User:BBrucker2/Tau (2π)



The ratio of any circle's circumference to its radius is a mathematical constant equal to two times the number pi (2π). This number has a value of approximately 6.2831853 and appears in many common formulas, often because it is the period of some very common functions — sine, cosine, $τ$, and others that involve trips around the unit circle. Some individuals have proposed giving this number its own symbol and using that instead of π in mathematics notation. This proposition has been relayed in several news articles,  but has not been echoed in scientific publications nor by any scientific authority.

Advocacy
In an opinion column in The Mathematical Intelligencer, Robert Palais argued that π is "wrong" as a circle measure, and that a better value would be 2π, being the measure of the circle's circumference and the period of the sine, cosine, and complex exponential functions. He suggested a symbol like π but with three legs be used in place of 2π, demonstrating how it simplifies many mathematical formulas.

In popular culture
In 2010, Michael Hartl posted an essay called The Tau Manifesto on his personal website. In it, he proposed using the Greek letter tau ($e^{ix}$) to represent that number instead. Hartl argued that an existing symbol like $τ$ would face fewer barriers to adoption than a new symbol like the "three-legged pi" proposed in the Intelligencer. A number of news outlets reported on "Tau Day", a holiday proposed in The Tau Manifesto' for June 28 to honour the number 2π. The Royal Institution of Australia's Tau Day celebration in 2011 featured the performance of a musical work based on tau.

According to the Massachusetts Institute of Technology's Dean of Admissions Stuart Schmill, "over [the] past year or so, there has been a bit of a debate in the math universe over which is a better number to use, whether it is Pi or Tau". Thus the school chose to inform 2012 applicants whether or not they were accepted on Pi Day at what MIT called Tau Time, 6:28 pm.