Pi Day is Actually July 22nd!
43sChallenges the widely accepted March 14th Pi Day with a controversial date switch, sparking debate and curiosity.
▶ Play ClipAI Summary
The video features a grumpy mathematician arguing that Pi Day should be celebrated on July 22 (22/7) rather than March 14 (3.14), because 22/7 is a better approximation of pi. The discussion expands into date formatting conventions, with little-endian, middle-endian, and big-endian approaches, and touches on astronomers' use of Julian dates.
Chapters
[00:14]
July 22 as Pi Day
Pi Day is traditionally March 14 (3.14), but the speaker argues that July 22 (22/7) is a better approximation of pi and should be considered Pi Day, especially for those who write dates day/month.
[00:44]
22/7 Approximation
22/7 is a pretty good approximation to pi, though not exact, and it's at least as good as 3.14 for representing pi.
[01:27]
Date Formatting: Little Indian vs Big Indian
The speaker describes little-endian (day/month/year) as starting with the smallest unit and big-endian (year/month/day) as starting with the largest. Little-endian is preferred because the day is the most immediate information.
[02:48]
US Date Format Criticism
The US uses middle-endian (month/day/year), which the speaker calls arbitrary and unjustified, noting that the US is unique in this convention.
[03:49]
Astronomers Use Julian Dates
Astronomers often use Julian dates, which count consecutive days since a fixed date, making it easy to calculate time intervals. This bypasses date format debates.
The speaker humorously argues for July 22 as Pi Day based on date format preferences, but ultimately dismisses the debate as trivial, noting that astronomers use Julian dates to avoid such issues.
Study Flashcards (5)
What date does the speaker propose as Pi Day?
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What date does the speaker propose as Pi Day?
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July 22 (22/7).
00:14
What is the approximation of pi given by 22/7?
easy
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What is the approximation of pi given by 22/7?
easy
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A pretty good, but not exact, approximation of pi.
00:44
What is 'little-endian' date format?
medium
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What is 'little-endian' date format?
medium
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Day, then month, then year (e.g., 22 July 2026).
01:27
What is 'big-endian' date format?
medium
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What is 'big-endian' date format?
medium
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Year, then month, then day (e.g., 2026 July 22).
01:41
What are Julian dates used for in astronomy?
hard
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What are Julian dates used for in astronomy?
hard
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A continuous count of days since a fixed date, making it easy to calculate time intervals.
03:49
💡 Key Takeaways
💡
Parochialism in Date Format
Highlights cultural biases in date writing and how they affect perceptions of Pi Day.
00:59
⚖️
Little-Endian Justification
Provides a logical reasoning for day-first date format based on information priority.
01:27
📊
US Date Exception
Points out that the US is the only country using middle-endian, making its Pi Day arbitrary.
02:48
🔧
Julian Date Solution
Offers a practical workaround used by astronomers to avoid date format confusion.
03:49Full Transcript
[00:01] I'm allowed to be. I'm I'm grumpy, I'm old, so So, you're here filming today because you know, you've only got a day to do the editing in. Uh I won't I wish to make the case that Pi Day is not actually the 14th of March. Pi Day is
[00:14] the 22nd of July, so you've got plenty of time. Pi Day, yes, is is uh March of time. Pi Day, yes, is is uh March 14th, 3.14, right? So, 3.14 3.14 Pi. But, it's only Pi Day if you put your month at the beginning and then your
[00:27] And sensible people put the day first then the month. So, tomorrow is the 14th of March, not March 14th. And 14.3 is not Pi. So, the reason why 22nd of July is Pi Day is because 22nd of July is written 22/7 or 22/7.
[00:44] And 22/7 is a pretty good approximation to Pi. But, not exact. It's like Is it Is it the best approximation among the months and days we've got? Absolutely. approximation to Pi. And it's certainly at least as good as 3.14 or or the March
[00:59] 14th. That assumes putting the 22 before the 7. Aren't you Aren't you guilty of the same kind of parochialism? Some people call it 7/22. They do, but yes, you want to talk about parochialism, most of the world talks about 22/7, not
[01:14] 7/22. And I think there are actually quite good reason You know, so okay. write a date, right? You could start You could write it the way that I just did of 22nd of July, 2026. Day, month, year.
[01:27] because you start with the little bit and work towards the big bit. You could write it the other way around. You could write 22 2026, July 22nd. That's the big Indian approach cuz you start with the the big bit, the
[01:41] year, and then work your way towards the little bit. And you call that big Indian end. Yes, I've never quite understood that, but anyway, nonetheless, little Indian is starting with a starting with the day, big Indian starting with the
[01:54] either of them, right? The reason you might want to start with the year is if you've got a whole bunch of strings with that date in it and you just sort them order. Which is quite a handy thing if you actually want to sort a bunch of
[02:09] quite useful in the sense that if somebody asks you what's the date, they probably know what year it is. It's quite likely they know what month it is. day is it. And therefore you start with
[02:22] what the day is. But that's reason for little Indian. >> Yeah, it's the probably the information that you're most likely to need, right? month is it? Right? What rather than what month it is it or what year is it.
[02:35] So you start with the important stuff. The approach that gives you pi day being March the 14th is called middle Indian because you start with the middle bit. And there is no justification for that at all that I can think of. It's just a
[02:48] arbitrary. I think the US is the only country in the world that does it. >> What do you call the terrorist attacks that happened in New York in 2001? >> Uh what do Americans call the 4th of July?
[03:07] they? >> So once in a while they slip and writing dates, but that Anyway, look, I should hasten to point out I don't take this at all seriously. You know, I don't wish to offend anybody. I really don't
[03:21] care how you choose to write your date. It just amuses me um that it's such a >> You're an astronomy professor. You're a retired astronomer. What Indian do scientists prefer in their like catalogs and data and, you know, observations?
[03:36] And if I'm looking at a picture that was taken by the Hubble Space Telescope and >> So generally if you're going to write out down a date, you write it big Indian it that way. >> Start with the year.
[03:49] >> Start with the year. But actually astronomers use a thing called date, which is just basically counting days. It's just a number and every day the So every day has a number.
[04:01] useful way in astronomy for counting dates because actually what you want to did something happen? Just need to subtract that Julian date from today's long ago it happened. If you want to know the time between two things, you
[04:13] Julian dates. >> Do you know what Julian dates we need to >> Do you know what Julian dates we need to look up? 3 31 314 3,141 >> We need a very yeah and we and we're up to very big ones now. So actually we'll
[04:28] be you might have a long time to wait for it. And we are and again we also having base 10 centric. >> Absolutely. Yes, very so. >> Pi was historically really calculated
[04:42] this way because it is notoriously inaccurate to try and get I know we're idiots. It's notoriously inaccurate to try and calculate pi try and calculate pi by measuring a circle.
