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What is a simulation?

Every factual claim in the film, in the order you hear it, with links to where it comes from.

Claims
75
Sources
88
Runtime
13:12
Checked
4 October 2026

How to read this page

  • High A primary source, or two good sources that agree.
  • Medium One good source, or a careful summary of several. The film’s wording is hedged to match.
  • Low Thin or contested. We say so on screen, or the line is cut.

A few sources are books or papers without a stable link; they are listed by author and title. Spotted something wrong? Tell us in the comments under the film and we’ll check it.

Start here

  1. Bostrom (2003), the simulation argument paper — Philosophical Quarterly 53(211), 243–255 (PDF)

    The original three-way argument and its numbers, in his own words.

  2. Chalmers, Reality+ (2022) — excerpt (PDF), consc.net

    Why a simulated world can still be fully real.

  3. Kipping (2020), A Bayesian Approach to the Simulation Argument — arXiv:2008.12254

    The fifty-fifty calculation and the flip when we build conscious simulations.

  4. Vazza (2025), Astrophysical constraints on the simulation hypothesis for this Universe: why it is (nearly) impossible that we live in a simulation — arXiv:2504.08461

    The energy-cost objection to brute-force simulation of reality.

  5. Stanford Encyclopedia of Philosophy — Computer Simulations in Science

    A careful definition of what counts as a computer simulation.

  6. Google (Aug 2024), GameNGen — arXiv:2408.14837

    A neural network that generates DOOM frame by frame.

  7. FlyWire adult fruit fly brain connectome — Nature papers, 2 Oct 2024 (PMC)

    The complete fruit fly brain wiring map.

  8. Shiu et al. (2024), A Drosophila computational brain model reveals sensorimotor processing — Nature (PMC)

    The brain simulation built from that map, with its test results.

  9. Eon Systems (10 Mar 2026) — How the Eon Team Produced a Virtual Embodied Fly

    Eon's own account of the embodied fly, including its caveats.

  10. The Transmitter — 'Digital sphinx' raises questions about connectome models

    Scientists' critique of the claim that a fly was uploaded.

0:00Cold open

  1. A simulated fruit fly, shown by Eon Systems in March 2026, grooms its antennae, finds food and feeds, all inside a computer.

    HighThese are the behaviors Eon demonstrated: antennal grooming, foraging and feeding.

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  2. The fly's 'brain' is a model wired like a real fly's brain, about 140,000 neurons running as math. Its body, floor, food and light are simulated too.

    HighThe wiring was copied from a real fly, not the brain itself; about 140,000 is the company's own rounding.

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0:46What a simulation is

  1. A simulation is a model of something, run forward in time. A model can exist on paper; a simulation has to actually be run.

    High

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  2. Every simulation needs a state (a snapshot of what matters now), rules for how it changes, and a clock. Each tick applies the rules to produce a new state.

    MediumA teaching frame built from standard definitions of simulation, not a quotation from one source.

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  3. Simulations leave things out on purpose, and how much detail they keep is called fidelity.

    MediumThe idea of leaving detail out (abstraction) is standard in simulation; the framing here is the video's own.

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1:43The Game of Life

  1. Mathematician John Conway invented the Game of Life in 1970; it reached the public through Martin Gardner's Scientific American column that October.

    High

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  2. In the Game of Life, cells die from loneliness (under two neighbors) or crowding (over three), survive with two or three, and an empty cell with exactly three neighbors is born.

    HighThese are the four rules as usually stated; they are sometimes compressed into three.

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  3. A glider is a small pattern of five cells that walks diagonally across the grid forever.

    HighForever holds on an unbounded grid.

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  4. Gosper's glider gun, found in 1970, fires a new glider every 30 generations.

    High

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  5. People have built working computers inside the Game of Life; it can compute anything computable.

    High

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  6. The Game of Life has been built inside itself: a 2048 by 2048 block of cells (about four million) behaves like one single cell.

    HighThis is the OTCA metapixel, built by Brice Due in 2005–06.

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2:40A short history of fake worlds

  1. More than 2,000 years ago, Greek engineers built a bronze gear machine, the Antikythera mechanism, that tracked the motions of the sun and moon.

    HighIt predicted sun and moon positions and eclipse cycles; it is dated to roughly 205–87 BC.

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  2. Ed Link built his flight trainer in 1929 using organ-making parts, and more than 500,000 American pilots trained on Link simulators by the end of World War II.

    HighBuilt with pumps, valves and bellows from his family's piano and organ business.

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  3. In 1950 ENIAC re-forecast a day of weather from 1949 data, and the 24-hour forecast took about 24 hours to compute, barely keeping pace with the weather.

    HighThese were retrospective forecasts from real 1949 data, and the 24 hours includes handling punch cards by hand.

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3:14Simulations run the world

  1. Europe's weather center, ECMWF, receives about 800 million observations a day.

    HighThat is what it receives; about 60 million are quality-checked for use in the forecast model.

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  2. ECMWF's global forecasts have simulated the atmosphere on a grid of boxes about 9 kilometers wide since June 2023.

    High

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  3. The last US nuclear test was in September 1992; since then the nuclear stockpile has been checked with experiments and advanced simulation.

    HighSimulation works alongside non-explosive experiments and inspections, not alone. Test counts differ by source.

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  4. Supercomputers such as El Capitan, which serves US stockpile work, perform nearly two quintillion calculations a second.

    HighEl Capitan measured 1.809 exaflops on the June 2026 TOP500 list; it is no longer the world's fastest machine.

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  5. Astronomers simulated the universe with about 10 billion particles in 2005 (Millennium Simulation) and about 4 trillion in 2025 (Frontier-E).

    HighThe 2025 figure comes from a paper posted to arXiv on 3 October 2025.

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  6. Factories now have digital twins: BMW runs digital twins of its factories.

    MediumBased on NVIDIA and trade-press reports.

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  7. Cities have digital twins too: Virtual Singapore is a detailed 3D city model used for planning.

    Medium

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  8. The Living Heart Project built a lifelike 3D virtual copy of the human heart, used with the FDA to explore virtual testing of treatments.

    HighIt is a generic virtual heart, not one patient's.

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  9. The European Union is building digital twins of the Earth system through its Destination Earth program, launched in June 2024.

    HighStill under construction; the first twins focus on climate adaptation and weather extremes.

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4:08Games, VR and the art of cheating

  1. A game repeats one loop every frame: read the controller, update the world, draw it. At 60 frames a second that leaves about 16.7 milliseconds per frame.

    High

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  2. Games save work by skipping what you can't see and using less detail far from the camera.

    MediumOut-of-view objects are skipped in drawing only; the game still tracks them. No percentage is claimed.

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  3. No Man's Sky has about 18 quintillion planets, none built by hand; each is generated from a seed number when you visit.

    High18,446,744,073,709,551,616 is 2 to the 64th power. The game still stores player changes, such as bases and discoveries.

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  4. VR feels convincing when the world responds to your head movement in under about 20 milliseconds.

    HighThe key measure is motion-to-photon delay, not screen refresh rate alone.

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5:00Where machines learn

  1. In 2021 an ETH Zurich and NVIDIA team trained a four-legged robot to walk on flat ground in under four minutes, using thousands of simulated robots at once.

    HighUnder four minutes is training time on flat ground, on a single workstation graphics card.

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  2. OpenAI's robot hand practiced the Rubik's cube for about 13,000 years' worth of experience, all in simulation.

    HighOn the real hand it solved about 60% of typical scrambles, so it practiced a lot but was far from perfect.

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  3. Simulations are never exactly right, so a robot trained in one perfect fake world can stumble in the real one. This is called the sim-to-real gap.

    High

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  4. Domain randomization trains robots across many deliberately varied simulated worlds, with different gravity, colors and object sizes, so reality is just one more variation.

    HighOpenAI's version kept widening the randomized size, mass, friction and gravity as the robot improved.

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  5. Waymo's self-driving cars have driven over 200 million miles with no one at the wheel, plus billions of miles in simulation.

    HighWaymo's safety page showed about 220 million driverless miles through March 2026; it gives virtual miles only as 'billions'.

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6:09Machines that dream worlds

  1. Traditional simulators run on rules people wrote down. A newer kind of AI, a world model, instead learns from huge amounts of video to guess what happens next.

    HighFor example, NVIDIA's Cosmos world models were trained on 20 million hours of video.

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  2. In 2024 Google researchers showed a neural network that generates DOOM frame by frame at 20 frames a second, responding to the player's button presses, with no game engine running.

    HighThe network predicts each next frame from earlier frames and the player's inputs; a human plays it.

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  3. Google DeepMind's Genie 3 lets you type a sentence and move around the world it generates, and you can change it with text, such as making it rain.

    HighAccess is limited: a research preview, later opened to paying subscribers with 60-second worlds.

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  4. A physics engine is a rulebook someone wrote; a world model is a habit learned by watching. That makes world models flexible but prone to drift, forgetting and broken physics.

    HighAn explanatory framing built from the cited systems, not a quote from one source.

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  5. World models are still glitchy: in one test, simulated cars drove through each other, and Genie 3's visual memory reaches back only about a minute.

    HighThe car glitch was seen in Decart's Oasis 3; the one-minute memory limit is Genie 3's.

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  6. Waymo uses a world model, built on Genie 3, to simulate rare events such as tornadoes and elephants for its cars to practice on.

    High

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7:11A brain made of numbers

  1. In 2024 scientists published a complete wiring diagram of an adult fruit fly's brain (FlyWire).

    High

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  2. To make the map, one fly brain was sliced into about 7,000 sections for electron-microscope imaging.

    MediumRoughly 7,000 sections about 40 nanometres thick; 'a thousand times thinner than a hair' is a deliberately conservative comparison.

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  3. AI traced every neuron in the images, and people then spent about 33 combined years fixing its mistakes.

    HighAround 33 person-years of manual proofreading, spread over roughly five calendar years.

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  4. The fly brain map contains about 139,000 neurons and about 54 million connections (synapses).

    HighExact counts: 139,255 neurons and about 54.5 million synapses.

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  5. A research team turned that wiring map into a simulation, treating each neuron as a simple equation and each connection as a wire.

    HighSimple 'leaky integrate-and-fire' neurons, built from wiring and neurotransmitter type, with one adjustable parameter.

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  6. In the simulation, a virtual taste of sugar sends a signal through the model to the neurons that extend the fly's mouth toward food, as in a real fly.

    High

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  7. Across 164 testable predictions, the brain model was consistent with real fly experiments 91% of the time.

    HighExcluding one large screening dataset, the figure is 84%.

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  8. Other teams built simulated fly bodies; one, flybody from DeepMind and Janelia, has controllers trained to walk and fly by imitating real flies.

    HighThat body's controller is an ordinary trained neural network, not the fly's brain.

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  9. In March 2026, the startup Eon Systems connected the simulated fly brain to a simulated fly body, which groomed, fed and walked.

    HighBased on Eon's own posts (7–10 March 2026); no peer-reviewed paper was found as of October 2026.

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  10. Eon called its result an upload ('We've Uploaded a Fruit Fly'), and many scientists pushed back, saying it was a connected model, not an upload.

    High

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  11. The Eon model can't learn and has no hunger or other internal states, and its connection strengths are estimates based on synapse counts, not measurements.

    HighThese limits are Eon's own stated caveats, plus the FlyWire paper's note that synaptic strength was not measured.

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  12. Critics note that the simulated body's built-in controllers do much of the walking, so the brain model's role is easy to overstate.

    HighOne preprint showed a worm's wiring driving the fly body could also learn to walk.

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  13. Philip Shiu, who created the brain model, said it is "not a full blown copy of a fly."

    HighShiu is now head of engineering at Eon Systems.

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  14. Researchers are training neural networks wired like a fly's brain to control a simulated fly body so it walks.

    HighIn this work (FlyGM) the connection strengths are learned, not measured; the fly wiring serves as the network's shape.

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  15. Eon has said its next target is a mouse brain, which has about 70 million neurons, roughly 500 times the fly's.

    HighEon's stated goal; no mouse result had been found as of early October 2026.

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  16. The human brain has roughly 600,000 times more neurons than a fly's, at about 86 billion versus 139,000.

    High86 billion is an estimate, and the ratio (about 617,000 times) is calculated from it.

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  17. There is no scientific consensus on how to tell whether an artificial system could feel anything, so nobody knows where that line is.

    HighThe video claims neither that such a model feels nor that it can't.

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  18. The fly model lacks features, such as hunger-like internal states, memory formation and learning, that make real insects candidates for sentience.

    HighBased on Eon's stated limits and the criteria discussed in Jonathan Birch's book.

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9:12Are we in one?

  1. Over 2,000 years ago the Chinese philosopher Zhuangzi dreamed he was a butterfly and woke unsure whether he was a man who had dreamed it or a butterfly dreaming he was a man.

    HighThe text dates to roughly the 3rd–4th century BC.

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  2. In 2003 philosopher Nick Bostrom published the simulation argument.

    HighPublished in Philosophical Quarterly in 2003; a first version dates from 2001.

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  3. Bostrom roughly estimated that a planet-sized computer could simulate all of humanity's mental history in under a millionth of a second.

    HighA rough estimate: the computing power is borrowed from another author, and it covers minds, not the whole universe.

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  4. If a few advanced civilizations each run many such simulations, simulated minds would vastly outnumber real ones.

    HighThe conclusion needs each simulating civilization to run many simulations.

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  5. Bostrom argues that at least one of three things is true: civilizations die out before getting that powerful, advanced ones almost never run such simulations, or we are almost certainly in one.

    HighBostrom does not claim we are simulated; he argues one of the three must hold.

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  6. Elon Musk said in 2016 that the odds we are in base reality, the real one, are one in billions.

    HighQuoted from news reports of his June 2016 Code Conference remarks.

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  7. Philosopher David Chalmers speculates there is at least a 25% chance we are in a simulation.

    HighChalmers calls this speculation and says he wouldn't call it 'likely'.

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  8. Astronomer David Kipping's calculation puts the chance we are simulated at just under 50%, so almost exactly fifty-fifty, tilted slightly toward real.

    High

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  9. Astrophysicist Franco Vazza argues it is nearly impossible: simulating just Earth down to the tiniest scale would take roughly the energy locked in a cluster of stars.

    MediumThe star-cluster comparison is approximate. Vazza's result limits brute-force, same-physics simulation; it doesn't rule out cheaper ones.

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  10. Bostrom suggested a simulator could fill in detail only where needed, and if something went wrong could skip back a few seconds and rerun it.

    HighThis is Bostrom's computing shortcut, separate from anything in quantum physics.

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  11. Physics has limits people compare to computer specs: a top speed (light), a possible smallest length scale, and a cap on how much information a patch of space can hold.

    MediumOffered only as analogy; the video states that none of this is evidence.

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  12. The popular 'clues' for the idea are not evidence, because a universe with no programmer could look exactly the same.

    MediumPhysicists such as Hossenfelder and Aaronson call the idea unfalsifiable, not disproven.

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  13. Particles do not 'render' only when someone looks: in quantum physics a detector counts as looking, and no conscious mind is required.

    High

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  14. We can't currently prove or disprove it: from the inside, a perfect simulation could hand any experiment the answer 'real', and only a leaky one could be caught.

    HighBeane and colleagues proposed one test for crude grid-like simulations; it only probes that kind and found no sign of one.

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  15. Kipping's twist: on the day we build a simulation with conscious beings inside, the odds flip from about fifty-fifty to almost certainly simulated.

    HighWhether machines can be conscious is still unknown.

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  16. If it can be done once, it has probably been done before: Bostrom notes that unless we are simulated, our descendants will almost certainly never run such a simulation.

    HighA summary of Bostrom's and Kipping's reasoning, not a direct quote.

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12:08So what?

  1. Chalmers argues a simulated world isn't a fake one: its objects and experiences are real, just built from something different underneath, like atoms being mostly empty space under a solid table.

    HighThe table analogy is an illustration in the spirit of Chalmers' argument, not a direct quote.

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  2. If we ever simulate rich minds, we become the simulators, and what we owe them depends on whether a mind can run on any suitable substrate, not just brains.

    HighThe ethical question is the video's own framing; Bostrom's argument assumes minds can run on any suitable substrate.

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  3. Bostrom notes that if no one can be sure they are at the base level, even the base civilization may have reason to behave ethically.

    HighBostrom frames this as speculation.

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