>>12466435no, the idea that it was just a fluctuation is basically not an viable idea in the modern perspective. for one, quantum fluctuations basically live in the realm of quantum field theory, and rely on a background spacetime already existing. the big bang is the origin of spacetime itself so it goes beyond the branch of physics where quantum fluctuations are studied (quantum field theory).
furthermore, a quantum fluctuation is canonically bound by heisenberg uncertainty and doesn’t go to macroscopic extent. if you are relying on quantum fluctuations then at best you see some small effects, not something giant.
more generally you should think of the inflationary field and/or the cosmological constant. near the big bang, the entirety of the (observable) universe underwent something like a phase change, or several. (think of electroweak symmetry breaking like in the higgs mechanism). quantum fluctuations are localized and do not manifest like this. a quantum fluctuation like e.g. a temporary hole forming in a semiconductor just goes away after a while, whereas the EW symmetry breaking caused a universe-wide transition to a new vacuum state. this is not something you could account for with just a quantum fluctuation, imho
