If the universe did indeed start with the big bang why is the universe not spherically symmetric?
As per Wikipedia entry on Big Bang, (and my understanding as well) big bang is the best explanation as of now.
The Big Bang is the scientific theory that is most consistent with observations of the past and present states of the universe, and it is widely accepted within the scientific community.
Basically considering the universe as a sphere (all points equidistant from a center) for any given state at any given point, there should have existed an identical state at the other end (line passing through the center) of the sphere. Also, all points equidistant from the center should have had the same 'state'.
What is the explanation for the 'asymmetry' that we have today?