Pi Day is Calculated Wrong.

[swestrup]

I wrote this as a comment in musicdieu's journal, but I think it should be said to a wider audience:

Pi day is stupid, not because Pi is unworthy of celebration, but because the math is bad. Express Pi in a different notation, or different base, and you end up with a different day.

Instead, consider a year to be a circle (actually, its not-quite elliptical if you look at it as a path traced by the Earth around the Sun, but very close to a circle), because you know, years are cyclical.

So, since Pi radians is half a cycle (for very deep and interesting mathematical reasons). Thus Pi day should be in the exact middle of the year...

Comments

[taxlady.livejournal.com]

I never thought of Pi radians. I guess it would be.

[azrhey.livejournal.com]

there is no Pi day in the gregorian calendar.

There is no 14th month.

[swestrup]

Yet another example of how the usual calculation gets it wrong!

[musicdieu.livejournal.com]

I was going to make this reply in my journal, but I think this topic deserves its own header.

I don't think Pi day is stupid, and the reason is that no matter where you place it in the year, you're making some silly generalization or simplification which justifies its placement.

In your argument above, you even mention yours; you simplify the Earth's orbit into a circle. Its orbit is indeed elliptical, not to mention that due to gravimetric forces, the acceleration isn't constant at all points, so there is no guarantee that we've traversed 'half' of the ellipse by the midpoint of the year.

The 'traditional' view assumes a base 10 representation of Pi with irrational numbers that everyone has learned since grade school. I think this is a far more reasonable simplification, especially given the relatively limited celebration of Pi day; making more obscure justifications for it certainly won't garner more attention.

I suppose you can make up many justifications and put Pi day in many places; I just like my bloody pie!

[swestrup]

While its true that I made the assumption that Earth orbit was circular, if you do the real math, taking the real shape of the ellipse into consideration and the precession of the orbit due to general relativity, you'll end up with a time that disagrees with the exact center of the year, by no more than a few hours.

Should someone we willing to do the math, I'd happily endorse that point as the actual 'Pi Time', but the day it falls on is very likely to be the same.

[musicdieu.livejournal.com]

I still think that, even assuming the math is correct, you're just taking one view of pi vs. another view, the 'base 10 expand the digits view.'

Neither seems correct to me from the other perspective.