5 ms·

Since you can’t travel faster than light in continuous space time there is no way to answer this. At the speed of light relativistic distortions lead to a singu

by simonh 5y ago

Since you can’t travel faster than light in continuous space time there is no way to answer this. At the speed of light relativistic distortions lead to a singularity, so bye bye spacetime. The one even faint possibility we know of, the Alcubier effect, puts you in a bubble of space time and warps that so it propagates at FTL speeds, but within that space time bubble you are stationary. You wouldn’t see anything outside the bubble though as it’s beyond an extreme distortion of space time that light cannot penetrate.

Maursault 5y ago
> Since you can’t travel faster than light The Relativity prohibition is that anything with mass can not travel as fast as light because approaching c, mass increases requiring more and more energy while time slows, such traveling at c increases apparent mass to infinity, requires infinite energy, and time slows to a stop. The same thing could be said for anything moving FTL, as it approaches c, mass increases and time slows to zero. Relativity does not prohibit FTL travel, only travel at c.
- contravariant 5y ago
  The problem is a bit deeper than that, it doesn't just require infinite energy there simply is no isometry of space that can transform something faster than the speed of light into something slower than the speed of light and vice-versa. So really there's no way to map the laws of physics for something faster than light onto those for something moving slower than light. For similar reasons there are no known elementary particles that can maintain their existence in a superluminal trajectory.
  - simonh 5y ago
    Right, so the maths works for superluminal trajectories, but that doesn’t mean it corresponds to anything physical and to get ‘there’ from ‘here’ you need to get past that singularity.
    - contravariant 5y ago
      Well saying the math 'works' is not quite right. If anything the math doesn't work out because there is no way to transform a normal trajectory into a superluminal one. Sure you can just define a line through space-time that is superluminal. That's basically equivalent to just defining a singular moment in time, the same way that an (inertial) trajectory defines a constant position.
- deleted 5y ago
  [deleted]
perl4ever 5y ago
Particles that travel faster than light have been theorized about for a long time. However, if something was traveling faster than light speed it apparently could never slow down to light speed. https://en.wikipedia.org/wiki/Tachyon https://en.wikipedia.org/wiki/Tachyon

by simonh 5y ago

Maursault 5y ago

> Since you can’t travel faster than light The Relativity prohibition is that anything with mass can not travel as fast as light because approaching c, mass increases requiring more and more energy while time slows, such traveling at c increases apparent mass to infinity, requires infinite energy, and time slows to a stop. The same thing could be said for anything moving FTL, as it approaches c, mass increases and time slows to zero. Relativity does not prohibit FTL travel, only travel at c.

contravariant 5y ago
The problem is a bit deeper than that, it doesn't just require infinite energy there simply is no isometry of space that can transform something faster than the speed of light into something slower than the speed of light and vice-versa. So really there's no way to map the laws of physics for something faster than light onto those for something moving slower than light. For similar reasons there are no known elementary particles that can maintain their existence in a superluminal trajectory.
- simonh 5y ago
  Right, so the maths works for superluminal trajectories, but that doesn’t mean it corresponds to anything physical and to get ‘there’ from ‘here’ you need to get past that singularity.
  - contravariant 5y ago
    Well saying the math 'works' is not quite right. If anything the math doesn't work out because there is no way to transform a normal trajectory into a superluminal one. Sure you can just define a line through space-time that is superluminal. That's basically equivalent to just defining a singular moment in time, the same way that an (inertial) trajectory defines a constant position.
deleted 5y ago
[deleted]

perl4ever 5y ago

Particles that travel faster than light have been theorized about for a long time. However, if something was traveling faster than light speed it apparently could never slow down to light speed. https://en.wikipedia.org/wiki/Tachyon https://en.wikipedia.org/wiki/Tachyon