A simulation is a representation of something else, like a model of the Empire State building that represents it. An information simulation is a model made of information, as computers simulate the weather to predict it, and flight simulators let pilots experience a plane before they fly it. An information simulation then represents something physical but is itself just information.
The simulation hypothesis, that our world is a simulation created by a physical computer in another world, was portrayed in the film The Matrix, where Morpheus says:
“What is real? How do you define ‘real’? If you’re talking about what you can feel, what you can smell, what you can taste and see, then ‘real’ is simply electrical signals interpreted by your brain.”
The hero Neo then discovers that his reality is actually a simulation of New York in 1999, fed into his brain as electrical signals, by machines in the future that are using him as a battery, but is that possible? Can physical machines simulate the world we see?
The classical processing needed to simulate a system increases exponentially with the particles in it, because they interact, so our computers can only calculate the behavior of a few photons (Eck, 2017). To simulate even a few hundred electrons requires more atoms than exist in our universe (Kendra, 2017), let alone simulating New York city. These calculations aren’t just implausible but logically impossible (Faizal et al., 2025), so physics concludes that we aren’t living in a computer simulation.
Undeterred, simulation theory advocates note that simulations are fake, so that logic fails. For example, why simulate the billions of years of history before humans, or galaxies and stars we can’t visit, or quantum events we can’t see? Instead, just show a far-off galaxy as a dot of light that appears real, as movies do, so simulation theory predicts holes in our reality because it is fake.
The big computer of simulation theory (Campbell, 2003) can’t calculate quantum events, so quantum theory must be flawed (Campbell, Owhadi, Sauvageau, & Watkinson, 2017), but critics have failed to falsify it for over a century now, so this is unlikely to succeed. And even if it did, finding a flaw in quantum theory would just result in its revision, not simulation theory support.
Current physics finds simulation theory impossible, so machines, aliens, or our future-selves aren’t simulating our world from another, but this isn’t the only version of virtualism. Annex 1 reviews the various ways a virtual reality can be generated, and concludes that a virtual world like ours can’t have a physical base. This excludes not only physical virtualism (the Matrix option), but also information virtualism (Wheeler’s It from Bit), and even mind virtualism (Kastrup, 2019), as nothing based on physical events can generate a world like ours.
Yet this still leaves quantum virtualism, that quantum events cause physical events, because unlike classical processing, quantum processing increases exponentially with size. It scales up with size as particle interactions do, so a quantum network the size of our universe can generate it. Processing costs aren’t now an issue, as every point of space is a processor, so every moment of the past fourteen billion years happened, every far-away galaxy in our telescopes exists, and quantum events actually happen. However hard we look, in the past, far away, or microscopically, we see no cracks or rifts in our world.
Quantum reality can only generate physical reality if it isn’t limited by physical laws, so if our world is virtual, it isn’t a copy of what causes it. It isn’t then a simulation but if it isn’t simulating something, why does it exist? Our universe is on a scale we can’t imagine, so we don’t need to know what is going on any more than all the animals that have lived and died knew that they were part of an evolution. It took billions of years to evolve sentience, but why?