MDBCs 28 Jun 2024

Tau Day, an anti-Pi Day holiday, is an unofficial observance held every year since 2010 on June 28, or 06/28 as written in the American date format.

The day began as a way to recognize tau, τ, a ratio constant describing the relationship between the circumference and the radius of a circle. In recent years, some mathematicians and physicists have argued for the replacement of pi (π) by tau.

Replacing Pi

The concept of replacing pi by tau as a better way to describe the relationship between a circle’s circumference and its radius was first brought up by mathematics professor, Bob Palais in the Mathematical Intelligencer in an article called π is wrong!. This was followed by the publishing of the Tau Manifesto by physicist Michael Hartl. Both of these articles called for the replacement of pi by tau. Tau, the ratio of a circle's circumference to its radius, is equal to 2 π or 6.283.

Not Widely Accepted

Tau is not yet widely accepted within the scientific community, though there is a large community of scientists and technologists who have called for the replacement of pi by tau.

Other Mathematical Dates

The Gregorian Calendar is full of dates that when written in a special manner represent a mathematical or scientific concept. Some of these include Yellow Pig Day, Mole Day, Fibonacci Day, Palindrome Day, and e-Day. Use our Date Pattern Calculator to find out other interesting calendar dates during the year.

How to Celebrate?

Because the value of tau is twice the value of pi, proponents of tau day call for “twice as much of pie” and to eat circular shaped food. So, instead of one slice of pie, eat two or four.
If you are a teacher, use this day to encourage students to get interested in mathematics and to consider mathematics as a career choice.

Did You Know…

… that Michael Hartl, called for renaming March 14 (3/14) or Pi Day to Half Tau Day?

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Inspirational speaker Dr. Wayne Dyer still remembers the card his kids gave him for his 64th birthday. The front said, "Inside is a message from God."

Pleased they finally appreciated his work, he opened it to read, "See you soon!"

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My husband uses scraps of wood, called "shorts," for carving. In a lumber store, he saw some lovely pieces in a bin behind the counter. But he had a lot of explaining to do after he asked the clerk,

"Do you mind if I come around and poke through your shorts?"

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I arrived home to find the place ransacked. Fortunately, my niece and her husband, PJ, were with me.

Grabbing a golf club, PJ searched the house to make sure the robber was gone. Then he looked at the club -- a three iron.

"I should have taken the wedge," he said.

"Why?" I asked.

"Lately I've been having trouble hitting anything with my three."

***

Shortly before our 25th wedding anniversary, my husband sent 25 long-stemmed yellow roses to me at my office. A few days later, I plucked all the petals and dried them. On the night of our anniversary, I spread the petals over the bed and lay on top of them, wearing only a negligee.

As I'd hoped, I got a reaction from my husband.

When he saw me, he shouted, "Are those potato chips?"