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The true circle constant that we should be using is circumference/radius. It would make so many things easier. Defining a circle by diameter doesn't even make sense as there are lots of shapes that can have the same diameter where as a radius uniquely defines a circle.

Learn something new and then tell your friends that Pi is the wrong circle constant. https://tauday.com/tau-manifes...

Still it is cool when anyone does something to promote math.

As someone who believes in Tau (see the Tau Manifesto here: https://tauday.com/tau-manifes... ), I still want to thank Larry Shaw. I've eaten many good American pies because of him.

Tau day has never quite gotten the commercial backing that Pi day has. I blame Hallmark https://www.hallmarkecards.com... . Damn Pagans!

If you're going to mention tau, you have to provide a link. http://tauday.com/tau-manifest...

Then have you heard of tau, which is 2pi? http://tauday.com/

The real mystery is why the diameter was chosen instead of the more logical ratio of the circumference to the radius. Euclid would not approve.

Why is the radius "more logical"? It depends on the practical use of the relationship. It seems "more logical" to use a radius as a primary circle measurement if you're using a modern mathematical definition of a set of points equidistant (by the radius) from a central point. And it seems logical to adopt this measurement if you constructed a circle in this manner.

On the other hand, if you are confronted with an existing circle and wish to determine the circumference, measuring the diameter is more straightforward than measuring the radius. (Fix one point on the circumference, and use your straightedge, rope, whatever to find the longest distance on the opposite part of the circle.) Sure, finding the radius is simply dividing by 2, but that's an extra step.

I don't know if this is the rationale for using the diameter in the pi definition, or if it might also have to do with the formula for circle area (pi*r^2), which is slightly simpler without the additional factor of 2, or whatever.

Nowadays, there seem to be many good mathematical reasons for defining the ratio of circumference to radius as more fundamental. However, most of these were unknown or not primary concerns when pi was first adopted as a primary ratio. There's no "logical" priority to one or the other measurement -- it depends on practical usage for calculations, and I suspect that pi was probably just used slightly more often than 2*pi in practical calculations centuries ago.

Pi is wrong.
True mathematics nerds will celebrate on June 28, 2031

Calculate Pi in 10 steps without Guns, only Zombies!

Step 0: Kill a zombie by removing its head or destroying its brain. In a pinch you can lure one up high and shove it to the ground below.

Step 1: Detach one of the bigger bones of the arm or leg. If you have access to a cooler or are far enough north or south you may use the whole frozen zombie.

Step 2: Create your unit of measure. Detach a small straight segment of zombie -- the little bone at the end of the hand or foot will work. This will be our Zinch.

Step 3: Spin the larger zombie part while anchoring one end to create a circle of blood upon a flat bit of ground.
      a. If the ground is uneven and you have only the corner of a wall, stand the zombie part in the corner and let it fall over to create a quarter circle arc.
      b. Repeat 3a if you have a flat wall but no corner, falling the other direction to create a half circle.

Step 4: Place the Zinch on the edge of the whole, half, or quarter circle. Count the number of Zinches along the perimeter of the circle or arc.
      a. For a quarter circle arc multiply this zinches by 4.
      b. For a half circle arc multiply the zinches by 2.

Step 6: Count the number of Zinches of the larger zombie part. This is your Radius.

Step 7: Calculate Pi using the Radius and Circumference from step 4:
      Circumference = 2 * Pi * Radius;
            Thus:
      Pi = Circumference / (Radius * 2).

Step 8: For accuracy, each Mathematician present should repeat the above with a different zombie / zinch then average your values.

Step 9: Congratulations! You have managed to distract all of the other Mathematicians long enough for them to be eaten by Zombies!

Step 10: Enjoy rebuilding society using the superior Tau constant!
      There are Tau radians in one circle
      Tau = Circumference / radius

In a post-apocalyptic world, why not fix the mistake and calculate the correct constant, tau?

If everybody's forgotten any approximation of pi better than "about 3," then it's likely generations have passed and we're essentially starting over from scratch. If they pick this method for determining it, we may be even worse off. The new math we create could end up using a new constant equal to pi/4 (tau/8). Then instead of having factors of 2 all over the place, we'll have factors of 8.

In a post-apocalyptic world, why not fix the mistake and calculate the correct constant, tau?

Real aliens would use the digits of Tau, not Pi.

tau is the new pi

http://tauday.com/

Tau Day

That would be April 2, right?

Oh? Sorry, I thought you said "towell day".

Tau Day

We settle for Pi when you can have Tau?

http://tauday.com/

I could go for base 60 but base 64? Need a system that is also easily divisible by 3. And speaking of pi we should switch to using tau (2*pi) instead of pi.

plus we can define pi to be 3 to make things simpler.

Too late: http://tauday.com/

You mean Tau/3 and 5Tau/3 right?

http://tauday.com/

In case you haven't seen it yet, the Tau manifesto proposes we should use Tau (2xPi) instead.

But officer... Tau is not very funny!

I am a little happy that Pi day is noticed, and perhaps gives an excuse to think deeply about something rather than just bake pies - but it's a pretty lame list. I propose my own:

1) Read about Tau vs. Pi. The arguments for what we can choose in mathematics vs. what is given, require one to think quite a bit about what is useful in math vs. what is convention and makes one, frankly, appreciate pi far more than any of the activities in the article.

2) Actually try to measure pi. Note I didn't say, 'calculate'. It is revealing how hard it is to actually measure things in the real world beyond three or four significant figures, and it makes one appreciate the beauty of abstract calculations.

3) Read about e. e is actually much cooler in many ways, but because there is no ridiculuously simple, visualizable definition of it, it doesn't get the limelight (such as it is.) A great historical book on e: "e": The Story of a Number

But if you insist on knowing what the slideshow list of ten things is:

1) Make a pi-themed pie
2) Rock a Pi Day T-shirt
3) Write Pi-kus or Pi-ems
4) Go on a pi scavenger hunt (this, at least, has some vague mathematical attraction, although you could accomplish the same with a random sequence)
5) See how many digits of pi you can recite
6) Watch "Pi" the movie (gibberish math, but a cool movie that gets a little bit of the obsessional nature that can capture those who dive into abstract mathematics)
7) Listen to Pi music
8) Tell Pi Day jokes
9) Celebrate Albert Einstein's birthday (same day)
10) Read a book about pi (they don't even suggest the classic historical work on pi, by Beckman: A History of Pi

Like I said - mostly silly, not very mathematical. I would prefer pi day be a day of observance rather than a secular holiday :-)

In case you haven't seen it yet, the Tau manifesto proposes we should use Tau (2xPi) instead.

This is covered in the Tao Manifesto. tau*r^2/2 is more consistent with other formulas that are the result of integration. For example Distance fallen is g*t^2/2, Spring energy k*x^2/2, and Kinetic energy m*v^2/2. Think of it this way 1/2 was there but got canceled out by the 2 in 2*pi.

Quadratic Forms

While you're right to point out that there's no "last digit of pi", the following reasoning is flawed:

Mathematically there are an infinite number of points around a circle. Therefore, as pi depends on that, there are an infinite number of decimal places in pi.

If that were valid, by the same argument I could say: Mathematically there are an infinite number of points in a square. Therefore, as square roots depend on that, there are an infinite number of decimal places in any square root. But then 2 = sqrt(4) would violate that.

The reason that there's infinitely many decimal digits isn't because there are infinitely many points on a circle (what would it mean for there not to be infinitely many points in a continuous curve segment?). It's because pi is an irrational number - indeed this means there's infinitely many digits using any integer number base.

Oh, and besides, we should be talking about tau rather than pi.

That's all well and good, but what about digits of tau?

As a Tauist, I rate the original post a 6.28

I know I'm a few days late, but TFA explicitly has an entire section to address this:

Fortunately, although the letter appears in some current contexts, there are surprisingly few common uses. ... Despite these arguments, potential usage conflicts are the greatest source of resistance to . ... But scientists and engineers have a high tolerance for notational ambiguity, and claims that -the-circle-constant can’t coexist with other uses ignores considerable evidence to the contrary. For example, in a single chapter (Chapter 9) in a single book (An Introduction to Quantum Field Theory by Peskin and Schroeder), I found two examples of severe conflicts that, because of context, are scarcely noticeable to the trained eye.

More examples are given, but the point is that many mathematical symbols, including , are already overloaded, and we get along fine.

Just read this, and you'll at least note how many mathematical operations are simplified with a constant that means "a whole turn through a circle": http://tauday.com/ Tau = 2*Pi, just a single constant value off, so the math isn't much more difficult to do, but the meaning of what you're doing can be masked by that constant.

Tau as a symbol is already used in math related to pi (pi/2, not 2pi). We need to start using futhark runes or something.

Check out what it does to Euler's Identity. That and the straightforward definition of radians has made me a convert, too.

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 explains. Wikipedia lists a whole bunch of other meanings of pi.

Perhaps you shouldn't tell her about tau....

I doubt it, though I do like that series. I can't quite remember generalizations of it, though.... That is, what is zeta(m) for m a positive integer? Wikipedia lists a formula valid at positive even integers here, wherein \zeta(2n) = \frac{(-1)^{n+1} B_{2n}(2 \pi)^{2n}}{2(2n)!}, so for instance 1 + 1/2^4 + 1/3^4 + ... = pi^4 / 90, and in general 1 + 1/2^(2n) + 1/3^(2n) + ... converges to r*pi^(2n) for some rational number r that can be found quite easily. I presume Euler's method (the one which first proved your identity) can be extended to prove this case. I don't remember a characterization for the odd integers though.... Isn't it wonderful that the formula I listed uses \tau = 2 \pi? I'm convinced; I don't recall seeing any good evidence for using \pi over \tau other than for historical reasons. I certainly use it in my own work. The Apery's constant (that is, \zeta(3)) Wikipedia page lists some formulas, but nothing even remotely as elegant as the above even integer characterization. I suppose there isn't one currently known :(.

Especially given that pi is a stupid constant that makes no sense.

If they're scientific, they should be actually scientific, like Kelvin or Light-seconds, instead of faux-scientific like Celcius or Meters.

If you're complaining that meters are 1/299,792,458 of a light-second, or that temperatures are stated in offsets from 273.15 K, consider this: Why are kelvins 25/6829 of the triple point of water and not some other fraction? Why are seconds 9,192,631,770 cycles of cesium-133 radiation and not some other number? Why pi instead of tau?

unless you're boiling water on a daily basis, you really don't care about 0 or 100C

Let me guess: you don't cook. An ice-cold Coke is 0, and the boiling water for pasta or for the first stage of hard-cooking an egg is 100.

I too was once an ardent pi supporter. However, I have seen the light... let us eliminate spurious factors of two everywhere and embrace a more reasonable transcendental number: tau

Agree. Pi es definitely overrated.

I too was once an ardent pi supporter. However, I have seen the light... let us eliminate spurious factors of two everywhere and embrace a more reasonable transcendental number: tau

Stop being silly. Perhaps after reading this, you will understand why it's simply retarded to even mention pi: http://tauday.com/

It's sad that so much work has been done to find digits of one-half of the REAL circle constant, Tau. http://tauday.com/

http://www.tauday.com/

http://tauday.com/ I endorse the views expressed in above piece.

I would go for Euler's equation, but using Tau instead of Pi.

e^(i*tau) = 1

At this point, the expositor usually makes some grandiose statement about how Euler’s identity relates 0, 1, e, i, and Pi —sometimes called the “five most important numbers in mathematics”. Alert readers might then complain that, because it’s missing 0, Euler’s identity with Tau relates only four of those five. We can address this objection by noting that, since sin(Tau) = 0, we were already there:

e^(i*tau) = 1 + 0

This formula, without rearrangement, actually does relate the five most important numbers in mathematics: 0, 1, e, i, and Tau.

As mathematician Bob Palais notes in his delightful article “Pi Is Wrong!”, Pi is wrong. It’s time to set things right. (More info).

Most common question in response to this argument:

Are you serious?
Of course. I mean, I’m having fun with this, and the tone is occasionally lighthearted, but there is a serious purpose. Setting the circle constant equal to the circumference over the diameter is an awkward and confusing convention. 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 noted in Section 2.1,Pi is a pedagogical disaster. Try explaining to a twelve-year-old (or to a thirty-year-old) why the angle measure for an eighth of a circle—one slice of pizza—is Pi/8. Wait, I meant Pi/4. See what I mean? It’s madness—sheer, unadulterated madness.

I would go for Euler's equation, but using Tau instead of Pi.

e^(i*tau) = 1

At this point, the expositor usually makes some grandiose statement about how Euler’s identity relates 0, 1, e, i, and Pi —sometimes called the “five most important numbers in mathematics”. Alert readers might then complain that, because it’s missing 0, Euler’s identity with Tau relates only four of those five. We can address this objection by noting that, since sin(Tau) = 0, we were already there:

e^(i*tau) = 1 + 0

This formula, without rearrangement, actually does relate the five most important numbers in mathematics: 0, 1, e, i, and Tau.

As mathematician Bob Palais notes in his delightful article “Pi Is Wrong!”, Pi is wrong. It’s time to set things right. (More info).

Most common question in response to this argument:

Are you serious?
Of course. I mean, I’m having fun with this, and the tone is occasionally lighthearted, but there is a serious purpose. Setting the circle constant equal to the circumference over the diameter is an awkward and confusing convention. 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 noted in Section 2.1,Pi is a pedagogical disaster. Try explaining to a twelve-year-old (or to a thirty-year-old) why the angle measure for an eighth of a circle—one slice of pizza—is Pi/8. Wait, I meant Pi/4. See what I mean? It’s madness—sheer, unadulterated madness.

I would go for Euler's equation, but using Tau instead of Pi.

e^(i*tau) = 1

At this point, the expositor usually makes some grandiose statement about how Euler’s identity relates 0, 1, e, i, and Pi —sometimes called the “five most important numbers in mathematics”. Alert readers might then complain that, because it’s missing 0, Euler’s identity with Tau relates only four of those five. We can address this objection by noting that, since sin(Tau) = 0, we were already there:

e^(i*tau) = 1 + 0

This formula, without rearrangement, actually does relate the five most important numbers in mathematics: 0, 1, e, i, and Tau.

As mathematician Bob Palais notes in his delightful article “Pi Is Wrong!”, Pi is wrong. It’s time to set things right. (More info).

Most common question in response to this argument:

Are you serious?
Of course. I mean, I’m having fun with this, and the tone is occasionally lighthearted, but there is a serious purpose. Setting the circle constant equal to the circumference over the diameter is an awkward and confusing convention. 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 noted in Section 2.1,Pi is a pedagogical disaster. Try explaining to a twelve-year-old (or to a thirty-year-old) why the angle measure for an eighth of a circle—one slice of pizza—is Pi/8. Wait, I meant Pi/4. See what I mean? It’s madness—sheer, unadulterated madness.

Um, if you're gonna get it tattoo'd, you probably want to go with the more traditional form of: e^(i*pi) + 1 = 0. This single equation shows a relationship between 5 important mathematical constants, as opposed to the other form, which just shows 3 (I don't think -1 qualifies, as i is the more fundamental).

So you tattoo something safe, and then people start using tau instead of pi.

Did you mean:
e^(i*tau)=1