Question

what heated up the universe in the first place? type your answer in the boxes

Explanation:

In the early universe, processes like particle - antiparticle annihilation and the decay of unstable particles released a vast amount of energy in the form of radiation, heating up the universe. Also, the expansion and contraction dynamics along with the conversion of potential energy to kinetic energy contributed to the heating.

Answer:

Processes such as particle - antiparticle annihilation, decay of unstable particles, and energy conversions during the early universe's dynamics.