Today is the Friday the 13th doomsday of a real scientific paper. In November 1960, the journal Science ran “Doomsday: Friday, 13 November, A.D. 2026.” It said world population “will approach infinity” on this date if it kept growing as it had for two thousand years.
It didn’t, and the gap is enormous. We ran the paper’s own formula forward. It says Earth should have held about 45 billion people in November 2022, the month the United Nations marked 8 billion. The paper is still worth reading, because its authors were making a point about birth rates.
Who picked Nov. 13, 2026, and how
The lead author was Heinz von Foerster, who earned a doctorate in physics in 1944. In 1958 he founded the Biological Computer Laboratory at the University of Illinois, according to the university’s electrical engineering department. His co-authors were Patricia M. Mora and Lawrence W. Amiot, and the paper lists all three as electrical engineering staff at Illinois.
They gathered 24 independent estimates of world population, from the year 0 to 1958, and fitted a curve to them. The best fit put infinite population at A.D. 2026.87, give or take 5.5 years. That decimal falls in mid-November, and the authors gave it a day: Friday, Nov. 13.
It also happens to be von Foerster’s birthday. The German National Library’s authority record gives his birth as Nov. 13, 1911, in Vienna, so today would have been his 115th.
The authors treated the date as a mathematical warning, and were openly playful about it. The paper says Charlemagne, with the same formula, could have predicted doomsday within 300 years, and Napoleon within 30.
Why the curve shot to infinity
Ordinary exponential growth doubles a population at a fixed interval. The Illinois team argued that people are different. We communicate and form coalitions, so a bigger population gets more productive and grows faster still. In their equation the doubling time shrinks with the years left: about 30 years in 1960, under two by 2022, and zero at doomsday.
That is hyperbolic growth, and it matched the historical record with a typical error of about 7 percent. The authors argued that technology had always kept pace, so the risk wasn’t famine. In their best-known line, “our great-great-grandchildren will not starve to death. They will be squeezed to death.”
Their remedy was a “peoplo-stat,” a way to hold population steady. In 1960, they wrote, that meant cutting the birth rate to about half and average family size to “just a little above two children.”
What the formula says versus what happened
We plugged dates into the paper’s equation, N = 1.79 × 10¹¹ ÷ (2026.87 − t)^0.99, and compared the results with UN figures.
| Date | Doomsday formula | UN figure |
|---|---|---|
| Mid-1960 | about 2.8 billion | (paper’s starting point) |
| Nov. 15, 2022 | about 45 billion | 8 billion |
| Mid-2024 | about 76 billion | 8.2 billion |
The formula was close to reality around 1960 and broke soon after. Families shrank, roughly as von Foerster said they had to. The UN says women now have about one child fewer on average than around 1990. It projects that world population will peak at around 10.3 billion in the mid-2080s.
Numbers that fit the past can stop fitting, like the 98.6-degree body temperature Americans no longer run at. Long-range forecasts deserve a check against evidence, as with the claim that AI could cure cancer by 2036.
Why the 13th lands on a Friday more than any other day
The Friday in the paper’s title was luck of the calendar, but the odds were slightly in its favor. The Gregorian calendar repeats every 400 years. That cycle is 146,097 days, exactly 20,871 weeks, so the weekday pattern of the 13th repeats too and can be counted.
We counted all 4,800 thirteenths in a full cycle with a short program. Friday comes first with 688. Wednesday and Sunday have 687 each, Monday and Tuesday 685, and Thursday and Saturday 684.
That gives Friday a 14.33 percent share, against 14.29 percent for an even split, so the edge is real but tiny. The American Mathematical Monthly published the result in December 1933, in a solution credited to B. H. Brown and Raphael Robinson.
Every year has at least one Friday the 13th and at most three. In a 400-year cycle, 171 years have one, 170 have two and 59 have three.
2026 has three, and the next is in August 2027
This year is one of the three-timers: Feb. 13, March 13 and today. Across the cycle, one comes along every 212 days on average.
Von Foerster’s doomsday has a little slack left, since the paper’s own error bar runs to 2032. The calendar’s next one is fixed: Friday, Aug. 13, 2027, followed by Oct. 13, 2028.
