In the last 15 years, a phenomenon known as the Tau Movement has grown and is apparently gaining more and more followers (called Tauists). You can even buy a t-shirt to wear proudly on June 28, Tau Day, and on Pi Day, March 14, to stick it to the Pi supporters. https://teespring.com/tauday

The number π (Pi) is likely the most widely known mathematical constant and is the ratio of a circle’s circumference to its diameter, commonly approximated as 3.14159… It has been represented by the Greek letter “π” since the mid-18th century. The Tau movement is promoting the use of τ (Tau) as a replacement for Pi. To undercover both sides of the issue, you can read The Pi Manifesto and The Tau Manifesto as well as a number of other articles. In a nutshell, here are the arguments.

Tauists claim that π is the wrong circle constant and believe the true circle constant should be τ (τ =2π). “Tauists argue that by using the constant τ=2π a lot of formulas become simpler. Unfortunately, the Tao Manifesto is full of selective bias in order to convince readers of the benefits of τ over π. They pinpoint formulas that contain 2π while ignoring other formulas that do not.” says the writer of the Pi Manifesto.

The Tau Manifesto reads, “It should be obvious that π is not “wrong” in the sense of being factually incorrect; the number π is perfectly well-defined, and it has all the properties normally ascribed to it by mathematicians. When we say that “π is wrong”, we mean that π is a confusing and unnatural choice for the circle constant.” Michael Hartl, Tau Day founder and author of The Tau Manifesto is an educator and entrepreneur who previously taught theoretical and computational physics at Caltech. He is a graduate of Harvard College, and has a Ph.D. in Physics from the California Institute of Technology.

Both manifestos detail mathematical formulas that use 2π and π, each arguing that their viewpoint is correct and makes mathematics simpler and more beautiful. Having read and listened to the information given by both sides, it seems to boil down to this; Tau supporters argue that many formulas require the use of 2π so why not make them less confusing and just use τ. Pi supporters show many formulas in which a sole π is used and so don’t understand why something that has worked for thousands of years should be changed.

The Pi or Tau debate continues. Which side are you on?

Sources: The Pi Manifesto, The Tau Manifesto, Tau Day, Scientific American

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