Can Entropy and Time Reversal Coexist with Irreversible Wavefunction Collapse?

In summary, the conversation discusses the relationship between time reversal of wave function and the second law of thermodynamics of entropy. Some believe that projection is not time-reversible, while others argue that time-reversible laws can still lead to non-time-reversible dynamics under special initial conditions. The second law of thermodynamics is not necessarily contradictory to time-symmetrical microdynamics, and some suggest that irreversible wave function collapses may be the reason for the increase in entropy. However, it is also possible to explain the second law of thermodynamics through statistical behavior, as demonstrated by Feynman.
  • #1
leonchik1976
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How time reversal of wave function and 2nd law of thermodynamics of entropy are settle together?
 
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  • #2
leonchik1976 said:
How time reversal of wave function and 2nd law of thermodynamics of entropy are settle together?

Several answers are possible. One possible answer is that some people will say that projection is not time-reversible, so if projection is taken seriously, this kills time-symmetry in physics.

But even if you do not consider this possibility, I'd say that the answer is the same as in classical physics, where time-reversible LAWS can give rise to non-time-reversible *coarse-grained* dynamics: namely by special initial conditions.
If you start out (in a classical, time-reversible dynamics) with a highly peculiar initial state, and you only look at low-order correlation functions (coarse-graining), then you obtain a time-irreversible dynamics of these correlation functions until they reach their equilibrium values.

Mind you, I'm not saying that this is what explains finally the entropy increase in our universe. I'm only giving the example that there is no contradiction between time-reversible dynamics, and a second law of thermodynamics which prescribes the irreversibility of low-order correlation functions: it is sufficient to take a peculiar initial state.
It might of course be that there are genuinly irreversible laws too.
But there is no *contradiction* between the second law of thermodynamics, and time-symmetrical microdynamics.
 
  • #3
It is just a question of time !
 
  • #4
From what i know of, irreversible wave function collapses are supposedly the reason for the second law of thermodynamics.

Am I right here?
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  • #5
I guess you can live without believing irreversible wavefunction collapse.
Following Feynman's example, increasing entropy is a consequence of statistical behavior.
 
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1. What is entropy?

Entropy is a measure of the disorder or randomness in a system. It is a thermodynamic quantity that increases over time in closed systems, reflecting the tendency of energy to disperse and become more evenly distributed.

2. How does entropy relate to the second law of thermodynamics?

The second law of thermodynamics states that the total entropy of an isolated system will never decrease over time. This means that in any natural process, the total entropy of the universe will always increase. This also means that time reversal is unlikely, as it would require a decrease in entropy.

3. Can entropy be reversed?

In a closed system, entropy will always increase and cannot be reversed. However, in open systems, such as living organisms, it is possible to decrease entropy locally by using energy to create order and decrease randomness.

4. How does time reversal relate to entropy?

Time reversal is the concept of reversing the direction of time and observing the system evolve backwards in time. However, due to the second law of thermodynamics, this is highly unlikely as it would require a decrease in entropy, which goes against the natural tendency of the universe.

5. What are the practical applications of understanding entropy and time reversal?

Understanding entropy and time reversal has many practical applications, such as in engineering, where it is important to minimize entropy to increase efficiency. It also has implications in fields such as biology and cosmology, providing insights into the evolution and structure of the universe.

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