## Pi Day Is Coming — But Tau Day Is Better 241

Posted
by
Soulskill

from the circular-logic dept.

from the circular-logic dept.

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.'"*
## Considering the counterpoints (Score:3, Interesting)

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 [thepimanifesto.com].

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.

## Four thirds pi! (Score:5, Interesting)

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!

## Re:Agreed (Score:5, Interesting)

## Bah. e is better than them all (Score:3, Interesting)

## Tau (Score:3, Interesting)

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).

## Re:Considering the counterpoints (Score:4, Interesting)

The imperial system actually makes more sense for some things, depending on which measure you're talking about and what you're using it for. The whole 12 inches/foot thing can be easier to work with when you have to divide things evenly in quarters and thirds; by having something divisible by 12 instead of 10, you can easily divide by 3 or 4 without the math becoming complex. That's the whole reason 12 was the base for these units; back in medieval times, when they didn't have calculators and measurements were crude, it was easy to work with. Even now, woodworkers generally prefer English units for this reason.

Miles, however, don't make so much sense since they in fact are equal to 5280 feet. The big problem with conversion however, at least here in America, is that many things are based on miles. For instance, here in Phoenix, all the main streets are laid out along a 1-mile grid system. It's stupidly easy to see how far you'll travel from one point to another (using Manhattan lengths; except for Grand Ave, all the roads are N-S or E-W) just by looking at a map and counting the number of main roads in each direction. If we tried to convert to km, it'd be a mess. If I ask "How far is it from Baseline to Ray?" the answer is a simple "5 miles", just by counting the roads in between (Guadalupe, Elliot, Warner, Ray). In km, I'd count the roads and then multiply by 1.6, getting 6.4km, not exactly a convenient measure.

## Re:"wrong" is a sensationalist word. (Score:2, Interesting)

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 honest. 8 (or 16) is good when working with computers since it's easier than binary, but that's about it.

It's 360 degrees for the same reason there's 60 minutes in an hour. Base 12. Remember, degrees have smaller units: minutes and seconds.

## Re:Agreed (Score:5, Interesting)