4 ms·

If you were to teleport to the appropriate space coordinates upon seeing the event, the event being in the past (since you are seeing the event with light delay

by haneul 4y ago

If you were to teleport to the appropriate space coordinates upon seeing the event, the event being in the past (since you are seeing the event with light delay), you would not arrive in time to see it up close. If you wanted to see it up close, you would have to travel into the past, since your teleportation would have to include a translation of time coordinates, not just of space coordinates. Also, although order of events is variable, causality is (I believe) currently assumed to be absolute, so while two observers can differ on which came first between events A and B, this is only possible if A and B’s light (really, information) cones do not intersect such that one precedes the other causally. Suppose A does not intersect B by light cone, and you can instantly teleport. Then you can interact at A, teleport and interact at B, then immediate teleport everywhere in the universe, causally intertwining all frames before causality can physically propagate to those coordinates. Then you have time traveled to such an extent that I have no idea how the universe reconciles such a thing.

anonymouskimmer 4y ago
It seems to me a bit like scattering a bunch of sand onto a still body of water. The sand hits simultaneously at all points, creating waves that interfere and reinforce each other. Why does the universe have to reconcile? Just let the waves do what they do and move on from that.
- haneul 4y ago
  The simultaneity and single reference frame of the sand hitting example means there are no contradictions present. Assuming a finite speed limit to information transfer exists, exceeding that limit means you can create a potentially unlimited number of contradictions in state. It would be like watching the waves do what they do, but none of it happened, because no matter what you think you saw, there is at least one contradiction (due to the teleporting meddler). Like if you imagine any one state, and you meddle it to be impossible, as if doing Cantor’s diagonalization on the potential state space (if you can do literally instant teleportation and action with no cooldown).
  - anonymouskimmer 4y ago
    The sand hitting is an analogy for the transition from a 3-dimensional reference frame to a 2-dimensional reference frame (ala Flatland). I honestly don't understand what you're talking about with respect to contradictions. You aren't traveling back in time by instantaneously jumping. Is the universe supposed to be one cohesive thing? What are you talking about when you reference states in relation to the universe?
    - anonymouskimmer 4y ago
      I lost the edit window so I'll tack on that I've been thinking about this with respect to conventional faster than light travel. I think that sort of relativistic speed travel basically requires traveling back in time, because time is supposed to slow as one gets close to the speed of light. If hitting the speed of light was actually possible for a massive particle, then presumably time would stop (I think)? So for that case I guess time would have to reverse if speed could increase, though I don't know that causality would have to reverse. Maybe under these conditions there could be paradoxes of various kinds. I'm not a relativity physicist, and don't even know if these questions and suppositions are even the right things to be asking. If one could travel faster than the speed of light by teleportation, I don't think time travel or an unsyncing of the fabric of reality seems like it would need to happen. But what do I know. Thought experiments don't always reflect reality.
      - haneul 4y ago
        Since fast moving objects appear to contract (to an outside observer) the faster they go, if you have an object traveling at near light speed, it will appear vanishingly short, regardless of its true length. So let there be a one mile long object, let it travel at nearly light speed for five seconds. As God, freeze time after 5 seconds and place two measuring stations: one touching the head of Object from Observer's point of view, and one touching the tail of Object from Object's point of view (we can teleport around instantly so we can verify that we've got everything set up correctly with no penalty). Observer Head thinks Object Head and Object Tail are at about 5 light-seconds + 1 mile from origin (because Object is vanishingly short, and Object Head started at 1 mile from origin). But within Object, the Tail is 1 mile behind. So Object Tail will signal Observer Tail at about 1 mile/c before it reaches where it supposedly is, and Observer Tail instantly signals Observer Head, thus Observer Head receives causality from its signal before it sends its signal. Not sure how the universe resolves that. Unless the universe can "overclock" and become indefinitely fast at propagating and processing information when need be. I think my example isn't entirely sound because I forget the exact math (it's been a long time), so you might have to tweak the example to be fully mathematically sound, but the general concept of causal contradiction within one's own frame of reference should be sound, I think.

by haneul 4y ago

anonymouskimmer 4y ago

It seems to me a bit like scattering a bunch of sand onto a still body of water. The sand hits simultaneously at all points, creating waves that interfere and reinforce each other. Why does the universe have to reconcile? Just let the waves do what they do and move on from that.

haneul 4y ago
The simultaneity and single reference frame of the sand hitting example means there are no contradictions present. Assuming a finite speed limit to information transfer exists, exceeding that limit means you can create a potentially unlimited number of contradictions in state. It would be like watching the waves do what they do, but none of it happened, because no matter what you think you saw, there is at least one contradiction (due to the teleporting meddler). Like if you imagine any one state, and you meddle it to be impossible, as if doing Cantor’s diagonalization on the potential state space (if you can do literally instant teleportation and action with no cooldown).
- anonymouskimmer 4y ago
  The sand hitting is an analogy for the transition from a 3-dimensional reference frame to a 2-dimensional reference frame (ala Flatland). I honestly don't understand what you're talking about with respect to contradictions. You aren't traveling back in time by instantaneously jumping. Is the universe supposed to be one cohesive thing? What are you talking about when you reference states in relation to the universe?
  - anonymouskimmer 4y ago
    I lost the edit window so I'll tack on that I've been thinking about this with respect to conventional faster than light travel. I think that sort of relativistic speed travel basically requires traveling back in time, because time is supposed to slow as one gets close to the speed of light. If hitting the speed of light was actually possible for a massive particle, then presumably time would stop (I think)? So for that case I guess time would have to reverse if speed could increase, though I don't know that causality would have to reverse. Maybe under these conditions there could be paradoxes of various kinds. I'm not a relativity physicist, and don't even know if these questions and suppositions are even the right things to be asking. If one could travel faster than the speed of light by teleportation, I don't think time travel or an unsyncing of the fabric of reality seems like it would need to happen. But what do I know. Thought experiments don't always reflect reality.
    - haneul 4y ago
      Since fast moving objects appear to contract (to an outside observer) the faster they go, if you have an object traveling at near light speed, it will appear vanishingly short, regardless of its true length. So let there be a one mile long object, let it travel at nearly light speed for five seconds. As God, freeze time after 5 seconds and place two measuring stations: one touching the head of Object from Observer's point of view, and one touching the tail of Object from Object's point of view (we can teleport around instantly so we can verify that we've got everything set up correctly with no penalty). Observer Head thinks Object Head and Object Tail are at about 5 light-seconds + 1 mile from origin (because Object is vanishingly short, and Object Head started at 1 mile from origin). But within Object, the Tail is 1 mile behind. So Object Tail will signal Observer Tail at about 1 mile/c before it reaches where it supposedly is, and Observer Tail instantly signals Observer Head, thus Observer Head receives causality from its signal before it sends its signal. Not sure how the universe resolves that. Unless the universe can "overclock" and become indefinitely fast at propagating and processing information when need be. I think my example isn't entirely sound because I forget the exact math (it's been a long time), so you might have to tweak the example to be fully mathematically sound, but the general concept of causal contradiction within one's own frame of reference should be sound, I think.