Hi there. I am a layman, and I have a question. As far as I have gathered, the prevalent view in cosmology is that the universe appeared as a result of the Big Bang, which in turn occurred due to expansion of singularity. Ok. Some go further and propose that singularity appeared through quantum fluctuation. Herein lies my question. Assuming there was no spacetime 'before' the Big Bang, where did these quantum fluctuations happen? In a vacuum that preceded spacetime? I always thought that even vacuum had to be in space. PS: since we're on the topic, I'd also appreciate if you could throw in some recommendation of a pop-physics book which deals with these questions. I have read brief history of time, long ago, but that's about it.