- Dec 11, 2006
- 7,851
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Since phase velocity can be faster than light, why can't it be used for faster than light communication?
From the wiki page:
http://en.wikipedia.org/wiki/Phase_velocity
From an unrelated but similar page explaining more:
http://www.mathpages.com/home/kmath210/kmath210.htm
So normally it's assumed that the phase velocity can exceed the speed of light, but the information it carries cannot. I fail to understand why a signal beam couldn't be established beforehand and have the phase velocity signal layered on top of that? I would think that communication would be able to be layered on top of the existing radiation source in either direction.
The other thing that confuses me is this Cherenkov radiation:
https://en.wikipedia.org/wiki/Cherenkov_radiation
It seems that you're exceeding the speed of light within a substance causing a "sonic boom" of light. It also happens when astronauts are working in space and they get a stray particle that beams through their optic nerves:
https://en.wikipedia.org/wiki/Cosmic_ray_visual_phenomena
From the wiki page:
http://en.wikipedia.org/wiki/Phase_velocity
From an unrelated but similar page explaining more:
http://www.mathpages.com/home/kmath210/kmath210.htm
So normally it's assumed that the phase velocity can exceed the speed of light, but the information it carries cannot. I fail to understand why a signal beam couldn't be established beforehand and have the phase velocity signal layered on top of that? I would think that communication would be able to be layered on top of the existing radiation source in either direction.
The other thing that confuses me is this Cherenkov radiation:
https://en.wikipedia.org/wiki/Cherenkov_radiation
It seems that you're exceeding the speed of light within a substance causing a "sonic boom" of light. It also happens when astronauts are working in space and they get a stray particle that beams through their optic nerves:
https://en.wikipedia.org/wiki/Cosmic_ray_visual_phenomena
