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Astrophysical constraints on the simulation hypothesis for this Universe: why it is (nearly) impossible that we live in a simulation
arxiv.orgWe assess how physically realistic the ''simulation hypothesis'' for this Universe is, based on physical constraints arising from the link between information and energy, and on known astrophysical constraints. We investigate three cases: the simulation of the entire visible Universe, the simulation of Earth only, or a low resolution simulation of Earth, compatible with high-energy neutrino observations. In all cases, the amounts of energy or power required by any version of the simulation hypothesis are entirely incompatible with physics, or (literally) astronomically large, even in the lowest resolution case. Only universes with very different physical properties can produce some version of this Universe as a simulation. On the other hand, our results show that it is just impossible that this Universe is simulated by a universe sharing the same properties, regardless of technological advancements of the far future.
That does assume that the universe would be simulated for our benefit and that intelligent life is not just a side effect. If that was the case then why even bother including hundreds of billions of galaxies worth of stars in the simulation.
The simulation wouldn’t actually include all those billions of stars and galaxies. In this kind of simulation, it’s all just a skybox. If you point a telescope at a distant star, then the simulation spins up a sub-simulation to produce what output a real star would experience in that situation. You include the stars and galaxies because the real universe contains them, and you want your simulation to be realistic.
It actually does make sense that the simulation would be created for us. Compare the level of computing power required to create a limited human-centric simulation to trying to simulate an entire universe. The whole-universe simulation would be some absurd power of ten times more difficult to simulate. If it is possible to simulate a world convincingly, then it’s reasonable to assume that there are many, many more low-res human-scale simulations than giant full universe simulations.
With the whole universe simulation, you also have the problem of scale. It’s hard to imagine that an entire universe can be simulated at the atomic level with anything less complex than the universe itself. Unless you have a universe-sized computer, you probably aren’t simulating an entire universe with atomic accuracy. A human-scale simulation could be performed in a universe no more complex or different from the one we observe. An atomic-scale universe-spanning simulation would have to be run from a higher level that has completely different physical laws than the one we inhabit. Occams’ razor applies. If you want to assume a simulation, it makes sense to assume a type that requires the least exotic higher-order “real” universe possible.