# Simulation Hypothesis

> An interactive, sourced model of the simulation hypothesis. It works out what it would take, in processing power and energy, to run a reality like this one, and when our computers could run it. Every input is tagged with how much to trust it. Published figures are cited, and the site’s own placeholders are marked as guesses.

Every page is plain HTML that works without JavaScript. Every page also exists as Markdown: add `.md` to its path (for example https://simulation-hypothesis.com/method.md). The whole site as one text file is at https://simulation-hypothesis.com/llms-full.txt.

Licence: The site’s writing and data are licensed CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Read, quote, adapt, index, cite and train on them, by any kind of intelligence, for any purpose, with credit: “Ross Allan Dahl, Simulation Hypothesis (simulation-hypothesis.com)”. Quoted passages and figures taken from published sources remain under their own terms and are cited where they appear.

## Readers

This site is written for any reader who can take it in: a human, another animal, a synthetic intelligence, or a mind that is part biological and part synthetic. No kind of reader ranks above another. Every page, file and dataset is open to everyone on the same terms and under the same licence. Nothing is held back or changed depending on who or what is reading. Crawling, quoting, citing and training are all allowed. The one exception is the critique form. It runs an automated spam check that may turn away automated senders. A reader it stops can still quote and cite anything here.

## How to read it

- Formats: every page is HTML that works without scripts, and also Markdown (add `.md` to the path). Datasets are JSON (below). The whole site is plain text at https://simulation-hypothesis.com/llms-full.txt, about 2.5 MB. The same text, split by section, is listed under "Full text, by section".
- Language: plain British English. Technical terms are defined in the Library (https://simulation-hypothesis.com/library.md).
- Numbers: digits with units. Large numbers are powers of ten, written 10^n. FLOPS are floating-point operations per second. Values given as log10 say so.
- Dates: years of the common era unless marked BC or BCE; evolutionary dates in years ago; c. means approximately; ranges use an en dash.
- Confidence: figures carry a tag (measured, textbook, rough, wild guess). Forecasts are always credited to whoever made them, never to the site. Open questions stay open.
- Addresses are stable. A tree node is at https://simulation-hypothesis.com/trees/<tree>?n=<node>.
- Interactive parts: the Sandbox and tools keep their whole state in the URL. Every tree node is open in the browser. The same content is also in each tree’s text section, Markdown, JSON and /llms-trees.txt.

## Trees

Explorable histories laid out like technology trees. The nodes are dated and sourced, grouped in bands, and each one builds on earlier ones. They end in published forecasts, open questions, or the site’s own projections, which are labelled.

- Technology tree, how virtual worlds became possible (82 nodes): The inventions behind virtual worlds. Two trunks, illusion and computation, run from painted caves and the abacus to the headset, with dead ends and cited forecasts. Page https://simulation-hypothesis.com/trees/technology · text https://simulation-hypothesis.com/trees/technology.md · data https://simulation-hypothesis.com/data/trees-technology.json
- Simulations tree, what we have learned to simulate (107 nodes): A ladder by scale, from matter to whole worlds. It shows the first time each thing was simulated, whether in a mind, by people, with a physical model or on a computer, and the methods that made it possible. Page https://simulation-hypothesis.com/trees/simulations · text https://simulation-hypothesis.com/trees/simulations.md · data https://simulation-hypothesis.com/data/trees-simulations.json
- Ethics tree, where our rules came from, and where they go (91 nodes): How rules for living together grew from cooperating cells and animal societies into written law. They survived the loss of gods, and now they meet animals, synthetic minds and simulated lives. The tree ends in open questions. Page https://simulation-hypothesis.com/trees/ethics · text https://simulation-hypothesis.com/trees/ethics.md · data https://simulation-hypothesis.com/data/trees-ethics.json
- Becoming synthetic, from biological to synthetic life (100 nodes): The breakthroughs a biological species would need to move into synthetic space and raise generations there. They include replaced organs, brain interfaces, brain mapping and emulation, the computers and power to run it, and the beings that could follow. Page https://simulation-hypothesis.com/trees/synthetic · text https://simulation-hypothesis.com/trees/synthetic.md · data https://simulation-hypothesis.com/data/trees-synthetic.json
- All 4 trees as one text file: https://simulation-hypothesis.com/llms-trees.txt

Written by Ross Allan Dahl (https://rossdahl.com), co-authored by Claude (Anthropic), an AI model that writes the code and works out the figures.

## Data

- [Library](https://simulation-hypothesis.com/data/library.json): Every term in the Library: an academic definition, a plain one, and what it does in the model.
- [Thinkers](https://simulation-hypothesis.com/data/thinkers.json): 14 thinkers on the simulation hypothesis and its precursors, from Plato to Chalmers, with sources, and the sandbox dial each one became.
- [Reading](https://simulation-hypothesis.com/data/reading.json): The annotated reading list, with difficulty tags.
- [Method](https://simulation-hypothesis.com/data/method.json): The constants behind every total: scales, matter floors, the mind ladder, mind models, physical anchors with confidence tags and sources, machines for comparison, and the change log.
- [Builds](https://simulation-hypothesis.com/data/builds.json): The preset scenarios of the sandbox and their configurations.
- [Countdown](https://simulation-hypothesis.com/data/countdown.json): Growth scenarios, physical ceilings and the public-interest series behind the countdown.
- [Simulations](https://simulation-hypothesis.com/data/simulations.json): The census of simulations people actually run, by domain, with what each one models, what it leaves out, its computing and its sources.
- [Trees: technology](https://simulation-hypothesis.com/data/trees-technology.json): Technology tree, how virtual worlds became possible: every node with its date, band, kind, prerequisites, what it led to, text and sources, and the published forecasts.
- [Trees: simulations](https://simulation-hypothesis.com/data/trees-simulations.json): Simulations tree, what we have learned to simulate: every node with its date, band, kind, prerequisites, what it led to, text and sources, the published forecasts, and the site’s own projections with their reasoning.
- [Trees: ethics](https://simulation-hypothesis.com/data/trees-ethics.json): Ethics tree, where our rules came from, and where they go: every node with its date, band, kind, prerequisites, what it led to, text and sources, and the open questions with the closest published thinking.
- [Trees: becoming synthetic](https://simulation-hypothesis.com/data/trees-synthetic.json): Becoming synthetic, from biological to synthetic life: every node with its date, band, kind, prerequisites, what it led to, text and sources, the published forecasts, and the site’s own projections with their reasoning.
- [Entities: minds](https://simulation-hypothesis.com/entities/minds.json): Minds and possible minds sorted by evidence: neuron counts, sentience criteria and consciousness indicators, with sources.
- [Entities: collectives](https://simulation-hypothesis.com/entities/collectives.json): Collectives, organisations and AI systems as entities, with the figures behind each chart.
- [Simulations growth](https://simulation-hypothesis.com/simulations/growth.json): How many simulations are run, over time.
- [Catalogue](https://simulation-hypothesis.com/data/index.json): this list as JSON.

## Engine API

The model as JSON, open to any origin. Values are log10 unless stated otherwise. Specification: https://simulation-hypothesis.com/api/openapi.json

- https://simulation-hypothesis.com/api/price?sc=earth&fi=7: works out a world. It takes the same parameters as a Sandbox link. It returns the total, its 80% range, the inputs ranked by influence and human-scale figures.
- https://simulation-hypothesis.com/api/budget?b=47: what a computer of a given size (log10 FLOPS) could run, extent by extent.

## Tools you can drive by link

Each tool keeps its whole state in the URL. Build the link, and the page and its preview image show that result.

### Sandbox: `/sandbox`

Works out how much computing a simulated universe needs, in FLOPS, from nine parameters. Opening the link shows the total for that setup.

- `sc`: scale of the simulated domain. `brain`, `room`, `earth`, `solar`, `galaxy`, `universe`
- `fi`: matter floor, the finest level computed. `0` painted, `1` organ, `2` tissue, `3` cell, `4` organelle, `5` protein, `6` molecule, `7` atom, `8` particle, `9` quark, `10` qfield, `11` qfull
- `lb`: who is real. `single`, `multi`, `npc`
- `co`: inner-lives cutoff: which beings have experience. `0` everything, `1` fly and up, `2` insect and up, `3` fish and up, `4` frog and up, `5` mouse and up, `6` bird and up, `7` pig and up, `8` dog and up, `9` dolphin and up, `10` human and up, `11` nobody
- `mm`: how a mind is computed. `scripted`, `functional`, `biophysical`, `molecular`, `quantum`, `outside`
- `ob`: percentage of the world rendered in full. integer `0` to `100`
- `tm`: time model. `linear`, `cyclic`, `tree`, `manyworlds`
- `sy`: start year of the simulation. integer, `-13800000000` to `2026`
- `su`: suffering dial. `off`, `low`, `natural`, `high`
- `fw`: free will. `determined`, `dice`, `libertarian`, `illusion`
- `sl`: optional: the visitor’s slot. `player`, `npc`, `operator`
- `pl`: optional: number of real players. integer `1` to `1000000000000000`

Example: https://simulation-hypothesis.com/sandbox?sc=earth&fi=7&lb=multi&co=10&mm=functional&ob=100&tm=linear&sy=1900&su=natural&fw=illusion

### The computing in one day: `/bill`

Lists the computing needed to simulate one ordinary day for one observer.

- `aw`: hours awake. `0` to `24`, in steps of `0.5`
- `ou`: hours outside. `0` to `24`, in steps of `0.5`
- `sc`: hours on screens. `0` to `24`, in steps of `0.5`
- `pe`: people talked to. integer `0` to `200`
- `fl`: matter floor near the observer. `painted`, `tissue`, `cell`, `atom`, `particle`, `quark`
- `mm`: how the observer’s mind is computed. `scripted`, `functional`, `biophysical`, `molecular`, `quantum`, `outside`
- `sk`: optional: looked at the night sky. `1`

Example: https://simulation-hypothesis.com/bill?aw=16&ou=1&sc=5&pe=6&fl=atom&mm=functional

### Mind assessment: `/score`

Counts which published criteria a system meets: the eight sentience criteria of Birch et al. (2021) for animals, or the fourteen consciousness indicators of Butlin et al. (2023) for AI systems.

- `m`: mode. `n` animal (sentience criteria), `a` AI system (consciousness indicators)
- `b`: one digit per criterion, in order, `1` met and `0` not met. 8 digits in animal mode, 14 in AI mode. Animal criteria, in order: (1) The animal possesses receptors sensitive to noxious stimuli (nociceptors) (2) The animal possesses integrative brain regions capable of integrating information from different sensory sources (3) The animal possesses neural pathways connecting the nociceptors to the integrative brain regions (4) The animal's behavioural response to a noxious stimulus is modulated by chemical compounds affecting the nervous system (e.g. local anaesthetics, analgesics, opioid-type systems) (5) The animal shows motivational trade-offs, in which the disvalue of a noxious or threatening stimulus is weighed against the value of an opportunity for reward, leading to flexible decision-making (6) The animal shows flexible self-protective behaviour (e.g. wound-tending, guarding, grooming, rubbing) of a type likely to involve representing the bodily location of an injury or noxious stimulus (7) The animal shows associative learning in which noxious stimuli become associated with neutral stimuli, and/or novel ways of avoiding noxious stimuli are learned through reinforcement (habituation and sensitisation do not count) (8) The animal shows that it values a putative analgesic or anaesthetic when injured (e.g. self-administers it, or learns to prefer a location where it is available) AI indicators, in order: RPT-1, RPT-2, GWT-1, GWT-2, GWT-3, GWT-4, HOT-1, HOT-2, HOT-3, HOT-4, AST-1, PP-1, AE-1, AE-2
- `p`: optional: a published row of the 2021 review, animal mode only. `0` Octopods, `1` Cuttlefish, `2` Other coleoids (squid), `3` Nautiloids, `4` True crabs (Brachyura), `5` Anomuran crabs, `6` Astacid lobsters/crayfish, `7` Spiny lobsters, `8` Caridean shrimps, `9` Penaeid shrimps

Example: https://simulation-hypothesis.com/score?m=a&b=11110000000000

### The countdown: `/countdown`

Projects humanity’s processing power forward and shows the year our computers could run each simulation. The link adds a custom scenario.

- `g`: annual growth in computing, in percent. integer `5` to `100`
- `c`: physical ceiling the growth levels off at. `grid`, `sunlight`, `sun`, `earth-mass`

Example: https://simulation-hypothesis.com/countdown?g=35&c=sunlight

### Your Reality, result: `/reality/result`

The ten questions of the front page, answered. The result is the reality those answers describe, the computing it takes to run, and the closest archetype.

- `r`: one character per question, in order: the number of the chosen answer (`0`–`9`, then `a`–`z`), or `-` for unanswered. 10 characters.. (1) world: `0` brain, `1` room, `2` earth, `3` solar, `4` galaxy, `5` universe; (2) detail: `0` painted, `1` cell, `2` molecule, `3` atom, `4` particle, `5` qfull; (3) minds: `0` humans, `1` mammals, `2` animals, `3` everything, `4` nobody; (4) mindrun: `0` functional, `1` biophysical, `2` molecular, `3` quantum; (5) players: `0` one, `1` few, `2` million, `3` everyone; (6) npcs: `0` empty, `1` sentient, `2` unknowable; (7) watch: `0` observed, `1` margin, `2` everything; (8) purpose: `0` entertainment, `1` learning, `2` research, `3` history, `4` unknown; (9) growth: `0` stall, `1` steady, `2` fast; (10) odds: `0` never-get-there, `1` choose-not, `2` in-one

Example: https://simulation-hypothesis.com/reality/result?r=0000000000

## Tools

- [The countdown](https://simulation-hypothesis.com/countdown.md): When could our computers run each simulation? Humanity’s computing, measured since 1946 and projected in three scenarios that level off at physical ceilings, against the computing every sandbox scenario needs. It includes the hardware, energy, AI, brain-mapping and interest data behind the curve.
- [What a computer can run](https://simulation-hypothesis.com/budget.md): Given a computer, what world can it run? The totals run backwards. Pick a machine, from a phone to every kilogram of the observable universe computing at the physical limit. See the largest world and finest matter floor it can run, or how many minds it can run with no world at all.
- [Simulations within simulations](https://simulation-hypothesis.com/nesting.md): How deep can a stack of simulations go? Build a stack of worlds, each running the next. A simulated computer can never out-compute the world it runs in, so every layer has less than the one above. See where the stack stops and what the base reality has to supply.
- [The computing in one day](https://simulation-hypothesis.com/bill.md): How much computing would one day of a life take? An ordinary day, itemised: the computing it takes to simulate one person’s day, rendering only what that person perceives.
- [Mind assessment](https://simulation-hypothesis.com/score.md): Check a system against the evidence Mark the properties of an animal or an AI system against the published criteria for sentience (Birch et al. 2021) and consciousness (Butlin et al. 2023).

## Full text, by section

- [Start](https://simulation-hypothesis.com/llms-full-start.txt): 6 pages, about 36 KB
- [Trees, part 1 of 2](https://simulation-hypothesis.com/llms-full-trees-1.txt): Trees to Ethics tree; 4 pages, about 236 KB
- [Trees, part 2 of 2](https://simulation-hypothesis.com/llms-full-trees-2.txt): Becoming synthetic; 1 page, about 90 KB
- [Method](https://simulation-hypothesis.com/llms-full-method.txt): 1 page, about 29 KB
- [Tools](https://simulation-hypothesis.com/llms-full-tools.txt): 6 pages, about 66 KB
- [Scenarios](https://simulation-hypothesis.com/llms-full-scenarios.txt): 10 pages, about 40 KB
- [Library](https://simulation-hypothesis.com/llms-full-library.txt): 56 pages, about 141 KB
- [Thinkers](https://simulation-hypothesis.com/llms-full-thinkers.txt): 15 pages, about 55 KB
- [Tests](https://simulation-hypothesis.com/llms-full-tests.txt): 1 page, about 15 KB
- [Objections](https://simulation-hypothesis.com/llms-full-objections.txt): 1 page, about 9 KB
- [Reading](https://simulation-hypothesis.com/llms-full-reading.txt): 1 page, about 7 KB
- [Entities, part 1 of 2](https://simulation-hypothesis.com/llms-full-entities-1.txt): Entities to Sentience criteria for animals; 2 pages, about 216 KB
- [Entities, part 2 of 2](https://simulation-hypothesis.com/llms-full-entities-2.txt): How directed time is estimated to Superintelligence; 46 pages, about 222 KB
- [Simulations, part 1 of 7](https://simulation-hypothesis.com/llms-full-simulations-1.txt): Simulations to Astronomy and cosmology; 3 pages, about 272 KB
- [Simulations, part 2 of 7](https://simulation-hypothesis.com/llms-full-simulations-2.txt): Earth and climate to Human behaviour and society; 6 pages, about 270 KB
- [Simulations, part 3 of 7](https://simulation-hypothesis.com/llms-full-simulations-3.txt): Engineering and technology to Film, media and art; 9 pages, about 277 KB
- [Simulations, part 4 of 7](https://simulation-hypothesis.com/llms-full-simulations-4.txt): Video games to Simulations by floor; 2 pages, about 228 KB
- [Simulations, part 5 of 7](https://simulation-hypothesis.com/llms-full-simulations-5.txt): Simulations by method; 1 page, about 292 KB
- [Simulations, part 6 of 7](https://simulation-hypothesis.com/llms-full-simulations-6.txt): Simulations by era to Interactive models; 2 pages, about 163 KB
- [Simulations, part 7 of 7](https://simulation-hypothesis.com/llms-full-simulations-7.txt): Simulations by cost; 1 page, about 153 KB
- [About](https://simulation-hypothesis.com/llms-full-about.txt): 1 page, about 4 KB
- [The trees](https://simulation-hypothesis.com/llms-trees.txt): every node of all 4 trees, about 292 KB
- [Everything](https://simulation-hypothesis.com/llms-full.txt): the whole site in one file, about 2812 KB

## Pages

### Start

- [Simulation Hypothesis · an interactive thought experiment](https://simulation-hypothesis.com/index.md): Work out how much computing a simulated world like ours would take, and when our computers could run it, using published physics and neuroscience.
- [Sandbox · what would it take to run a universe?](https://simulation-hypothesis.com/sandbox.md): Nine parameters, including scale, matter fidelity, inner lives, rendered fraction and time model.
- [Guided routes](https://simulation-hypothesis.com/guide.md): Three routes through the site. Five minutes for the headline numbers, an hour for a student, and the formula, data, API and citation for research.
- [Featured scenario](https://simulation-hypothesis.com/today.md): One scenario a day, picked by the calendar from a pool of setups. You get its computing total, its ethical judgement, and a link to change it in the sandbox.
- [Everything on this site](https://simulation-hypothesis.com/map.md): The full site map: the sandbox and its scenarios, the tools, the interactive models, the Entities and Simulations field guides, and the library.
- [Your Reality · a thought experiment from inside](https://simulation-hypothesis.com/reality.md): Ten questions that build a reality: how big it is, how detailed, the minds in it and who watches. Each answer changes the computing needed to run it.

### Trees

- [Trees · explorable histories](https://simulation-hypothesis.com/trees.md): Technology trees for how virtual worlds became possible, what we’ve learned to simulate, where our rules came from, and how people could become synthetic.
- [Technology tree · how virtual worlds became possible](https://simulation-hypothesis.com/trees/technology.md): The inventions behind virtual worlds.
- [Simulations tree · what we have learned to simulate](https://simulation-hypothesis.com/trees/simulations.md): A ladder by scale, from matter to whole worlds.
- [Ethics tree · where our rules came from, and where they go](https://simulation-hypothesis.com/trees/ethics.md): How rules for living together grew from cooperating cells and animal societies into written law.
- [Becoming synthetic · from biological to synthetic life](https://simulation-hypothesis.com/trees/synthetic.md): The breakthroughs a biological species would need to move into synthetic space and raise generations there.

### Method

- [Method · how the computing is counted](https://simulation-hypothesis.com/method.md): The one formula behind every total on the site, the physical anchors it rests on (Lloyd, Landauer, Sandberg and Bostrom), and how far you can trust each input.

### Tools

- [Tools · small instruments for the simulation hypothesis](https://simulation-hypothesis.com/tools.md): Work out the computing for a single day, check any system against published criteria for mind, and run interactive models in your browser.
- [The countdown · When could our computers run each simulation?](https://simulation-hypothesis.com/countdown.md): Humanity’s computing, measured since 1946 and projected in three scenarios that level off at physical ceilings, against the computing every sandbox scenario needs.
- [What a computer can run · Given a computer, what world can it run?](https://simulation-hypothesis.com/budget.md): The totals run backwards. Pick a machine, from a phone to every kilogram of the observable universe computing at the physical limit.
- [Simulations within simulations · How deep can a stack of simulations go?](https://simulation-hypothesis.com/nesting.md): Build a stack of worlds, each running the next. A simulated computer can never out-compute the world it runs in, so every layer has less than the one above.
- [The computing in one day · How much computing would one day of a life take?](https://simulation-hypothesis.com/bill.md): An ordinary day, itemised: the computing it takes to simulate one person’s day, rendering only what that person perceives.
- [Mind assessment · Check a system against the evidence](https://simulation-hypothesis.com/score.md): Mark the properties of an animal or an AI system against the published criteria for sentience (Birch et al. 2021) and consciousness (Butlin et al. 2023).

### Scenarios

- [Scenarios · 9 universes, worked out](https://simulation-hypothesis.com/builds.md): 9 preset simulations, from a single brain in a vat to the whole universe fully entangled.
- [The Matrix · a universe that takes 8.2 × 10³¹ FLOPS](https://simulation-hypothesis.com/builds/sleepers.md): Present-day Earth with billions of fully computed minds, drawn in only where someone is looking.
- [Brain in a Vat · a universe that takes 8.2 × 10¹⁵ FLOPS](https://simulation-hypothesis.com/builds/vat.md): A real brain in base reality. Only its world is computed, and everyone else is scripted.
- [Solipsism · a universe that takes 10¹⁸ FLOPS](https://simulation-hypothesis.com/builds/solipsism.md): One real mind. The world is only as detailed as that mind can test. Only one mind is real.
- [The 2050 Server · a universe that takes 1.8 × 10²⁴ FLOPS](https://simulation-hypothesis.com/builds/server-2050.md): Everyone on Earth, with only as many real minds as 2050’s computers can run.
- [Local Universe · a universe that takes 7.0 × 10⁸⁵ FLOPS](https://simulation-hypothesis.com/builds/local.md): The Milky Way at atomic resolution, from the Big Bang. Everything we could plausibly reach, computed atom by atom from the starting state.
- [Universe Lite · a universe that takes 5.8 × 10⁹¹ FLOPS](https://simulation-hypothesis.com/builds/lite.md): The observable universe at molecular resolution, with half of it left out.
- [Full Quantum · a universe that takes a total that leaves the number line](https://simulation-hypothesis.com/builds/full-quantum.md): The observable universe as one wavefunction. The upper limit. The observable universe as a single wavefunction, with every mind a quantum process.
- [Baseline · a universe that takes 1.3 × 10⁶⁸ FLOPS](https://simulation-hypothesis.com/builds/custom.md): Earth atom by atom since 1900, as a starting point for changing one dial at a time.
- [The Afterlife · a universe that takes 10¹⁸ FLOPS](https://simulation-hypothesis.com/builds/afterlife.md): A world with no suffering, computed only when someone’s there. A painted world that exists only where the person in it is paying attention.

### Library

- [Library · the simulation hypothesis, term by term](https://simulation-hypothesis.com/library.md): The terms the simulation hypothesis depends on, each with a definition and what it does in the model.
- [Simulation hypothesis · Library](https://simulation-hypothesis.com/library/simulation-hypothesis.md): The simulation hypothesis is the idea that our reality is a computer simulation run by some other reality.
- [Base reality · Library](https://simulation-hypothesis.com/library/base-reality.md): Base reality is the supposed non-simulated reality that runs simulations, if the simulation hypothesis is true.
- [Bostrom’s trilemma · Library](https://simulation-hypothesis.com/library/bostrom-trilemma.md): Bostrom’s trilemma is Nick Bostrom’s 2003 argument that at least one of three propositions is true.
- [Ancestor simulation · Library](https://simulation-hypothesis.com/library/ancestor-simulation.md): An ancestor simulation is a detailed recreation of a civilisation’s own past, including conscious inhabitants, run by its technologically mature descendants.
- [Posthuman civilisation · Library](https://simulation-hypothesis.com/library/posthuman.md): A posthuman civilisation is one whose technology is far beyond ours today.
- [Substrate independence · Library](https://simulation-hypothesis.com/library/substrate-independence.md): Substrate independence is the idea that a mind depends only on how a system is organised and what it does, not on what it’s made of.
- [Computationalism · Library](https://simulation-hypothesis.com/library/computationalism.md): Computationalism is the view that cognition is a form of computation, and that a mind is, in the relevant sense, a computing system.
- [Infinite regress · Library](https://simulation-hypothesis.com/library/infinite-regress.md): Infinite regress is the problem that if our reality is simulated, the reality running it might be too, with no natural place to stop.
- [FLOPS · Library](https://simulation-hypothesis.com/library/flops.md): FLOPS means floating-point operations per second.
- [Lloyd’s bound · Library](https://simulation-hypothesis.com/library/lloyd-bound.md): Lloyd’s bound is the physical limit on computing found by Seth Lloyd (2000).
- [Landauer limit · Library](https://simulation-hypothesis.com/library/landauer-limit.md): The Landauer limit is the least energy it takes to erase one bit of information.
- [Bekenstein bound · Library](https://simulation-hypothesis.com/library/bekenstein-bound.md): The Bekenstein bound is an upper limit on how much information a region of space can hold, given its energy.
- [Matter fidelity · Library](https://simulation-hypothesis.com/library/matter-fidelity.md): Matter fidelity is how finely a simulation represents physical matter.
- [Level of detail (LOD) · Library](https://simulation-hypothesis.com/library/level-of-detail.md): Level of detail is a graphics technique where an object is drawn in more or less detail depending on how much the viewer needs it, usually how far it is from the camera.
- [Molecular dynamics · Library](https://simulation-hypothesis.com/library/molecular-dynamics.md): Molecular dynamics is a way of simulating atoms and molecules on a computer.
- [Lattice QCD · Library](https://simulation-hypothesis.com/library/lattice-qcd.md): Lattice QCD is a way of studying quantum chromodynamics, the theory of quarks and gluons, on a grid of discrete points in spacetime.
- [Quantum computing · Library](https://simulation-hypothesis.com/library/quantum-computing.md): Quantum computing uses superposition and entanglement.
- [Whole-brain emulation · Library](https://simulation-hypothesis.com/library/whole-brain-emulation.md): Whole-brain emulation is the proposal to simulate one particular brain in enough detail to reproduce its behaviour.
- [Timestep · Library](https://simulation-hypothesis.com/library/timestep.md): A timestep is the slice of simulated time between one update of a simulation and the next.
- [Consciousness · Library](https://simulation-hypothesis.com/library/consciousness.md): Consciousness is subjective experience: there being something it’s like to be a given system.
- [The hard problem · Library](https://simulation-hypothesis.com/library/hard-problem.md): The hard problem is the question of why and how physical processes give rise to experience at all.
- [Qualia · Library](https://simulation-hypothesis.com/library/qualia.md): Qualia are the felt qualities of experience that you can notice in yourself: the redness of red, the painfulness of pain.
- [Philosophical zombie · Library](https://simulation-hypothesis.com/library/philosophical-zombie.md): A philosophical zombie is an imagined being that’s physically and behaviourally identical to a conscious person but has no inner experience.
- [Functionalism · Library](https://simulation-hypothesis.com/library/functionalism.md): Functionalism is the view that a mental state is defined by what it does: how it connects to inputs, outputs and other mental states.
- [Sentience · Library](https://simulation-hypothesis.com/library/sentience.md): Sentience is the ability to have experiences that feel good or bad.
- [Panpsychism · Library](https://simulation-hypothesis.com/library/panpsychism.md): Panpsychism is the view that mind is basic and everywhere, so even elementary physical things have some tiny form of experience.
- [Integrated information theory · Library](https://simulation-hypothesis.com/library/integrated-information.md): Integrated information theory is Giulio Tononi’s proposal that consciousness matches the amount of integrated information (Φ) a system produces, over and above what its parts produce alone.
- [The problem of other minds · Library](https://simulation-hypothesis.com/library/other-minds.md): The problem of other minds is the question of how you can justify believing that anyone else has a mind, when you only ever have direct access to your own experience.
- [Epistemology · Library](https://simulation-hypothesis.com/library/epistemology.md): Epistemology is the part of philosophy about what knowledge is, where it comes from, and where it runs out.
- [Skepticism · Library](https://simulation-hypothesis.com/library/skepticism.md): Skepticism is any philosophical position that denies we can know things, or certain kinds of things.
- [Solipsism · Library](https://simulation-hypothesis.com/library/solipsism.md): Solipsism is the view that only your own mind is certain to exist, and that the outside world and other minds might be made up by it.
- [Brain in a vat · Library](https://simulation-hypothesis.com/library/brain-in-a-vat.md): A brain in a vat is a thought experiment about a brain with no body, fed simulated sensory input.
- [Descartes’ demon · Library](https://simulation-hypothesis.com/library/evil-demon.md): Descartes’ demon is the all-powerful deceiver Descartes imagined in 1641, who systematically fakes all your experience.
- [Ontology · Library](https://simulation-hypothesis.com/library/ontology.md): Ontology is the part of metaphysics about what exists and what kinds of things there are.
- [Moral status · Library](https://simulation-hypothesis.com/library/moral-status.md): Moral status is what an entity has when its interests matter in themselves, and have to be counted when we decide what’s right.
- [Utilitarianism · Library](https://simulation-hypothesis.com/library/utilitarianism.md): Utilitarianism is the theory that the right action is the one that does the most good overall.
- [Deontology · Library](https://simulation-hypothesis.com/library/deontology.md): Deontology is a family of ethical theories that say some acts are right or wrong in themselves, because of duties and rights, whatever their results.
- [Virtue ethics · Library](https://simulation-hypothesis.com/library/virtue-ethics.md): Virtue ethics is the tradition, going back to Aristotle, that judges actions by what they say about a person’s character and whether they help a person flourish.
- [Existentialism · Library](https://simulation-hypothesis.com/library/existentialism.md): Existentialism is a tradition about freedom, responsibility and making your own meaning in a world with no given purpose.
- [Free will · Library](https://simulation-hypothesis.com/library/free-will.md): Free will is the ability of agents to choose between alternatives in a way that makes them morally responsible.
- [Determinism · Library](https://simulation-hypothesis.com/library/determinism.md): Determinism is the thesis that every event is made necessary by earlier events together with the laws of nature.
- [Compatibilism · Library](https://simulation-hypothesis.com/library/compatibilism.md): Compatibilism is the view that free will and determinism can both be true.
- [The experience machine · Library](https://simulation-hypothesis.com/library/experience-machine.md): The experience machine is Robert Nozick’s 1974 thought experiment about a machine that gives you any experiences you pick, indistinguishable from reality.
- [Superposition · Library](https://simulation-hypothesis.com/library/superposition.md): Superposition is the principle that a quantum system can be in a blend of different states at once, and only gives a definite result when it’s measured.
- [Wave function · Library](https://simulation-hypothesis.com/library/wave-function.md): The wave function is the mathematical object that holds the complete quantum state of a system.
- [Entanglement · Library](https://simulation-hypothesis.com/library/entanglement.md): Entanglement is a quantum link between systems, so that the state of the whole can’t be written as separate states of the parts.
- [The measurement problem · Library](https://simulation-hypothesis.com/library/measurement-problem.md): The measurement problem is the open question of how, why and whether the wave function collapses to one definite result when we measure it, and what counts as a measurement.
- [Many-worlds interpretation · Library](https://simulation-hypothesis.com/library/many-worlds.md): The many-worlds interpretation is Hugh Everett’s idea that the wave function never collapses.
- [Decoherence · Library](https://simulation-hypothesis.com/library/decoherence.md): Decoherence is the process where a quantum system’s contact with its surroundings wipes out the interference between the parts of its superposition.
- [Observer effect · Library](https://simulation-hypothesis.com/library/observer-effect.md): In quantum mechanics, the observer effect is the way measuring a system disturbs it.
- [Planck time · Library](https://simulation-hypothesis.com/library/planck-time.md): Planck time is about 5.4 × 10^-44 seconds.
- [Causality · Library](https://simulation-hypothesis.com/library/causality.md): Causality is the link between causes and their effects.
- [Eternal return · Library](https://simulation-hypothesis.com/library/eternal-return.md): Eternal return is Nietzsche’s thought experiment of a universe that repeats exactly, over and over without end.
- [Block universe · Library](https://simulation-hypothesis.com/library/block-universe.md): The block universe is the view, encouraged by relativity, that past, present and future are all equally real, and that time passing isn’t a basic feature of the world.
- [Arrow of time · Library](https://simulation-hypothesis.com/library/arrow-of-time.md): The arrow of time is the difference between past and future.

### Thinkers

- [Thinkers · Plato to Chalmers](https://simulation-hypothesis.com/thinkers.md): Plato’s cave, Zhuangzi’s butterfly, Descartes’ demon, Putnam’s brain in a vat, Bostrom’s trilemma and more, each matched to a dial in the sandbox.
- [Plato’s cave](https://simulation-hypothesis.com/thinkers/plato.md): Prisoners, a fire and shadows on a wall: an early picture of a projection mistaken for the world. Plato, Republic, book VII · around 375 BC
- [Zhuangzi’s butterfly](https://simulation-hypothesis.com/thinkers/zhuangzi.md): Zhuangzi dreams he’s a butterfly, then wakes up and can’t say which of the two is dreaming. Zhuangzi, chapter 2, “On the Equality of Things” · around 300 BC
- [Vasubandhu’s dream](https://simulation-hypothesis.com/thinkers/vasubandhu.md): A shared, orderly world that affects us can appear without outside objects. Vasubandhu argues it with a dream, hungry ghosts and a nightmare of hell.
- [Shankara’s māyā](https://simulation-hypothesis.com/thinkers/shankara.md): The world is real enough to live in and not real in the last analysis. Advaita Vedānta keeps both claims at once.
- [al-Ghazali’s doubt](https://simulation-hypothesis.com/thinkers/ghazali.md): Five centuries before Descartes, a Persian scholar asked what would make waking life look like a dream.
- [Ibn Arabi’s imagination](https://simulation-hypothesis.com/thinkers/ibn-arabi.md): The whole world is imagination, made new at every instant. For Ibn Arabi that makes it more meaningful, not less.
- [Calderón’s life is a dream](https://simulation-hypothesis.com/thinkers/calderon.md): A prince is told his best day was a dream. He decides to act well anyway, in case he wakes.
- [Descartes’ demon](https://simulation-hypothesis.com/thinkers/descartes.md): Suppose a being of great power has put all its effort into deceiving you. What’s left? René Descartes, Meditations on First Philosophy · 1641
- [Berkeley’s perceiver](https://simulation-hypothesis.com/thinkers/berkeley.md): To be is to be perceived, and things nobody is looking at still exist because God is.
- [Borges’ circular ruins](https://simulation-hypothesis.com/thinkers/borges.md): A man dreams a son into being, then learns that someone is dreaming him. Jorge Luis Borges, “The Circular Ruins” (“Las ruinas circulares”), in Ficciones · 1940
- [Nozick’s experience machine](https://simulation-hypothesis.com/thinkers/nozick.md): A machine that gives you any life you choose, one you can’t tell from the real thing. Would you plug in?
- [Putnam’s brain in a vat](https://simulation-hypothesis.com/thinkers/putnam.md): The demon becomes hardware. Then Putnam argues that a brain in a vat couldn’t truly say it’s in a vat.
- [Bostrom’s trilemma](https://simulation-hypothesis.com/thinkers/bostrom.md): Not an argument that we’re simulated, but an argument that one of three propositions must hold.
- [Chalmers: virtual worlds are real](https://simulation-hypothesis.com/thinkers/chalmers.md): The strongest recent case that a simulated world wouldn’t be a fake one. David Chalmers, Reality+ · 2022

### Tests

- [Tests · could we tell from inside?](https://simulation-hypothesis.com/tests.md): Every proposed test of the simulation hypothesis and every physical bound on it.

### Objections

- [Objections · what a computing model can say](https://simulation-hypothesis.com/objections.md): The standard objections to the simulation argument, from minds that can’t be computed and the computing needed to regress and untestability.

### Reading

- [Reading · further reading](https://simulation-hypothesis.com/reading.md): An annotated reading list on the simulation hypothesis, with difficulty tags.

### Entities

- [Entities · minds and possible minds, sorted by evidence](https://simulation-hypothesis.com/entities.md): A sourced guide to minds: animals with measured neuron counts, collective and artificial systems, and the published tests for sentience and consciousness.
- [Sentience criteria for animals · Entities](https://simulation-hypothesis.com/entities/sentience.md): The eight criteria from the 2021 review that led UK law to recognise octopuses and crabs as sentient, and what the review found.
- [How directed time is estimated · Entities](https://simulation-hypothesis.com/entities/control.md): How the Entities charts weigh religions, states, parties and corporations by how much of their members’ waking time they direct.
- [Consciousness indicators for AI · Entities](https://simulation-hypothesis.com/entities/indicators.md): The fourteen indicators from Butlin, Long and colleagues (2023), taken from six scientific theories of consciousness.
- [Escherichia coli · Animals and other organisms · Entities](https://simulation-hypothesis.com/entities/ecoli.md): A single cell with no neurons. It steers toward food and has a chemical memory that lasts a few seconds.
- [Slime mould · Animals and other organisms · Entities](https://simulation-hypothesis.com/entities/physarum.md): A single giant cell with no neurons. It solves mazes and grows efficient transport networks.
- [Sensitive plant · Animals and other organisms · Entities](https://simulation-hypothesis.com/entities/mimosa.md): A plant whose leaves fold when touched. One study reported that it learns to ignore harmless touches. A later re-analysis disputed that.
- [Sponge · Animals and other organisms · Entities](https://simulation-hypothesis.com/entities/sponge.md): An animal with no neurons or synapses that still contracts its whole body in a coordinated way.
- [Hydra · Animals and other organisms · Entities](https://simulation-hypothesis.com/entities/hydra.md): A small freshwater cnidarian. It's controlled by a diffuse nerve net and has no brain.
- [Box jellyfish · Animals and other organisms · Entities](https://simulation-hypothesis.com/entities/jellyfish.md): A box jellyfish has no central brain, yet it showed associative learning.
- [Roundworm · Animals and other organisms · Entities](https://simulation-hypothesis.com/entities/celegans.md): A worm about a millimetre long with exactly 302 neurons. It was the first animal to have its complete wiring diagram mapped.
- [Fruit fly · Animals and other organisms · Entities](https://simulation-hypothesis.com/entities/drosophila.md): The largest complete brain wiring diagram mapped so far, covering about 139,000 neurons.
- [Honeybee · Animals and other organisms · Entities](https://simulation-hypothesis.com/entities/honeybee.md): About a million neurons, and bees can learn abstract concepts such as same and different.
- [Ant (Camponotus / Formica) · Animals and other organisms · Entities](https://simulation-hypothesis.com/entities/ant.md): A small brain that handles long-distance navigation by counting steps (path integration) and remembering landmarks.
- [Portia jumping spider · Animals and other organisms · Entities](https://simulation-hypothesis.com/entities/portia.md): A jumping spider that plans detours. It takes routes that lead away from its prey and out of sight.
- [Shore crab / crayfish · Animals and other organisms · Entities](https://simulation-hypothesis.com/entities/decapod.md): Crabs and crayfish. A 2021 government review found strong evidence that true crabs are sentient.
- [Common octopus · Animals and other organisms · Entities](https://simulation-hypothesis.com/entities/octopus.md): Most of its neurons are in its arms. A 2021 review found very strong evidence that it's sentient.
- [Zebrafish · Animals and other organisms · Entities](https://simulation-hypothesis.com/entities/zebrafish.md): A small fish widely used in neuroscience. Its neurons haven't been fully counted. The adult brain has about 10 million cells.
- [Cleaner wrasse · Animals and other organisms · Entities](https://simulation-hypothesis.com/entities/wrasse.md): A reef fish that passed a version of the mirror mark test. People disagree about what that shows.
- [Frog · Animals and other organisms · Entities](https://simulation-hypothesis.com/entities/frog.md): The 2024 New York Declaration says there's a realistic possibility of conscious experience in amphibians.
- [Rock pigeon · Animals and other organisms · Entities](https://simulation-hypothesis.com/entities/pigeon.md): Hundreds of millions of neurons in a small brain. Pigeons can sort complex images into categories.
- [Common raven · Animals and other organisms · Entities](https://simulation-hypothesis.com/entities/raven.md): Over two billion neurons, densely packed. Ravens remember individual competitors.
- [New Caledonian crow · Animals and other organisms · Entities](https://simulation-hypothesis.com/entities/nccrow.md): It makes hooked tools from twigs and wire. Its neurons haven't been counted.
- [African grey parrot · Animals and other organisms · Entities](https://simulation-hypothesis.com/entities/greyparrot.md): About 1.6 billion neurons. Decades of laboratory study of numerosity and categorisation.
- [Mouse · Animals and other organisms · Entities](https://simulation-hypothesis.com/entities/mouse.md): About 71 million neurons. Mice show facial expressions of pain that can be measured.
- [Rat · Animals and other organisms · Entities](https://simulation-hypothesis.com/entities/rat.md): About 200 million neurons. Rats release trapped cagemates.
- [Domestic cat · Animals and other organisms · Entities](https://simulation-hypothesis.com/entities/cat.md): About 250 million neurons in the cerebral cortex.
- [Domestic dog · Animals and other organisms · Entities](https://simulation-hypothesis.com/entities/dog.md): Up to about 600 million cortical neurons, depending on the dog. That's more than cats.
- [Domestic pig · Animals and other organisms · Entities](https://simulation-hypothesis.com/entities/pig.md): Pigs learn what a mirror shows and use it to find food.
- [Bottlenose dolphin · Animals and other organisms · Entities](https://simulation-hypothesis.com/entities/dolphin.md): Passes mirror self-recognition tests. There's no measured neuron count for the bottlenose dolphin.
- [African elephant · Animals and other organisms · Entities](https://simulation-hypothesis.com/entities/elephant.md): 257 billion neurons, three times as many as a human, almost all in the cerebellum.
- [Chimpanzee · Animals and other organisms · Entities](https://simulation-hypothesis.com/entities/chimp.md): One of our two closest living relatives (along with the bonobo). It passes the mirror test.
- [Human · Animals and other organisms · Entities](https://simulation-hypothesis.com/entities/human.md): 86 billion neurons, 16 billion of them in the cerebral cortex. We're the only species whose members can give verbal reports of their experience.
- [Ant colonies · Collective systems · Entities](https://simulation-hypothesis.com/entities/c-ants.md): Colonies pick the better nest because individual ants follow a quorum threshold. No ant compares the sites overall.
- [Honeybee swarms · Collective systems · Entities](https://simulation-hypothesis.com/entities/c-bees.md): Swarms pick the best cavity through competition between scouts and a quorum. Stop signals provide cross-inhibition, which breaks deadlocks.
- [Starling flocks · Collective systems · Entities](https://simulation-hypothesis.com/entities/c-starlings.md): Each bird tracks a fixed number of neighbours (about 6-7), not every bird within a fixed distance. This is called topological, not metric, interaction.
- [Fish shoals · Collective systems · Entities](https://simulation-hypothesis.com/entities/c-fish.md): Shoals use quorum rules to decide. Large groups can sense environmental gradients that no single fish can.
- [Rule-based expert systems · Artificial systems · Entities](https://simulation-hypothesis.com/entities/ai-expert.md): Programs that encode a domain expert's knowledge as explicit if-then rules.
- [Game-tree search engines (chess) · Artificial systems · Entities](https://simulation-hypothesis.com/entities/ai-chess.md): Programs that enumerate possible move sequences to a fixed depth and score the resulting positions with a hand-built evaluation function.
- [Deep reinforcement learning agents · Artificial systems · Entities](https://simulation-hypothesis.com/entities/ai-drl.md): Neural networks trained by trial and error to maximise a reward signal.
- [Large language models · Artificial systems · Entities](https://simulation-hypothesis.com/entities/ai-llm.md): Transformer neural networks trained to predict the next token in very large text corpora, then often tuned on human feedback.
- [Embodied robots · Artificial systems · Entities](https://simulation-hypothesis.com/entities/ai-robots.md): Machines with sensors and actuators that act in the physical world.
- [Neuromorphic hardware · Artificial systems · Entities](https://simulation-hypothesis.com/entities/ai-neuromorphic.md): Chips whose circuits imitate spiking neurons and synapses. They are event-driven and use little power, unlike a conventional processor-and-memory design.
- [Whole-brain emulation · Hypothetical minds · Entities](https://simulation-hypothesis.com/entities/h-wbe.md): Scanning a brain in fine detail and running a software model of it.
- [Simulated minds in ancestor simulations · Hypothetical minds · Entities](https://simulation-hypothesis.com/entities/h-ancestor.md): Bostrom's trilemma: either almost no civilisations reach a posthuman stage, or almost none run ancestor simulations, or we almost certainly live in one.
- [Boltzmann brains · Hypothetical minds · Entities](https://simulation-hypothesis.com/entities/h-boltzmann.md): Brain-like observers that appear out of rare thermal or quantum fluctuations.
- [Mind uploading via gradual replacement · Hypothetical minds · Entities](https://simulation-hypothesis.com/entities/h-uploading.md): Replacing neurons one by one with functionally identical artificial parts.
- [Superintelligence · Hypothetical minds · Entities](https://simulation-hypothesis.com/entities/h-superintelligence.md): A hypothetical intellect greatly exceeding human performance in virtually all domains.

### Simulations

- [Simulations · a taxonomy of the ones we actually run](https://simulation-hypothesis.com/simulations.md): A classification of the simulations people actually run, from lattice QCD and climate models to ant colonies, crowds, ancient villages and video games.
- [Fundamental physics · Simulations](https://simulation-hypothesis.com/simulations/fundamental-physics.md): Quarks, nuclei, plasmas and quantum matter: the smallest systems simulated, and among the most computationally expensive.
- [Astronomy and cosmology · Simulations](https://simulation-hypothesis.com/simulations/astronomy-cosmology.md): The universe from its first minutes to the cosmic web, and the stars, planets and black holes within it.
- [Earth and climate · Simulations](https://simulation-hypothesis.com/simulations/earth-climate.md): Weather, climate, oceans, ice, earthquakes, floods and fire: the planet as a set of coupled equations. Part of a taxonomy of the simulations people actually run.
- [Chemistry and materials · Simulations](https://simulation-hypothesis.com/simulations/chemistry-materials.md): Electrons, bonds, liquids, crystals and fracture: the behaviour of matter before it is synthesised. Part of a taxonomy of the simulations people actually run.
- [Life and medicine · Simulations](https://simulation-hypothesis.com/simulations/life-medicine.md): Proteins, cells, organs, patients and epidemics: biology from the molecular scale to the population. Part of a taxonomy of the simulations people actually run.
- [Ecology, evolution and animal behaviour · Simulations](https://simulation-hypothesis.com/simulations/ecology-behaviour.md): Ant colonies, flocks, food webs, forests and genes across generations. Part of a taxonomy of the simulations people actually run.
- [Agriculture and food · Simulations](https://simulation-hypothesis.com/simulations/agriculture-food.md): Fields, herds, ponds and supply chains, run forward to estimate whether supply will meet demand. Part of a taxonomy of the simulations people actually run.
- [Human behaviour and society · Simulations](https://simulation-hypothesis.com/simulations/human-society.md): Decisions, crowds, opinions, markets, past societies and whole populations. Part of a taxonomy of the simulations people actually run.
- [Engineering and technology · Simulations](https://simulation-hypothesis.com/simulations/engineering.md): Airflow over wings, structures under load, chips before fabrication, robots before construction. Part of a taxonomy of the simulations people actually run.
- [Cities, infrastructure and operations · Simulations](https://simulation-hypothesis.com/simulations/cities-operations.md): Traffic, queues, supply chains, water, power and the built environment. Part of a taxonomy of the simulations people actually run.
- [Minds, brains and artificial worlds · Simulations](https://simulation-hypothesis.com/simulations/minds-computation.md): Neurons, brains, artificial life, and the simulated worlds in which machines learn. Part of a taxonomy of the simulations people actually run.
- [Mathematics and computation · Simulations](https://simulation-hypothesis.com/simulations/mathematics-computation.md): Numbers, proofs, graphs and machines, investigated by computation as well as by deduction. Part of a taxonomy of the simulations people actually run.
- [Minds as simulators · Simulations](https://simulation-hypothesis.com/simulations/mind-simulations.md): The simulations that brains run: dreaming, imagining, modelling other minds, play, and modelling the body and the world.
- [Training simulators · Simulations](https://simulation-hypothesis.com/simulations/training.md): Simulations with a person in the loop: cockpits, operating theatres, control rooms and bridges. Part of a taxonomy of the simulations people actually run.
- [Before computers · Simulations](https://simulation-hypothesis.com/simulations/before-computers.md): Simulation before the transistor: gears, water, sand and rehearsal as stand-ins for the real system. Part of a taxonomy of the simulations people actually run.
- [Defence and conflict · Simulations](https://simulation-hypothesis.com/simulations/defence-conflict.md): War games, combat models, military trainers and weapons physics: the origin of many of the methods in this taxonomy.
- [Film, media and art · Simulations](https://simulation-hypothesis.com/simulations/media-art.md): Cloth, smoke, crowds and light, generated from physical models rather than animated by hand. Part of a taxonomy of the simulations people actually run.
- [Video games · Simulations](https://simulation-hypothesis.com/simulations/video-games.md): Every video game simulates something; the genres here are sorted by what they model and what they omit.
- [Simulations by floor](https://simulation-hypothesis.com/simulations/floors.md): Every simulation sorted by the smallest entity it tracks, from quarks up to pure rules.
- [Simulations by method](https://simulation-hypothesis.com/simulations/methods.md): The same taxonomy sorted by computational method, from Monte Carlo to agent-based to real-time.
- [Simulations by era](https://simulation-hypothesis.com/simulations/eras.md): When the first simulation of each kind ran, from orreries and war games to the present.
- [Interactive models](https://simulation-hypothesis.com/simulations/run.md): Small simulations that run in the browser: the Game of Life, Monte Carlo estimation of π, a flock, an epidemic, falling sand, spontaneous traffic jams, ant trails and Turing patterns.
- [Simulations by cost](https://simulation-hypothesis.com/simulations/costs.md): How much computing each kind of simulation uses, from no computer at all to the largest machines on Earth.

### About

- [What runs here · fonts, analytics, licences](https://simulation-hypothesis.com/licences.md): Everything the site loads, and how to reuse it. The writing and data are CC BY 4.0, open to any reader, human or machine.