兰扬石门，位于英格兰康沃尔郡的一座兰扬新石器时代石棚墓，英国 Lanyon Quoit, a Neolithic dolmen in Cornwall, England (© Helen Hotson/Alamy)

兰扬石门，位于英格兰康沃尔郡的一座兰扬新石器时代石棚墓，英国 Lanyon Quoit, a Neolithic dolmen in Cornwall, England (© Helen Hotson/Alamy)

圆周率的古老启示 An ancient angle on Pi

庆祝圆周率日

在圆周率尚未有名字之前，人们就被它的奥秘所吸引。每年的3月14日，被定为“圆周率日”，以纪念数学中最著名的常数之一。这个日期正好对应圆周率π的前三位数字(3.14)，即圆的周长与直径之比。圆周率无穷且不循环的小数部分长期以来一直令学者们着迷。现代的庆祝活动始于1988年，当时物理学家拉里·肖(Larry Shaw)用一种特别的方式纪念这一天：享用美味的派(pie)。

今天的画面带我们来到英国西南部的康沃尔，那里矗立着兰扬石门——其形状仿佛圆周率的符号 π，从开阔的荒原上拔地而起。这座新石器时代的石墓建于公元前3500年至前2500年之间，曾是更大型建筑的一部分。抬起巨大的顶石需要精确的平衡与比例知识，这些早期的理念让建筑者在文字数学出现之前，就能够掌握形状与尺度的运用。

在圆周率日，这样的遗迹提醒我们：数学思维源于实践中的挑战。在符号出现在黑板之前，人类对测量的理解已经在石头中塑造着世界。

Celebrating Pi Day

Long before pi had a name, people were drawn to its mystery. Every year on March 14, Pi Day highlights one of math's most recognizable constants. The date reflects the first three digits of pi (π), the ratio of a circle's circumference to its diameter: 3.14. Pi's infinite, nonrepeating decimal has fascinated thinkers for a long time. The modern celebration began in 1988, when physicist Larry Shaw marked the day with a fitting tribute: serving pie.

Today's image takes us to Cornwall in southwestern England, where Lanyon Quoit—in the shape of π—rises from open moorland. Built between 3,500 and 2,500 BCE, this Neolithic dolmen once stood as part of a larger structure. Raising its massive capstone required knowledge of balance and proportion. These early concepts helped builders work with shape and scale long before written mathematics existed.

On Pi Day, sites like this remind us that mathematical thinking evolved from practical challenges. Even before symbols appeared on chalkboards, ideas about measurement were already shaping the world in stone.