On Sun, Oct 18, 2020 Alan Grayson <[email protected]> wrote: *> If the very early universe is a hot photon gas, wouldn't that be a very > high entropy initial condition?*
That would be true if gravity was not an important factor as is the case for most experiments we can produce in the lab where gravity can be safely ignored, but in the very early universe gravity was enormously important and can not be ignored. The early universe was very smooth but, due to random quantum variations, not perfectly smooth. So some parts of the universe had very slightly more mass/energy than other parts. As time progressed, because of gravity, the slightly denser regions pulled in slightly more particles into themselves than the slightly less dense regions did, and so those tiny variations started to grow larger. As a result of that growth of variations entropy increased and the Universe never again reached the very low entropy level it had when it was young. *> For a given volume, the entropy is what it is, related to the possible > microstates as given by Boltzmann's formula. If the volume increases, the > entropy increases, and it starts at a maximum level depending on the volume > of the very early universe. So I see no distinguishing the Actual Entropy > from the Maximum Possible Entropy. AG* The point is that if the universe is expanding (and accelerating) then there is no such thing as the universe having a Maximum Possible Entropy, whatever entropy value you give me no matter how large I can show you a time when the universe will have an even larger entropy. John K Clark -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/everything-list/CAJPayv1ypibppLzRSQXrgKHLU3TB3KuveknctpVrhGjGy9iwXg%40mail.gmail.com.
