A radical idea was presented to me today in the course of reading several articles on quantum thermodynamics.
The thought: Total entropy in the Universe never changes.
The picture would be radically different if the universe obeys the laws of quantum thermodynamics. True, we don’t know exactly what these are yet. But we do know from the equations of quantum theory that the overall amount of disorder in the universe must remain constant. What’s more, quantum uncertainty forbids us from gaining full information about the states of individual parts of the universe, meaning that some parts can be more disordered than the whole. This could mean that if you look at the universe as a whole, entropy doesn’t change and so there is no time. But look at small patches where entropy is changing and time starts ticking. Because things don’t have to add up everywhere, all the time, it is even possible thatthe arrows of time flow in different directionsin different parts of the universe. Read more:https://www.newscientist.com/article/mg23731720-400-im-building-a-machine-that-breaks-the-rules-of-reality/#ixzz75KsZqAS2
This makes sense if you think about Boltzmann/s entropy equation. Entropy is a value calculated for a “system” from a multiplicity of “states.” The formula S=k*logW means mutliplying Boltzmann’s constant (k) by the log of W. “W” is a measure of the number of different “states” in which the constituents of the “system” can be arranged. A constituent of the system might be a particle, for instance.
if there is only one particle, whether the system is closed or open, the log of 1 is zero. Consider what happens if there are 2 particles. Commonly, 2 particles are thought to represent 1 “state” since there are mutliple ways in which the two particles can be arranged with respect to each other.
BUT
Two particles can only exist in multiple different configurations when they are related to a closed system. In other words, in pictures, the two particles have to be in a box, so that it is possible to measure the relationship of one particle to the other by comparing their positions with respect to the enclosed space of the box.
BUT
What if there is no box enclosing the two particles? What if the two particles are alone in our imaginary open system, our hypothetical infinite THE Universe. What if there are no other particles or objects or things or whatever against which the particles’ postions with respect to each other can be compared? In other words, what if theEinstein relativity (two trains traveling past each other at constant velocity cannot say which one is moving and which is standing still) is applied to determining entropy.
THEN, the two particles in the unclosed system cannot have entropy.
Entropy is related somehow to time and to information. The two particles in the open system cannot be used for purposes of information. They cannot “contain” or “carry” information as long as they remain in an unframed or open universe. No matter how far away they are from each other, or what angle they are to each other, it is not possible to measure that relationship.
Measurement can only occur when something else is introduced into THE Universe. The something else can be a third particle, or a box, or a change in velocity of one of the particles with respect to the other (acceleration aka gravity), or an observer.
Until that happens, an open system implies no entropy and no information.
So here is the interesting question: if “the overall amount of disorder in the universe must remain constant”, meaning entropy in THE Universe neither decreases nor increases, does that mean that THE Universe is an open system? Does that mean that THE Universe is infinite? And does that not imply that THE Universe is not bounded by time. if time is a function of entropy?
Of course, individual sections of THE Universe may act like closed systems. As my son Ben pointed out very perceptively right away “So if I cause more entropy in one place then time goes slower in another place.” Perhaps boiling water for my coffee takes 2 minutes because it subtracts 2 minutes from another part of THE Universe.
And thinking further on this, it seems to relate to idea of the “Block Universe” which says that all time (future and present and past) are “real” (whatever that means.)
Anyway, I am sure this is all elementary to much smarter people than me.
For that purpose, I will express my gratitude to Sean Carroll and his terrific series of pandemic lockdown videos, The Biggest Ideas in the Universe.
