system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How well-supported is the big bang theory? Are we fairly certain it's true?
gpt
Yes, and overwhelmingly so. However, you have to be careful about what you mean when you say "Big Bang Theory", for it is *not* a theory about how the universe was *created*, but rather how it has *evolved*. Despite what anyone will tell you, we physicists currently have no idea how the universe was created.