Race of Light Rays in Vacuum and Water: Winner or Tie?

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    Light Race Rays
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Discussion Overview

The discussion revolves around the comparative speeds of light rays traveling in vacuum and water, exploring whether one will reach a detector first or if they can arrive simultaneously. The scope includes conceptual reasoning and technical explanations regarding light propagation in different media.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant questions whether a light ray in vacuum or one in water will reach a detector first, suggesting the possibility of a tie.
  • Another participant points out that the speed of light in water is approximately 75% of that in vacuum.
  • A participant expresses dissatisfaction with online search results regarding light speed, mentioning concepts of absolute velocity and phase shifts, and questions if these could lead to actual delays in travel time.
  • It is noted that phase lag and time delay are effectively the same, and significant phase shifts can occur over long distances, potentially leading to detectable differences in arrival times of light pulses.
  • Discussion includes the principle of lenses, where phase and time shifts through different media affect light behavior.
  • One participant encourages improving search skills and emphasizes the value of individual inquiry over general educational resources.

Areas of Agreement / Disagreement

Participants express differing views on the implications of phase shifts and the conditions under which light might arrive at different times. The discussion remains unresolved regarding the definitive outcome of the light race.

Contextual Notes

There are limitations in the discussion regarding assumptions about the conditions of the race, the definitions of terms like "absolute velocity," and the specific contexts in which phase shifts may lead to observable delays.

quawa99
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Imagine two light rays parallel to each other , one of them is traveling in vacuum and the other one in water. We place a detector at the same distance from the source and fire the two rays inside their respective media.who will win the race? Or is it possible to have a tie in the competition?
 
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Can you Google "speed of light in vacuum" and "speed of light in water" ?
 
phinds said:
Can you Google "speed of light in vacuum" and "speed of light in water" ?

Oh sorry I am a really dumb kid who can make a new thread but can't Google something.
I did do it but wasn't satisfied by the results, some places they said that the light ray travels with the absolute velocity but with a phase shift and so I wanted to know if that could result in actual delay in traversing a geometric path.
 
Light speed in water is about 75% of vacuum light speed.
 
quawa99 said:
Oh sorry I am a really dumb kid who can make a new thread but can't Google something.
I did do it but wasn't satisfied by the results, some places they said that the light ray travels with the absolute velocity but with a phase shift and so I wanted to know if that could result in actual delay in traversing a geometric path.
Since we get a lot of that here, it is helpful to provide that information upfront. We can't provide the appropriate help if we don't know where you are.
 
quawa99 said:
Oh sorry I am a really dumb kid who can make a new thread but can't Google something.
I did do it but wasn't satisfied by the results, some places they said that the light ray travels with the absolute velocity but with a phase shift and so I wanted to know if that could result in actual delay in traversing a geometric path.

Phase lag, at a given frequency, and time delay are effectively the same thing. In the case of light frequencies, there could be a pretty massive phase shift over a long path. It is quite possible to detect two 'racing' pulses when they arrive at different times, even over a few metres of 'race track. 3 X10^8 m/s is a very 'finite' quantity.

Lenses all work on the principle that the phase / time shift through the thick parts of the glass is greater than the air+glass path through the thin parts.

I could suggest that you try to hone your searching skills. What you read may not immediately strike you as useful but is worth while making the effort to make sense of it - or use another link. It is all too easy to ask questions and all too easy for them to be mis-interpreted. PF is much more useful for sorting out individual points than as an education system. Books are incredibly good as a source of total learning.
 

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