Part of the problem with the classic big bang theory apparently arises from its base in the Schwarzchild metric and its simplistic view that assumes such conditions as a vacuum, zero electric charge, zero angular momentum, and a universal cosmological constant of zero.
Stephen Hawking acknowledges the problems and says on this topic:
the universe, and time itself, had a beginning in the Big Bang, about 15 billion years ago. The beginning of real time, would have been a singularity, at which the laws of physics would have broken down. Nevertheless, the way the universe began would have been determined by the laws of physics, if the universe satisfied the no boundary condition. This says that in the imaginary time direction, space-time is finite in extent, but doesn't have any boundary or edge. The predictions of the no boundary proposal seem to agree with observation. The no boundary hypothesis also predicts that the universe will eventually collapse again. . . .
The expansion will start with an inflationary phase, but the collapse will not in general end with an anti inflationary phase. Moreover, the small departures from uniform density will continue to grow in the contracting phase. The universe will get more and more lumpy and irregular, as it gets smaller, and disorder will increase.
1) The classic big bang theory describes a singularity wherein the laws of physics break down. I'm concerned that this allows one to sweep any inconveniences under the rug. INFINITE energy and mass in a single point? No problem, because physics laws have broken down. Conservation of angular momentum problem? No problem, because physics laws have broken down. (This would be an even greater issue if Hawking is right in the second part of the quote above that the contracting universe were more lumpy and irregular, since that would lead to GREATER angular momentum)
2) The best hawking can propose to reconcile the problems is to map time/space and the universe onto an imaginary timescale and a finite but unbounded space. But I'm unconvinced that this resolves the gaps: the infinite energy, infinite compression, and failure to account for what may be the largest force in the universe, angular momentum. It merely places the big bang in a larger imaginary
time and space context. As he describes it, instead of an infinitely compressed big bang and nothing outside of it, imagine a big bang at the north pole that expands over the surface of the earth (a finite but unbounded surface). His imaginary dimensions echo what I posed at the beginning this question: "does it become real and something that our universe can expand into only through the power of our imagination?"