5 ms·

> The field still moves slower than light. Everything moves slower than [the speed of] light. Unless you are in a scifiction story or a conspiracy theorist wh

> The field still moves slower than light. Everything moves slower than [the speed of] light. Unless you are in a scifiction story or a conspiracy theorist who believes in that sort of thing and stuff like perpetual motion machines.

wyager 10y ago
Well yes, but if you introduce the kind of topologies you can get with wormholes, things can take the shorter path through the wormhole, so it "looks like" they are moving faster than light.
- aaron695 10y ago
  No. You can't go faster than light. There are no loop holes. The paper bending, sticking a pencil through explanation is science fiction. That is faster than light travel and hence impossible.
  - PeCaN 10y ago
    Point is, you can go less distance at the same speed. Do less work, not faster work.
  - swsieber 10y ago
    Then what makes a worm-hole special? I always thought it was that a worm-hole made a smaller path between two points than could normally exist in plain space.
    - antidamage 10y ago
      It's a hypothetical mechanism for the transmission of information. It's not taking a shortcut, it's just a different mechanism for getting there, in the same way entanglement propagation can't exceed the speed of light. And that's why this technique is being described as a wormhole - it's a relatively good simulation of one in terms of some of the measurements they want to make and can be used to carry one of the properties we think a wormhole should be able to carry.
  - noobermin 10y ago
    Hmm...I am not an expert in GR, but absent some other constraint, lorentz invariance is a local theory, right? Not a global one... I mean, I send two light beams simultaneously, one directly to you, one off angle to a mirror which reflects and then reaches you too[0]. The direct one reached first because it had a shorter route, they both travel at c...we don't violate lorentz. I think you're referring to a topology that would allow closed timelike loops which would imply grand father paradox issues? That doesn't violate lorentz which is local and doesn't care about global structure, but it leads to logical inconsistencies (which is global, I think...)? Enlighten me. Again, my expertise is not GR. [0] If you want to be pedantic, we are both in the same lorentz frame...needs not to be said, but just in case :)
  - wyager 10y ago
    > No. You can't go faster than light. There are no loop holes. That's what I just said. Your objection is silly. You're basically saying "Look, if light follows an extrinsically curved geodesic that goes into a black hole it takes 10 minutes to reach the singularity. But if we shoot it straight into the black hole, the math says it only takes 9 minutes. Impossible! That's science fiction! It's going faster than light!" Information traveling through a wormhole is emphatically not going faster than light. It's just taking a shorter route to get to the other side. You can't necessarily violate causality like this; you can just bring objects closer together. The mathematics on wormholes is quite solid and appears to admit traversable wormholes in principle. There are many reasons why it might not actually feasible to build or use one, but your objection isn't one of them.
    - aaron695 10y ago
      Traversable wormholes also imply time travel the idea is just cra cra. If wormholes can exist you won't be able to send information through them. I idea of information being sent faster than light is nuts. It might be mathematically interesting but that's it. I really don't get the tolerance around this idea of faster than light travel which also means time travel.
      - wyager 10y ago
        There are several resolutions to this complaint. One popular suggestion is that any causality-violating wormholes would cause a feedback loop of virtual particles to accumulate inside the wormhole and destroy it. > It might be mathematically interesting but that's it That's exactly what they said about photons and antimatter. Both were discovered mathematically before they were discovered physically. "Oh, this is just a mathematical fluke, this couldn't exist in the real world." The best physical theory we currently have admits the existence of wormholes. If you have a problem with that, then feel free to try to come up with an alternate physics that explains the world better than we can right now.
        aaron695 10y ago
        > One popular suggestion is that any causality-violating wormholes would cause a feedback loop of virtual particles to accumulate inside the wormhole and destroy it. I would imagine a more likely solution is, wormholes either can't exist or can't transmit information. > The best physical theory we currently have admits the existence of wormholes. Just because the maths says it can exist in one set of equations, doesn't mean it can/does exist in our universe, especially lacking any evidence. I'm not saying to stop researching the idea, but anyone sensible knows the outcome. They will not be possible not matter how much you want them to be true. Just because something can exist doesn't mean it's either likely or not crazy.
  - Confusion 10y ago
    The paper bending, sticking a pencil through explanation is science fiction. There is nothing science fiction about a curved 2D surface in a 3D space and travelling to a different location on the 2D surface via the 3rd dimension. I can both demonstrate the 'fiction' on my kitchen table and mathematically describe the system, showing that something seems to have moved from A to B faster-than-light. It's entirely unclear why you believe this would be impossible if our observable 4D universe is curved and embedded in one or more additional spatial dimensions.

wyager 10y ago

Well yes, but if you introduce the kind of topologies you can get with wormholes, things can take the shorter path through the wormhole, so it "looks like" they are moving faster than light.

aaron695 10y ago
No. You can't go faster than light. There are no loop holes. The paper bending, sticking a pencil through explanation is science fiction. That is faster than light travel and hence impossible.
- PeCaN 10y ago
  Point is, you can go less distance at the same speed. Do less work, not faster work.
- swsieber 10y ago
  Then what makes a worm-hole special? I always thought it was that a worm-hole made a smaller path between two points than could normally exist in plain space.
  - antidamage 10y ago
    It's a hypothetical mechanism for the transmission of information. It's not taking a shortcut, it's just a different mechanism for getting there, in the same way entanglement propagation can't exceed the speed of light. And that's why this technique is being described as a wormhole - it's a relatively good simulation of one in terms of some of the measurements they want to make and can be used to carry one of the properties we think a wormhole should be able to carry.
- noobermin 10y ago
  Hmm...I am not an expert in GR, but absent some other constraint, lorentz invariance is a local theory, right? Not a global one... I mean, I send two light beams simultaneously, one directly to you, one off angle to a mirror which reflects and then reaches you too[0]. The direct one reached first because it had a shorter route, they both travel at c...we don't violate lorentz. I think you're referring to a topology that would allow closed timelike loops which would imply grand father paradox issues? That doesn't violate lorentz which is local and doesn't care about global structure, but it leads to logical inconsistencies (which is global, I think...)? Enlighten me. Again, my expertise is not GR. [0] If you want to be pedantic, we are both in the same lorentz frame...needs not to be said, but just in case :)
- wyager 10y ago
  > No. You can't go faster than light. There are no loop holes. That's what I just said. Your objection is silly. You're basically saying "Look, if light follows an extrinsically curved geodesic that goes into a black hole it takes 10 minutes to reach the singularity. But if we shoot it straight into the black hole, the math says it only takes 9 minutes. Impossible! That's science fiction! It's going faster than light!" Information traveling through a wormhole is emphatically not going faster than light. It's just taking a shorter route to get to the other side. You can't necessarily violate causality like this; you can just bring objects closer together. The mathematics on wormholes is quite solid and appears to admit traversable wormholes in principle. There are many reasons why it might not actually feasible to build or use one, but your objection isn't one of them.
  - aaron695 10y ago
    Traversable wormholes also imply time travel the idea is just cra cra. If wormholes can exist you won't be able to send information through them. I idea of information being sent faster than light is nuts. It might be mathematically interesting but that's it. I really don't get the tolerance around this idea of faster than light travel which also means time travel.
    - wyager 10y ago
      There are several resolutions to this complaint. One popular suggestion is that any causality-violating wormholes would cause a feedback loop of virtual particles to accumulate inside the wormhole and destroy it. > It might be mathematically interesting but that's it That's exactly what they said about photons and antimatter. Both were discovered mathematically before they were discovered physically. "Oh, this is just a mathematical fluke, this couldn't exist in the real world." The best physical theory we currently have admits the existence of wormholes. If you have a problem with that, then feel free to try to come up with an alternate physics that explains the world better than we can right now.
      - aaron695 10y ago
        > One popular suggestion is that any causality-violating wormholes would cause a feedback loop of virtual particles to accumulate inside the wormhole and destroy it. I would imagine a more likely solution is, wormholes either can't exist or can't transmit information. > The best physical theory we currently have admits the existence of wormholes. Just because the maths says it can exist in one set of equations, doesn't mean it can/does exist in our universe, especially lacking any evidence. I'm not saying to stop researching the idea, but anyone sensible knows the outcome. They will not be possible not matter how much you want them to be true. Just because something can exist doesn't mean it's either likely or not crazy.
- Confusion 10y ago
  The paper bending, sticking a pencil through explanation is science fiction. There is nothing science fiction about a curved 2D surface in a 3D space and travelling to a different location on the 2D surface via the 3rd dimension. I can both demonstrate the 'fiction' on my kitchen table and mathematically describe the system, showing that something seems to have moved from A to B faster-than-light. It's entirely unclear why you believe this would be impossible if our observable 4D universe is curved and embedded in one or more additional spatial dimensions.