# Happy Tau Day, Everyone!

In case you want to know why Pi is wrong, you should read this

Hemant Mehta is the editor of Friendly Atheist, appears on the Atheist Voice channel on YouTube, and co-hosts the uniquely-named Friendly Atheist Podcast. You can read much more about him here.

• David McNerney

I’m sorry dude – that’s completely irrational.

• CS42

Fracking Tauists.

• The Other Weirdo

Love the use of TeX for the mathematics, but the actual substance is quite beyond me.

• Casey

As a math professor myself, I have to admit… who cares? I’ve read about tau. It’s 2pi. And pi is 1/2tau. So it seems to me that, unless you’re a moron, you could use EITHER ONE. What’s important about them is that they are transcendental. As far as formulas go, who freaking cares which one you use? So happy tau day. And I suppose in march we’ll have pi day again. Of course, July 22nd should actually be pi day, but most people wouldn’t understand why…

• Pseudonym

The “case” for tau is, of course, mostly tongue in cheek, but it’s a case of “ha ha only serious”.

There are a only a small number of places where it makes a practical difference, such as working out Planck units. But more to the point, this is one of those examples of situations in the history of science where some important convention which was established before the full implications were known, and it turns out we did it the wrong way and are now stuck with it.

Another classic example is in physics, where electrical current flows in the wrong direction. Physicists had to pick one direction to be “positive” and one to be “negative”, and had no reason to pick one over the other, since the electron had not yet been discovered. So they accidentally gave electrons a negative charge instead of the positive charge that they should have. So now we’re stuck in the bizarre situation that, for example, when lightning strikes the ground, current flows up, not down.

Planck’s constant is another example, but thankfully that one was caught early.

Now the factor of two, or the negative sign, or whatever, doesn’t really hurt our ability to do calculations. But as a math professor, you must agree that beauty is important, and the better your notation is, the more effective discovery is.

That factor of two hides some important connections which could help in education, as well as in practice. For example, consider the property that the area of a disc is the integral of the circumference of a circle:

∫ 2πr dr = πr²

Anyone can understand that. But you’re more likely to immediately notice the connection it if it’s expressed like this:

∫ τr dr = 1/2 τr²

That right-hand side looks like like the integral of a linear equation, in the same that linear kinetic energy in classical physics looks like the integral of linear momentum w.r.t. velocity:

∫ mv dv = 1/2 mv²

Notation does matter, and sometimes it matters a lot. Good notation enables better and faster discoveries than bad notation. Even if it’s 0nly a minus sign or a factor of two.

• gAytheist

I can’t go along with this.  Tau already has too many other uses.  For example, in relativity it stands for proper time.  Let’s just stick with 2*pi.

• Pseudonym

There are a lot of problems in maths and mathematical physics caused by the fact that all of the good Greek letters are taken. Cantor famously had to start raiding the Hebrew alphabet. It’s only a matter of time before we’re using Linear B.

• Reginald Selkirk

Pi isn’t “wrong,” it is just non-optimal for certain purposes.

• Zeggman

Chalk up another convert, I’m drinking the Kool Aid. Never heard of this before, but it makes sense. Still, though I like the manifesto and found it persuasive (the first half, anyway, which is all I read), I don’t really care for the song. Get Joni Mitchell to write you another one, and I think this movement will really take off.

Oh, I’m sorry. I thought this had something to do with Warhammer 40k. What I got instead was a boring video about math.

• Bruce the Moose

No, really, pi is right:  http://www.thepimanifesto.com/

• Shaun McGonigal

I just realized that ‘Hemant Mehta’ is an anagram for ‘Thee Math Man.’  So, the next time I see him I shall call to him, saying “thee, math man!” and he’ll run away in horror of my terribleness.

Happy Tau day!

• http://boldquestions.wordpress.com/ Ubi Dubium

Or “e, the Math Man”.  More irrationality!

• Shaun McGonigal

Yeah, that too! I’m sure there are other good ones too, but I’ve geeked out enough today (wait, did I just say that?)

• EricBoucher

Pi is not wrong, it might not always be the best but it is pointless to try and change the standard for something that is only better half the time.  Plus you can eat Pie on Pi, what are you gonna do on Tau day?  Eat Taow?  No of course not.

Lets stick with Pi, its better as often as Tau is.

My youngest son was born on March 14th.  He’s pretty amazing,  and I guess what I’m trying to say is . . . . why do you hate my child?  What did he ever do to you?

• Bob

Like tau, pi also has lots of other uses in math – the prime counting function,  projection functions, homotopy groups, and users figure it out from context. I don’t think you could do this with pi, but 6.28… is natural!:
http://www.math.utah.edu/~palais/ArchimedesFormula.html

• Bob

P.S. I’m glad this topic made me aware of Hemant and this wonderful site and the work of Foundation Beyond Belief. From `Pi is wrong!’: `What really worries me is that the first thing we broadcast to the cosmos to demonstrate our “intelligence” is 3.14… I am a bit concerned about what the lifeforms who receive it will do after they stop laughing at creatures who must rarely question orthodoxy.’  The popularity of tau in recent years gives me some optimism.
http://www.math.utah.edu/~palais/pi.html

• http://www.cstdbill.com/ Bill

So…

eiτ/2+1=0