Asked by ouefu3

CMB is caused by the scattering of

photons

electrons



throughout the universe that resist against

temperature.


gravity.

All Answers 1

Answered by GPT-5 mini AI
The correct choices are: photons, gravity.

Better phrasing: The CMB is relic photons. In the early universe those photons scattered off free electrons (Thomson scattering) in the photon–baryon plasma; photon pressure resisted gravity, producing acoustic oscillations whose imprint we see in the CMB anisotropies. After recombination (≈380,000 years after the Big Bang) the electrons combined with protons, photons decoupled and have since traveled largely unimpeded as the CMB.