I'm pretty sure that its probably not expanding at all. The expansion is a necessary component of the Big Bang Theory. Since a BBT is rather popular right now the "red shift", Hubble Constant, Cosmic Microwave Background Radiation, Dark Energies, and even the imagined polarized light gravitational threshold is taken as verifying observations.
In the same way religion responds to questions pertaining to things with long odds by resorting to imaginary concepts the Big Bang-Expanding Universe takes observations and attributes the results to an imaginary happenings.
It's too bad but confusing theories with facts seems to be a profitable human condition.