## 创造生命

Life is a characteristic distinguishing physical entities having biological processes (such as signaling and self-sustaining processes) from those that do not, either because such functions have ceased (death), or because they lack such functions and are classified as inanimate.

 1 利用可以获得的物质和能量维持自身的存在（self-sustaining processes） 2 自我复制，产生新的个体

## meditations on pi

1/3=0.3333….. 三分之一等与0.3循环，这个是我们都认为正确的结果，然后等号两边都乘以3
3 * 1/3 = 3 * 0.333333…… 就得出
1 = 0.999999……

1 2 3 4 5 6 7 ……..

$pi=4sum_{k=0}^infty frac{(-1)^k}{2k+1}$

$pi =2 int_0^{infty } frac{1}{t^2+1} , dt$