No, really, pi is wrong: The Tau Manifesto (Tau Day, 2010) • Hacker News Board

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

#81

Post by amalcon » Mon, Jun 28, 2010, 7:26 PM UTC

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 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.

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

#82

Post by rudd » Mon, Jun 28, 2010, 7:29 PM UTC

dgritsko wrote: post #44

drblast wrote: post #39

e^(tau*i/2)+1=0 ??? Ewwww, yuck.

Did you get all the way down to here? http://tauday.com/#sec:euler_s_formula e^(i*tau) = 1 Much nicer that way.

I actually disagree that that is nicer. e^(ipi) = -1, which means you can square both sides to come to the also factual statement, e^(itau) = 1. However, if you only knew the latter you'd be wondering whether e^(i*pi) would be 1 or -1.

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

#83

Post by TheBurningOr » Mon, Jun 28, 2010, 7:31 PM UTC

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.

I would argue though that the torque example is a particularly problematic symbol conflict as any equations involving torque are by definition going to include many, many references to the circle constant. Yes there are other symbol conflicts in math, but usually they are separated by logical fields (you generally are not doing using e when dealing with the charge of an electron constant (except in the case that you are dealing with magnitude of the electric field as a function of distance) and even when you are, it is hardly a problem because you never use the natural logarithmic constant except as a power function).

I think the appropriate change here though would be to change the symbol for torque to say, 'q' or something. Probably not going to happen, but wouldn't be as much of an issue.

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

#84

Post by sroerick » Mon, Jun 28, 2010, 7:34 PM UTC

steveklabnik wrote: post #51

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…

Ugh, I know this is slightly offtopic, but there's nothing more I dislike than B.C.E and C.E. I can understand not trying to promote a Christian-centric worldview, but by only changing the labels, they accomplish nothing. Now, the birth of Christ sets a 'common era,' which arguable makes it _more_ 'offensive' than just acknowledging what happened on that particular day.

Don't forget, though, AD stands for Anno Domini, which means "in the year of our Lord." Which is a little more than just acknowledgement.

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

#85

Post by Arun2009 » Mon, Jun 28, 2010, 7:37 PM UTC

rick_2047 wrote: post #20

I may get down modded for this but I just have to say, this is more like a religious propaganda than science. Throughout the article they have only demonstrated how a particular community is more comfortable with using double pi. I totally believe in what wwortiz said in his/her(sorry cannot open your website) post. If they like the tau so much they should be writing papers on its advantage. I think scientists should…

Notation is a pretty big deal in Mathematics. As software people we should be able to appreciate how evocative notation can get rid of unnecessary cognitive load when dealing with complexity.

Here is a link that talks about notation in Maths: http://www.cut-the-knot.org/language/index.shtml . Here's another link: http://en.wikipedia.org/wiki/Nabla_symbol . The example from calculus is also pretty famous.

Also, FWIW, I didn't downvote you.

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

#86

Post by klodolph » Mon, Jun 28, 2010, 7:46 PM UTC

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…

AD vs. BC: I prefer using CE with negative numbers, as suggested by ISO 8601. E.g., year -30 CE is year 31 BC.

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

#87

Post by nolochemical » Mon, Jun 28, 2010, 7:48 PM UTC

whyenot wrote: post #17

I really like this "modest prpoposal." In its spirit, I suggest that from now on we refer to 13 pies as a "taue," sort of a bakers' dozen of pies as it were. Tau Day will be the new Pi day, but students would be inspired to bring and share many times more delicious home baked goods as before.

Sweet, another nerd holiday I can actually prove with math!!

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

#88

Post by dgritsko » Mon, Jun 28, 2010, 7:50 PM UTC

rudd wrote: post #82

dgritsko wrote: post #44

Earlier quoted context omitted.

Did you get all the way down to here? http://tauday.com/#sec:euler_s_formula e^(i*tau) = 1 Much nicer that way.

I actually disagree that that is nicer. e^(i pi) = -1, which means you can square both sides to come to the also factual statement, e^(i tau) = 1. However, if you only knew the latter you'd be wondering whether e^(i*pi) would be 1 or -1.

By "much nicer", I was merely attempting to point out that drblast's formula:

     e^(tau*i/2)+1=0

could be stated as:

     e^(i*tau) = 1

As in the article. Whether that's intrinsically "better" than Euler's Identity is a different question, but not what I was discussing here.

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

#89

Post by mitjak » Mon, Jun 28, 2010, 7:52 PM UTC

edanm wrote: post #80

I really hope this convention gains wide adoption. It's pretty obvious to me that it just makes mathematics make more sense, at exactly the time when it needs to make more sense (people learning maths in high school). Until then, here's the trick I'm using: whenever I need to use pi, especially when it comes to the unit circle and radians, I'm just going to do it in terms of tau, then convert at the end. I just wish…

>It's pretty obvious to me that it just makes mathematics make more sense, at exactly the time when it needs to make more sense (people learning maths in high school).

People have been studying math at schools for quite a few centuries from what I recall. There's never a better time in this case.

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

#90

Post by samatman » Mon, Jun 28, 2010, 7:53 PM UTC

TheBurningOr wrote: post #83

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 would argue though that the torque example is a particularly problematic symbol conflict as any equations involving torque are by definition going to include many, many references to the circle constant. Yes there are other symbol conflicts in math, but usually they are separated by logical fields (you generally are not doing using e when dealing with the charge of an electron constant (except in the case that you…

I would suggest a change to uppercase Gamma, which looks like a T, kinda. Also, it has always struck me as a looking kind of like a moment arm.

Something like this is bound to happen if mathematics pedagogy moves to tau as the circle constant, which it should. The math department has no motivation to respect physics convention, and the physics department will just have to get in line, eventually.