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Math Education Science

Pi Day Is Coming — But Tau Day Is Better 241

PerlJedi writes "A few months ago, a Tweet from Randal Schwartz pointed me to a YouTube video about 'Triangle Parties' made by Vi Hart. My nerdiness and my love of math made it my new favorite thing on YouTube. Now, with Pi Day coming up later this week, I thought it would be an appropriate time to point people to another of her YouTube videos: Pi is Wrong. The website she mentions at the end, Tauday, has a full explanation of the benefits of using Tau rather than Pi. Quoting: 'The Tau Manifesto is dedicated to one of the most important numbers in mathematics, perhaps the most important: the circle constant relating the circumference of a circle to its linear dimension. For millennia, the circle has been considered the most perfect of shapes, and the circle constant captures the geometry of the circle in a single number. Of course, the traditional choice for the circle constant is pi — but, as mathematician Bob Palais notes in his delightful article "Pi Is Wrong!", pi is wrong. It's time to set things right.'"
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Pi Day Is Coming — But Tau Day Is Better

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  • Agreed (Score:5, Funny)

    by Ardeaem ( 625311 ) on Monday March 12, 2012 @02:12PM (#39329039)
    What, pi is 14.3? When did that happen?
    • Re:Agreed (Score:5, Funny)

      by Harold Halloway ( 1047486 ) on Monday March 12, 2012 @02:18PM (#39329169)

      Being English, old-fashioned and inaccurate, I prefer to celebrate Pi Day on July 22nd.

      • Re:Agreed (Score:5, Interesting)

        by wjh31 ( 1372867 ) on Monday March 12, 2012 @02:22PM (#39329245) Homepage
        22/7 is actually more accurate than 3.14 (0.05% vs 0.04%)
        • by Hatta ( 162192 )

          22/7 is misleading, in that people often think it's an exact value. I actually had math teachers in middle school who claimed as much, and refused to understand the term "transcendental number".

    • by Hentes ( 2461350 )

      Because that's not the standard [].

    • Dude, you put the more significant digits first.

      Pi is now 201203.14 (201.203,14 with European punctuation).

      • Actually with European punctuation it is 14/3 - 2012 which is around 2008BC or something

      • Pi is now 201203.14 (201.203,14 with European punctuation).

        Depends upon which part of Europe you are from. In the English speaking part it would be 201,203.14

      • by plj ( 673710 )

        “European punctuation” is an unfortunately generic term, if one includes the digit group separator in that definition, as you just did. While all of continental Europe (as well as the entire South America!) indeed uses comma as decimal separator, digit group separator varies. For example, Germans, Greeks, Italians and Swedes would group digits with dots, while Czechs, we Finns, as well as French and Poles would use spaces. (Thin) space is also used in some applications elsewhere in the world, du

    • What, pi is 14.3? When did that happen?

      It is a consequence of neutrinos going faster than light- all the laws of the universe are now backwards. And yes, Pie is now 14.3... or as an estimation 7 divided by 22.

  • by Kenja ( 541830 ) on Monday March 12, 2012 @02:12PM (#39329047)
    Thing is, we like pie. Being able to eat a Pi sized slice of Pi at 1:59 on 3.14 is a geeky excuse to consume treats.
    • You beat me to it. I'm the chief promoter of Pi Day at my workplace, and it's mostly almost all about the pie. One of the secretaries likes to sing Pi Carols, but it's pretty much about the pie eating.
      • I'm trying to imagine Pi Carols...

        Oh Pie Tree, Oh Pie Tree,
        How lovely is your crust baked...

        Rudolf the red cherry piedeer

        We three fillings, of orient are,
        figs, plums, kiwis stored in a jar

        Timer Bells, Timer Bells
        Time to open the oven

      • One of the secretaries likes to sing Pi Carols

        Wow, is your secretary some kind of frustrated geek or something?

        I didn't even know there were Pi carols.

        • Hmmm maybe not Pi Carols but there are at least two Carol Pi's in the US according to

        • >Wow, is your secretary some kind of frustrated geek or something?

          Yes. Nice voice though.

          >I didn't even know there were Pi carols.

          Google is your friend, or not. You may not want to know. For starters: try this. []

    • If you want to observe the festivities with a more phonetically accurate English language reinterpretation of the ancient Greek letter name "Pi", you should go to the restroom and urinate. That can be a very satisfying feeling as well.
    • by buchner.johannes ( 1139593 ) on Monday March 12, 2012 @02:45PM (#39329667) Homepage Journal

      With Tau, you can have two pies.

      • With Tau, you can have two pies.

        Actually, if you are a particle physicist you can have a lot more - one tau can decay into 5 pis (although 3 is more common).

      • I just watched the "tau" video and ... I actually agree with it. Making it the ratio of diameter/circumference instead of radius/circumference was a dumb move.

        While we're at it can we swap the + and - on our electronic circuits?

    • by CAIMLAS ( 41445 )

      Bah, they're both boring. Let me know when it's Summer Glau Day.

    • Ah, but you can do this: On June 28 at 3:18, everybody leaves work early to contemplate the nature of existence (which simply cannot be done at work). Mathematically religious holiday! That means you can eat pie at home in your underpants* WITHOUT your dumbass co-workers stealing your fork.

      *According to wikipedia, this is the ONLY way to properly contemplate existence, unless, of course, my edit was edited.
    • Right, but if you have a cylinder with radius z and height a, its volume is Pizza. Who needs pie when we can have wonderful, tasty, Pizza?
  • There are 14 months in a year now?
    • It's the year 3141?
    • by ae1294 ( 1547521 )

      Well with everyone so interested in the Mayans with thought; Oh, the Mayan calendar is 13 months long. We're gonna make ours 1 better you see? 14 is 1 better than 13. Our new calendar goes to 14!

  • Darn.
      I read that wrong.

    I say we stick with pi. It's too labor-intensive to rewrite all the textbooks to read "tau" instead of "2*pi" and reteach everyone the new formulas.

    • by Mr Z ( 6791 ) on Monday March 12, 2012 @03:07PM (#39329975) Homepage Journal

      And, I think it's perhaps a little wrongheaded anyway. The area of a circle is pi*r^2. That'd become tau*r^2/2... You took the 2 out of one place and put it in another. And it does nothing for spheres: Volume = (4*pi*r^3)/3 = (2*tau*r^3)/3; Surface area = (4*pi*r^2) = (2*tau*r^2).

      And besides, tau's already claimed as the "time constant" variable, so n'yah!

      • The area of a circle is pi*r^2.

        For most people, yes.
        For some (including me), however, it will always be pi.d^2/4, for the simple reason that you can't easily measure an object's radius (measuring d then halving doesn't count). Seeing it that way might be ugly/wrong from a mathematical standpoint but practically speaking it seems more natural.

  • by Bob the Super Hamste ( 1152367 ) on Monday March 12, 2012 @02:16PM (#39329121) Homepage
    Tau day is better because I have an excuse to get 2 pies instead of just one. I still celebrate pie day as well as groundhog day, mmmmm ground hog).
  • It's the day we're all comfortable with Sin(), further we're so accomodating we'll embrace Cos().

  • by Anonymous Coward on Monday March 12, 2012 @02:20PM (#39329203)

    I do think tau is the 'better' constant, and both exploring the possibilities of what tau can do, and just 'playing around' with the math involved, has been enjoyable. However, to evaluate it properly and determine just how strong it is, a strong counterpoint is needed - and it is supplied in The Pi Manifesto [].

    Both its author and I recommend reading The Tau Manifesto (and Bob Palais's original work; both are linked in the article above) before reading The Pi Manifesto, to make proper sense of it.

    In the end, I think tau is a much stronger choice than pi for some aspects of math; others, deserve further investigation. It may all be academic discussion, given how firmly pi is entrenched in our mathematics, but perhaps there's a solid place for both - with pi reserved for certain advanced concepts, and tau used through introductory geometry, trig and calculus.

    • Hmm. The Pi Manifesto's first three arguments are "Tau is silly.", "It doesn't matter which one we use." and "Physicists are dumb. Even the Babylonians used Pi." Then it goes on to argue the Tau Manifesto uses cherry-picked examples by .... cherry picking examples. I think, if we had to decide on the number now, without the long history of Pi, Tau should win by a hair, as described by this analogy of Pi to 1/2 and Tau to 1 (from the Tau Manifesto):

      "Imagine we lived in a world where we used the lette
  • Four thirds pi! (Score:5, Interesting)

    by Geoffrey.landis ( 926948 ) on Monday March 12, 2012 @02:21PM (#39329209) Homepage

    Wait, what about four-thirds pi, the constant that relates the volume of a sphere to the radius???

    Using 2pi as the so-called "constant" is two-dimensional chauvinism!

    • 4/3 pi r^3 is actually 2/3 or of a circumscribed cylinder or 2/3 tau r^3..

      This tau thing kind of makes sense, though I tend to call it 2 pi.. If pie is good, two pi is twice as good.

    • by ardiri ( 245358 )

      four-thirds pi = eight-thirds tau

      just as complex in both cases.. neither case holds up as being singular for the sphere.

  • by Matt_Bennett ( 79107 ) on Monday March 12, 2012 @02:27PM (#39329341) Homepage Journal
    Who cares about pi or tau? e shows a much more in depth understanding of mathematics.
  • by mjrauhal ( 144713 ) on Monday March 12, 2012 @02:29PM (#39329373) Homepage

    Tau is twice the constant Pi ever was!

  • I remember arguing with my geometery teacher years ago, she kept saying pie are squared. I can't recall ever seeing a square pie. (Cobbler perhaps but never a square pie.)
  • tau is wrong (Score:2, Insightful)

    by w_dragon ( 1802458 )
    Division is harder than multiplication. Given the choice between sometimes multiplying by 2, and sometimes dividing by two, we should pick the constant that forces the multiplication. Also, e^(pi * i) is nicer than e^((tau / 2) * i).
    • Re: (Score:3, Informative)

      by artor3 ( 1344997 )

      I know that some people will point out that e^(tau * i) = 1, which they'll claim is nicer than e^(pi * i) = -1

      But the most beautiful equation in mathematics is e ^ (pi * i) + 1 = 0. The five most fundamental constants, being combined with the three most fundamental operators (addition, multiplication, exponentiation -- sorry, tetration), all equaling out, with absolutely nothing extra. There's no way to make it work as elegantly with tau.

      • Re:tau is wrong (Score:5, Insightful)

        by mrnobo1024 ( 464702 ) on Monday March 12, 2012 @03:50PM (#39330575)

        Sure there is: e^(tau * i) + 0 = 1.

        Hey, it's really not any more ridiculous than "... + 1 = 0".

        • by artor3 ( 1344997 )

          How in your mind is "x+1=0" ridiculous in the sense that "x+0=1" is? The former is a perfectly valid equation. Setting things equal to zero is extremely common, as anyone with even a middle school level education ought to know. Do you complain that x^2+2x+1=0 is a ridiculous equation too?

        • Especially since Euler had to hack in a +1 to turn a -1 into that oh-so-elegant zero.

          That's like finding out all of Bob Ross' happy little trees were Photoshopped in during the commercial break. Tao is a "full-circle" representation, literally, while Pi is simply "half" assed. =)
  • by deego ( 587575 ) on Monday March 12, 2012 @02:40PM (#39329573)

    Seriously? People devote all this energy to replace a centuries-old constant by twice its value?

    Isn't "wrong" a sensationalist word to use?

    This is like many other things that are "wrong" - in the sense that there are technically better conventions to use, but the weight of history and inertia often keeps us from switching. Examples:

    - Km vs. Mile. (SI units vs. Imperial..)
    - Why are there 60 minutes per hour? Wouldn't it be better to have 100?
    - Why do we use base 10 to express numbers? We should rather use base 8.
    - Why 360 degrees? Why not 100 or 1000 (which is using base 8, of course, as mentioned above) instead.

    • I'm in the minority I know- but I would be in favour of switching to a metric clock. Sure it would cause confusion at first. I'd be in favour of measuring degrees in fractions of 100 or 1000.

      There again- I'm always in favour of confusion. It's always more fun than the status quo.

      • by deego ( 587575 )

        haha, same here - actually in favor of switching for that case. That one was a bad example, then, I guess.

    • Re: (Score:2, Interesting)

      by Grishnakh ( 216268 )

      You complain about miles instead of km, but then you complain about using base 10? You're not even being consistent; if you favor base 8, then you should be against switching to kilometers or any SI unit for that matter, as their entire existence is based on the supposed superiority of base 10.

      And why base 8? Why not base 12? 12 is evenly divisible by both 3 and 4, which is very useful in many real-world situations. 10 is only divisible by 2 and 5. 8 is only divisible by 2, so it really sucks to be hon

  • Tau (Score:3, Interesting)

    by brianerst ( 549609 ) on Monday March 12, 2012 @02:43PM (#39329615) Homepage

    I'm not a mathematician, but that Tau "article" seems to steal a few bases.

    It whines about A=(pi)r2 while C=(pi)D and how that shows that diameter is fundamental. But that's not the way I learned it anyway - the formula was always C=2(pi)r. Radius was fundamental, not diameter.

    Which is even more obvious when you go into spheres, where everything is based off radius (A=4(pi)r2, V=4/3(pi)r3).

    If we use diameter, you have to remember additional divisors (4 for the areas, 8 for the volumes). I can't speak on whether the whole "one turn" argument would help understanding other concepts, but aside from people who are working to become mathematicians, I suspect that the fact that the radius-based "magic formulas" are simpler will keep them around...

    p.s. What magic brew do you have to use to get Slashdot to accept HTML codes like pi? Or Unicode? Every attempt ended up getting stripped, so I went with (pi).

    • A circle in n dimensions is defined as the set of all points at a given distance from a fixed point, the center. Circles are defined by the radius, not the diameter. The "standard" equation for a circle is x^2+y^2=r^2. Etc, etc. The diameter is not more fundamental.
  • by Bob Hearn ( 61879 ) on Monday March 12, 2012 @02:45PM (#39329657) Homepage
    I managed to get bib # tau for a marathon last year []. Gave the timekeeper fits.
  • by sdhankin ( 213671 ) on Monday March 12, 2012 @02:46PM (#39329685)

    Both are irrational.

  • The problem with Tau is that it will always be associated with Pooh thanks to the book the "Tau of Pooh".

    Pi day sounds way more appetizing than Pooh day. In the land of prunes, every day is a Pooh day.

  • by Oswald McWeany ( 2428506 ) on Monday March 12, 2012 @03:00PM (#39329871)

    Oh and obligatory:

    Taumorrow, Taumorrow, I love you, Taumorrow, you're only a day away......

  • For sufficiently large values of nerd.

  • I recently saw an image of a Pi-Cake with the caption, "It's cake. But it's pi. But it's CAKE. But it's PI. BUT IT'S CAKE!!!"

    After a little research, I even found a recipe for pi-cake. Pi-Cake []
    While an irrational pursuit, it looks to be a tasty one. Anyone thinking about making one?
  • the circle has been considered the most perfect of shapes

    And yet, the circle needs a point to define the center, and an infinite number of points around the circumference to define the circle itself. The most perfect of shapes is a point. It is the basis for all other shapes, both in flatworld, in 3d space, and in space-time. Without the point, there would be no point (pun intended) to trying to define a circle either as pi or tau (where is your center to get your diameter or radius from, hmmmm?).


  • Let me see if I get this straight... Tau = 2*Pi and Tau is right. But Pi is wrong. So, by this rational, two wrongs make a right?
  • by sootman ( 158191 ) on Monday March 12, 2012 @04:28PM (#39331039) Homepage Journal

    Pi will always be around because it relates to the diameter, which is easily measurable by actual humans in actual circumstances.

    If there's a big circle on the floor, you can measure the diameter with a tape measure and one other person: stand on opposite sides of the circle, one end of the tape stays in one spot, and the other end gets moved back and forth until its length is as long as possible. The widest part of the circle == the diameter.

    You can determine "the widest part of the circle" with simple physical measurements. Measuring the radius only requires a way to accurately determine where the center is, which is a non-trivial exercise. (Compared to the above.) Or you could measure the diameter and then divide by 2, but "measure the diameter" will always be one less step than "determine the radius."

"More software projects have gone awry for lack of calendar time than for all other causes combined." -- Fred Brooks, Jr., _The Mythical Man Month_