Recent results from very bright supernovae in very distant galaxies seem to indicate that the expansion of the universe
A) is continuing at a constant rate and has done so since just after the Big Bang.
B) has now stopped and the universe will shortly begin to contract again toward a recollapse.
C) is accelerating (speeding up).
D) is decelerating (slowing down).

Question

Quizplus · Accepted Answer

Recent results from very bright supernovae have shown that they are actually fainter than expected, indicating that they are farther away than predicted. This suggests that the expansion of the universe is accelerating, which is only possible if there is some sort of repulsive force at work (such as dark energy). Option A is incorrect, as a constant rate of expansion would not explain the observed faintness of very distant supernovae. Option B is also incorrect, as there is no evidence to suggest that the expansion has stopped. Option D is also incorrect, as slowing down would lead to a cessation of expansion at some point, which is not what the data show.

Recent Results from Very Bright Supernovae in Very Distant Galaxies