Quantum Field Theory Can't Explain the Big Bang?

Quantum field theory can't explain the Big Bang as like a singularity, right? You can do quantum field theory on curved space or on expanding space. But what we don't know how to do is how to have those fields themselves create that curved space which is what you sort of need for quantum gravity. So it's possible to do quantum field Theory on other funny spaces or other dimensions or expanding spaces that gets very, very complicated. Can it even then explain the BigBang? Or not at all?