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If we imagine the universe as a quantity of ideal gas, expanding into a pre-existing void (not including dark energy expansion yet), this expansion is easily explained as being "driven" by entropy: w, and therefore log(w), increases as the gas particles are distributed over more space.
If instead we view the gas as already expanded to fill some container, but then the container begins to expand (only dark energy expansion now), presumably the larger volume allows for greater log(w) in the same way. It seems to me that there shouldn't be any difference between expanding a container by standard means or by spatial expansion. But, if there is no difference, the entropy increase of either such system should be a function of the amount of gas in the system.Does the entropic contribution to the free energy required for expansion affect the rate of expansion on any local basis? (is it more favorable for hot and/or dense regions of the universe to expand than for cold and sparse regions? is there any observation of different rates of expansion in different parts of the universe?)
Quote from: chiralSPOIf we imagine the universe as a quantity of ideal gas, expanding into a pre-existing void (not including dark energy expansion yet), this expansion is easily explained as being "driven" by entropy: w, and therefore log(w), increases as the gas particles are distributed over more space.I don't understand how you see the gas expanding.
If the expansion of the gas is an isentropic process then the entropy remains constant. An isentropic process is a process in which entropy remains constant. Such processes occur during adiabatic processes. So if you can find an argument which concludes that such a process as you've described is an adiabatic one then the entropy will remain unchanged. Unfortunately I don't know the answer to such a question. Sorry.
... so it shouldn't matter how the process occurred, only that it did.
If a process is isentropic and reversible it must be adiabatic. But it does not follow that adiabatic proceses are isentropic, or that isentropic proceses are adiabatic.
And if you are saying that entropy is not a state function: ...
Quote from: chiralSPOIf a process is isentropic and reversible it must be adiabatic. But it does not follow that adiabatic proceses are isentropic, or that isentropic proceses are adiabatic.Yes. I know that all too well. I simply made a mistake when I wrote that post. I've now corrected it.
I don't think whether a process is adiabatic or not has anything to do with the change in entropy associated with that process. Entropy is a state function, so it shouldn't matter how the process occurred, only that it did.
Quote from: chiralSPO... so it shouldn't matter how the process occurred, only that it did.Not true at all. However to explain why would require an in-depth discussion of thermodynamics and I hate thermodynamics. Lol! Plus it's been a long long time since I've thought about it so I've forgotten a great deal of it. However this is one thing that I do remember.
Chiral? I'm not sure I follow it correctly here, but are you thinking of it as being equal (energy), acting as a gas containing kinetic energy. pushing/pressuring 'boundaries', to another model in where a gas is 'inert', but expanding/adapting to boundaries that 'move'?=The first one is a real headache, if it is correct. As I don't see that 'energy' in any measurements except inferred from a accelerating expanding universe. If we then assume this energy to also be dynamically produced inside a container one has to define from where. And if we then use the way you defined it before, as happening 'in each point', which seem the logical way to look at it to me too, it becomes even trickier, from a container model that is. There are alternatives, as a holographic universe etc, in where one might be able to define it (energy) differently possibly?so yes, I think I see why you took up the other model, but in that one you still assume a container of some sort, expanding but now also diluting its 'energy' as I presume a defined amount to exist.Maybe it is possible to think of it as if each patch of SpaceTime I measure on belongs to the same principles rules etc. In that case, for it to exist and be found to expand, it 'lends' from what's outside a arrow. Energy is after all a coin of exchange, and if a arrow is a construction, and limits, then what's unmeasurable (inside our universe, and local arrow) can have as much 'energy' as you like. Thinking that way conservation laws is a artifact belonging to a arrow. then again, so would we be What it means would then be that first came principles, rules etc, they setting limits 'c'. Or better expressed, 'c' is your local arrow, casualty, and the reason we are able to define physics. It is this last one I like the most, because you get away from the container, although it still will exist in our measurements. Getting away from it allow 'energy' to be in a equilibrium, inside what we measure in time on. And even thought the universe then can be defined as 'infinite' it also will be able to inflate as well as expand. There is no container in the usual mean, if one use that one, instead we find conservation laws, constants and limits. And we need them, to exist.(I'm not referring to 'virtual particles' btw. I don't like that interpretation, although it's highly usable it constricts you. A way to define it would be from the Big Bang initiation. Even before that first light 'moving', you then must have those limits, rules principles etc secured. Which makes a lot of sense to me, assuming 'c' to only be a speed doesn't, though
So if the expansion of the universe is just a dilation that increases the scale of the coordinates we use, then I don't think it would increase the overall entropy. But, if the expansion is actually increasing the amount of information needed to describe the state of the universe, then entropy should increase with the expansion
I'm not sure I understand your point of confusion.