizplus · Accepted Answer

The problem of flatness in cosmology arises because the observed total amount of matter, even when dark matter is included, does not seem sufficient to account for the flatness of the universe as suggested by observations.

Why Is Flatness a Problem in Cosmology