If the universe is expanding uniformly from a big bang. How do you get galaxies?
It was a live question in astronomy and cosmology, a few years back. If the big bang was perfectly uniform, galaxies would not have formed. It only needed very small variation however, to produce the differences in gravitational attraction that would result in stars and galaxies. Now it’s got even more fun… Observations in the cosmic background radiation, (perhaps the “oldest” piece of evidence that can actually be directly measured) have confirmed lack of uniformity, but not enough to account for galaxies. But this has tied into other data and observations, and prompted the search for dark matter and dark energy.
