1960 'Doomsday equation' predicts infinite population on Friday, November 13, 2026

November 13, 2026 is the "doomsday" derived by mathematical extrapolation in von Foerster et al.'s 1960 paper, "Doomsday: Friday, 13 November, A.D. 2026": the population N tends to infinity on that day. On November 11, @csvoss posted a thread of tweets explaining the paper's derivation and launched a playful CFP called DOOMSDAY. With the date fast approaching, this "prophecy" has drawn renewed attention.

Confirmed

• The paper extrapolates from two thousand years of population growth data, concluding that population N tends to infinity on November 13, 2026.
• Key assumption: for interacting populations, productivity a is a monotonically increasing function of population N, taken as a = a₀·N^(1/k) (k≈1).
• Motivation: the classic logistic equation includes a competition term; the authors argue that, in fairness, a term capturing human cooperation and technological progress should be added, and justify the assumption with historical urbanization and the rise of mass communication.
• The solution takes the form N = N₁·((t₀−t₁)/(t₀−t))^k, and the authors name the characteristic date t₀ "doomsday"; the paper wryly summarizes that a consequence of this modeling is that "we shall eventually crowd ourselves off the planet" through collective success.
• Years ago, @csvoss created a Google Calendar event titled "Doomsday: Friday, 13 November, A.D. 2026," whose description links only to the 1960 paper — the tweet thread grew out of that event.

Why it matters

• What sets this model apart from ordinary population regression is its explicit modeling of positive feedback from cooperation and technological progress, making it a classic example of super-exponential growth.
• With the predicted date approaching, the paper has resurfaced in discussion as a topic blending history of science with dark humor, and @csvoss's CFP has turned it into a playful community event.

2026-11-11 ~ 2026-11-11 · 6 related posts

• [source] A 1960 paper predicted human population hits infinity on November 13, 2026 — csvoss · 2026-11-11
• A Google Calendar Event Titled "Doomsday: Nov 13, 2026" Links Only to a 1960 Paper — csvoss · 2026-11-11
• The Key Assumption: Productivity a = a0·N^(1/k) in the Doomsday Paper — csvoss · 2026-11-11
• Why the Doomsday Paper Added a Collaboration Term to Logistic Growth — csvoss · 2026-11-11
• [source] How the Doomsday Solution Diverges: N Goes to Infinity at t = t0 — csvoss · 2026-11-11
• [source] The 1960 Doomsday Equation That Predicts Infinite Population on Nov 13, 2026 — csvoss · 2026-11-11