In stars, helium can sometimes be fused into carbon and heavier elements (in their final stages of life). Why didn't the same fusion processes produce carbon and heavier elements in the early universe?
A)Temperatures in the early universe were never above the roughly 100 million Kelvin required for helium fusion.
B)Helium fusion occurred, but the carbon nuclei that were made were later destroyed by the intense radiation in the early universe.
C)By the time stable helium nuclei had formed, the temperature and density had already dropped too low for helium fusion to occur.
D)No one knows-this is one of the major mysteries in astronomy.

Question

Quizplus · Accepted Answer

By the time stable helium nuclei had formed, the temperature and density had already dropped too low for helium fusion to occur.

In Stars, Helium Can Sometimes Be Fused into Carbon and Heavier