Superconductivity for light beams?

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Discussion Overview

The discussion centers around the concept of superconductivity and its potential application to light beams, specifically whether there exists a material that allows light to propagate without any losses. Participants explore the differences between electrical current and light propagation, as well as the implications of superconductivity in this context.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • Some participants question the feasibility of superconductivity for light, suggesting that light behaves differently from electrical current.
  • One participant proposes that the question could be reframed to inquire about "lossless mediums" for light propagation, citing optical fibers as a low-loss option, though not entirely lossless.
  • Another participant emphasizes the need for clarity in terminology, suggesting that "lossless medium" is a more appropriate phrase than "superconductivity" when discussing light propagation.
  • Concerns are raised about the differences in propagation mechanisms between electric current (conduction) and light (radiation), with some arguing that discussing superconductivity in relation to light is meaningless.
  • Participants express confusion about the similarities and differences between electrical current and light, particularly regarding their propagation speeds and the role of electromagnetic fields.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the applicability of superconductivity to light propagation. There are competing views on the nature of light and electrical current, as well as the terminology used to describe loss in materials.

Contextual Notes

Some participants highlight the need for a clearer understanding of the underlying principles of light and electrical current, as well as the limitations of current materials in achieving lossless propagation of light.

  • #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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