4 ms·

> Being able to send messages faster than the speed of light grants the ability to send messages to yourself in the past. No, it doesn't. Even if we will be a

by drran 5y ago

> Being able to send messages faster than the speed of light grants the ability to send messages to yourself in the past. No, it doesn't. Even if we will be able to communicate instantly (0 delay = infinite faster than speed of light), we will not be able to send a message to the past (negative delay).

nl 5y ago
It does. Read the numerical example on https://en.m.wikipedia.org/wiki/Tachyonic_antitelephone https://en.m.wikipedia.org/wiki/Tachyonic_antitelephone
- drran 5y ago
  1) It's not applicable for this kind of drive. Isn't? 2) It's an unsolved problem, which waits for a correct solution. 3) Next time, please read what you are posting, please.
  - nwallin 5y ago
    1) It's applicable for any kind of ... thing ... which lets you send a message faster than the speed of light. It doesn't matter if you build this kind of drive into a USPS truck, or if it's a special closet in an unused bedroom, or a carrier pigeon that flies really fast, or a garden gnome that you hand an envelope to and he's just not there when you go to look for him until he then pops up and says "speedy delivery!" and hands you an envelope from yourself from the future. 2) It's an unsolved problem because it's built on a foundation which is also an unsolved problem -- namely faster than light travel/communication. If -- if -- we solve the problem that it's built on, all indications are that sending a message to your past will become possible. That being said, I expect that it's impossible because I expect that FTL travel/communication is impossible.
    - nl 5y ago
      These responses are correct. I'll add: 3) yes I read it. It's an example Einstein created, so possibly worth responding to the points made there rather than attacking me for "not reading it".
      - drran 5y ago
        If you read it and understood it, can you show us how to apply this formula to the warp drive, please? I cannot ask Einstein, obviously.
        nl 5y ago
        It exactly applies to a warp drive. Just saying "warp drive" doesn't have magical qualities - it's exactly what Einstein was talking about. So you put in the numbers in the same way as that numerical example on Wikipedia, and it shows the same thing. Edit: the only exception I can think of is if causality can be reversed.
    - drran 5y ago
      1) It's formula for time dilution. It's not applicable for a warp drive, because Alice will be shielded from relativistic effects, so no time dilution will occur. Alice's space will be dragged at speed > c, but Alice will live a normal life at normal speed, like a passenger in a supersonic airplane is protected from supersonic effects. 2) It's an unsolved problem because formula is defined for [0..c] only and for EM communication only. For a•v = c² it predicts dT=0, so time will stop for unshielded Alice, like it stops for photon, so she will not be able to communicate at all. For a•v > c², the formula is not defined at all (it is the unsolved problem). In reality, we expect to see Cherenkov radiation. In theory, according to this formula, EM processes should go in reverse, which is not possible at all, because it requires all photon emitted by Alice to reverse their direction and hit Alice at her new location.
      - nwallin 5y ago
        ...what? We're sitting here talking about how 1+2=3 and you're telling us that we're wrong, and that the sky is actually blue. I have no basis to object to your argument, other than to tell you the thing you're arguing against clearly doesn't have anything to do with what the rest of us are talking about.

by drran 5y ago

nl 5y ago

It does. Read the numerical example on https://en.m.wikipedia.org/wiki/Tachyonic_antitelephone https://en.m.wikipedia.org/wiki/Tachyonic_antitelephone

drran 5y ago
1) It's not applicable for this kind of drive. Isn't? 2) It's an unsolved problem, which waits for a correct solution. 3) Next time, please read what you are posting, please.
- nwallin 5y ago
  1) It's applicable for any kind of ... thing ... which lets you send a message faster than the speed of light. It doesn't matter if you build this kind of drive into a USPS truck, or if it's a special closet in an unused bedroom, or a carrier pigeon that flies really fast, or a garden gnome that you hand an envelope to and he's just not there when you go to look for him until he then pops up and says "speedy delivery!" and hands you an envelope from yourself from the future. 2) It's an unsolved problem because it's built on a foundation which is also an unsolved problem -- namely faster than light travel/communication. If -- if -- we solve the problem that it's built on, all indications are that sending a message to your past will become possible. That being said, I expect that it's impossible because I expect that FTL travel/communication is impossible.
  - nl 5y ago
    These responses are correct. I'll add: 3) yes I read it. It's an example Einstein created, so possibly worth responding to the points made there rather than attacking me for "not reading it".
    - drran 5y ago
      If you read it and understood it, can you show us how to apply this formula to the warp drive, please? I cannot ask Einstein, obviously.
      - nl 5y ago
        It exactly applies to a warp drive. Just saying "warp drive" doesn't have magical qualities - it's exactly what Einstein was talking about. So you put in the numbers in the same way as that numerical example on Wikipedia, and it shows the same thing. Edit: the only exception I can think of is if causality can be reversed.
  - drran 5y ago
    1) It's formula for time dilution. It's not applicable for a warp drive, because Alice will be shielded from relativistic effects, so no time dilution will occur. Alice's space will be dragged at speed > c, but Alice will live a normal life at normal speed, like a passenger in a supersonic airplane is protected from supersonic effects. 2) It's an unsolved problem because formula is defined for [0..c] only and for EM communication only. For a•v = c² it predicts dT=0, so time will stop for unshielded Alice, like it stops for photon, so she will not be able to communicate at all. For a•v > c², the formula is not defined at all (it is the unsolved problem). In reality, we expect to see Cherenkov radiation. In theory, according to this formula, EM processes should go in reverse, which is not possible at all, because it requires all photon emitted by Alice to reverse their direction and hit Alice at her new location.
    - nwallin 5y ago
      ...what? We're sitting here talking about how 1+2=3 and you're telling us that we're wrong, and that the sky is actually blue. I have no basis to object to your argument, other than to tell you the thing you're arguing against clearly doesn't have anything to do with what the rest of us are talking about.