When I saw your question,I decided to make some research on the big bang theory.Although,its a theory I have heard about before but I never bothered to make some research on it.
The big bang theory explains how the universe came into existence Some of us believe it was created by a supreme being and we believe he is the only one that pulls the string of the universe. Scientists don't lean towards that belief.They believe that the universe started with a small singularity,then inflated over some 13.8 billion years to the cosmos.
The current instruments don't allow scientists to peer back at the universe birth ,much of what we understand about the big bang theory comes from mathematical calculations and models.
Majority of the astronomical community believe this theory why others offer alternative explanations besides the big bang.
The honest truth is the big bang theory doesn't make any sense to me and whoever came up with that explanation is just brain dead.