Can air, glass, and water slow down the speed of light?

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Discussion Overview

The discussion revolves around the behavior of light as it travels through different media such as air, glass, and water. Participants explore the mechanisms behind the apparent slowing of light and the interactions between photons and atoms in these materials. The conversation includes theoretical aspects and conceptual clarifications regarding light propagation and refraction.

Discussion Character

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

Main Points Raised

  • Some participants propose that while the speed of light remains constant in a vacuum, its effective speed appears slower in media due to absorption and re-emission processes.
  • Questions arise regarding the mechanisms of absorption and re-emission of photons by electrons in atoms, including how energy levels are involved.
  • There is a query about whether the index of refraction affects different wavelengths of light differently, potentially due to the lattice structure of the material.
  • Some participants express curiosity about the nature of light's path through media, questioning why light does not travel straight and whether any light travels directly without scattering.
  • The conservation of momentum is mentioned as a reason for the directionality of re-emitted photons after absorption.
  • A participant references a previous discussion on a similar topic, suggesting a continuity of inquiry in the forum.

Areas of Agreement / Disagreement

Participants exhibit a mix of agreement and disagreement, particularly regarding the mechanisms of light interaction with matter and the implications of these interactions on the speed of light. No consensus is reached on the specifics of these processes.

Contextual Notes

Limitations include potential misunderstandings of the absorption and re-emission processes, as well as the complexity of light behavior in different media that may not be fully addressed in the discussion.

Who May Find This Useful

This discussion may be of interest to those studying optics, physics, or materials science, particularly in understanding light-matter interactions and the principles of refraction.

billy_boy_999
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how does air/glass/water slow down light?
 
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It doesn't really.. light speed remains the same. However, photons are absorbed and re-emitted on the way through the medium and it is the time that this takes that makes them appear to travel slower.
 
Why are they absorbed and re-emitted? How?
 
Basically photons carry a certain amount of energy with them. Electrons bound to an atom (not free electrons) will be able to absorb this energy and fly up an energy level or two. When they go back down they will emit a photon.

Question, does the index of refraction reflect colors of different wavelengths differently because the latice structure of the compound? Also, how come there is no light that goes straight, or is there just a tiny amount due to probability of not being scattered.
 
Also, how come there is no light that goes straight

Light moves "straight" through a vacuum.
 
Goalie_Ca said:
Basically photons carry a certain amount of energy with them. Electrons bound to an atom (not free electrons) will be able to absorb this energy and fly up an energy level or two. When they go back down they will emit a photon.
Why is it then re-emitted in the same (or opposite, whatever you want) direction that it has been absorbed?
 
kuengb said:
Why is it then re-emitted in the same (or opposite, whatever you want) direction that it has been absorbed?

Conservation of momentum.
 

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