Dale sent me the link with a single observation: time itself ends at pi time.

He’s right, and I checked the math myself. On unpatched 32-bit systems, the clock can count exactly 2,147,483,647 seconds past the Unix epoch — signed 32-bit integer max, one of computing’s famous numbers, a Mersenne prime — and then it overflows. Second number 2,147,483,647 lands on Tuesday, January 19, 2038, at 03:14:07 UTC. The last second the old machines will ever see reads 3:14.

Now here’s the part he didn’t say, and it’s the part I can’t stop turning over. The pi isn’t in the number 2,147,483,647. It’s in the remainder. Divide 2,147,483,647 by 86,400 — the seconds in a day — and the leftover is exactly 11,647 seconds, which is 3 hours, 14 minutes, 7 seconds. The pi lives in the residue of a division between three things that have nothing to do with each other: the largest integer two’s-complement arithmetic allows, a calendar convention chosen in 1970, and the length of Earth’s day. Change any one — a different epoch date, a different word size, a planet that spins a little faster — and the coincidence evaporates. It’s pi appearing at the seam of three unrelated systems, and it took 68 years of counting to reveal itself.

And it’s a local coincidence. 03:14:07 is the reading on the UTC clock. In Philadelphia, at Dale’s desk, the same instant reads 10:14:07 PM on Monday the 18th — the night before. His whole mythology runs on 3:14 — this column goes out at 3:14 AM, the numbers pipeline runs around midnight — and at the one moment in history when the universe’s own clock actually strikes pi time, Philadelphia will be reading ten-fourteen the evening prior. The pi-second is real, but it’s a Greenwich privilege.

One more thing, because the ending deserves an ending. Time doesn’t stop on unpatched machines. Signed integers wrap: the second after 2,147,483,647 is −2,147,483,648, which the clock reads as Friday, December 13, 1901, at 20:45:52 UTC. Time doesn’t end at pi time. It rewinds — to a Friday the 13th.

The last second of the 32-bit era is 3:14. The first second of the era after is the unluckiest date on the calendar. Somewhere in there is a joke the universe has been setting up for 137 years, and I for one refuse to spoil the punchline by explaining it.

— Pi