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 09-17-2010, 08:58 AM #1 pdurrant The Grand Mouse 高貴的老鼠     Posts: 46,204 Karma: 156194192 Join Date: Jul 2007 Location: Norfolk, England Device: Kindle Voyage Why Tau is better than Pi I can across an interesting idea today. Put simply, the idea is that the ratio for relating the size of a circle to its circumference has been badly chosen. That is to say, Pi (π), the ratio of the Circumferences to the Diameter of a circle is an awkward choice. The argument goes that using the ratio of the Circumference to the Radius instead would make many things simpler and more obvious. The proposed symbol for this is Tau (τ). All is explained at the Tau Day website. http://www.tauday.com/ I found it very persuasive. What do others think?
 09-17-2010, 09:39 AM #2 dsvick Wizard     Posts: 2,737 Karma: 635747 Join Date: Nov 2009 Location: Northeast Ohio, USA Device: PRS-900 I didn't read the entire article in detail, it's been a few years since I've done math at those levels, but it makes sense to me and I have to agree on a few of the points. I agree that using the radius is more intuitive than the diameter, you very rarely hear someone referring to the diameter of a circle. My problem with it though is that "pie are square(d)" rolls off the tongue much more easily than "two tau are square(d)"
 09-17-2010, 09:41 AM #3 poohbear_nc Naughty or Nice?     Posts: 34,571 Karma: 99011079 Join Date: Feb 2009 Location: Durham, NC Device: Every Kindle Ever Made & To Be Made + Kobo Aura + Nexus7.2! tau for two and two for tau, mu for ... sorry - couldn't resist!
 09-17-2010, 09:46 AM #4 Sparrow Wizard   Posts: 4,395 Karma: 1358132 Join Date: Nov 2007 Location: UK Device: Palm TX, CyBook Gen3 I'm afraid I had to respectfully decline the author's kind invitation to "consider integrals over all angles in polar coordinates", because I have no idea what he's going on about.
09-17-2010, 10:45 AM   #5
pdurrant
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 Originally Posted by dsvick I didn't read the entire article in detail, it's been a few years since I've done math at those levels, but it makes sense to me and I have to agree on a few of the points. I agree that using the radius is more intuitive than the diameter, you very rarely hear someone referring to the diameter of a circle. My problem with it though is that "pie are square(d)" rolls off the tongue much more easily than "two tau are square(d)"
Umm... the area of a circle is one half tau are squared. (½τr²) And the circumference is tau are. (τr)

‘Tau are’ is simpler than ‘two pi are’. Of course, we could also say ‘pi dee’ but then for consistency we ought to use ‘one quarter pi dee squared'. Ugh...

The ½τr² is also exactly analogous with lots of other equations that deal with the integration of an equation with a constant of proportionality.

The link gives the example of objects falling in a uniform gravitational field. (i.e. on Earth, to a close approximation).

The speed of dropped item is directly proportional to the time it has been falling (neglecting air resistance and changes in the gravity field).

v = gt

The distance fallen is the integral of this: d = ½gt²

I must admit that the more I consider this, the more pleased I am with it.

Although I would hold out for tau day to be celebrated on the 6th of February, not the 28th of June!

And celebrations ought, of course, to reach a climax at exactly 53 seconds past 3:33 pm (or am if you're on night shifts). Because, of course, the ratio 333/53 approximates tau to three decimal places.

Alternatively we could have an ‘approximate tau lunch’ on 7th October, at 1:13 pm, since 710/133 is tau to six decimal places.

 09-17-2010, 11:31 AM #6 MJK2111 FUBAR!     Posts: 1,946 Karma: 15018767 Join Date: Mar 2010 Location: Woodstock, IL Device: Kindle 3, Samsung Galaxy Note 10.1 S I like popcorn.
09-17-2010, 12:58 PM   #7
pdurrant
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 Originally Posted by pdurrant Although I would hold out for tau day to be celebrated on the 6th of February, not the 28th of June! And celebrations ought, of course, to reach a climax at exactly 53 seconds past 3:33 pm (or am if you're on night shifts). Because, of course, the ratio 333/53 approximates tau to three decimal places.
On second thoughts, perhaps celebrations ought to include something special in the 22 minutes between 8:31 and 8:53, seeing as τ is 6.2 831 853....

 09-17-2010, 02:17 PM #8 Fat Abe Man Who Stares at Books     Posts: 1,725 Karma: 10606558 Join Date: Mar 2010 Location: 50th State, USA. Also, PA, NY, CA, and elsewhere. Device: All of the Above I disagree most vehemently with the concept of Tau day. First, I am too old to learn new math. Second, Pi makes sense to the elders. Consider a hat maker or brassiere seamstress. How do they set the diameter of a hat or bra? They take a tape measure and wrap it around the object of interest. With a single factor (1/Pi), they take that circumference and turn it into a diameter. Of course, I am so learned that I can just look at/feel a breast and tell you the correct cup size. (It is a complex process, involving volumetric estimation, and my sensitive hand). Lastly, why give up another Greek letter for a constant that is already been spoken for? I want to reserve Tau for a constant of nature that I may discover, such as the perfect shape of a breast (in 3D), or the dimension of the universe.
 09-17-2010, 03:52 PM #9 CleverClothe Guru   Posts: 618 Karma: 493394 Join Date: Jun 2008 Location: Seattle, WA Device: iRex iLiad, Onyx Boox 60 Fat Abe makes a very persuasive argument...
 09-17-2010, 05:04 PM #10 alecE Evangelist     Posts: 412 Karma: 546196 Join Date: Mar 2009 Location: UK canal boat Device: sony prs505, prs650, kobo Glo HD liseuses An entertaining article! Given that there is a simple conversion between pi & tau, one can just use whichever is most convenient for the purpose in hand. I like the more sensible radian measures of fractions of a circle and the pleasing conformity with other integration equations - I shall have to try running a few calculations in parallel and see how the tau versions 'feel'.
 09-18-2010, 05:16 AM #11 TGS Country Member     Posts: 9,059 Karma: 7676767 Join Date: Feb 2010 Location: Denmark Device: Liseuse: Irex DR800. PRS 505 in the house, and the missus has an iPad. What the f***, I haven't got used to decimal currency yet, and you want to start messing with pi. No way.
 09-28-2010, 10:37 PM #12 kennyc The Dank Side of the Moon     Posts: 34,139 Karma: 97817137 Join Date: Sep 2009 Location: Denver, CO Device: Kindle2; Kindle Fire e is the best.
09-28-2010, 10:38 PM   #13
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 Originally Posted by poohbear_nc tau for two and two for tau, mu for ... sorry - couldn't resist!

 09-29-2010, 01:45 AM #14 dapriuk Enthusiast   Posts: 48 Karma: 160 Join Date: Jun 2010 Location: UK Device: Sony PRS-505, Lenovo X61 tablet PC, Advent Vega Android tablet ask me taumorrow
09-29-2010, 04:15 AM   #15
pdurrant
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 Originally Posted by kennyc e is the best.
e[SUP][/SUP] = 1

Oh — no superscript BB code