Question

1. how does the big bang theory explain the existence of cosmic background radiation?

allan a. et al chapter 30 stars, galaxies, and the universe section 4 the big bang theory transparency 134 timeline of the big bang holt mcdougal earth science holt mcdougal larson, hawkes publishing co., 2010.

Explanation:

The Big Bang Theory posits that the universe began from a hot, dense state and expanded. As the universe expanded and cooled, the initial high - energy radiation (from the early, hot universe) should have cooled down over time. Cosmic background radiation is predicted to be the residual heat left over from the Big Bang. When the universe was very young (about 380,000 years after the Big Bang), it became transparent to radiation as atoms formed (recombination). The radiation that was present at that time, which was in thermal equilibrium with the matter, has been expanding and cooling with the universe ever since. This leftover radiation is the cosmic background radiation, and its properties (like being nearly uniform in all directions and having a black - body spectrum with a temperature around 2.725 K) match the predictions of the Big Bang Theory.

Answer:

According to the Big Bang Theory, cosmic background radiation is the residual thermal radiation left over from the early stages of the universe. In the early, hot and dense universe, radiation was in thermal equilibrium with matter. As the universe expanded and cooled, around 380,000 years after the Big Bang (recombination), atoms formed and the universe became transparent to radiation. The radiation present at that time has been expanding and cooling with the universe, resulting in the cosmic background radiation we observe today (with a nearly uniform temperature of ~2.725 K and a black - body spectrum), matching the theory's predictions.