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¸ç質ç¹ã®éåã¯ãããã«ãã³ã®éåæ¹ç¨å¼ \begin{eqnarray} \frac{dx}{dt}&=&\frac{\partial H}{\partial p}(x,p) \\ \frac{dp}{dt}&=&-\frac{\partial H}{\partial x}(x,p) \end{eqnarray} ãæºããããã«ä½ç½®$x$ã¨éåé$p$ãæéå¤åããåå¦ã®çè«ã¨ãã¦æ±ããã¦ãã¾ãã ããããéåè«ã¨å¯¾æ¯ããã¨ã確çã¢ãã«ã®ä¸ç¨®ã§ããã¨èããæ¹ãé½åãè¯ãã§ãã ä½ç¸ç©ºéä¸ã®ç¢ºçå¯åº¦åå¸$\rho(x,p,t)$ã®æéçºå±ã¯ãªã¦ã´ã£ã«æ¹ç¨å¼ \begin{eqnarray} \frac{\partial \rho}{\partial t}&=&\frac{\p