The pi birthday exists in the same vein as the "half birthday"; an essentially purposeless occasion that serves only as an excuse to celebrate.
Pi birthdays are usually celebrated only twice in the course of one's life. The first is when you're 3.14159265 years old. As most people are unable to party for themselves at this age, the event serves as a cute mathematically-themed photo-op for the family album.
When a person is 31.41592653 years old, they can throw themselves a fun, themed get-together to celebrate their second pi birthday. Friends are encouraged to bring circular gifts. Pie is enjoyed by all. Endurance recitation contests are held and celebrators are encouraged to do things irrationally.
In the future, a third pi birthday may be celebrated at age 314.15926535. I have no doubt that it will be an equally festive occasion.-- DrWorm, Jan 25 2011 Exponential birthday intervals Exponential_20birthday_20intervalsA similar idea [hippo, Jan 25 2011] List of transcendental numbers-- http://en.wikipedia...s_and_open_problems [ldischler, Jan 25 2011] Oh yes, definitely. But strictly speaking it would occur at an unknown instant so finely defined that special relativity would make it different for each person and different parts of the same person.
For myself, i'll be pi times a dozen and two about a week before my forty-fourth birthday. Makes me wonder how close it gets to whole years in someone's lifetime.-- nineteenthly, Jan 25 2011 Birthdays should be at 1, 3.14, 9.87, 31.01, and 97.41 years old - i.e. pi^n where n=0, 1, 2, 3, 4-- hippo, Jan 25 2011 Exponential birthday intervals make sense because time speeds up as you get older, but slicing pi (ooh!) decimally like that is too much of a concession to base ten for me.-- nineteenthly, Jan 25 2011 How about celebrating not just pi, but every transcendental number?-- ldischler, Jan 25 2011 Isn't nearly every decimal number transcendental? You'd be having a birthday every few nanoseconds.-- hippo, Jan 25 2011 There may be many transcendentals, but only a few have names. I especially like Chaitin Day, which is transcendental, yet unknown and unknowable. (More like a death day.)-- ldischler, Jan 25 2011 Having missed the only two Pi Birthdays that I'm ever likely to have, I'd like to propose birthdays based on the first Feigenbaum constant instead, so I've still got one to look forward to.-- Wrongfellow, Jan 25 2011 I'm all for celebrating every (named) transcendental number. And if it's too difficult to exactly place the instant of the pi birthday, I think it would be acceptable to use 22/7 as a replacement.-- DrWorm, Jan 25 2011 //a birthday every few nanoseconds// Presents! Cakes!-- pocmloc, Jan 25 2011 //a birthday every few nanoseconds//
It's even better than that - you'd have uncountably many birthdays in any finite interval of time.-- Wrongfellow, Jan 25 2011 Yes, but so would everyone else. Assuming you only remembered a finite number of your friends' birthdays you would therefore fail to remember an infinite number of your friends' birthdays. The ratio of remembered birthdays to forgotten birthdays would thus be zero, and none of your friends would like you any more.-- hippo, Jan 25 2011 I don't think that's a problem. People generally don't try to remember their friends' birthdays with infinite accuracy; identifying the date alone is fine. So there's no remembering needed, because you know by definition that each of your friends has uncountably many birthdays every day.-- Wrongfellow, Jan 25 2011 Even though I missed both my pi-bdays, I like the idea! [+] I think there should be party hats that look like, well, you know - pi...-- xandram, Jan 25 2011 Why base it on years? Pi days alive or multiples of pi days make more sense to me.-- RayfordSteele, Jan 25 2011 Perhaps, but a celebration every three-and-change days is a bit much. Months might work.-- DrWorm, Jan 26 2011 Birthdays are already set up based on pi: one year is an orbit, or a complete circle around the sun. However, the circle is not a very engineeringly accepted unit - it should be considered to be 2*pi AU. So it would make more sense from an engineering standpoint to have a birthday (AU day? Radian day?) every 12/(2*pi) months.
(Or 365.24/(2*pi) days = about every 58 days, 3 hrs, 7 minutes. (Rounded up 'cause most alarms don't do seconds.))-- lurch, Jan 26 2011 It's not a circle though. Pi presumably comes into it at some point but this planet's orbit has an eccentricity of roughly one five-dozenth, and it varies in speed so it would cover the same angular distance variably (hence the Martian Rotterdam month-naming system, since on Mars the issue is more severe). Also, there are several different kinds of year, for instance tropical and sidereal.-- nineteenthly, Jan 26 2011 Means you can have a cycle of uphill-birthdays and downhill-birthdays, plotted out on an analemma...-- lurch, Jan 26 2011 I'll see you when I'm 314 years, 7 weeks, 2 days, 16 hours, 21 minutes, and 38.88 seconds old.-- Voice, Jan 26 2011 That's both neat and true, [lurch]. My personal preference would be to celebrate one's birthday according to the orbit of the planet governing one's sun sign.-- nineteenthly, Jan 26 2011 A close member of my family has her birthday on pi day: 14 of March, and in 2015 it had two extra digits to it. 3.14.15
Vi Hart has some videos extensively attacking pi and proposing the representation of a full circle instead, called Tau. (Her birthday is on the 28th of June... and her chosen name rhymes with pi...)-- pashute, Feb 12 2018 random, halfbakery