The early universe had a large flux of neutrinos and antineutrinos. What happened to them?
A)They annihilated to produce protons and antiprotons.
B)They are still present as a cosmic background.
C)They were absorbed by matter, giving it some of the additional energy required for inflationary expansion.
D)They were absorbed by neutrons to form protons and electrons.

Question

Quizplus · Accepted Answer

Neutrinos and antineutrinos are extremely weakly interacting particles, which means they do not get absorbed by matter easily. They would have continued to travel through the universe without interacting significantly with other particles, forming a cosmic background of neutrinos. This relic neutrino background is still present today and is considered a "hot" component of dark matter in the universe.

The Early Universe Had a Large Flux of Neutrinos and Antineutrinos