Tuesday, April 30, 2019

entropy - How does this new theory of a possible infinitely old universe not violate the second law of thermodynamics


I read the following article: http://phys.org/news/2015-02-big-quantum-equation-universe.html


And followed it back to this journal reference : http://arxiv.org/abs/1404.3093


It appears to be legitimate. I wonder how, in an infinitely old universe, the entropy in the universe is not also infinite considering that entropy always increases.


Edit: entropy is disorder so it increases to infinity rather than decreases to zero.


Edit 2: Thank you for the links to related questions about this article and chats. It appears to me that the likelihood of this theory being correct is quite low.



With regard to my question about entropy in a cyclical universe it appears that solution is to assume that the universe is not exactly the closed system we thought it was.



Answer



Consider the function $e^x$: it is monotonically increasing and yet defined for all negative $x$.


Just because something increases monotonically doesn't mean it must reach infinity (or even its maximum value) in a finite amount of time.


As a side note, please don't refer to entropy as disorder. It's very common but also very wrong: https://www.youtube.com/watch?v=vSgPRj207uE


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