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No, really, pi is wrong: The Tau Manifesto (Tau Day, 2010)

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Re: No, really, pi is wrong: The Tau Manifesto (Tau Day, 2010)

#131

Post by orangecat »

joe_the_user wrote: post #62

What I would like to see is an informational analysis where you take something like a thousand common equations and look at how they would be expressed with pi versus with tau. If you can show they would take significantly fewer bits of information using tau, then tau would be objectively superior.

Really that reduces to looking at how often pi appears by itself (without being multiplied by a constant) versus how often 2pi appears. If there's a multiple other than 2 it's a wash; "4/3 pi r^3" isn't any better or worse than "2/3 tau r^3". And 2pi shows up all over the place, while the most common occurrence of a single pi is the area of a circle, which the proposal convincingly argues should have a 1/2 factor.

Re: No, really, pi is wrong: The Tau Manifesto (Tau Day, 2010)

#132

Post by Locke1689 »

amalcon wrote: post #81
mhartl wrote: post #73

Earlier quoted context omitted.

I mention torque in the manifesto, but I wasn't specific enough in this case, and I've added an example addressing this issue at http://tauday.com/#sec:four_arguments . The short version is that when necessary you can easily add a subscript to avoid ambiguity, such as tau_R for rotational torque. (Superscripts work, too. Particle physicists deal with pions, which are represented by the letter pi, but all the symbols…

The thing is, torque is a particularly bad thing to conflict with. While you're not using torque every time you work with pi, you usually end up using pi every time you work with torque. edit: It's much like using i for both sqrt(-1) and for current. Electrical engineers need to use both of these all the time, so they often use j for sqrt(-1) instead.

Agreed. He mentions overloading the pi symbol for the prime counting function but the difference is that you very rarely encounter pi in the prime counting function.

Re: No, really, pi is wrong: The Tau Manifesto (Tau Day, 2010)

#133

Post by mhartl »

amalcon wrote: post #38
tc wrote: post #2

Perfect; to my lisp startup file was just added: (defconstant tau #.(* 2 pi)) Regarding adoption, I think it's worth pointing out that these sorts of conventions can and do shift within a generation. I recall quite clearly while growing up the convention for indicating years = the year one [1] was B.C. and A.D. It seems like over the past few years we've definitively decided on B.C.E. and C.E. instead [2]. All it rea…

I have no problem with people trying to do this in principle. I really don't care enough, but other people can. The symbol "tau", however, is an especially poor choice for a trigonometric symbol, because it's also used for torque. You won't get many physics teachers to change over if every time you try to calculate a torque from a force and radius, you run into a symbol conflict.

This torque issue was really bothering me, and I finally realized why: I was pretty sure I'd already seen torque represented by a letter other than tau. Sure enough, I checked my copy of Introduction to Electrodynamics by David Griffiths, which is a popular (and truly great) intermediate E&M text, and there it was on p. 162: torque written as N = r X F. The same usage appears in several other places in that book, and Introduction to Electrodynamics is a standard text, so I'm confident that other sources use it as well. So we see that the idea of using a letter other than tau for torque is not some theoretical possibility—it has already happened, and in a standard textbook to boot. I've updated the manifesto with a note to this effect at http://tauday.com/#sec:four_arguments.

I realize that this may not convince you, but I urge you to reserve the right to change your mind about tau. After all, I changed my mind about pi. ;-)

Re: No, really, pi is wrong: The Tau Manifesto (Tau Day, 2010)

#134

Post by stassats »

tc wrote: post #2

Perfect; to my lisp startup file was just added: (defconstant tau #.(* 2 pi)) Regarding adoption, I think it's worth pointing out that these sorts of conventions can and do shift within a generation. I recall quite clearly while growing up the convention for indicating years = the year one [1] was B.C. and A.D. It seems like over the past few years we've definitively decided on B.C.E. and C.E. instead [2]. All it rea…

There is no need in "#.".

Re: No, really, pi is wrong: The Tau Manifesto (Tau Day, 2010)

#135

Post by eru »

Groxx wrote: post #43
tc wrote: post #2

Perfect; to my lisp startup file was just added: (defconstant tau #.(* 2 pi)) Regarding adoption, I think it's worth pointing out that these sorts of conventions can and do shift within a generation. I recall quite clearly while growing up the convention for indicating years = the year one [1] was B.C. and A.D. It seems like over the past few years we've definitively decided on B.C.E. and C.E. instead [2]. All it rea…

Except BC/AD -> BCE/CE is a label change, not a numbering change, and it's arguably for largely P.C. reasons; conforming to P.C. is the "in" thing. We in America have also changed from Indians to Native Americans to American Indians to Indigenous Peoples to whatever, and N* to Black to Colored to African American to something supposedly unoffensive while still defining the same group. http://en.wikipedia.org/wiki/Com…

> I'm voting for positive values == CE and negative values == BCE. They're already numbered that way, just adopt the frickin' sign instead of the suffix!

Nope, not really. There's no year 0. Neither A.D. nor B.C.--that's because zero wasn't known to the guys who invented this numbering system, and also because those guys counted years with ordinal numbers (first year, second year, etc) and not with cardinal numbers since Christ.

You see the same confusion over death (Friday) and resurrection (Sunday): Jesus rose on the third day, not after three days. (Since the weekdays are not given in the bible directly, you can also find alternative suggestions for the weekdays.)

Disclaimer: Words like Jesus, Christ, death and resurrection are used purely as labels to describe stuff some people believe in. No judgement implied.

Re: No, really, pi is wrong: The Tau Manifesto (Tau Day, 2010)

#136

Post by mhartl »

mhartl wrote: post #73
amalcon wrote: post #38

Earlier quoted context omitted.

I have no problem with people trying to do this in principle. I really don't care enough, but other people can. The symbol "tau", however, is an especially poor choice for a trigonometric symbol, because it's also used for torque. You won't get many physics teachers to change over if every time you try to calculate a torque from a force and radius, you run into a symbol conflict.

I mention torque in the manifesto, but I wasn't specific enough in this case, and I've added an example addressing this issue at http://tauday.com/#sec:four_arguments . The short version is that when necessary you can easily add a subscript to avoid ambiguity, such as tau_R for rotational torque. (Superscripts work, too. Particle physicists deal with pions, which are represented by the letter pi, but all the symbols…

The parent comment is now obsolete; I came up with something even better: http://news.ycombinator.com/item?id=1470379

Re: No, really, pi is wrong: The Tau Manifesto (Tau Day, 2010)

#137

Post by eru »

mhartl wrote: post #133
amalcon wrote: post #38

Earlier quoted context omitted.

I have no problem with people trying to do this in principle. I really don't care enough, but other people can. The symbol "tau", however, is an especially poor choice for a trigonometric symbol, because it's also used for torque. You won't get many physics teachers to change over if every time you try to calculate a torque from a force and radius, you run into a symbol conflict.

This torque issue was really bothering me, and I finally realized why: I was pretty sure I'd already seen torque represented by a letter other than tau. Sure enough, I checked my copy of Introduction to Electrodynamics by David Griffiths, which is a popular (and truly great) intermediate E&M text, and there it was on p. 162: torque written as N = r X F. The same usage appears in several other places in that book, and…

And there are only so many letters in the alphabet(s). Although I have to admit common usage hasn't really exhausted the hebrew alphabet, yet.

And when the Chinese finally take over, we will have enough short symbols to last us for millenia.

Re: No, really, pi is wrong: The Tau Manifesto (Tau Day, 2010)

#138

Post by [deleted] »

Groxx wrote: post #121
vorg wrote: post #119

Earlier quoted context omitted.

Why a multi-glyph symbol 2π when a single-glyph symbol 2π would be better. By creating a new symbol by joining the bottom-right of the 2 to the topleft of the π, we can make a new one-glyph symbol, perhaps put it next to € in Unicode. And instead of saying two words "Two Pi", we could say it as one word "Twopi", with stress on the first syllable, much like the word "teenager" used to be spoken and written as two word…

I like the idea of "Twopi". Looks like it could be pronounced like "Toupee". (yes, it'd be a mispronunciation, but people do that) Do you also favor the almighty interrobang‽

[deleted]

Re: No, really, pi is wrong: The Tau Manifesto (Tau Day, 2010)

#139

Post by eru »

Groxx wrote: post #121
vorg wrote: post #119

Earlier quoted context omitted.

Why a multi-glyph symbol 2π when a single-glyph symbol 2π would be better. By creating a new symbol by joining the bottom-right of the 2 to the topleft of the π, we can make a new one-glyph symbol, perhaps put it next to € in Unicode. And instead of saying two words "Two Pi", we could say it as one word "Twopi", with stress on the first syllable, much like the word "teenager" used to be spoken and written as two word…

I like the idea of "Twopi". Looks like it could be pronounced like "Toupee". (yes, it'd be a mispronunciation, but people do that) Do you also favor the almighty interrobang‽

We pronounce the constant as pee in German anyway. (No confusion with bodily fluids there.)

Or we might as well go with dvapee (Russian), or tsveypee (German (zweipi, written so that you can pronounce it the English way and it'll come out ok)).

We can go for pronouncing the thingy pipi. (Though would lead to confusion with bodily fluids in German.)

Re: No, really, pi is wrong: The Tau Manifesto (Tau Day, 2010)

#140

Post by Kadin »

mhartl wrote: post #133
amalcon wrote: post #38

Earlier quoted context omitted.

I have no problem with people trying to do this in principle. I really don't care enough, but other people can. The symbol "tau", however, is an especially poor choice for a trigonometric symbol, because it's also used for torque. You won't get many physics teachers to change over if every time you try to calculate a torque from a force and radius, you run into a symbol conflict.

This torque issue was really bothering me, and I finally realized why: I was pretty sure I'd already seen torque represented by a letter other than tau. Sure enough, I checked my copy of Introduction to Electrodynamics by David Griffiths, which is a popular (and truly great) intermediate E&M text, and there it was on p. 162: torque written as N = r X F. The same usage appears in several other places in that book, and…

I remember vaguely from my time using Griffiths' book that he uses a lot of non-standard (or at least not the same as other, more introductory textbooks) notation. He pretty freely reassigns the symbols used by things that you're supposed to understand, in order to free them up for other purposes.

Or at least that's my vague recollection. It's been a few years now since I've cracked open his Electrodynamics. It was a pretty decent book though, better than a lot of textbooks (I kept it and still have my edition around somewhere, something that I didn't do if I thought a textbook was crummy).

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