- 28 Jun '11 22:22Debra Black

Staff Reporter

Michael Hartl believes the mathematical symbol Pi (or 3.14) is a “confusing and unnatural choice” for characterizing the geometry of a circle.

And he wants the world to embrace the mathematical symbol Tau (6.28) instead.

Hartl, who has a bachelor degree in physics from Harvard University and a Ph.D. in theoretical physics from Caltech, got the idea after reading a two-page argument by Bob Palais of the University of Utah that was published in 2001 in The Mathematical Intelligencer.

He was so fired up he decided to write his own manifesto supporting and expanding Palais’ ideas.

And thus the life of Tau was born, so to speak. And its birthday is today – Tuesday, June 28 (6.28, or 3.14 times two) – the calendar version of its mathematical value. It has its own Facebook page and is accessible on Twitter.

Not to be outdone. And for those who care about such things, Pi also has its own day – celebrated on March 14 (or 3.14).

It was created by Larry Shaw in 1988 at the San Francisco Exploratorium where Shaw worked as a physicist.

In 2009 the U.S. House of Representatives passed a non-binding resolution recognizing March 14, 2009 as National Pi Day.

For Hartl and his supporters, though, Tau trumps Pi. And so Tau Day this year will culminate with a lecture/party at California Institute of Technology where a band of fellow Tau enthusiasts will eat (what else) pie with whipped cream and ice cream.

There Hartl will discuss the elegance of Tau. He and his supporters will be wearing Tau Day t-shirts, described as a way to tell the world that Pi is a lie.

For the non-mathematical among us, here’s a quick explanation of the debate, according to Hartl.

Pi traditionally is the ratio of a circle’s circumference to its diameter. Tau is the ratio of a circle’s circumference to its radius. For Hartl and others, this is crystal clear. For many of the rest of us, not so much.

So here’s the nugget of the issue: “The problem is, a circle is more naturally characterized by its radius,” Hartl explained in a phone interview with the Star. That makes Tau a more natural tool to characterize a circle.

“The diameter (of a circle) is equal to twice the radius by definition. So what Pi really is is the ratio of a circle’s circumference to twice its radius.”

And that’s where all mathematical hell breaks loose, according to Hartl. That factor of two makes Pi confusing, Hartl argues.

Simply put: “Pi is not beautiful. It’s not elegant, and it’s confusing.

Tau on the other hand, says Hartl, is much better at characterizing the geometry of a circle because it is the ratio of a circle’s circumference to its radius.

Hartl, a 37-year-old California physicist and entrepreneur who makes videos and writes books for Web development, believes strongly in his cause and has the academic cred to back up his remarks.

“There’s no question in my mind from the aesthetic point of view Pi is ugly and confusing. The real problem is Pi is an ambassador for people outside mathematics. If they know anything, they know about Pi.

“But if you’re going to elevate a number to that status, you should be really sure it’s up to the task. The problem is it doesn’t respond to scrutiny.” - 28 Jun '11 22:53

really?!?... and*Originally posted by uzless***Debra Black**

Staff Reporter

Michael Hartl believes the mathematical symbol Pi (or 3.14) is a “confusing and unnatural choice” for characterizing the geometry of a circle.

And he wants the world to embrace the mathematical symbol Tau (6.28) instead.

Hartl, who has a bachelor degree in physics from Harvard University and a Ph.D. in theoretical phy ...[text shortened]... , you should be really sure it’s up to the task. The problem is it doesn’t respond to scrutiny.” - 29 Jun '11 03:35

I can't believe im even taking this seriously, but I dont think that the circumference of a circle is readily measured...and thus would not be prefered over the linear measurement of radius or diameter. Also, the whole speel is that expressions of circles are better in terms of radius than diameter ( not that I believe that statement), and you are using circumference in your "tie breaker formula for Area", which consequently seems to be incorrect as*Originally posted by wolfgang59***Expressing the area of a circle with tau is ugly.**

Pi wins.

Incidently where does tau come from? i believe pi was chosen as the Greek P for Perimeter Ratio.

EDIT: maybe not A = (c/tau)^2

A= (c/tau)^2 = ((2*pi*r)/(2*pi))^2 = r^2 =/= pi*r^2

I think the correct formula using "C" would be

A = C^2/(2*tau) - 29 Jun '11 15:33

Since the area of a circle is defined as PI*(r^2) if you try to use Tau, it would be*Originally posted by mikelom***Simply put. He's in it for the money and exposure.**

Pi will never be replaced by it's doubled sister, Dianametres...

-m.

Tau/2*(r^2). Doesn't seem to be less ugly than just PI R^2.

In frequency equations, for instance, resonant frequency is 1/(2PI*((L*C)^1/2)) Which is a clumsy way to write it but with Tau, it would be 1/(Tau*((L*C)^1/2))

Not a whole lot of difference IMO. - 11 Jul '11 05:52

A more natural tool? I think not.*Originally posted by uzless***So here’s the nugget of the issue: “The problem is, a circle is more naturally characterized by its radius,” Hartl explained in a phone interview with the Star. That makes Tau a more natural tool to characterize a circle.**

How are wheels measured? By their diameter. Describing them by their radius would be way confusing. 8" wheel? Baloney, I can plainly see that wheel is 16".

What about pipes? Same thing. Calling a 2" pipe a 1" pipe is just stupid.

Balls are measured by their diameter, as are wrenches, torpedoes, ropes, vinyl records, gears, gun barrels, pies, floppy discs, speakers, and I could go on, but you get my drift.

Almost anything round is measured by diameter. This seems to make diameter the "more natural tool to characterize a circle". - 11 Jul '11 06:32

The thing they are talking about here is not just simple diameter, it's area, PI R squared.*Originally posted by Suzianne***A more natural tool? I think not.**

How are wheels measured? By their diameter. Describing them by their radius would be way confusing. 8" wheel? Baloney, I can plainly see that wheel is 16".

What about pipes? Same thing. Calling a 2" pipe a 1" pipe is just stupid.

Balls are measured by their diameter, as are wrenches, torpedoes, ropes, vinyl ...[text shortened]... y diameter. This seems to make diameter the "more natural tool to characterize a circle".

So using only diameter, you have to go PI*(D/2)^2. It just adds to the equation. In math most circles are given in radii. In the real world you go with diameters. Or you can tape measure the circumference and divide by Tau/2 - 11 Jul '11 06:52Since we are talking about maths and equations, what really matters is radians ie angles as measured as a proportion of the radius to the perimiter. Now if you had tauans, it would seem a bit odd when using a pie slice, and instead of measuring the radius (one side of the pie) to the perimieter (the curved side of the pie), you measure the diameter (one side of the pie plus an imaginary extention).

But then again, 1 circle is 2pi or 1 tau, and the latter seems to make more sense. - 11 Jul '11 13:39

But when you talk about a pie slice section of a circle, by definition, the straight sides of the pie are exactly one radii not a diameter. Can you clarify that?*Originally posted by twhitehead***Since we are talking about maths and equations, what really matters is radians ie angles as measured as a proportion of the radius to the perimiter. Now if you had tauans, it would seem a bit odd when using a pie slice, and instead of measuring the radius (one side of the pie) to the perimieter (the curved side of the pie), you measure the diameter (one s ...[text shortened]... xtention).**

But then again, 1 circle is 2pi or 1 tau, and the latter seems to make more sense. - 12 Jul '11 01:01

Whether speaking of Pi or Tau, the common factor is circumference, not area. Circumference is 2Pi(r), or diameter * Pi, or radius * Tau. Since we use diameter way, way more than radius, Pi is the obvious choice.*Originally posted by sonhouse***The thing they are talking about here is not just simple diameter, it's area, PI R squared.**

So using only diameter, you have to go PI*(D/2)^2. It just adds to the equation. In math most circles are given in radii. In the real world you go with diameters. Or you can tape measure the circumference and divide by Tau/2

"Or you can tape measure the circumference and divide by Pi" -- glad to see we agree. - 12 Jul '11 01:20 / 1 edit

That last was a lame attempt at humor*Originally posted by Suzianne***Whether speaking of Pi or Tau, the common factor is circumference, not area. Circumference is 2Pi(r), or diameter * Pi, or radius * Tau. Since we use diameter way, way more than radius, Pi is the obvious choice.**

"Or you can tape measure the circumference and divide by Pi" -- glad to see we agree.

Like the math class planted a tree in honor of their math professor: It had square roots