---
title: "Eternal return · Library · Simulation Hypothesis"
url: https://simulation-hypothesis.com/library/eternal-return
description: "Eternal return is Nietzsche’s thought experiment of a universe that repeats exactly, over and over without end."
license: https://creativecommons.org/licenses/by/4.0/
credit: "Ross Allan Dahl, Simulation Hypothesis (simulation-hypothesis.com)"
---

## Time & causality

# Eternal return

Definition

Eternal return is Nietzsche’s thought experiment of a universe that repeats exactly, over and over without end. He posed it as a test of whether you’d say yes to your own life.

On this site

The Cyclic time model, which stores one cycle and replays it.

Role in the model

The Cyclic time model stores one cycle of the universe and replays it. It takes no more than linear time plus a very long tape. It also puts Nietzsche’s question to every inhabitant: would you say yes to living this exact life again, forever?

Related

[Existentialism](https://simulation-hypothesis.com/library/existentialism)[Causality](https://simulation-hypothesis.com/library/causality)

In the trees

[The death of God · Ethics](https://simulation-hypothesis.com/trees/ethics?n=g-nietzsche)

## The people behind the terms

14 short pages, one per thinker, each with its matching dial. See also the [reading list](https://simulation-hypothesis.com/reading).

[Plato’s cave](https://simulation-hypothesis.com/thinkers/plato)[Zhuangzi’s butterfly](https://simulation-hypothesis.com/thinkers/zhuangzi)[Vasubandhu’s dream](https://simulation-hypothesis.com/thinkers/vasubandhu)[Shankara’s māyā](https://simulation-hypothesis.com/thinkers/shankara)[al-Ghazali’s doubt](https://simulation-hypothesis.com/thinkers/ghazali)[Ibn Arabi’s imagination](https://simulation-hypothesis.com/thinkers/ibn-arabi)[Calderón’s life is a dream](https://simulation-hypothesis.com/thinkers/calderon)[Descartes’ demon](https://simulation-hypothesis.com/thinkers/descartes)[Berkeley’s perceiver](https://simulation-hypothesis.com/thinkers/berkeley)[Borges’ circular ruins](https://simulation-hypothesis.com/thinkers/borges)[Nozick’s experience machine](https://simulation-hypothesis.com/thinkers/nozick)[Putnam’s brain in a vat](https://simulation-hypothesis.com/thinkers/putnam)[Bostrom’s trilemma](https://simulation-hypothesis.com/thinkers/bostrom)[Chalmers: virtual worlds are real](https://simulation-hypothesis.com/thinkers/chalmers)