spxtr comments on Entropy and Temperature - Less Wrong

26 Post author: spxtr 17 December 2014 08:04AM

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Comment author: spxtr 18 December 2014 04:37:11AM 2 points [-]

I posted some plots in the comment tree rooted by DanielFilan. I don't know what you used as the equation for entropy, but your final answer isn't right. You're right that temperature should be intensive, but the second equation you wrote for it is still extensive, because E is extensive :p

Comment author: Grothor 18 December 2014 05:38:47AM *  2 points [-]

your final answer isn't right

You're right. That should be ε, not E. I did the extra few steps to substitute α = E/(Nε) back in, and solve for E, to recover DanielFilan's (corrected) result:

E = Nε / (exp(ε/T) + 1)

I used S = log[N choose M], where M is the number of excited particles (so M = αN). Then I used Stirling's approximation as you suggested, and differentiated with respect to α.

Comment author: spxtr 18 December 2014 06:15:29AM 0 points [-]

Good show!