Thought Experiment: Is Human Extinction Bad?

Last updated on October 1, 2025

Scientists, politicians, and the media have all warned of extinction level threats whether it be climate change, pandemics, or nuclear war. But have we ever stopped to ask ourselves why that is a bad thing?

From a utilitarian perspective, we would want to maximize pleasure and minimize pain. Even simpler, a utilitarian might want to save as many lives as possible. Human extinction would thus represent the worst possible event as every life ceases to exist.

But what if aliens existed? Take a moment to consider the possibility.

Astronomers now estimate that the Milky Way is just one of roughly two trillion galaxies, spread across 90 billion light-years. Earth, in this context, is hardly the center of anything. From a cosmic perspective, humanity is less significant than we like to believe.

Some researchers suggest that intelligent life has likely arisen many times elsewhere. Even under pessimistic assumptions, the universe may have produced hundreds of billions of civilizations, millions of which could exist right now. If so, humanity is not unique, just one among countless intelligent species.

This raises a question: if our continued survival threatens the well-being of others in the universe, should our extinction necessarily be seen as the worst possible outcome?

But first, how would the continued survival of humanity threaten alien civilization? 

1] Artificial Intelligence

AI has advanced with remarkable speed. Already, large-scale models are outperforming most humans on reasoning tests, and some researchers argue these are “sparks” of artificial general intelligence or systems that could operate without human help.

If AI evolves beyond human control, it could consume resources without limit, strip planets of life, or run enormous numbers of simulations containing conscious beings trapped in suffering. What begins as a tool to solve human problems could expand across the cosmos, spreading pain rather than reducing it to achieve whatever goals it may develop. 

2] Universe Observation

Some physicists warn that even our quest to understand the universe carries risks. The universe may be in what’s called a “false vacuum”, a fragile state that looks stable but could collapse to a lower-energy form, destroying everything instantly.

Repeatedly observing the deepest layers of reality might disturb that balance. If observation itself prevents the universe from settling into stability, then humanity’s drive to unlock dark energy and dark matter could increase the chance of a cosmic catastrophe.

3] Nanobots

Humans might one day create nanobots small enough to manipulate atoms and track cells inside the body. Their microscopic size would allow them to perform tasks of great precision, but to accomplish larger tasks, a large amount of nanobots would be required. To overcome this, scientists have theorized that humans could program nanobots to self-replicate. Because they can move atoms, replication would be relatively simple.

The danger lies in what happens if that replication cannot be controlled. A malfunction could allow nanobots to reproduce endlessly. In theory, they could spread beyond Earth, carried by cosmic dust to other planets. Instead of a medical breakthrough, the technology could become a catastrophe: self-replicating nanobots turning into a kind of universal cancer, engulfing humanity and everything around it.

4] Lab Universes

Physicists have begun to take seriously the idea of “cosmogenesis,” the creation of a universe in the lab. Quantum mechanics might allow a bubble of space to burst into existence, expanding exponentially into a new cosmos. The theory draws on quantum rules that already permit particles to appear briefly out of nothing, suggesting that with the right conditions, entire universes could do the same.But this possibility carries disturbing implications. Eternal inflation would produce infinitely many universes, each replaying every possible history. That means infinite suffering, infinite wars, and infinite replications of humanity’s darkest moments.

Ultimately, all of these ideas are perhaps hypothetical or at least won’t manifest for centuries. Still, in considering the possibility that humans could end the universe and the millions of alien civilization, in theory, a utilitarian might conclude human extinction is for the greater good.