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Can entities inside the simulation get info about your CPU architecture? (From HAKMEM): Item 154 (Bill Gosper): The myth that any given programming language i

Can entities inside the simulation get info about your CPU architecture? (From HAKMEM): Item 154 (Bill Gosper): The myth that any given programming language is machine independent is easily exploded by computing the sum of powers of 2. If the result loops with period = 1 with sign +, you are on a sign-magnitude machine. If the result loops with period = 1 at -1, you are on a twos-complement machine. If the result loops with period greater than 1, including the beginning, you are on a ones-complement machine. If the result loops with period greater than 1, not including the beginning, your machine isn't binary -- the pattern should tell you the base. If you run out of memory, you are on a string or bignum system. If arithmetic overflow is a fatal error, some fascist pig with a read-only mind is trying to enforce machine independence. But the very ability to trap overflow is machine dependent. By this strategy, consider the universe, or, more precisely, algebra: Let X = the sum of many powers of 2 = ...111111 (base 2). Now add X to itself: X + X = ...111110. Thus, 2X = X - 1, so X = -1. Therefore algebra is run on a machine (the universe) that is two's-complement.

andrewflnr 3y ago
> path-dependent nature of our hardware architecture, not anything fundamental Anyway, there's no reason entities in a physics simulation would have such direct access to the primitives of the underlying computer, and trying to crash your host simulation does not seem like a reliable, healthy, or in any other way advisable approach to finding out if you're in one.
- vidarh 3y ago
  There's no reason to assume we will know how to prevent such direct access in a way that isn't sufficiently more costly that simulations without sufficient protections are more likely than those who are. It would presume simulations are limited to being run more often by entities willing to be exceedingly conservative and careful than by entities making mistakes that creates openings. You don't need to try to crash your host simulation - trying to find a way to gain control to e.g. effectively become "gods" of the simulation, or find a way out, or just explore would all be other motivations. If I thought we were definitely in a simulation and could find a way to gain information about the outside, you can bet I'd want to be part of an effort to do just that - if we crash it, who cares? We'd be gone and wouldn't know we messed up. Severe corruption would be far worse than a crash.
  - andrewflnr 3y ago
    Or they'll figure out how to run good simulations once and copy paste it as desired? It wouldn't require them to be "exceedingly conservative", just a reasonable approach to their hardware and software. Again, that's assuming their reality looks anything like ours. This is the real problem with these discussions, we're speculating about the motives of entities we cannot even in principle have any information about. By the way, you might want to figure out how much you're actually worried about breaking the simulation, since you acknowledge that corruption would be a problem. Reasoning from human simulations, as seems to be your wont, do you think that risk of corruption is small enough to be so gung ho about messing with things?

andrewflnr 3y ago

> path-dependent nature of our hardware architecture, not anything fundamental Anyway, there's no reason entities in a physics simulation would have such direct access to the primitives of the underlying computer, and trying to crash your host simulation does not seem like a reliable, healthy, or in any other way advisable approach to finding out if you're in one.

vidarh 3y ago
There's no reason to assume we will know how to prevent such direct access in a way that isn't sufficiently more costly that simulations without sufficient protections are more likely than those who are. It would presume simulations are limited to being run more often by entities willing to be exceedingly conservative and careful than by entities making mistakes that creates openings. You don't need to try to crash your host simulation - trying to find a way to gain control to e.g. effectively become "gods" of the simulation, or find a way out, or just explore would all be other motivations. If I thought we were definitely in a simulation and could find a way to gain information about the outside, you can bet I'd want to be part of an effort to do just that - if we crash it, who cares? We'd be gone and wouldn't know we messed up. Severe corruption would be far worse than a crash.
- andrewflnr 3y ago
  Or they'll figure out how to run good simulations once and copy paste it as desired? It wouldn't require them to be "exceedingly conservative", just a reasonable approach to their hardware and software. Again, that's assuming their reality looks anything like ours. This is the real problem with these discussions, we're speculating about the motives of entities we cannot even in principle have any information about. By the way, you might want to figure out how much you're actually worried about breaking the simulation, since you acknowledge that corruption would be a problem. Reasoning from human simulations, as seems to be your wont, do you think that risk of corruption is small enough to be so gung ho about messing with things?