Does the Universe Ever Reach Maximum Entropy?

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The discussion centers on the concept of maximum entropy in the universe, particularly in relation to the heat death theory. It highlights conflicting information regarding whether the universe can ever reach maximum entropy, suggesting that the maximum value may increase faster than the universe's entropy. A distinction is made between maximum entropy within a Hubble volume, which occurs when it is empty space, and the entropy of a comoving volume that continues to expand. As the universe expands, the entropy within a comoving volume increases indefinitely, indicating that maximum entropy may never be achieved. The conversation seeks observational evidence to support these claims about entropy and the universe's fate.
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My knowledge of physics/cosmology is limited but from what I've read in the wiki article entitled "heat death of the universe" there is some conflicting information on whether or not maximum entropy is ever reached. There is an idea that the universe will never reach a state of maximum entropy because the value of maximum is increasing faster than the entropy of the universe. However no citation was provided for this information on wiki and I'm having trouble finding any follow-up information. I would appreciate it if anyone can elaborate on this. Was there any observational evidence to back this claim?
 
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steenpat said:
My knowledge of physics/cosmology is limited but from what I've read in the wiki article entitled "heat death of the universe" there is some conflicting information on whether or not maximum entropy is ever reached. There is an idea that the universe will never reach a state of maximum entropy because the value of maximum is increasing faster than the entropy of the universe. However no citation was provided for this information on wiki and I'm having trouble finding any follow-up information. I would appreciate it if anyone can elaborate on this. Was there any observational evidence to back this claim?
Well, it depends upon what measure you use. There is a state of maximum entropy within a Hubble volume. That maximum entropy occurs when that volume is nothing but empty space. Such a universe has a constant entropy density.

An alternative definition of maximum entropy is the entropy of a comoving volume. That is, a volume that expands along with space. Once the universe has reached a constant entropy density, it still continues to expand. So with a constant entropy density + growing volume, you get a larger and larger entropy within the comoving volume for all time. There is, in effect, no maximum entropy for a comoving volume, period.
 

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