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If 99.999 % of the universe is fake, than you only have to simulate 0.001 % of the universe but you also only have 0.001 % of a universe to turn into a computer

If 99.999 % of the universe is fake, than you only have to simulate 0.001 % of the universe but you also only have 0.001 % of a universe to turn into a computer and run a simulation on.

elorant 9y ago
Does a computer that runs a simulation of the universe has to be as big as the universe? In which case the universe is the simulation.
- danbruc 9y ago
  I don't know the answer but I guess one could at least put limits on that with information theoretical or thermodynamical methods. My intuition is that you can trade size for execution speed, i.e. you can simulate the entire universe with a small computer if you are willing to wait long enough. On the other hand storing the configuration of the simulated universe would probably take up the entire universe, or at least to me it is not obvious how you could compress the state of the universe in the general case. There are certainly low entropy states that would require less memory than the system provides but they are extremely rare. The only way out I can imagine is storing a low entropy state and spending even more time to calculate parts of higher entropy states on demand but never trying to store those high entropy states. But it is again not obvious to me that this would actually work because it would require rather strong bounds on possible intermediate states. And I don't think it would be meaningful to say the universe is the simulation. A processor executing some code is not a simulation of a processor executing some code, an electron flying across the room is not a simulation of an electron flying across the room, a dog walking down the sidewalk is not a simulation of a dog walking down the sidewalk. A simulation requires, at least that would be my ad hoc definition, one system recreating the states and behaviors of a different system, they can not be the same system.

If 99.999 % of the universe is fake, than you only have to simulate 0.001 % of the universe but you also only have 0.001 % of a universe to turn into a computer and run a simulation on.

elorant 9y ago

Does a computer that runs a simulation of the universe has to be as big as the universe? In which case the universe is the simulation.

danbruc 9y ago
I don't know the answer but I guess one could at least put limits on that with information theoretical or thermodynamical methods. My intuition is that you can trade size for execution speed, i.e. you can simulate the entire universe with a small computer if you are willing to wait long enough. On the other hand storing the configuration of the simulated universe would probably take up the entire universe, or at least to me it is not obvious how you could compress the state of the universe in the general case. There are certainly low entropy states that would require less memory than the system provides but they are extremely rare. The only way out I can imagine is storing a low entropy state and spending even more time to calculate parts of higher entropy states on demand but never trying to store those high entropy states. But it is again not obvious to me that this would actually work because it would require rather strong bounds on possible intermediate states. And I don't think it would be meaningful to say the universe is the simulation. A processor executing some code is not a simulation of a processor executing some code, an electron flying across the room is not a simulation of an electron flying across the room, a dog walking down the sidewalk is not a simulation of a dog walking down the sidewalk. A simulation requires, at least that would be my ad hoc definition, one system recreating the states and behaviors of a different system, they can not be the same system.