Scientists indicate that the first stars probably formed at a redshift z ~ 20.At that time the universe was about
A) 5 percent its current size.
B) 50 percent of Earth's size.
C) as big as an atom.
D) about 100 AU across.
E) the size of a grapefruit.

Question

Quizplus · Accepted Answer

At a redshift of z ~ 20, the universe was about 5 percent of its current size, as redshift is a measure of how much the universe has expanded since the light was emitted.

Scientists Indicate That the First Stars Probably Formed at a Redshift