#数学
圆周率π是最常见的两个无理数之一（另外一个是自然常数e），数学上已经对这些无理数的意义做了充分的解释。《疑犯追踪》S02E11中男主对π的解读是最浪漫的：

Student Girl: My Friend Has A Question, Mr. Swift . “What Is Any Of This Good For, And When Would We Ever Use It?”

(The Class Laughs.)

Finch : Let Me Show You. Π. The Ratio Of The Circumference Of A Circle To Its Diameter . And This Is Just The Beginning. It Keeps On Going. Forever. Without Ever Repeating. Which Means That Contained Within This String Of Decimals Is Every Single Other Number. Your Birth Date, Combination To Your Locker , Your Social Security Number. It’s All In There Somewhere. And If You Convert These Decimals Into Letters, You Would Have Every Word That Ever Existed In Every Possible Combination. The First Syllable You Spoke As A Baby, The Name Of Your Latest Crush , Your Entire Life Story From Beginning To End. Everything We Ever Say Or Do, All Of The World’s Infinite Possibilities Rest Within This One Simple Circle . Now What You Do With That Information, What It’s Good For, Well, That Would Be Up To You.

“Pi 一个圆的周长与它的直径的比，但不仅是这些而已，还有更多，永无止境，毫无重复。小数点后的这一串数字，每一个都是单一个体，你的生日、寄物柜锁密码、社会保险号码，都在这一串数字某处。如果你把这些数字转换成字母，你会得到每一个词，在每一个可能的组合中出现，你婴孩时开口讲的第一个音节、你心上人的名字、你从头至尾整个人生的故事、所有我们说的话和做的事…这个世界所有无尽的，可能性都在这个简单的圆里。你拿这些信息做什么…有什么用处…全都取决于你。”

B站上截取出来这一集的相关视频。

补充信息：但是π目前并没有证明是一个正规数（Normal Number），即数字显示出随机分布，且每个数字出现机会均等的实数，也就是说：虽然π是个无理数，但是也不能保证任意数字一定会出现在这个无理数的数字序列里。