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The article calling it FTL isn't entirely correct. You aren't travelling faster than light. Spacetime can, and routinely does, exceed c. One possible solution

The article calling it FTL isn't entirely correct. You aren't travelling faster than light. Spacetime can, and routinely does, exceed c. One possible solution to the problem is time expansion in the bubble: taking a 200ly trip would age the universe by 200 years outside the bubble (from the frame of reference of those inside).

FreeFull 6y ago
But if you travel at close to the speed of light (without exceeding it), the universe will age 200 years when you take a 200ly trip. In which case, I'm not sure if there is any benefit to dragging around a bubble of spacetime?
- zamalek 6y ago
  The bubble would let you surpass c, and would "only" need the mass-energy of Jupiter (without optimizations) vs. the entire mass-energy of the universe.
6gvONxR4sf7o 6y ago
But isn't the entire thing that it appears faster than c to an outside observer? Like, that's the definition? In which case an outside observer would have less than 200 years until the thing went 200ly.
- zamalek 6y ago
  To the outside observer, they would be time travelling. "Appear to" and "actually" are two very different things. A traveller with a different procession of time will appear to be going faster or slower than they really should. There are galaxies moving faster than c away from us right now.
  - 6gvONxR4sf7o 6y ago
    It's a bit mindblowing to apply relativity to that. To any observer, it'll seem like they're time traveling. (any sublight observer, or just any outside observer?)
    - zamalek 6y ago
      Special Relativity (the first and ironically simpler of the two, given the name) is really mind-blowing... up until the moment it isn't. In my mind the "cascade of simplicity" occurred when I subconsciously realized that bullet-time mechanics could really occur is a multiplayer game. The player in bullet-time would experience higher tickrate that anyone else, meaning that anyone else would see them speeding away. There's more to make it possible in a simulation, but that's unimportant: you can reason about these scenarios. My reasoning maybe incorrect, but it does afford me the ability to approach these mind-blowing subjects. Either way, it may be impossible for a subluminal observer to identify a superluminal apart from a warp traveller (aside from the former being outright impossible). The observation is identical, the cause is completely different.

FreeFull 6y ago

But if you travel at close to the speed of light (without exceeding it), the universe will age 200 years when you take a 200ly trip. In which case, I'm not sure if there is any benefit to dragging around a bubble of spacetime?

zamalek 6y ago
The bubble would let you surpass c, and would "only" need the mass-energy of Jupiter (without optimizations) vs. the entire mass-energy of the universe.

6gvONxR4sf7o 6y ago

But isn't the entire thing that it appears faster than c to an outside observer? Like, that's the definition? In which case an outside observer would have less than 200 years until the thing went 200ly.

zamalek 6y ago
To the outside observer, they would be time travelling. "Appear to" and "actually" are two very different things. A traveller with a different procession of time will appear to be going faster or slower than they really should. There are galaxies moving faster than c away from us right now.
- 6gvONxR4sf7o 6y ago
  It's a bit mindblowing to apply relativity to that. To any observer, it'll seem like they're time traveling. (any sublight observer, or just any outside observer?)
  - zamalek 6y ago
    Special Relativity (the first and ironically simpler of the two, given the name) is really mind-blowing... up until the moment it isn't. In my mind the "cascade of simplicity" occurred when I subconsciously realized that bullet-time mechanics could really occur is a multiplayer game. The player in bullet-time would experience higher tickrate that anyone else, meaning that anyone else would see them speeding away. There's more to make it possible in a simulation, but that's unimportant: you can reason about these scenarios. My reasoning maybe incorrect, but it does afford me the ability to approach these mind-blowing subjects. Either way, it may be impossible for a subluminal observer to identify a superluminal apart from a warp traveller (aside from the former being outright impossible). The observation is identical, the cause is completely different.