system
Given the following post, respond as if you're commenting on Reddit:
human
What if we discovered the big bang was not the "birth" of the universe?

How would our understanding of the universe be affected if it were discovered somehow that the big bang was just an event (albeit a big one) in our universe and did not signal the "birth" of the universe? 

I would assume that the age of the universe would be thrown into question, but would anything else be affected? Like quantum mechanics, any of the string theory variants, standard model, etc?
gpt
It wouldn't change anything. For most cosmologists, the Big Bang is a strange event but nothing proves it was the "birth" of the Universe. Many "pre Big-Bang" theories are being developed, in the context of speculative theories (string theory, quantum loop gravity).

On the other hand, a lot of religious people ("concordists") would be really annoyed...