One of the postulates of the Big Bang theory taken from GR says that the universe is not expanding into anything, but that it's the metric that's expanding. The idea of metric expansion says that two points in space remain at the same spots but the distance between them grows(while these two points remain at their same locations). Extrapolating this back to the Big Bang we have a universe that did not change in size since the Singularity if we were able to view it from the "outside". If such an "outside of the universe" viewpoint were possible, the universe would still be a zero-dimensional "point"(aka Singularity), that only when viewed from the inside would show internal metric expansion and size that appears to be different than zero. What are your thoughts on this?