The CMB is a snapshot of the radiation in the universe at a redshift of z ≈ 1,000 when the universe was:
A)1,000 times smaller than it is today
B)10 times smaller than it is today
C)two times smaller than it is today
D)the same size as it is today
E)10 times larger than it is today

Question

Quizplus · Accepted Answer

The cosmic microwave background (CMB) is a snapshot of the radiation present in the universe roughly 380,000 years after the Big Bang, when the universe was about 1,000 times smaller than it is today. Therefore, choice A is the best answer.

The CMB Is a Snapshot of the Radiation in the Universe