## Happy Tau Day 298

Forget about Pi Day, today we celebrate something twice as good: Tau Day. For far too long, Pi has been the bride and Tau has been the bridesmaid. As Michael Hartl points out in

*The Tau Manifesto*, "Pi is a confusing and unnatural choice for the circle constant." He is giving a talk at the California Institute of Technology based on the Manifesto, with pie served at the end. "Twice as many as you might expect," he says.

## Mmmm pi (Score:2)

As Weebl and Bob might say...

## Yin and yang (Score:2)

## Re:Yin and yang (Score:4, Funny)

So the tau that can be named is not the true tau?

## Fuck that, I've created Upsilon! (Score:4, Funny)

It's 4*Pi, which makes it TWICE as kick-ass as Tau!

## Re: (Score:2)

## Re: (Score:2)

Actually, Tau makes more sense than Pi or your Upsilon.

Pi = c/d or Pi = c/2r -- Which means it's a ratio between the circumference and the diameter, but radians are based on the radius, so a full circle is 2Pi radians.

Tau = c/r -- Which makes life a lot easier, because then the circle is Tau radians.

So what? Well, that means when graphing trigonometric functions becomes a whole lot easier:

See [youtube.com]

Tau makes it harder to teach. The stereotypical constructive geometric way to teach Pi is to use a string anchored at the center and a pencil at the other end to draw the circle using the geometric definition of what a circle is, and then figure the ratio of the string to the drawing. Tau... That's not obvious how to teach using constructive geometry and mathematical manipulatives.

## Re: (Score:2)

Tau makes it harder to teach. The stereotypical constructive geometric way to teach Pi is to use a string anchored at the center and a pencil at the other end to draw the circle using the geometric definition of what a circle is, and then figure the ratio of the string to the drawing. Tau... That's not obvious how to teach using constructive geometry and mathematical manipulatives.

I don't understand your point. The length of the string must is equal to the radius but what is the drawing equal to, the circumference? If so then you have drawing/string = C/r = 2Pi = Tau.

## Re: (Score:2)

I don't understand your point.

That's because I'm too spaced out this early in the morning. Yeah, I guess I'm now converted to the Tau side, too.

## Re: (Score:2)

## 2x the pies (Score:2)

## Always show your work (Score:3, Funny)

After that I could write stuff like 67*pi = 188.40 + 21.98 = 210.38 (vertically)

The teacher never commented on showing my work after that...

## Re:Always show your work (Score:5, Informative)

Then you teacher failed. Showing your work is about knowing the procedure to do something.

Even the dimmest child can look at: 4 * X = 8 and KNOW X=2. But the real lesson is showing the work so when it's not that easy you can get a correct answer.

You use an easy example so when they finish going through the correct steps they can know they did it correctly.

## Re: (Score:2)

One of the worst things you can do to a student that truly understands the material is to drag them down and force them to do what they consider menial tasks. It is a fine line, because I agree that it is important that students learn how to work through more complicated problems. However, when someone has already demonstrated their ability and is effectively doing homework and writing tests simply to "jump through the hoops", you can seriously cripple their interest in pursuing the field entirely and drive

## Re:Always show your work (Score:5, Interesting)

Now for the anecdote part relating how a "one-size-fits-all" education scheme doesn't work in practice:

In elementary school, my brother's teacher would give the class spelling quizzes. He scored 100% on the first quiz. The second quiz rolled around and he scored 100% again. He was distraught because many of his colleagues had gotten stickers on their returned quizzes as rewards, and yet he had gotten nothing. The teacher's explanation was that the rewards were for

improvementon the quizzes -- if you did better than last time, you got a sticker.His response was to intentionally fail the subsequent quiz, and then slowly build up his score to 100%, and then restart the process. The teacher was concerned about his inconsistent spelling skills and thought he might have problems with distraction; my parents understood what had happened immediately.

When you reduce education to the lowest common denominator, you remove any chance for the gifted, the skilled, the interested, and the excited students to excel at their studies.

Aikon-

## Re: (Score:3)

And my teacher taught my that "seperate" is a verb, while "separate" is an adjective. She also taught the hard-and-fast "i before e" rule and caused me to lose a spelling bee, ironically by misspelling "forfeit".

I'll believe pretty much any crazy story you tell me about dumb ways of teaching spelling.

## Re:Always show your work (Score:4, Insightful)

One of the worst things you can do to a student that truly understands the material is to drag them down and force them to do what they consider menial tasks.

Exactly. What the teacher should have done is give them a question that they cannot do in their heads. If they can do 67pi then how about 67e or 123*sqrt(3) etc. That does not drag them down but does teach them that, smart as they are, there are always more difficult problems out there so they should not get too cocky.

## Re: (Score:3)

Showing your work to me was never a benefit for me. Grading homework, I actually much preferred the people who just put down the answer. Is it right? Full points. Is it wrong? Zero points. I could whip through a 20 part homework in about 30 seconds flat. When they showed their work, I actually had to follow through and check for mistakes. It was 100% upside for the students: if they made a boneheaded mistake (64 bitshifted twice to the right = 256), they got nearly full points. Showing your work meant that

## Writing as quickly as thinking? (Score:2)

But the real lesson is showing the work so when it's not that easy you can get a correct answer.

So it has become a problem of input devices. I think divide by 4 on each side, but how do I write this down as quickly as I think it?

## Re: (Score:2)

## Re: (Score:3)

Then your teacher failed at teaching you about significant figures. 67*pi=210.49, not 210.38. The difference is small, but you were only working with 3 significant figures of pi, so everything past the decimal point is going to be random. It just so happens that the next decimal places are small (.00159), which helps on the next digit, but the final digit is pretty much entirely junk.

210 is good enough for most purposes, for the same reason that 3.14 is good enough for most purposes, and the teacher shou

## Re: (Score:2)

## Re: (Score:2)

Why did you need to memorize it? I just ran through them in my head really quickly.

John von Neumann? We thought you were dead!

## Re: (Score:2)

Ramanujan lives!

## They've got a point (Score:2)

Angles: 2Pi in a full circle? Somehow it's more satisfying if the proportion of a circle were between 0 and 1: xTau. So half a circle would be (1/2)Tau, not the whole-looking 1Pi.

If you look at various "important" equations, you often end up seeing 2Pi in there. Gaussian, Riemann, Fourier. Another one: h/2Pi, h being Planck's constant. Why not make 2Pi the constant?

Even Pi*r^2 is more appropriate as (Tau/2)r^2, if you compare with (1/2)mv^2.

I have to admit I was not violently emotional when I read the argum

## Re: (Score:2)

I think it's a false dichotomy to say you have to have one or the other.

Yes, calculating circles, cosines, etc, with Tau is going to be way easier than using 2Pi, but, for most non-math types, I can't imagine them needing that kind of distinction.

Plus additional greek letters always look cool.

## Re: (Score:2)

And why not scrap even Tau and have just 0-1 for a full circle? Yes I know the advantages of radians, but I've always found it useful to use cycles/revolutions for any trigonometric work. I'm amazed that it's not in more common use. With calculators, you get radians and degrees, but never cycles.

## Re: (Score:2)

Yes, but e^(i*Pi)+1=0 Overrules pretty much everything.

The whole idea of Tau is for people who are too stupid to multiply by 2.

Throwing in

e(the irrational number whose powers are the inverse of natural logarithms) andi(the imaginary square root of negative one) is gonna confuse them even more than taking Sara Palin to a book reading club.## Re: (Score:2)

No, it's for people who are too lazy to multiply by 2. Consider that physicists have two constants for the same physical constant -- h and hbar -- because tracking the 2*pi factors is a pain. (For that matter, tracking the 2's with pi is also a pain. It's not really intuitive to look at 4*pi^3 and realize that in this case, that's because it's (1/2)*(8*pi^3).)

## Re: (Score:2)

e^(i*tau) - 1 = 0

## Re: (Score:2)

e^(i*Tau)=1+0

## Re: (Score:2)

RTFA e^(i*tau)=1

## Re: (Score:3)

You lose the concepts of addition and zero in that.

The elegance of e^(i*pi)+1=0 is that it includes addition, multiplication, exponents, e, i, pi, 0, 1 and equality.

Basically, everything that forms the foundations of math is included. You exclude zero and addition, well, who cares if you're using pi, tau, lambda or cheese whiz?

## Re: (Score:2)

Yes, but e^(i*Pi)+1=0

Overrules pretty much everything.

On the contrary, when you do e^(i*Pi)=-1, everything's upside down and backwards. Any point on the complex plane times e^(i*Pi) is rotated through a half-turn.

It's only when we do e^(i*Tau)=1 that everything comes full circle. I never really understood Euler's identity until I saw that.

## Re: (Score:2)

Or if you want the constant 0 in it too, e^(i*Tau) - 1 = 0 :)

## Re: (Score:2)

Replace the + by a - and the pi by a tau and the equation equals zero too.

The 1 + 0 thing of the tau manifesto looks weird. I think the one with the - is nicer.

By the way, I find e^(i*tau) = 1 to be pretty elegant as well! It's like, we take e and 2pi, mix a complex number in the bunch, raise it to each others power, and instead of being some number with lots of decimals, it's one!

## ^^This (Score:2)

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## Re: (Score:3)

You lose the addition and the zero, though. If ANYTHING in math can be considered fundamental, it's + and 0, along with 1.

Everything else is gravy.

Simplifying the equation loses the elegance it has. Also, tacking "+ 0" to the end of the tau version is an uglier hack than "+1 = 0"...when do you ever regularly add zero.

## Re: (Score:2)

Simplifying the equation loses the elegance it has. Also, tacking "+ 0" to the end of the tau version is an uglier hack than "+1 = 0"...when do you ever regularly add zero.

I'm not happy with making an equation more complex and harder to understand just so that you can gain an addition and a zero. Using tau you can explain the equation as:

A rotation by one turn is 1.

Using Pi, the explanation would be:

A rotation by 1/2 a turn is -1.

Whatever happened to simple = elegant?

## Re: (Score:2)

RTFA, tauday.com. Figure 1.

Looks a bit confusing to me though.

## Tau and pi: tally marks in the denominator (Score:2)

Why call it tau? Couldn't you call it, say, two-pi

The symbol for tau is a line over one vertical mark (/ I). The symbol for pi is a line over two vertical marks (/ II). You could consider this to represent a fraction bar with a Roman numeral in the denominator, and thus tau and pi represent different denominators: tau is the circle constant divided by 1, and pi is the circle constant divided by 2.

## Tau is used everywhere. I prefer k_k (Score:2)

Of course, it's pronounced "cake".

## Re: (Score:2)

## Re: (Score:2)

There seems to be some mom

## Re: (Score:2)

Also, 2pi takes 3 characters, tau takes 3 characters, while .5tau takes 5, 1/2tau and 0.5tau take 6, (1/2)tau 8.

## Re: (Score:2)

If you're writing out "2pi" and "(1/2)tau", you're doing it wrong.

2 pi either takes two characters, one of which is Greek, or four: 2 \pi.

## Re: (Score:2)

"2 \pi"

Funny, I count 5 there.

## Re: (Score:2)

Right. I meant to say five. It's offensive LaTeX notation to fail to separate the 2 and the \pi with a space.

## Re: (Score:2)

## Date formats on the rest of the planet (Score:2)

Wait, it's not the 62nd of August yet... ...you insensitive clod!

## by Livius (318358) on 2011-06-28 11:16 (Score:2)

## Obligatory Southpark... (Score:2)

"... Yer a Tau!"

## Happy tau day to you too! (Score:2)

:)

## Tau is already used (Score:2)

## Re: (Score:2)

Although I would love to see mathematicians change their ways, I’m not particularly worried about them; they can take care of themselves. It is the neophytes I am most worried about, for they take the brunt of the damage

## As is pi (Score:2)

Tau is already used to describe the relationship of speed to the apparent speed of the passage of time.

And pi is already used to describe conjugate momentum, as Tau Manifesto [tauday.com] explains. Wikipedia lists a whole bunch of other meanings of pi [wikipedia.org].

## For the moment, not persuaded. (Score:2)

I

mightagree that it makes sense to switch from pi to tau after I agree it makes sense to change from imperial measurement to the metric system.Note that at this time I do

notagree that it makes sense to switch to metric, so we may be in for a bit of a wait...## Re: (Score:2)

Luckily, you can easily write T=2Pi in your equations. No need to reprint thousands of T-Shirts.

I think the main point of the rant is that Tau somehow seems more fundamental. What defines a circle? A locus of points on a plane equidistant from a certain point. That distance is somehow more fundamental than 2r, even if the distinction is trivial.

## Re: (Score:2)

What possible reason could you have not to finish switching to metric?

## Re: (Score:2)

Because outside of the world of digital calculators metric sucks?

We can have a quarter pounder with cheese. You have the Royale with cheese. One tells you how much you are actually getting. Otherwise you've got to rattle off "I want a 113.398093g with cheese".

## Re: (Score:2)

So labels confuse you?

By your reasons the 'Big Mac' doesn't make sense and no one could possible know how much meat is there. In fact, how many burgers are known by there weight? A very few, overall.

It is far easier to teach kids metric then imperial. They get it faster, it makes sense. Kids like there to be a graspable reason for doing things. Metric has that.

It's also become incredible more expensive and difficult to work outside the US without using metric.

That said, if the US official went metric, that

## Re: (Score:2)

Aren't England's road signs in miles as well (and weight still given as stones by the populace)? Great example of metric adoption there.

## Re: (Score:2)

But I'm sure Americans are gonna love the Quarter-Kilo with Cheese. More than double the beef of the Quarter Pounder!

## Re: (Score:2)

No, McDonalds would have to go to the 1 Hectogram with Cheese for economic reasons (and it'd make dietary sense too), and they'll lose just a little meat. "Hectogram" just sounds so scientific and mathematical and not so tasty.

## IT'S ALSO WORLD CAPSLOCK DAY (Score:3)

(Which apparently triggers the lameness filter...)

IN MEMORY OF BILLY MAYS! DON'T JUST CLEAN IT, SCREAM AT IT!

Why does the lameness filter think Billy Mays is lame?

## Re: (Score:2)

why is Billy Mays so popular

Go on YouTube and search for suicide jack, suicide putty, or suicide hooks.

## Tau is already used (Score:2)

And if he didn't know that, then he should get back to the books and stop wasting time.

## Re: (Score:2)

Pi is used for things other than the circle constant, too...

## Re: (Score:2)

See, this is what I get for not taking my own advise and using a tilde.

And if he didn't know that, then he should get back to the books and stop wasting time~

now it's funny.

## Re: (Score:2)

All of the Greek and Latin characters are used for more than one thing just in physics alone -- to say nothing of subscripts, typographical variants like blackletter, decorator symbols, and the occasional Hebrew letter.

## Why not both? (Score:2)

Tau for uber math nerds, physicists, EE geeks and anyone else who needs to calculate an arc tangent and Pi for everyone who just needs to figure out what diameter pipe they need to fix their sink?

## Re: (Score:2)

## Re: (Score:2)

Pi is better for uber math nerds, physicists and EE geeks because there are lots of circumstances where you deal with the integer multiples of Pi, including odd multiples. The only people who like 'tau' are the math/science groupies online who worship, not practice, and think that Fermat's Last Theorem was an important problem.

## Beautiful (Score:2)

## Re: (Score:2)

I hope you're joking. The instruments make it sound better than it really is.

You do realize you'd get similar crap with random numbers.

## 2*Pi Day? (Score:2)

Celebrate a day based on 2*pi? No thanks. However, I will celebrate 2.556*pi day. I will likely even have cake on that day. It's the day that I turn approximately 11.46*pi years old.

## Re: (Score:2)

## Re: (Score:2)

Teach both sides.

## Re: (Score:2)

Teach both sides.

The lack of a constant between Pi day and Tau day proves that constants did not evolve on their own. Unless you can find a constant between Pi and Tau in the Holy Book of Knuth, or in the text of the Apocrypha/Art of Electronics, I must conclude that an intelligent designer created both Pi day and Tau day instead of a mere theory of slashdot dupe article evolution. Unfortunately the intelligent designer was not intelligent enough to make either day interesting enough for me to care, so sorry.

## Tau ... zero? (Score:2)

## Re: (Score:2)

It's creative. It's mathematical. It's something that a non-nerd would struggle to appreciate. It's even under

idle. So what's the problem?## Re: (Score:2)

Seriously? A few weak arguments? I see 2pi way, way more often than pi.

## Re: (Score:2)

## Re: (Score:3)

## Re: (Score:2)

## Re: (Score:2)

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## Re: (Score:2)

Having a trig function have a 2 or not doesn't make it more elegant.

Ok, let's go with one of the simplest trig functions around, converting angles.

With radians expressed in fractions of pi, a full circle is 2*pi radians.

With radians expressed in fractions of tau, a full circle is tau radians.

So half a circle angle.. is 1/2 tau radians. A quarter is 1/4 tau radians.

An eighth of a circle 1/4 pi radians. A quarter is 1/2 pi radians.

I know which looks more elegant to me...

## Re: (Score:2)

No, radius is the principal measurement of a circle, a sphere, a hypersphere, and so on. The diameter is the mathematically unnatural measurement. The diameter is used

nowherebut in the relation of circumference to diameter. All other calculations use the radius, and factors of 2 pi.Pi was chose as it was because it is more practical to physically measure the diameter than the radius. This does not make it a mathematically sound choice, however.

## Re: (Score:2)

Those other calculations are not any more difficult then they were before. Changing to Tau here is again a net benefit for mathematics.

## Re: (Score:2)

## Re: (Score:2)

ha ha. You're not a nerd. ha ha!

shut up Nelson

## Re: (Score:2)

I see you're protesting Euler's main number.

## Re: (Score:2)

Fo' shizzle.

## Re: (Score:2)

Fahrenheit.

## Re: (Score:3)

I have never heard "Shut your Tau hole!"

That's because the Tau that can be shut is not the true Tau.

## Re: (Score:2)

Thanks man, it's been a long day, and that gave me a really good laugh. ;-)

## Re: (Score:2)

Who cares? How is this in any way relevant to the discussion?

## Re: (Score:2)

The odd and even numbers are subsets of the integers... neither pi nor tau is odd or even.