Slashdot Mirror
Pi Day Is Coming — But Tau Day Is Better
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.'"
What, pi is 14.3? When did that happen?
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.
"Have you ever thought about just turning off the TV, sitting down with your kids, and hitting them?"
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).
Time to offend someone
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.
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!
http://www.geoffreylandis.com
Tau is twice the constant Pi ever was!
Then, when somebody wants to argue that twice e is actually a better constant, we can say "2e or not 2e, that is the question."
Both are irrational.
It is? Like what? There's a lot of greek symbols that are used for different things, so you have to look at what domain you're in before you make any assumptions about their values. This also applies to latin symbols.
Quick: what is i? Well, that depends. If you're a mathematician, it's the square root of -1. However, if you're an electrical engineer, the answer is the AC current. In EE, j is the square root of -1. Omega, theta, tons of symbols like these are reused in different domains for different things.
Offhand, I don't remember tau being used for anything else in mathematics (specifically geometry), so it seems as good a symbol as any. According to Wikipedia, there's a handful of mathematical uses for tau already, but they seem pretty esoteric (or obsolete, in the case of the golden ratio, which more commonly uses phi). It is used for a bunch of things in physics and biology, but those are different domains, so that's pretty irrelevant. You don't use pi (the circle constant) much in biology either, I imagine.
However, there are some greek letters that are barely used, so maybe one of those would be better. Upsilon, for instance, only has one use listed in Wikipedia's list of greek letters used in math, science, and engineering, to represent an elementary particle. Only physicists would ever see that (I don't think I ever saw that in college, as I was a EE major), so maybe that'd be a better choice than tau.
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!
Program Intellivision!
Sure there is: e^(tau * i) + 0 = 1.
Hey, it's really not any more ridiculous than "... + 1 = 0".
No it isn't. It completely misses the point of e^(pi * i) = -1, which is that the left side gives you a bloody negative number.
The tau version is rather obvious, since you are squaring (-1). Put it another way, if e^(pi * i) had happened to equal 1, the tau version would be exactly the same. The tau version doesn't really tell you what is special about Euler's identity.
Umm, no!
e^(pi*i) = -1 implies e^(tau*i) = 1
e^(tau*i) = 1 does not imply e^(pi*i) = -1
The tau version follows from the pi version. The pi version does not necessarily follow from the tau version, because the tau version would still be true if e^(pi*i) = 1.
So the tau version is missing some very important information.