Question

Recent measurements of the expansion rate of the universe reveal that the expansion rate of the universe is doing something astronomers did not expect. What is that?

A) The measurements show that the universe may not be expanding at all.
B) The measurements show that the universe may be shrinking rather than expanding.
C) The measurements show that the expansion is accelerating, rather than slowing under the influence of gravity.
D) The measurements indicate that the universe is at least 30 billion years old, meaning that more than 10 billion years passed between the Big Bang and the formation of the first stars and galaxies.
E) The data show that the expansion rate varies widely in different parts of the universe

Answer 1

The unexpected discovery in recent measurements is that the universe's expansion is accelerating due to dark energy, contrary to the former expectation that gravity would cause the expansion to slow.

Step-by-step explanation:

Recent measurements of the expansion rate of the universe have indicated that the expansion is doing something astronomers did not expect. Instead of the rate of expansion slowing due to the gravitational attraction between galaxies, these measurements show that the expansion is indeed accelerating. Earlier theories predicted that the expansion should be decelerating because of gravity's pull, expecting the mutual attraction between galaxies to slow the expansion over time. However, a modern discovery involving the study of supernovae suggests that this rate of expansion has sped up, indicating the presence of a repulsive force known as dark energy.