The oldest photons we detect in the universe come from
A) distant quasars.
B) the first generations of stars.
C) the most distant galaxies.
D) the epoch of recombination.
E) the first supernovae.

Question

Quizplus · Accepted Answer

The oldest photons we detect are from the Cosmic Microwave Background Radiation, which originated during the epoch of recombination, when electrons and protons first combined to form neutral hydrogen, allowing photons to travel freely through space.

The Oldest Photons We Detect in the Universe Come from