[열 물리학 16] Entropy as a Logrithm

 

★Entropy as a Logrithm (엔트로피는 왜 로그인가?)

 

(1) Entropy of two independent system is the sum of the separate entropy

 

 

엔트로피 계산은 곱이 아니라 덧셈인 장점이 있다.

 

 

2) Entropy is insensitive to the precision $\delta u ~[\delta u \bullet \delta t \sim \hbar ]$

$\vartheta(u)$ : # of accessible state per unit energy range. (density of state- 고체물리학 참고)

[# of accessible state per unit energy between $u$and $u +\delta u$]

For N spin system, total number of state $2^N$, total energy $N  \times  \triangle $

( $ \triangle$ : average energy per particle)

 

 

 

->precision $\delta u$ negligible effect