Happy 15th anniversary to tau!
When I launched the first edition of The Tau Manifesto back on June 28, 2010, I hoped that Tau Day might become a “thing”, but its success so far has exceeded my wildest expectations. With tau featured in places like Apple’s iOS, Google’s official calculator, and the Python programming language, and with Tau Day featured in outlets like Science News and The Wall Street Journal, at this point there seems to be no stopping tau. And it’s all due to the enthusiastic support of tauists like you—those persons of rare discernment who recognize that the true circle constant is \( C/r \):
As always, I’ve prepared a State of the Tau update with some of the tau happenings since Tau Day last year. Here’s a brief summary:
The fourth annual Tau Day celebration from the Simons Laufer Mathematical Sciences Institute (SLMath)
Some cool tau GPS art
See the full State of the Tau 2025 for all the details.
Happy Tau Day!