People are wondering whether post humans are simulating their ancestors (us), using their high power computers. In other words people are wondering: Can in a base world like our universe there exist a simulation of the universe itself?
Consider these 3 facts:
- Type III civilizations do not exist because galaxies which had most of their energy used up for some artificial purpose will appear as a type of thermodynamic black-box in our surveys of the galaxies and There is a paper which looked for such black boxes and they did not find any galactic black-boxes in the observable universe. So it appears no civilization can reach Type III level of energy consumption.
- There are thermodynamic limits on energy consumption of computation (see Landauer’s principle) which says At 20 °C (room temperature, or 293.15 K), the Landauer limit represents an energy of approximately 0.0172 eV, or 2.75 zJ for a single bit flip. In 2014 physical experiments tested Landauer’s principle and confirmed its predictions.
- Simulation of an entire universe will take more energy than what is available in a galaxy because we need to simulate 10^80 fundamental particles which is the generally accepted number of all particles in the universe. Simulating a single iron atom in a lesser than perfect manner requires you to manipulate 10^78 numbers.
Since Type III civilizations do not exist we can safely say there is not enough energy in a sub-galactic structure (e.g. a few stars) to conduct a simulation of the entire universe within it. Similar arguments can apply to all universes that are purported to be simulating itself.
Appealing to the unobserved to counter my arguments e.g. breaking Landauer’s limit, or possibility of unobserved Type III civilizations is as of now magical thinking, and I will treat it with skepticism.