Best explanation for 1-way entropy?

  • Context: Graduate 
  • Thread starter Thread starter dydxforsn
  • Start date Start date
  • Tags Tags
    Entropy Explanation
Click For Summary

Discussion Overview

The discussion centers on the explanation for the law of increasing entropy, exploring its implications and underlying principles. Participants examine the concept from a thermodynamic perspective, considering both micro-state explanations and statistical interpretations.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification, Debate/contested

Main Points Raised

  • One participant questions why the increase of entropy is considered a law, suggesting it may be more of a general rule rather than an absolute law.
  • Another participant states that while entropy tends to increase, it is possible for a system to transition from higher to lower entropy, albeit with a very low probability.
  • A third participant adds that over an extremely long time scale, all equilibrium states would be accessed, leading to a null total entropy variation, which complicates the understanding of entropy increase.

Areas of Agreement / Disagreement

Participants express differing views on the nature of entropy increase, with some supporting the idea of it being a law and others suggesting it is more probabilistic and context-dependent. The discussion remains unresolved regarding the fundamental nature of entropy as a law.

Contextual Notes

Participants acknowledge the complexity of entropy over different time scales and the implications of statistical mechanics, but do not resolve the underlying assumptions or definitions related to entropy.

dydxforsn
Messages
104
Reaction score
0
What is the best explanation for why entropy must increase BY LAW. I can see it as being a good general rule, but I don't quite see why it's law, especially when you consider a micro-state explanation of entropy. What is the best argument for the law of increasing entropy?
 
Science news on Phys.org
My thermo is a bit rough, but the entropy of a system always increasing actually means the system, with overwhelming probability, tends towards states of increased entropy. You CAN see a system go from higher entropy to lower entry, but the probability is vanishingly small.
 
Statistically, what Peng said is right in a short time scale. When you consider a sufficiently huge amount of time (and this is very, very huge amount of time, many times the age of our universe), every equilibrium state would be accessed and the total entropy variation would be null.
 
Thank you both for the reply! I was thinking along those lines, but I wasn't sure at all. Physics Forums is such a good tool for this kind of thing..
 

Similar threads

High School Entropy change for reversible and irreversible processes
  • · Replies 12 ·
Replies
12
Views
3K
Undergrad Relating Entropy and the 2nd law
  • · Replies 2 ·
Replies
2
Views
2K
Undergrad Emergence of Complexity and Life
  • · Replies 35 ·
2
Replies
35
Views
5K
Undergrad How can the maximum entropy and minimum energy principles be physical?
  • · Replies 13 ·
Replies
13
Views
4K
Undergrad Why does the entropy of a closed system remain constant in a reversible process?
  • · Replies 10 ·
Replies
10
Views
4K
Undergrad Problem regarding understanding entropy
  • · Replies 3 ·
Replies
3
Views
2K
Undergrad Physics of paper absorbing Water -- Doesn't this decrease Entropy?
  • · Replies 1 ·
Replies
1
Views
2K
Undergrad Is Entropy the inexorable conversion of potential to kinetic energy?
  • · Replies 17 ·
Replies
17
Views
3K
Graduate Free expansion of an ideal gas and changes in entropy
  • · Replies 2 ·
Replies
2
Views
3K
Graduate Equilibrium, entropy, probability - Release of constraints
  • · Replies 2 ·
Replies
2
Views
2K