Superconductivity for light beams?

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The discussion centers on the concept of superconductivity and whether a material exists that allows light beams to propagate without losses, akin to how superconductors enable zero-resistance electrical current. Participants clarify that while superconductivity pertains to charge carriers, light does not require such carriers and propagates as an electromagnetic wave. They explore the idea of lossless mediums, suggesting that while optical fibers are low-loss, they are not entirely lossless, especially over long distances. The conversation emphasizes the fundamental differences between the propagation of electric current and light, ultimately concluding that no known material allows for completely lossless light propagation. The most lossless medium for both current and light is identified as a vacuum, although practical applications for information transmission remain challenging.
  • #31
StandardsGuy said:
As I recall, someone on this forum said that light doesn't require a medium. I argued, and put forth a "theory" of how vacuum was a medium. My post was deleted by an "official" of this forum.
Sounds appropriate. Personal speculation is not allowed here. If you had a problem with the Moderation, per the PF Rules you should contact the Mentor involved. [/off-topic]
 
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  • #32
StandardsGuy said:
As I recall, someone on this forum said that light doesn't require a medium. I argued, and put forth a "theory" of how vacuum was a medium.

I'm not impressed. "theories" like that are a dime a dozen on the 'net. Publish it, then you can boast about it on here. Otherwise, join the queue.

Something no one mentioned is that non-focused light dissipates as the square of the distance, even if there is no loss from the medium.

What does this have anything to do with a "medium"? It is simply a geometric effect due to 3D space. An electrostatic field from a point source has the same 1/r2 dependence. Has nothing to do with space being a medium or not.

Zz.
 
  • #33
rumborak said:
I'm a bit surprised to not see the obvious answer here: the most lossless medium for current and radiation is ... space.
No, space is not a good conductor of electric current at all.
 
  • #34
phinds said:
No, space is not a good conductor of electric current at all.

that's correct, but it doesn't stop a stream of electrons flowing ( controlled or otherwise) between two points in a vacuum :smile:
 
  • #35
davenn said:
that's correct, but it doesn't stop a stream of electrons flowing ( controlled or otherwise) between two points in a vacuum :smile:
But is that current? Can it do work? (particularly sustained work?)
 
  • #36
phinds said:
But is that current? Can it do work? (particularly sustained work?)

yes it's current ... how do you think an tube works ?

Electron-Tube-EL34-B-6V6GT-6146B-6L6GT-6146-EL34-B-.jpg
or the older TV picture tube ?

monito6.jpg


There is a current flowing from the cathode to anode across the vacuum :smile:Dave
 
  • #37
AAAGGG. Tubes. I hate tubes. Bah humbug.
 
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  • #38
phinds said:
AAAGGG. Tubes. I hate tubes. Bah humbug.

They were wonderful things for keeping the radio shack warm on cold winter nights :smile:
 
  • #39
davenn said:
They were wonderful things for keeping the radio shack warm on cold winter nights :smile:
Yes, and they were TERRIFIC in Mcintosh amps and preamps but I still hate them. It's a long story.
 
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  • #40
While superconductivity requires charged particles, in some special media, light can behave as a superfluid, i.e. propagate without losses. I think we had an article in the news section just some days ago:
https://phys.org/news/2017-06-stream-superfluid.html
 

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