I often find that in books or lectures discussing the arrow of time and entropy and trying to explain how we have such complexity that the explanation is that when the universe was in it's early stage and was just a relatively small ball of apparently high entropy gas that it was in fact very low entropy because of gravity. But that is not what I'm concerned about. What I find confusing is that in books or lectures discussing time, or Boltzman or entropy for example Brian Green's The Fabric of the Cosmos or Sean Carroll's From Eternity to Here, that we do not understand how it is that the Universe began in a relatively low entropic state, compared to now. The thing is I don't understand why it's a puzzle, because if the Universe began as something that was very much smaller than the size of a proton, then that would mean that all the mass and all the energy was contained in that tiny area at one point, so wouldn't it necessarily follow that if that were the case how could it be anything but a low entropic state? For example of you got a big box of gas as big as a house the gas would be in a high state of entropy, but if you then squashed that box down to the size of a pea, it would have to be in a much much lower state of entropy? So what is puzzling about the low entropy of the early Universe how could it not be low if it was all crammed into such a small space? My knowledge of this comes from books and lectures like the ones I've quoted and other similar books.