### Happy Super Pi Day, Everyone!

Posted:

**Sat Mar 14, 2015 2:41 pm UTC**So what are you planning on doing this Pi Day of the century? Eating lots of pie? Making a pi-themed song? Ranting about how Tau is far superior to pi?

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Posted: **Sat Mar 14, 2015 2:41 pm UTC**

So what are you planning on doing this Pi Day of the century? Eating lots of pie? Making a pi-themed song? Ranting about how Tau is far superior to pi?

Posted: **Sat Mar 14, 2015 2:59 pm UTC**

Well, I work all day today, but I'll probably be wishing guests a happy pi day and looking for opportunities to use my prodigious mathability to amuse and astound them, thus earning greater quantities of $$$$.

Posted: **Sat Mar 14, 2015 3:16 pm UTC**

sevenperforce wrote:Well, I work all day today, but I'll probably be wishing guests a happy pi day and looking for opportunities to use my prodigious mathability to amuse and astound them, thus earning greater quantities of $$$$.

Hahahaha

Mathability xD

Posted: **Sat Mar 14, 2015 3:21 pm UTC**

Gonna memorize a few more digits.

3.141592653589793238462643383279502884197169399375105820974944592307.

3.141592653589793238462643383279502884197169399375105820974944592307.

Posted: **Sat Mar 14, 2015 4:00 pm UTC**

I bought a copy of the movie Pi a couple of days ago, and today I'm gonna watch it. That and Vihart's newest video!

...Also I'll probably cook a frozen pizza since that's the closest thing to a pie around here.

...Also I'll probably cook a frozen pizza since that's the closest thing to a pie around here.

Posted: **Sat Mar 14, 2015 5:14 pm UTC**

I'm just disappointed that there's no pi day in a proper date format. Though I guess there will be one on 314159-265.

Posted: **Sat Mar 14, 2015 5:21 pm UTC**

gmalivuk wrote:I'm just disappointed that there's no pi day in a proper date format. Though I guess there will be one on 314159-265.

you could celebrate on 22/7.

Posted: **Sat Mar 14, 2015 5:25 pm UTC**

22/7 isn't ISO 8601 compliant, so how does that help?

Posted: **Sat Mar 14, 2015 6:56 pm UTC**

Meh, ISO is just an international agreement, no more or less correct than any other standard. Also, those damned Europeans probably use it, which makes it a gateway to socialism and godless anarchy. I prefer my god-fearing, gun-toting American date standards. God bless America, and God bless Pi(e) Day.

Posted: **Sat Mar 14, 2015 7:06 pm UTC**

No, Europeans do nonsense like saying 22/7 is a real day.

Posted: **Sat Mar 14, 2015 10:48 pm UTC**

gmalivuk wrote:No, Europeans do nonsense like saying 22/7 is a real day.

No such thing. The correct seperator is a hyphen: 22-7.

WibblyWobbly wrote:Meh, ISO is just an international agreement, no more or less correct than any other standard. Also, those damned Europeans probably use it, which makes it a gateway to socialism and godless anarchy. I prefer my god-fearing, gun-toting American date standards. God bless America, and God bless Pi(e) Day.

Thanks for throwing pi day into that mess of americentric, conservative, fundamentalist religious excrement. (I wanted to add a word for "anti-socialistic", but I couldn't find the right one. Any help?)

I'm looking forward to Tau Day instead.

Posted: **Sat Mar 14, 2015 11:43 pm UTC**

Flumble wrote:(I wanted to add a word for "anti-socialistic", but I couldn't find the right one. Any help?)

McArthyist?

Posted: **Sun Mar 15, 2015 1:03 am UTC**

And the correct order is (yyyy)-mm-ddFlumble wrote:gmalivuk wrote:No, Europeans do nonsense like saying 22/7 is a real day.

No such thing. The correct seperator is a hyphen: 22-7.

Posted: **Sun Mar 15, 2015 1:26 am UTC**

I'll try to post this at exactly the right time. Yay!

Posted: **Sun Mar 15, 2015 1:49 am UTC**

Oops, wrong time zone. And 4 seconds late. Oh, well.

I wanted to ask about something posted on another thread. The algorithm to generate pi is based on the Euclidian definition of a circle. But what if the curvature of space of this universe isn't *exactly* consistent with using the Euclidian definition of a circle? What if, as the universe expands (and the expansion seems to be accelerating!) the curvature is changing slightly?

So the exact value of pi might be

3.141592653589793238462643383270000000000000000000000000...

Cosmologists have found huge voids in the universe. Maybe somebody cleared out a region of 10 million lightyears of total vacuum so he could create a perfect circle made out of frozen hydrogen atoms. (Unperturbed by nearby gravitational influences).

And he's watching it, measuring the ratio between its circumference and its diameter, to see if it changes, and which algorithm its change is consistent with.

In the topic, 1292: Pi vs. Tau

gmalivuk wrote,

Some of the algorithms are derived directly from the definition of a (Euclidean) circle, and the rest of them can be proven to converge on the same number.

viewtopic.php?f=7&t=106764&p=3500217&hilit=gladiolas#p3500217

I'm sure it's likely gmalivuk knows way more about math than I do, but it seems to this amateur like all the algorithms use the same assumptions? Or maybe I'm way off base?

Anyway, happy pi day, but I forgot to save any pie to eat today. But I did have ice cream.

What is there about Tau Day that we could possibly celebrate, the way we do Pi Day?

I wanted to ask about something posted on another thread. The algorithm to generate pi is based on the Euclidian definition of a circle. But what if the curvature of space of this universe isn't *exactly* consistent with using the Euclidian definition of a circle? What if, as the universe expands (and the expansion seems to be accelerating!) the curvature is changing slightly?

So the exact value of pi might be

3.141592653589793238462643383270000000000000000000000000...

Cosmologists have found huge voids in the universe. Maybe somebody cleared out a region of 10 million lightyears of total vacuum so he could create a perfect circle made out of frozen hydrogen atoms. (Unperturbed by nearby gravitational influences).

And he's watching it, measuring the ratio between its circumference and its diameter, to see if it changes, and which algorithm its change is consistent with.

In the topic, 1292: Pi vs. Tau

gmalivuk wrote,

Some of the algorithms are derived directly from the definition of a (Euclidean) circle, and the rest of them can be proven to converge on the same number.

viewtopic.php?f=7&t=106764&p=3500217&hilit=gladiolas#p3500217

I'm sure it's likely gmalivuk knows way more about math than I do, but it seems to this amateur like all the algorithms use the same assumptions? Or maybe I'm way off base?

Anyway, happy pi day, but I forgot to save any pie to eat today. But I did have ice cream.

What is there about Tau Day that we could possibly celebrate, the way we do Pi Day?

Posted: **Sun Mar 15, 2015 1:52 am UTC**

- If space is curved, the Euclidean definition of pi remains the same, because it's defined to be Euclidean.
- No smooth curvature of space would lead to the circumference-to-diameter ratio being constant, except for 0 curvature.

Edit: and now I see that I already responded to basically the same point you tried to make in that other thread. The fact that you then left the thread doesn't magically make my argument from a year ago any less valid.

Posted: **Sun Mar 15, 2015 2:37 am UTC**

Flumble wrote:WibblyWobbly wrote:Meh, ISO is just an international agreement, no more or less correct than any other standard. Also, those damned Europeans probably use it, which makes it a gateway to socialism and godless anarchy. I prefer my god-fearing, gun-toting American date standards. God bless America, and God bless Pi(e) Day.

Thanks for throwing pi day into that mess of americentric, conservative, fundamentalist religious excrement. (I wanted to add a word for "anti-socialistic", but I couldn't find the right one. Any help?)

I'm looking forward to Tau Day instead.

I know. I cringed when I wrote it.

Posted: **Sun Mar 15, 2015 2:47 am UTC**

I'm sorry, I'll re-read it and think it through, maybe I'll understand it after a good night's sleep. Thanks.

Posted: **Sun Mar 15, 2015 7:04 am UTC**

gmalivuk wrote:And the correct order is (yyyy)-mm-ddFlumble wrote:gmalivuk wrote:No, Europeans do nonsense like saying 22/7 is a real day.

No such thing. The correct seperator is a hyphen: 22-7.

I can't see why anyone would ever want any date format other than year-month-day. That's the only way you can actually sort/order dates meaningfully.

Girl-With-A-Math-Fetish wrote:sevenperforce wrote:Well, I work all day today, but I'll probably be wishing guests a happy pi day and looking for opportunities to use my prodigious mathability to amuse and astound them, thus earning greater quantities of $$$$.

Hahahaha

Mathability xD

The mathability worked out! I made great quantities of $$$$ and many people were excited to celebrate Pi Day today.

Posted: **Sun Mar 15, 2015 9:25 am UTC**

I grew up in Canada where we would indeed use 3-14-(20)15 today. Now I live in a different country where it's 14-3-(20)15. I must say it makes a lot more sense this way, but it would be nice to have more Pi.

Posted: **Sun Mar 15, 2015 2:21 pm UTC**

Look, if you insist on ordering the date wrong *and* avoiding / as the delimiter, you've only got yourself to blame.

Posted: **Mon Mar 16, 2015 4:32 pm UTC**

sevenperforce wrote:I can't see why anyone would ever want any date format other than year-month-day. That's the only way you can actually sort/order dates meaningfully.

It's true that that format is best for sorting.

However, if you have data where the year remains constant (e.g. data for a particular course that takes place all in the same calendar year), then you could omit the year, and just write MM-DD or MM/DD.

This could be taken as an argument in favor of MM-DD over DD-MM.

Posted: **Mon Mar 16, 2015 5:35 pm UTC**

Whizbang wrote:Happy Tau Day!

Lemme guess: another tauvangelist complainint that pi somehow totally cripples mathematical education while doubling it would make kids love and excel at math?

Posted: **Mon Mar 16, 2015 5:49 pm UTC**

Teach the controversy.

Posted: **Mon Mar 16, 2015 6:03 pm UTC**

We ate pie. It was apple pie. It was good. I ate about a radian's worth, while wearing my Pi Day shirt.

Posted: **Tue Mar 17, 2015 4:42 am UTC**

He had a perfect opportunity to use the smallest defined metric prefix in a real sentence. And missed it.

For those who missed it (like me), on Saturday morning we experienced the only calendrical Pi Moment that most of us will experience in our lifetimes:

The above date-time of the moment is accurate to within a fraction of a yoctosecond (ys); it is also valid input for GNU date.

If you missed it, you'll have to wait 100 years for the next one. Or die trying.

Few people have experienced--or will experience--the moment twice.

For those who missed it (like me), on Saturday morning we experienced the only calendrical Pi Moment that most of us will experience in our lifetimes:

Code: Select all

`3/14/15 9:26:53.5897932384626433832795029`

The above date-time of the moment is accurate to within a fraction of a yoctosecond (ys); it is also valid input for GNU date.

If you missed it, you'll have to wait 100 years for the next one. Or die trying.

Few people have experienced--or will experience--the moment twice.

Posted: **Tue Mar 17, 2015 3:09 pm UTC**

I thought about how our artificial calendar and numbering system make pi day a coincidince, really. While writing this, I realized that summer and winter solstices make for excellent coordinate-independent pi days and mean twice the pie each year.

Posted: **Tue Mar 17, 2015 3:29 pm UTC**

z4lis wrote:I thought about how our artificial calendar and numbering system make pi day a coincidince, really. While writing this, I realized that summer and winter solstices make for excellent coordinate-independent pi days and mean twice the pie each year.

We should celebrate Tau day at aphelion on January 3 and Pi day at perihelion on July 4. Which would give rise to endless jokes about things being "American as Apple Pi".

Unfortunately, aphelion and perihelion are not altogether consistent with our calendar. That shouldn't stop us, though. There are plenty of holidays which fall on a different day every year because they are day-of-the-week-dependent.

Posted: **Tue Mar 17, 2015 3:29 pm UTC**

How are the solstices "pi days" in any meaningful way?

Posted: **Tue Mar 17, 2015 3:41 pm UTC**

pi is halfway around the circle!

Posted: **Tue Mar 17, 2015 4:18 pm UTC**

But the solstices aren't (quite). Perihelion and aphelion would work, though.

Posted: **Tue Mar 17, 2015 7:54 pm UTC**

gmalivuk wrote:But the solstices aren't (quite). Perihelion and aphelion would work, though.

IIRC, the solstices are exactly half a year apart, but they are not exactly a half-orbit apart because the speed of the Earth is not consistent through its orbit (it's moving fastest at aphelion and slowest at perihelion). Perihelion and aphelion are the only two points in the Earth's orbit which are both exactly pi radians apart AND exactly half a year apart.

What's the argument for deciding whether aphelion or perihelion should serve as the "start" (other than perihelion already being approximately the beginning of the year)? The shape of the orbit is a quadrilaterally symmetric ellipse so I can't think of any reason why placing the sun at one focus rather than the other would have any mathematical significance.

EDIT:

Random interesting fact I just calculated...Earth's orbit is so nearly circular that the Sun is less than two solar diameters away from the actual center point of the ellipse. However, thanks to the inverse-square law, the energy we receive from the sun at aphelion is a full 7% greater than at perihelion.

Posted: **Tue Mar 17, 2015 11:31 pm UTC**

By the revolution logic, I propose to celebrate tau every day at Solar noon –others may celebrate pi at noon and midnight.

Since aphelion, perihelion and solstices aren't coupled with the passing of the day, I would refrain from assigning a "day" to the event... and I like to celebrate mathematics more than a few times a year.

Since aphelion, perihelion and solstices aren't coupled with the passing of the day, I would refrain from assigning a "day" to the event... and I like to celebrate mathematics more than a few times a year.

Posted: **Tue Mar 17, 2015 11:42 pm UTC**

Flumble wrote:By the revolution logic, I propose to celebrate tau every day at Solar noon –others may celebrate pi at noon and midnight.

But the earth rotates nearly 361° in 24 hours. It only takes about 23 hours 56 minutes to rotate 2𝜋 radians. This is because, in the time it takes to rotate 2𝜋 radians, the earth has moved nearly 1° (on average) around its orbit around the sun.

Posted: **Tue Mar 17, 2015 11:50 pm UTC**

FancyHat wrote:Flumble wrote:By the revolution logic, I propose to celebrate tau every day at Solar noon –others may celebrate pi at noon and midnight.

But the earth rotates nearly 361° in 24 hours. It only takes about 23 hours 56 minutes to rotate 2𝜋 radians. This is because, in the time it takes to rotate 2𝜋 radians, the earth has moved nearly 1° (on average) around its orbit around the sun.

Except I observe the rotation of the Earth wrt. the Sun-Earth line, not wrt. the Earth-Sun orbit or the reference frame in which most of the universe is static from our viewpoint.

Posted: **Wed Mar 18, 2015 12:41 am UTC**

That would mess you up even more, since local noon-to-noon is sometimes shorter and sometimes longer than 24 hours exactly.

Also, there are more constants than pi and tau. You can celebrate math multiple times a year without needing to celebrate only those two numbers hundreds of times a year.

Also, there are more constants than pi and tau. You can celebrate math multiple times a year without needing to celebrate only those two numbers hundreds of times a year.

Posted: **Thu Mar 19, 2015 1:51 am UTC**

sevenperforce wrote:IIRC, the solstices are exactly half a year apart, but they are not exactly a half-orbit apart because the speed of the Earth is not consistent through its orbit (it's moving fastest at aphelion and slowest at perihelion).

Ignoring the process of the Earth's axis, the solstices have to be half way apart in angle with respect to the Sun, but in neither orbital distance or time. The solstices are defined as the days when the sun is highest or lowest (depending on season and hemisphere) in the sky. If the tilt of the Earth's axis is constant, these are by definition on opposite sides. But unless the solstices also correspond to perihelion and aphelion (they don't), then one side of the orbit is closer to the sun on average, being shorter in both distance and time, and the other half is further from the sun and longest in distance and time.