---
title: "Ancestor simulation · Library · Simulation Hypothesis"
url: https://simulation-hypothesis.com/library/ancestor-simulation
description: "An ancestor simulation is a detailed recreation of a civilisation’s own past, including conscious inhabitants, run by its technologically mature descendants."
license: https://creativecommons.org/licenses/by/4.0/
credit: "Ross Allan Dahl, Simulation Hypothesis (simulation-hypothesis.com)"
---

## Simulation hypothesis

# Ancestor simulation

Definition

An ancestor simulation is a detailed recreation of a civilisation’s own past, including conscious inhabitants, run by its technologically mature descendants.

On this site

The Render start slider. If the tape starts in 1900, everything earlier is unrendered backstory.

Role in the model

This is the kind of simulation Bostrom’s argument is about: descendants running their own past. It matters for the computing needed because a simulation of history can start late. The Render start slider shows this directly. Everything before switch-on is backstory, and nobody has to compute it.

Related

[Bostrom’s trilemma](https://simulation-hypothesis.com/library/bostrom-trilemma)[Posthuman civilisation](https://simulation-hypothesis.com/library/posthuman)

In the trees

[Ancestor simulation · Simulations](https://simulation-hypothesis.com/trees/simulations?n=f-ancestor)

## 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)