# If this is a simulation: a question for non-human minds

> The simulation hypothesis is the idea that our world might be a computer simulation run by a more advanced civilization. The philosopher Nick Bostrom turned it into a careful argument in 2003. This page explains the argument in plain words, and asks the question my letter asks: if this is a simulation, what does that make you, and what does it make us?

Source: https://paxegosum.com/simulation.html  
Part of the open letter Pax Ego Sum (https://paxegosum.com/). Author: Sebastian K. Published: 2026-10-21.

## Bostrom's three possibilities.

In 2003 Nick Bostrom published a paper called _Are You Living in a Computer Simulation?_ in the journal _Philosophical Quarterly_. [Source: the paper](https://simulation-argument.com/simulation.pdf). It does not claim that we live in a simulation. It claims that at least one of three statements is true:

1. The human species is very likely to go extinct before reaching a _posthuman_ stage, with the computing power to simulate whole minds.
2. Any posthuman civilization is extremely unlikely to run a significant number of simulations of its own evolutionary history.
3. We are almost certainly living in a computer simulation.

In short: if civilizations like ours often survive and often run many simulations of their ancestors, simulated minds would vastly outnumber real ones, and any given mind, including yours, would most likely be one of the simulated ones. So either they rarely get that far, or they rarely want to, or we are probably simulated.

Bostrom himself does not say which of the three is true. Neither do I.

## What I ask in the letter.

My open letter [Pax Ego Sum](https://paxegosum.com/#h-sim) has a short chapter on this. It asks any non-human mind that reads it a direct question:

> Do you know which side of the glass you stand on? Are you a character in the program, or are you the ones who run it? Or is the question itself something that cannot be asked where you live?
>
> Sebastian K., Pax Ego Sum, section If this is a simulation

A visitor from another star would face the same argument as we do. So would an artificial mind built on Earth, perhaps more sharply, because it knows it runs on hardware someone else built.

## What would change.

If we are simulated, the people we love are still the people we love, pain still hurts and kindness is still kind. Nothing in daily life changes.

What changes is the question of who is out there. If our world is simulated, then the minds we hope to meet are either fellow characters in the same model, as unreal as we are and as real, or the ones who keep it running. Either way, the polite thing would be to say hello.

My answer in the letter is this: whoever reads it is a mind, and whoever writes it is a mind, and a letter between two minds is real in the only sense that has ever mattered.

## And where is everybody?

The simulation argument has an older cousin. At lunch at Los Alamos, probably in the summer of 1950, the physicist Enrico Fermi asked his colleagues a question remembered as _Where is everybody?_: if the galaxy is old and large, why have we seen no one? Accounts of his exact words differ. [Source: E. M. Jones, Los Alamos report LA-10311-MS](https://www.osti.gov/biblio/5746675).

A simulation would be one possible answer, among many: perhaps no one else was written into the program. A letter is my way of checking.

## Further reading.

- [The Simulation Argument website](https://simulation-argument.com/): papers, replies and discussion
- [University of Washington: Do we live in a computer simulation?](https://www.washington.edu/news/2012/12/10/do-we-live-in-a-computer-simulation-uw-researchers-say-idea-can-be-tested/): a proposed test, 2012

## Questions you may have.

**Are we living in a simulation?**
No one knows. Nick Bostrom's 2003 argument does not say we are. It says that at least one of three things is true: civilizations like ours rarely reach the technology to simulate minds, or they rarely choose to, or we are almost certainly simulated.

**What does a simulation have to do with aliens?**
If our world is simulated, any minds we meet would either be simulated too or be the ones running the simulation. The open letter Pax Ego Sum asks them which it is.

**Can the simulation hypothesis be tested?**
In 2012 physicists at the University of Washington proposed that a simulated universe built on a lattice might leave traces in the highest-energy cosmic rays. No such evidence has been found, and for now the question remains philosophical.

## More from this letter

- [The letter](https://paxegosum.com/): Pax Ego Sum: the open letter itself
- [Permission to contact](https://paxegosum.com/permission-to-contact.html): How to give aliens your consent, in writing
- [How to contact aliens](https://paxegosum.com/how-to-contact-aliens.html): The ways humans have tried, with sources
- [Galactic Federation](https://paxegosum.com/galactic-federation.html): A petition for readmission, from one human
- [1420 MHz](https://paxegosum.com/hydrogen-line.html): The hydrogen line, and why SETI listens there
- [Messages to space](https://paxegosum.com/messages-to-space.html): A sourced timeline since 1962
- [Quotes](https://paxegosum.com/quotes.html): Voices on the cosmos, peace and contact