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Entropy of a system can be understood as "the number of states that are macroscopically indistinguishable from the state its currently in". (Sean Carroll, "The Big Picture")
Given that the early universe was such a tiny thing with all matter and energy compressed in it, why does it make sense to assume that the universe had extremely low entropy in the past?
How do we know that it was highly non-uniform at that time. I mean, intuitively speaking, how can we even imagine things in such a small space to be "in separate chunks"?