1) Almost all civilizations like ours go extinct before reaching technological maturity.
2) Almost all technologically mature civilizations lose interest in creating ancestor simulations: computer simulations detailed enough that the simulated minds within them would be conscious.
3) We're almost certainly living in a computer simulation.
It seems like there's a fourth possibility here, which is that a full simulation of the universe is not possible. Anyone care to comment on the computability of something like that?
There's no reason to believe our universe is uncomputable. It may require vast resources, in excess of what our universe possesses (by definition, in some sense), but we have no ability to say that there can exist no other possible universe that may not only possess these resources, but consider our entire universe the moral equivalent of a homework problem running on a toy computer.
Even if our universe is in some sense based on real numbers (in the math sense), there's no apparent reason to believe that arbitrarily accurate simulations couldn't be run of it. (Or, alternatively, our host universe may also have real numbers and be able to use them for simulation purposes.)
Also, it could be that the 'real' civilization is not simulating the entire universe, but rather just the solar system and simulating the light entering the solar system from outside the solar system, substantially reducing the computational complexity of the simulation.
Still, modeling every living being as a sort of cellular automaton and running the simulation would take a lot of quantum computers. What would be the computational complexity of modelling the consciousness of a human being?
Perhaps the "real" civilization could run the simulation slower than real-time. For instance, while a whole hour elapses in the real world, only a half hour might elapse in the simulation. To the person observing the simulation, everyone inside the simulation appears to be going slowly, while time flows normally for the people inside the simulation.
I think that this would reduce the computational intensity by a factor of 2.
This brings up an interesting question (or possibly interesting): how would one observe the simulation? Would we not be able to detect evidence of the observation?
My almost entirely uninformed idea was that observation of the universe by something that is external to the universe might somehow interfere with the conservation of energy or in some other way produce phenomena that contradict the laws of physics.
2) Almost all technologically mature civilizations lose interest in creating ancestor simulations: computer simulations detailed enough that the simulated minds within them would be conscious.
3) We're almost certainly living in a computer simulation.
It seems like there's a fourth possibility here, which is that a full simulation of the universe is not possible. Anyone care to comment on the computability of something like that?