Does the Equal A Priori Probabilities Assumption Hold for Interacting Gases?

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    Classical Gas
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Discussion Overview

The discussion revolves around the equal a priori probabilities assumption in the context of the microcanonical ensemble for interacting gases. Participants explore whether this assumption holds when considering systems of particles that interact with each other without external work or heat being applied.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification

Main Points Raised

  • One participant questions the validity of the equal a priori probabilities assumption for interacting systems, seeking clarification on its applicability.
  • Another participant asserts that if the system is in equilibrium, all microstates remain equally probable, even in the presence of interactions.
  • A further contribution discusses the implications of Noether's theorem regarding conservation laws in interacting systems and expresses interest in defining equilibrium for many interacting particles.
  • The same participant inquires about references related to ergodicity in interacting systems and the regular visitation of states over long times under the equal a priori probabilities assumption.
  • A later reply suggests that numerous references on ergodicity can be found through a simple online search.

Areas of Agreement / Disagreement

Participants express differing views on the applicability of the equal a priori probabilities assumption for interacting systems, with some asserting its validity under equilibrium conditions while others seek further clarification and references. The discussion remains unresolved regarding the specific conditions under which the assumption holds.

Contextual Notes

Limitations include the need for clearer definitions of equilibrium in interacting systems and the exploration of ergodicity, which remains a topic of interest without definitive conclusions provided in the discussion.

gonadas91
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Hi! My question has to be with the equal a priori probabilities assumption in the microcanonical ensemble when we consider an interacting system, that is, particles interacting between them but no external work or heat is done over the system. Does this assumption still hold for such a system? Thanks!
 
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Yes. If the system is in equilibrium, all microstates are equally probable, even for an interacting system.
 
So, because the interactions don't depend on time, the hamiltonian must be a conserved quantity according to Noether's theorem, and the total energy is conserved or fixed. However, I would like to know more about how to define equilibrium for a system of many interacting particles. Is there any reference to look at this closer? Also, the ergodic assumption is of interest for me, in the case of an interacting system. If you assume the equal a priori probabilities, then for very long times, all states are visited regularly with the same frecuency. Is there any reference too to see how this works? Or any attempts to prove that that have been made?

Thank you!
 
Several references on ergodicity in interacting systems. I just typed those words in google and got may pages.
 

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