Tau Day is an annual celebration of the circle constant $\tau = 6.283185\ldots$, which takes place every June 28 (6/28 in the American calendar system). To learn more about what $\tau$ (tau) is and why it’s important, read The Tau Manifesto, or watch one of the tau videos below.
Buy Print Edition
Get the print edition of The Tau Manifesto at Amazon!
Get your own Tau Tee
Celebrate Tau Day in style with a Tau T-shirt from Teespring!
Tau Day founder Michael Hartl is an educator, author, and entrepreneur. He is cofounder and principal author at Learn Enough and the Ruby on Rails Tutorial. Previously, he taught theoretical and computational physics at the California Institute of Technology (Caltech), where he received the Lifetime Achievement Award for Excellence in Teaching and served as Caltech’s editor for The Feynman Lectures on Physics. He is a graduate of Harvard College, has a Ph.D. in Physics from Caltech, and is an alumnus of the Y Combinator entrepreneur program.