Math predicts humans could go extinct in 17,000 years

A statistical doomsday argument—built on the idea that humans occupy no special place in the universe—tries to estimate how many people will ever be born. Using today’s estimated 117 billion people already born, the approach arrives at an upper limit of 2.34 t

On a planet that feels. day to day. relentlessly in motion. the number 117 billion has a way of pulling you up short. That’s the current estimate of how many people have lived on Earth so far—and it becomes the starting point for a math-based doomsday argument that reaches a stark place: 95 percent certainty that humans will inhabit the planet for. at most. another 17. 100 years.

The argument traces back to work put forward by astrophysicist Brandon Carter in 1983. Its foundation is a familiar Copernican principle: the idea that we do not occupy a privileged position in the universe. but rather a random one. Named after Nicolaus Copernicus. the principle is commonly used in cosmology to suggest our surroundings—our solar system included—are not special but rather fairly common.

From there, the reasoning takes a turn that feels almost too clean for a subject as messy as extinction. If you treat all human beings who will ever exist as points on an extremely long timeline—stretching across both the past and the future—you can start asking a question that only math can ask: given where we find ourselves on that timeline. what is the most extreme total population the universe would allow?.

The key move is built around a simple probability picture. Suppose you are the xth person ever born. If the distribution of being born before or after a particular person is equally likely. then your place on the “number line” from 0 to N—where N is the total number of people who will ever have been born—should fall in the first half or the second half with 50 percent probability.

Expand the interval. Instead of “half. ” think in terms of a 95 percent range: humans are 95 percent certain to be in the segment that runs from 0.05N to N. If x is known—about 117 billion, using current estimates—then the math implies x is greater than 0.05N. From there the argument deduces that 20x is greater than N. With 95 percent certainty, the maximum total number of people who will ever have lived is 20 × 117 billion, or 2.34 trillion.

To make that logic feel less abstract, the argument borrows from a thought experiment with two boxes. One box holds 10 ping-pong balls numbered 1 through 10. The other contains 100,000 balls labeled with ascending numbers. You don’t know which box a draw will come from. A ball numbered 4 is taken from the opening of a randomly chosen box. Most people would assume the almost-empty box—because the chance of drawing a 4 from the 10-ball box is 1 in 10. while in the 100. 000-ball box it’s 1 in 100. 000.

The same intuition is applied to people. Every person who has ever lived is treated like a ping-pong ball, and the two boxes represent different possible futures. A nearly empty box corresponds to the scenario where humanity ends sooner—destroying itself in the near future. A fuller box corresponds to the opposite: that humanity spreads across the galaxy and survives for extremely long periods.

And this is where the doomsday timeline starts to tighten. If 2.34 trillion is a 95 percent upper limit on the total number of people who will ever have lived, you can estimate when that limit might be reached using annual birth rates.

For the past 40 years, about 130 million children have been born each year. Even though the birth rate is declining, the population has still been increasing. So the argument makes an intentionally blunt assumption: if those 130 million births per year stay constant. it would take another 17. 100 years for the total population to reach the 2.34 trillion ceiling. The time could shift if births rise or fall, the argument allows, but the order of magnitude stays similar.

The cold math has company, though, in objections that push the end-date outward. The doomsday argument is described as highly controversial and rejected by many scientists. One critique is that the calculation could be broadened beyond our species. If you include all organisms that have ever existed. the numbers would expand and the apocalypse would move much farther into the future.

There’s also a challenge aimed at the very randomness the argument assumes. The reasoning says we should treat our position on the timeline as uniformly distributed under a Copernican principle. But critics argue that the doomsday argument emerged early in human history—once humans crossed a certain threshold of knowledge—so the assumption of uniformity might not hold. If we are not as randomly positioned as the model claims. then the estimate for N can’t be carried over so confidently.

Even with those pushbacks. the argument’s underlying emotional force is hard to ignore: it tries to translate a single fact about where we stand—117 billion people already born—into a ceiling on how long the human story can continue. Whether you trust it or dispute it, it forces a question that feels uncomfortably personal.

The piece that lays out this reasoning originally appeared in Spektrum der Wissenschaft and was reproduced with permission. It was translated from the original German version with the assistance of artificial intelligence and reviewed by editors.

doomsday argument Brandon Carter Copernican principle human extinction probability birth rate 17 100 years 2.34 trillion 117 billion