[ti:What Is Pi Day?]
[al:Science & Technology]
[ar:VOA]
[dt:2024-03-15]
[by:www.voase.cn]
[00:00.00]Math lovers celebrate Pi Day on March 14, or 3/14. Around the world, many people even mark the day by eating a tasty piece of pie.
[00:14.55]For those who do not know, pi is a mathematical constant, a value that never changes.
[00:22.81]It expresses the ratio of a circle's circumference (the distance around the circle) to its diameter (the distance across the circle, passing through its center.)
[00:35.62]The approximate value of this mathematical constant is 3.1415926535.
[00:45.66]But those are just the first 10 digits of pi. 
[00:49.66]The numbers go on infinitely, or forever.
[00:53.18]Pi can calculate the circumference of a circle by measuring the diameter and multiplying that by the 3.14-plus number.
[01:04.62]The formula has been used in physics, astronomy, engineering and other fields, dating back thousands of years.
[01:14.04]Long before computers, scientists such as Isaac Newton spent many hours calculating decimal places by hand. 
[01:22.92]But today, researchers use computers to come up with trillions of digits for pi. But there is no end.
[01:31.85]There are many uses for pi.
[01:34.74]The number helps calculate the size of paper rolls used in printers. 
[01:39.93]And it helps decide the necessary size of a container that serves heating and air conditioning systems in buildings of different sizes.
[01:50.70]Scientists use the number to point an antenna toward a satellite and calculate the orbits and positions of planets and other space bodies.
[02:02.93]Scientists with the American space agency NASA use pi to calculate when parachutes should open as a vehicle splashes down on Earth or lands on Mars.
[02:15.14]In 1706, British mathematician William Jones began using the Greek letter pi for the number 3.14... It is the first Greek letter in the words "periphery" and "perimeter." 
[02:31.13]Both words have similar meanings as circumference.
[02:35.93]Pi Day itself dates back to the year 1988.
[02:41.26]That was when physicist Larry Shaw began celebrations at the Exploratorium, a science museum in San Francisco, California.
[02:52.09]The so-called holiday did not gain national recognition until more than 20 years later.
[02:59.56]In 2009, the U.S. Congress declared every March 14 to be Pi Day as a way to bring more interest in math and science.
[03:10.18]The San Francisco museum that started the holiday organizes events, including a walk around a circular sign, called the Pi Shrine, 3.14 times. 
[03:23.79]Of course, there is also plenty of pie to eat.
[03:28.77]Many Pi Day events take place at colleges in the United States.
[03:34.42]For example, Nova Southeastern University (NSU) in Florida holds the "Mental Math Bingo" game with free pizza pies.
[03:45.30]Jason Gershman oversees NSU's math department. 
[03:49.97]He said, "Every year, Pi Day provides us with a way to celebrate math, have some fun and recognize how important math is in all our lives."
[04:02.60]NASA has its yearly "Pi Day Challenge" online. 
[04:07.09]The space agency offers games and puzzles, such as calculating the orbit of an asteroid or the distance a moon rover would need to travel each day to study a certain lunar area.
[04:21.58]If you still wonder why Pi Day is such an important day for math lovers, here are two more reasons: Albert Einstein, possibly the world's best-known scientist, was born on March 14, 1879. And famed physicist Stephen Hawking died on March 14, 2018, at age 76.
[04:48.61]Although pi is not a perfect number. 
[04:51.81]Hawking once had this to say: "One of the basic rules of the universe is that nothing is perfect.Perfection simply doesn't exist. Without imperfection, neither you nor I would exist."
[05:08.04]And Happy Pi Day!
[05:09.88]I'm Jill Robbins