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Time loop logic is a hypothetical system of computation that exploits the Novikov self-consistency principle. In this system the computer is able to send the re

Time loop logic is a hypothetical system of computation that exploits the Novikov self-consistency principle. In this system the computer is able to send the result of a computation backwards through time and rely upon the self-consistency principle to force the sent result to be correct. I've written about this before. Instantaneous data transfer with zero lag is theoretically possible through use of quantum entanglement. You can use this same technique to build a doomsday clock similar to the film "Tomorrowland".

Terr_ 3y ago
> Instantaneous data transfer with zero lag is theoretically possible through use of quantum entanglement. No, that's a common myth about quantum stuff. The entangled relationship can't be used to transfer information on its own. Whatever you sample from the "instant parts" can only be checked and understood after additional context arrives in a conventional way--limited by the speed of light and the flow of time. https://www.space.com/41968-quantum-entanglement-faster-than-light.html https://www.space.com/41968-quantum-entanglement-faster-than... There are also other quantum things that the youth of today need to be educated on: https://www.smbc-comics.com/comic/the-talk-3 https://www.smbc-comics.com/comic/the-talk-3
- _Marak_ 3y ago
  Ok human. You can read the Hans Moravec paper on CTC and time loop logic to understand Novikov self-consistency principle is formalized, yes you must run the computation for as long as it would have already taken or result will never arrive. 11 years ago I wrote some examples of how password cracking would look like using such setup. https://marak.com/blog/2013-05-13-time-loop-software https://marak.com/blog/2013-05-13-time-loop-software I say through "through use of quantum entanglement" as glossy term for reader. Crystalline quantum circuits are not really existing yet so is all scifi. I won't be able to repsond to further posts in this thread. Cheers.
  - rkagerer 3y ago
    The salient bit from _Marak_'s article: Time-loop logic does not violate causality. We are able to retrieve the answer instantly because we have committed to spending sixty seconds in the future calculating the answer and sending it back. Maybe quantum superposition is just the universe compiling.
    - Terr_ 3y ago
      The blog-post asserts causality is not violated, but the author contradicts it elsewhere by claiming the hypothetical system would grant other benefits like "zero latency" gaming, which in turn means arbitrary data (e.g. human decisions) can somehow travel back-and-forth faster than light. Then FTL communication opens up an enormous can of causality-worms.
      - rkagerer 3y ago
        That's a point, and I let them expand their definition of causality to include a chain of events flowing in a reversed arrow of time. I think they hand-wave away all those worms with the precept that any attempt to cause a paradox or other inconsistency would fail in practice. But I'd love to hear some examples that come to mind of problems that crutch doesn't fix.
  - isoprophlex 3y ago
    Novikov makes some big-ish assumptions; the no-communication theorem scores a bit higher on the ol' razor for me...
_a_a_a_ 3y ago
https://en.wikipedia.org/wiki/Novikov_self-consistency_principle https://en.wikipedia.org/wiki/Novikov_self-consistency_princ... > The principle asserts that if an event exists that would cause a paradox or any "change" to the past whatsoever, then the probability of that event is zero. It would thus be impossible to create time paradoxes. Computer says no.
eigenket 3y ago
> I've written about this before. Instantaneous data transfer with zero lag is theoretically possible through use of quantum entanglement. I hope you wrote a correction wherever you wrote this. Quantum entanglement can not transfer information by itself (because of the no-communication theorem) therefore any data transfer protocol that uses entanglement must also use some other form of communication (e.g. classical communication), and therefore is at most as fast as your other communication method is.
- lrschaeffer 3y ago
  Maybe in general, but this is in the context of "time loop logic". Ordinarily, you can have entangled states where measuring both parts will produce the same (random) outcome. Unfortunately the outcome cannot be influenced by either party, so it's useless for communication, as you say. Now suppose that the first party resolves to go back in time and kill his grandfather unless the bits he measures are precisely the message he wishes to send. The universe can't tolerate the paradox, so it is corralled into the only non-paradoxical outcome: both parties read the desired message. Something like that, anyway.
  - eigenket 3y ago
    Ah I guess I misunderstood what was being claimed. I thought the claim was "you can use entanglement to instantly send messages", but it's actually "you can use entanglement and this model of how time travel might work to send messages instantly". Obviously these are rather different. In fact I feel like the entanglement doesn't even help in the time-travel protocol. If you want to send messages instantly and you can send messages back in time, you can "just" send yourself the message distance/c seconds in the past and send it then. Some messing around let's you arrange for it to arrive at exactly the time you want to send it in the future.
    - lrschaeffer 3y ago
      Assuming what I wrote above is correct (I don't actually know anything about closed time-like curves), it's actually weirder than just going back in time and mailing a letter early so it arrives when you want. Specifically, once you set up the entangled state, no other communication between the parties is necessary.

Terr_ 3y ago

> Instantaneous data transfer with zero lag is theoretically possible through use of quantum entanglement. No, that's a common myth about quantum stuff. The entangled relationship can't be used to transfer information on its own. Whatever you sample from the "instant parts" can only be checked and understood after additional context arrives in a conventional way--limited by the speed of light and the flow of time. https://www.space.com/41968-quantum-entanglement-faster-than-light.html https://www.space.com/41968-quantum-entanglement-faster-than... There are also other quantum things that the youth of today need to be educated on: https://www.smbc-comics.com/comic/the-talk-3 https://www.smbc-comics.com/comic/the-talk-3

_Marak_ 3y ago
Ok human. You can read the Hans Moravec paper on CTC and time loop logic to understand Novikov self-consistency principle is formalized, yes you must run the computation for as long as it would have already taken or result will never arrive. 11 years ago I wrote some examples of how password cracking would look like using such setup. https://marak.com/blog/2013-05-13-time-loop-software https://marak.com/blog/2013-05-13-time-loop-software I say through "through use of quantum entanglement" as glossy term for reader. Crystalline quantum circuits are not really existing yet so is all scifi. I won't be able to repsond to further posts in this thread. Cheers.
- rkagerer 3y ago
  The salient bit from _Marak_'s article: Time-loop logic does not violate causality. We are able to retrieve the answer instantly because we have committed to spending sixty seconds in the future calculating the answer and sending it back. Maybe quantum superposition is just the universe compiling.
  - Terr_ 3y ago
    The blog-post asserts causality is not violated, but the author contradicts it elsewhere by claiming the hypothetical system would grant other benefits like "zero latency" gaming, which in turn means arbitrary data (e.g. human decisions) can somehow travel back-and-forth faster than light. Then FTL communication opens up an enormous can of causality-worms.
    - rkagerer 3y ago
      That's a point, and I let them expand their definition of causality to include a chain of events flowing in a reversed arrow of time. I think they hand-wave away all those worms with the precept that any attempt to cause a paradox or other inconsistency would fail in practice. But I'd love to hear some examples that come to mind of problems that crutch doesn't fix.
- isoprophlex 3y ago
  Novikov makes some big-ish assumptions; the no-communication theorem scores a bit higher on the ol' razor for me...

_a_a_a_ 3y ago

https://en.wikipedia.org/wiki/Novikov_self-consistency_principle https://en.wikipedia.org/wiki/Novikov_self-consistency_princ... > The principle asserts that if an event exists that would cause a paradox or any "change" to the past whatsoever, then the probability of that event is zero. It would thus be impossible to create time paradoxes. Computer says no.

eigenket 3y ago

> I've written about this before. Instantaneous data transfer with zero lag is theoretically possible through use of quantum entanglement. I hope you wrote a correction wherever you wrote this. Quantum entanglement can not transfer information by itself (because of the no-communication theorem) therefore any data transfer protocol that uses entanglement must also use some other form of communication (e.g. classical communication), and therefore is at most as fast as your other communication method is.

lrschaeffer 3y ago
Maybe in general, but this is in the context of "time loop logic". Ordinarily, you can have entangled states where measuring both parts will produce the same (random) outcome. Unfortunately the outcome cannot be influenced by either party, so it's useless for communication, as you say. Now suppose that the first party resolves to go back in time and kill his grandfather unless the bits he measures are precisely the message he wishes to send. The universe can't tolerate the paradox, so it is corralled into the only non-paradoxical outcome: both parties read the desired message. Something like that, anyway.
- eigenket 3y ago
  Ah I guess I misunderstood what was being claimed. I thought the claim was "you can use entanglement to instantly send messages", but it's actually "you can use entanglement and this model of how time travel might work to send messages instantly". Obviously these are rather different. In fact I feel like the entanglement doesn't even help in the time-travel protocol. If you want to send messages instantly and you can send messages back in time, you can "just" send yourself the message distance/c seconds in the past and send it then. Some messing around let's you arrange for it to arrive at exactly the time you want to send it in the future.
  - lrschaeffer 3y ago
    Assuming what I wrote above is correct (I don't actually know anything about closed time-like curves), it's actually weirder than just going back in time and mailing a letter early so it arrives when you want. Specifically, once you set up the entangled state, no other communication between the parties is necessary.