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This is the time travel I like to think about: Suppose we actually are simulated ancestors of an advanced civilization. Then time travel can take all sorts of i

This is the time travel I like to think about: Suppose we actually are simulated ancestors of an advanced civilization. Then time travel can take all sorts of interesting forms. For example, suppose our simulation is run sequentially. Then someone traveling back in time would travel back to an earlier state in the simulation that is already out of "RAM" and stored. This agent is "dead", the simulator does not bother to re-simulate the past just for them, they just disappear. Suppose instead the simulator is more flexible; then there's no reason they couldn't "fork" the timeline and let the gal do whatever she felt like and change the past going forward on their own. Since this would take vast computational resources, it would only be worth doing if you changed something big so maybe time travel wouldn't work unless your plans were grand enough. This also resolves the grandfather paradox; your grandpa is dead, you are never born in this timeline, but your simulated agent is just fine since it was copied from a different code base. You live out your life, reproduce, share technology, do whatever you want to do and life goes forward normally. In fact, it'd be likely they wouldn't bother simulating the whole world but just pull a Truman Show kind of thing and only propagate the changes, and copy from old data elsewhere. I'm sure there are even more interesting kinds of time-travel you could come up with given a simulated universe. It actually could be fun to write some sci fi short stories with this in the background, unexplained.

derefr 17y ago
> I'm sure there are even more interesting kinds of time-travel you could come up with given a simulated universe. It actually could be fun to write some sci fi short stories with this in the background, unexplained. I'm actually working with this exact idea, more or less, for a [roughly proposed] series of books, the first of which I'm procrastinating upon as I type this. :) Time travel, though, is a rather small part of what is possible with my metaverse model. I assume that the simulations are infinitely stacked, and each one has a 0:1 time-passage correspondence, so that for a "parent" simulation, the "child" simulation runs instantaneously, no matter the in-sim execution time, thus making Hypercomputation and such possible. All sorts of fun-with-philosophy falls out of that: The protagonists are Star Trek-style "everything is science" types, who discover that magic exists (for "magic," read "simulation runtime bugs.") They go on "Hard Science-based Fantasy" adventures using said magic for ten or twelve books, before figuring out that it was (very complicated) science all along. They then care for their own sim for a while, hacking it to fix some kinks (such as the inevitable existence, given probability, of a malevolent entity who has the root password.) Bored of that, they proceed to "break out" of their simulation, repeatedly, visiting "higher planes" that each have radically different physics and sometimes even logic, but that all share the property that Turing machines can be constructed within them. Eventually, they get to the "root" universe (really just a chroot jail) and meet God—that is to say, an AI who was left to run for an infinite time on an analogue computer and thus became omniscient merely by evaluating all possible states of all possible universes (that it could detect from within the chroot.) And that's only the first half of the sequence. 's called "Infinity's Tale", by the way. :)
- danteembermage 17y ago
  Now that's singularity fiction; I think speculative fiction really does well when there's a case for a truth or a worldview underneath, and like you said there are lots of "fun-with-philosophy" implications here. Good luck shipping!

derefr 17y ago

> I'm sure there are even more interesting kinds of time-travel you could come up with given a simulated universe. It actually could be fun to write some sci fi short stories with this in the background, unexplained. I'm actually working with this exact idea, more or less, for a [roughly proposed] series of books, the first of which I'm procrastinating upon as I type this. :) Time travel, though, is a rather small part of what is possible with my metaverse model. I assume that the simulations are infinitely stacked, and each one has a 0:1 time-passage correspondence, so that for a "parent" simulation, the "child" simulation runs instantaneously, no matter the in-sim execution time, thus making Hypercomputation and such possible. All sorts of fun-with-philosophy falls out of that: The protagonists are Star Trek-style "everything is science" types, who discover that magic exists (for "magic," read "simulation runtime bugs.") They go on "Hard Science-based Fantasy" adventures using said magic for ten or twelve books, before figuring out that it was (very complicated) science all along. They then care for their own sim for a while, hacking it to fix some kinks (such as the inevitable existence, given probability, of a malevolent entity who has the root password.) Bored of that, they proceed to "break out" of their simulation, repeatedly, visiting "higher planes" that each have radically different physics and sometimes even logic, but that all share the property that Turing machines can be constructed within them. Eventually, they get to the "root" universe (really just a chroot jail) and meet God—that is to say, an AI who was left to run for an infinite time on an analogue computer and thus became omniscient merely by evaluating all possible states of all possible universes (that it could detect from within the chroot.) And that's only the first half of the sequence. 's called "Infinity's Tale", by the way. :)

danteembermage 17y ago
Now that's singularity fiction; I think speculative fiction really does well when there's a case for a truth or a worldview underneath, and like you said there are lots of "fun-with-philosophy" implications here. Good luck shipping!