What was the significance of the end of the era of nucleosynthesis, when the universe was about 5 minutes old?
A)It marks the time at which the first stars formed.
B)The basic chemical composition of the universe had been determined.
C)The proportions of dark matter and luminous matter had been determined.
D)It marks the time at which the expansion of the universe had settled down to its current rate.

Question

Quizplus · Accepted Answer

At the end of the era of nucleosynthesis, about 5 minutes after the Big Bang, the basic chemical composition of the universe had been determined. This is because the fusion of protons and neutrons to form the nuclei of simple elements like hydrogen, helium, and lithium had occurred during this era, and their proportions had been set. This early composition has persisted throughout the universe's history, with later processes like supernova explosions and stellar evolution modifying it only slightly.

What Was the Significance of the End of the Era