Understanding Entropy: Calculations and Examples for Beginners

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Discussion Overview

The discussion revolves around the concept of entropy, particularly its calculations and implications in thermodynamics. Participants explore the basic understanding of entropy, its relationship to disorder and time, and seek clarity on its mathematical representation and practical examples.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Homework-related

Main Points Raised

  • One participant expresses a foundational understanding of entropy as related to disorder and its tendency to increase, except at absolute zero, linking it to the arrow of time.
  • The same participant seeks clarification on the calculation of entropy using the formula S=-k·Σ[Pilog(Pi)], asking for examples and the meaning of higher entropy values.
  • Another participant suggests a resource on statistical thermodynamics to aid understanding.
  • One participant shares a personal insight, equating entropy to a form of information.
  • Another participant offers a definition of entropy as "the amount of energy needed to complete a system," indicating a moment of clarity for them.

Areas of Agreement / Disagreement

Participants generally share a common interest in understanding entropy, but there are varying interpretations of its meaning and implications, particularly regarding its relationship to information and energy. The discussion remains unresolved with multiple perspectives presented.

Contextual Notes

Participants have not fully established the definitions of terms like "nanostate" or the units of entropy, and there is uncertainty regarding the calculation of probabilities in the context of entropy.

Who May Find This Useful

Individuals interested in thermodynamics, statistical mechanics, and the conceptual foundations of entropy may find this discussion beneficial.

infinitylord
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Hi guys! I'm new to the forum and had several questions about entropy. I am a bit of a physics newbie by a lot of standards but I understand a lot of it and love physics. I can understand the basics of entropy that it is (correct me if I'm wrong) basically just disorder, that it is always increasing except if it is at absolute 0. It creates an arrow of time in the way that we can't go back on what has happened and bring the order back just as we can't reverse time to stop a volcanic eruption. Now I get the principles of it but how is it calculated and what does it mean when it is? there are the more basic forumula's for thermodynamics but I was referring to
S=-k·Σ[Pilog(Pi)]. So I know what most of it means,
k=boltzmann constant,
Σ = sigma,
in the brackets = the probability that a particle will be in a certain nanostate * by the logarithm of the same probability.
but how is this applicable? I want an example. I tried to do one by myself but i was most likely horribly wrong on what to do.
So i'd like an example with the math written out and what it means really. how do you know the probability of a particle being in a nanostate? once you have the number what's the unit in... J/K^-1? and what does it mean if you have a higher entropy?
sorry for the bombardment of questions... I'm just trying to wrap my head around this
 
Science news on Phys.org
Thanks a ton.. this really helped!
 
Sorry about reviving, but I've thought of entropy as, well, sort of information.
 
yeah... I've got a better handle on it now. One good definition I read was "the amount of energy needed to complete a system." that's where it all just clicked for me I guess
 

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