Question

According to the big bang theory, how did the universe begin? what had to happen before atoms could form?

Answer 1

According to the big bang theory, the universe begin when a singularity expanded rapidly. During the expansion, it was too hot and it cooled down before atoms could form.

Answer 2

According to the Big Bang Theory, the universe began when an explosion had occurred 15 billlion years ago. It consist of an explosion of space within itself. Unlike an explosion of bomb where fragments are thrown upward in the theory it was an exact opposite. Atoms formed when the matter and anti-matter were formed together after it has cooled down.