Needles falling on paper will calculate pi, everyone鈥檚 favourite mathematical constant, on the day that bears its name.
Pi day is 14 March, or 3.14 as Americans might write it. The constant 鈥� the ratio of a circle鈥檚 circumference to its diameter 鈥� is a string of numbers beginning 3.14159, although it goes on forever.
Computers have crunched pi to trillions of digits. But this pi day, beginning at 1.59 pm GMT, Marcus du Sautoy of the University of Oxford will run , an online experiment to get people to calculate the constant using a 200-year-old method called Buffon鈥檚 needle, which anyone can take part in.
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The technique involves dropping a needle onto paper marked with evenly spaced parallel lines that are further apart than the needle鈥檚 length. The probability of the needle crossing a line is linked to the value of pi.
A single needle drop won鈥檛 give an accurate estimate, so the idea is to pool results from as many participants as possible.
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Wonky circles
When the Pi Day Live team tried Buffon鈥檚 needle themselves with a total of 100 drops, they got 2.63 as an estimate for pi, which would make for some pretty wonky circles. Du Sautoy hopes scaling up the experiment online will improve results. 鈥淭here will be errors in everyone鈥檚 calculation because it is a probabilistic method, but the more data we get coming in, the more we鈥檒l home in on pi,鈥� du Sautoy says.
The experiment will also look at other low-tech ways of measuring pi, such as , a method thought to have been used by the ancient Egyptians to compare a circle鈥檚 diameter to its area.
鈥淧i is so much part of our mathematical heritage,鈥� says du Sautoy. 鈥淢ost people can rattle off a few decimal places.鈥� Why is pi so universally beloved? After all, no one celebrates e day to commemorate 2.71, the constant that is the base of natural logarithms. It鈥檚 partly because 71 February doesn鈥檛 fit nicely with our calendar 鈥� but other mathematically themed days have failed to take off as well. 鈥淚 tried to introduce the perfect day, June 28th,鈥� says du Sautoy, chosen for the first two 鈥� numbers that are the sum of their factors (28 = 1 + 2 + 4 + 7 + 14, for instance). But nothing has the popularity of pi.
Perhaps it is just because circles are so important, both culturally and scientifically. 鈥淧i is historically one of the very first numbers mathematicians started trying to calculate and explore,鈥� says du Sautoy. So why not have a go yourself this pi day?
