Why does reversibility require equilibrium?

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Discussion Overview

The discussion centers around the relationship between reversibility and equilibrium in thermodynamic processes. Participants explore the conditions under which processes can be considered reversible and the implications of irreversibility, particularly in the context of statistical mechanics.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant questions why reversibility requires equilibrium, seeking clarification on the concept.
  • Another participant asks for sources or research that informed the original question, indicating a desire for a more informed discussion.
  • A participant references studying statistical mechanics, specifically mentioning Mehran Kerdar's work, suggesting a theoretical background related to the topic.
  • Several participants discuss irreversible processes, noting that mass, momentum, and heat transport occur at finite rates and cannot be reversed without affecting the surroundings. They highlight that these processes involve entropy generation within the system.
  • A participant expresses interest in learning about Boltzmann's H theorem, indicating a desire to connect the discussion to broader theoretical frameworks.
  • One participant admits to not knowing what Boltzmann's H theorem is, suggesting a gap in knowledge among participants.

Areas of Agreement / Disagreement

The discussion does not reach a consensus on the relationship between reversibility and equilibrium. Multiple viewpoints are presented, particularly regarding the nature of irreversible processes and the need for equilibrium.

Contextual Notes

Participants reference concepts such as entropy generation and finite rates of transport, but there are no detailed mathematical steps or definitions provided. The discussion appears to depend on participants' varying levels of familiarity with statistical mechanics and thermodynamic principles.

Who May Find This Useful

This discussion may be of interest to students and researchers in physics and engineering, particularly those studying thermodynamics and statistical mechanics.

member 743765
my question is short simply why reversibility requires equilibrium?
 
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What research have you done about this question? Can you post links to your reading that led to this question? Thanks.
 
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berkeman said:
What research have you done about this question? Can you post links to your reading that led to this question? Thanks.
I was studying mehran kerdarbook on statistical mechanics of particles
 
In irreversible processes, transport of mass, momentum and heat occur at finite rates, and these cannot be reversed for the system without also bringing about a net change in the surroundings. Mass transfer involves diffusion at finite rates. Momentum transfer involves viscous dissipation of mechanical energy to internal energy and involves finite viscous stresses at finite deformation rates. Heat Transfer involves heat conduction at finite temperature gradients. All of these involve entropy generation within the system, rather than entropy transport via heat flow across the boundary of the system.
 
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Chestermiller said:
In irreversible processes, transport of mass, momentum and heat occur at finite rates, and these cannot be reversed for the system without also bringing about a net change in the surroundings. Mass transfer involves diffusion at finite rates. Momentum transfer involves viscous dissipation of mechanical energy to internal energy and involves finite viscous stresses at finite deformation rates. Heat Transfer involves heat conduction at finite temperature gradients. All of these involve entropy generation within the system, rather than entropy transport via heat flow across the boundary of the system.
Where can I learn about boltzmann's H theorem?
 
I don’t even know what that is.
 
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