# Pi Is Wrong! Mathematicians Declare Today ‘Tau Day’

June 28, 2011

It may not be marked on your holiday calendar but today, June 28, is noted for being “Tau Day”, at least among strident detractors of pi, the ratio of a circle’s diameter to its circumference, BBC News is reporting.

Proponents of Tau Day suggest a constant called tau should replace pi, which comes close to twice the value of pi, or about 6.28 – hence the 28 June celebration. Fans say that for many problems in math, tau makes more sense and makes calculations easier.

Not all math geeks agree, however, and pi has a long, rich history which means it will be a difficult number to unseat. “I like to describe myself as the world’s leading anti-pi propagandist,” said Michael Hartl, an educator and former theoretical physicist, to BBC.

“When I say pi is wrong, it doesn’t have any flaws in its definition – it is what you think it is, a ratio of circumference to diameter. But circles are not about diameters, they’re about radii; circles are the set of all the points a given distance – a radius – from the center” Dr. Hartl explained.

Leeds University experts are backing the campaign for pi to be replaced by tau by making certain mathematical problems easier.

“How much simpler it would be if we just used tau instead of pi,” explains Dr. Kevin Houston, of the School of Mathematics at the University of Leeds. “The circle would have tau radians, a semicircle would have half tau, a quarter of a circle a quarter tau, and so on. You don’t have to think.”

Houston has also promoted Tau Day by making a YouTube video on the subject entitled “Pi is wrong!” which attempts to explain why tau would be a better alternative when making calculations. He argues that it would also make A-level math considerably easier while it would help people to better understand such complex topics as calculus, The Daily Mail reports.

‘We should be changing the textbooks,’ he insisted. ‘It would be much simpler than the shift from imperial to metric. If we were to start teaching tau from the moment kids start math, they would take to it straight away, as it’s more natural.’

Pi – taken from the first letter of the Greek word for ‘perimeter’ – was first given its name in 1706 by mathematician William Jones. Both the Ancient Egyptians and the Babylonians were believed to have known an approximate value of pi, while a version also appears in the Bible.

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