Speed of Light Colors: Experiments & Info

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Discussion Overview

The discussion centers around the speed of light in relation to different colors (frequencies) of light, exploring whether there are measurable differences in speed among them. Participants inquire about experimental evidence and theoretical implications, including references to specific theories such as Variable Speed of Light (VSL) theories.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • One participant, Mohammad, asks if the speeds of different colors of light are the same and whether this has been experimentally verified.
  • Another participant asserts that the speed of light is independent of frequency (color) and mentions lasers as an example.
  • Glenn raises the possibility that some VSL theories propose tiny differences in speed between colors, suggesting these differences may be currently unmeasurable.
  • There is a contention regarding the significance of any potential differences in speed, with one participant questioning the contradiction in claiming a tiny but significant difference.
  • Another participant explains that in a vacuum, the speed of light is the same for all wavelengths, but in other media, the refractive index varies with wavelength, leading to dispersion.
  • Discussion includes skepticism about the implications of VSL theories and the complexities of atmospheric conditions affecting light speed.

Areas of Agreement / Disagreement

Participants express differing views on whether there are measurable differences in the speed of light for different colors, with some asserting uniformity in a vacuum and others suggesting theoretical variations. The discussion remains unresolved regarding the implications of VSL theories and the significance of any potential differences.

Contextual Notes

Participants mention the complexity of dispersion in various media and the atmospheric conditions that may affect light speed, indicating that the discussion is limited by these factors and the current understanding of VSL theories.

Moe_the_Genius
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Hi,
Are the speeds of all different colors of light exactly the same? And has this been done experimentally? Have they actually let colors into a system where it calculated its speed. (I know that Albert Michelson measured the speed of pure light_I just don't know if he or anyone else has done the same thing experimentally with light colors) Is there a site where I can find info on this?
Thanks a lot,
Mohammad
 
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Yes the speed of light is indepentent of frequency (color). Yes it is well verified. Ever hear of a Laser?
 
Don't some VSL theories state that there are tiny differences between say red and purple light? So tiny that we can't measure them (yet?).

-Glenn
 
Integral said:
Ever hear of a Laser?
What about it? I believe that the speed of light and laser vary by a tiny amount (and I believe that is significant in studying Physics). Is that right? I need expert confirmation on this.
 
Moe_the_Genius said:
I believe that the speed of light and laser vary by a tiny amount (and I believe that is significant in studying Physics). Is that right?
No, it's not. The light produced in a laser travels at the same speed (in vacuum) as any other light.
 
Last edited:
Moe_the_Genius said:
What about it? I believe that the speed of light and laser vary by a tiny amount (and I believe that is significant in studying Physics). Is that right?
That's contradictory - if its a tiny amount, its not significant.
I need expert confirmation on this.
You got it!
 
Moe_the_Genius said:
What about it? I believe that the speed of light and laser vary by a tiny amount (and I believe that is significant in studying Physics). Is that right? I need expert confirmation on this.

Look at it this way,like a person who's got good logics,but doesn't know physics at all:
"If laser woudn't travel at the speed of light,why did they call it "LASER" (apud L.A.S.E.R.) ?"

Daniel.
 
Glenn said:
Don't some VSL theories ...

based on such a premise, i would be skeptical.

r b-j
 
Moe_the_Genius said:
What about it? I believe that the speed of light and laser vary by a tiny amount (and I believe that is significant in studying Physics). Is that right? I need expert confirmation on this.

There is no difference if propagation takes place in a vacuum, where the refractive index is 1 for all wavelength.

If it travels in another medium, the refractive index is generally not 1, and varies with wavelength. This variation is called the dispersion relation. Air can be considered as such a medium, but it is sufficiently close to vacuum in most cases (1.00...something...).

The atmosphere is composed of various air compositions depending on location and time, so its exact dispersion relation is not trivial.
 

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