3 ms·

you need to simulate unobserved events when they are observed. I'm not looking at the Nile river right now but when I look at in again in 50 years it better loo

you need to simulate unobserved events when they are observed. I'm not looking at the Nile river right now but when I look at in again in 50 years it better look correct for the 50 years that passed. For it to look correct requires simulating everything about it, everything feeding into it, everything it affects, from the moment I stopped looking at it until I looked at it again.

stevenhuang 8y ago
I'm not sure what you said refutes his point. It still doesn't require the entire universe to be simulated. If you observe the Nile, then yes it becomes an input, so that then would need to be simulated. This could take however long is necessary to do. It still does not necessitate simulating the entire universe down to the minutiae. Perhaps if the people in the simulation purposefully set out to "observe" somehow their entire universe in one timestep, in such way that _necessitates_ the complete simulation of their universe (like, say, running an experiment that involves all atoms interacting with all other atoms in their universe), then maybe it will be a problem. Then again, maybe the parent universe just has more atoms & computing power to throw at it, or it will generate a simulation that is "close enough" to the real thing that the people in the simulation will not be able to distinguish.
ChrisLomont 8y ago
>For it to look correct requires simulating everything about it, everything feeding into it, everything it affects, from the moment I stopped looking at it until I looked at it again. No, it only needs to at the two points you take inputs provide answers that satisfy your understanding on what the inputs should be, and your understanding is formed by other inputs you've been fed, making the entire thing much easier. Satisfying you is probably much easier than satisfying someone who really studies rivers. Neither you nor an expert needs simulating it much at all while you're not looking at it. And I doubt there's any case to simulate to any atomic or subatomic level. The gravitational pull of Neptune can likely be ignored. Neutrinos that may scatter from Antartic ice may hit it, but can probably ignored. And on and on. You're inspection is no where detailed enough to check if these things were taken into account for a decade while you were away. All of this detail is irrelevant. It may well be possible to do a good job with a very rough simulation of water and time, all of which could be computed on demand. So really all that needs stored is enough state to simulate in case you look at it again, and no work needs done on it between those looks. And this is a trivial amount of storage and computation to satisfy your two causal glances when compared to needing to simulate an entire universe down to all 10^120 subatomic particles.

stevenhuang 8y ago

I'm not sure what you said refutes his point. It still doesn't require the entire universe to be simulated. If you observe the Nile, then yes it becomes an input, so that then would need to be simulated. This could take however long is necessary to do. It still does not necessitate simulating the entire universe down to the minutiae. Perhaps if the people in the simulation purposefully set out to "observe" somehow their entire universe in one timestep, in such way that _necessitates_ the complete simulation of their universe (like, say, running an experiment that involves all atoms interacting with all other atoms in their universe), then maybe it will be a problem. Then again, maybe the parent universe just has more atoms & computing power to throw at it, or it will generate a simulation that is "close enough" to the real thing that the people in the simulation will not be able to distinguish.

ChrisLomont 8y ago

>For it to look correct requires simulating everything about it, everything feeding into it, everything it affects, from the moment I stopped looking at it until I looked at it again. No, it only needs to at the two points you take inputs provide answers that satisfy your understanding on what the inputs should be, and your understanding is formed by other inputs you've been fed, making the entire thing much easier. Satisfying you is probably much easier than satisfying someone who really studies rivers. Neither you nor an expert needs simulating it much at all while you're not looking at it. And I doubt there's any case to simulate to any atomic or subatomic level. The gravitational pull of Neptune can likely be ignored. Neutrinos that may scatter from Antartic ice may hit it, but can probably ignored. And on and on. You're inspection is no where detailed enough to check if these things were taken into account for a decade while you were away. All of this detail is irrelevant. It may well be possible to do a good job with a very rough simulation of water and time, all of which could be computed on demand. So really all that needs stored is enough state to simulate in case you look at it again, and no work needs done on it between those looks. And this is a trivial amount of storage and computation to satisfy your two causal glances when compared to needing to simulate an entire universe down to all 10^120 subatomic particles.