I'm a computer programmer, not an astronomer or physicist, so forgive me if my question has been addressed before. Is there any data or firm science to indicate that the expansion of the universe is uniform? Could different regions of space be expanding at slightly different rates. Granted, I don't know what might cause such irregularities, but I don't know what cuases the expansion either. I'm not comfortable with the ideas behind dark energy and everything, and cosmology has seemed to get a lot slipperier of late. But most of the stuff I've read on this topic seems to imply that the expansion of the universe is the same everywhere, and I was wondering if there's justification for this assumption.