Tagged Questions
5
votes
3answers
407 views
How does faster than light travel violate causality?
Let's say I have two planets that are one hundred thousand lightyears away from each other. I and my immortal friend on the other planet want to communicate, with a strong laser and a tachyon ...
3
votes
0answers
100 views
Would warp bubbles emit gravitational Cerenkov radiation in general relativity?
Inspired by the gravtiomagnetic analogy, I would expect that just as a charged tachyon would emit normal (electromagetic) Cerenkov radiation, any mass-carrying warp drive would emit gravitational ...
0
votes
1answer
153 views
Information faster-than-light and GR vs. QM
What is meant by the statement that information cannot travel faster than light?
If I write down something on a paper, isn't there according to QM a non-zero probability that an identical paper can ...
1
vote
1answer
225 views
Relationship between Alcubierre drive space-time evolution and speed of gravity
The top rated answer to this question about the Alcubierre drive asserts, "spacetime can dynamically evolve in a way which apparently violates special relativity," but according to the Wikipedia ...
3
votes
3answers
1k views
Harold White's work on the Alcubierre warp drive
I've read a bit on Harold White's recent work. (A paper on Nasa's site) I haven't been able to find any comments by people claiming to know anything about the physics involved. Is this really serious? ...
2
votes
2answers
291 views
Is it possible to have faster-than-light movement in General Relativity?
The speed of light as the maximal possible speed is build into Special Relativity as a premise of the theory. However I know of no such premise in General Relativity. When looking at two stars laying ...
5
votes
1answer
148 views
variable speed of light in cosmology
In this paper, D. H. Coule argues that warp drive metrics, like the one proposed by Alcubierre, require the exotic matter to be laid beforehand on the travel path by conventional travel. At section 5 ...
1
vote
2answers
215 views
How does gravitation propagate along curved spacetime?
In this wikipedia article it is described how a beam of light, with its locally constant speed, can travel "faster than light". That is to say it travels a distance, which, from a special relativistic ...
2
votes
2answers
738 views
Faster-than-light communication using Alcubierre warp drive metric around a single qubit?
The Alcubierre warp drive metric has been criticized on the points of requiring a large amount of exotic matter with negative energy, and conditions deadly for human travellers inside the bubble. What ...
3
votes
2answers
228 views
A simple thought experiment about traversable wormholes
Let's say I have a tube, of large radius (about 5 - 7 meters in diameter), with traversable wormholes at the ends. The wormholes are arranged as such that if something falls inside one hole from ...
1
vote
1answer
625 views
Neutrino unaffected by gravity
Are neutrinos affected by gravity?
If not, could that be a plausible reason for a neutrino taking a shorter path than light, since light is affected by gravity?
6
votes
3answers
722 views
Alcubierre Drive - Clarification on relativistic effects
On the Wikipedia article on the Alcubierre drive, it says:
Since the ship is not moving within this bubble, but carried along as the region itself moves, conventional relativistic effects such as ...
