Which of these statements correctly describes the universe for the entire first 380,000 years of its life?
A) The universe was filled with free quarks (not confined inside neutrons or protons).
B) All the fundamental forces of nature were unified into one force.
C) The universe was filled with a sea of nuclear particles undergoing violent reactions.
D) The universe was opaque.

Question

Quizplus · Accepted Answer

The universe was opaque for the first 380,000 years because it was filled with a hot, dense plasma of electrons and protons that scattered photons, preventing light from traveling freely. This period ended with recombination, when electrons combined with protons to form neutral hydrogen atoms, allowing the universe to become transparent.

Which of These Statements Correctly Describes the Universe for the Entire