兰洋夸特墓室，英国康沃尔郡 Lanyon Quoit burial chamber, Cornwall, England (© Guy Edwardes/Minden Pictures)

兰洋夸特墓室，英国康沃尔郡 Lanyon Quoit burial chamber, Cornwall, England (© Guy Edwardes/Minden Pictures)

天空中的圆周率...... It's just pi in the sky...

Pi Day

Did Neolithic humans build this structure to celebrate Pi Day? Not likely. Pi Day is a relatively recent phenomenon—invented by a physicist in 1988 and designated by Congress a national holiday in 2009. But it's already almost certainly the most popular holiday celebrating a mathematical constant. While Pi Day is a young tradition, the number π (pi) itself has been a fascination since antiquity, when it was first calculated as the ratio of a circle's circumference to its diameter.

You probably know that March 14 was chosen for Pi Day since the date expressed numerically (in month/date format) matches the number's first digits, 3.14. Aside from eating pie to celebrate, some people go to great lengths to memorize digits that go way beyond 3.141592…, which earns them bragging rights in some, um, circles. The world record is a staggering 70,000 digits after the decimal point—the remarkable feat was achieved by 21-year-old student Rajveer Meena in 2015.

Take a moment from your Pi Day revelry to appreciate the unintentional π symbol formed by this Neolithic burial chamber in Cornwall, England. As the morning sun warms Lanyon Quoit's ancient stones, it's impossible not to wonder who built it and how, since it predates metal tools and is older than Egypt's pyramids. Theories abound, of course, but could π have been involved?

圓周率日

新石器时代的人类建造这个建筑是为了庆祝圆周率日吗？不太可能。圆周率日是一个相对较新的现象，由物理学家在1988年发明，并在2009年被国会指定为全国性节日。但几乎可以肯定，这已经是庆祝数学常数最受欢迎的节日。虽然圆周率日是一个年轻的传统，但从远古时代开始，圆周率（Pi）本身就一直是一个令人着迷的数字，当时它最初被计算为圆的周长与直径之比。

你可能知道，3月14日被选为圆周率日，因为数字表示的日期（月/日格式）与数字的第一位数字3.14匹配。除了吃馅饼庆祝外，有些人会不遗余力地记住远远超过3.141592的数字，这让他们在一些圈子里大肆吹嘘。这项世界纪录在小数点后达到了令人震惊的70000位。这项了不起的壮举是由21岁的学生拉杰维尔·米娜在2015年创造的。

从你的π日狂欢中抽出一点时间，欣赏一下英格兰康沃尔新石器时代墓室无意中形成的π符号。当早晨的阳光温暖着拉尼恩·库伊特的古老石头时，我们不可能不去想它是谁建造的，是如何建造的，因为它比金属工具更早，比埃及的金字塔还要古老。当然，各种理论比比皆是，但π是否也会参与其中呢？