About bose-Einstein condensate

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Discussion Overview

The discussion revolves around the behavior of light as it passes through a Bose-Einstein condensate (BEC) and other media, particularly focusing on why light does not maintain its constant speed in these environments. Participants explore the underlying mechanisms and concepts related to light propagation in different media.

Discussion Character

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

Main Points Raised

  • One participant questions how light slows down when passing through a medium, noting a personal interest in understanding the phenomenon beyond common explanations.
  • Another participant explains that while the speed of light in a vacuum is constant, its apparent speed in a medium is affected by absorption and re-emission processes involving atoms in that medium.
  • A participant emphasizes the importance of distinguishing between group velocity and phase velocity, suggesting that a deeper understanding of optical conductivity is necessary to grasp the behavior of light in non-vacuum media.
  • One participant expresses frustration with repetitive explanations and suggests that providing mathematical backing could enhance discussions, particularly for those less familiar with the math involved.

Areas of Agreement / Disagreement

Participants express varying levels of understanding regarding the behavior of light in different media, with some agreeing on the need for further clarification of concepts like group and phase velocity. However, no consensus is reached on the best approach to explain these phenomena or the necessity of mathematical rigor in discussions.

Contextual Notes

Participants mention concepts such as optical conductivity and the mechanisms of light interaction with atoms, but the discussion does not resolve the complexities or assumptions underlying these ideas.

Who May Find This Useful

This discussion may be of interest to individuals exploring the properties of light in various media, particularly those studying optics, condensed matter physics, or seeking to understand the implications of Bose-Einstein condensates on light propagation.

Jim Beam
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how does light slow down considerably when it passes through one? i have always been told that lights speed remains constant. as with many questions, i have my own personaol theories for answers, but i want to find out for sure.
 
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The speed of light through a vacuum is constant; the speed at which light propogates through various substances can differ significantly. Now you must realize, the actual speed of the light is still constant, but the light passing through a medium will get absorbed by atoms within that medium (where the energy from the light "pauses" for a moment, not moving at all), then re-emitted. The amount of time the light energy is trapped in the atom determines the speed at which light appears to be moving through that medium, but this is actually the result of light coming to a dead stop, then moving on at c, over and over again.

This is not a property exclusive to BEC's, most if not all mediums slow the progress of light.
 
i see. i knew that light speed only remained constant in a vacuum, but i suppose my true question was why it didn't remain so in a medium
 
Jim Beam said:
i see. i knew that light speed only remained constant in a vacuum, but i suppose my true question was why it didn't remain so in a medium

Then you need to understand (i) the difference between group velocity and phase velocity; (ii) the mechanism of optical conductivity in gasses and non-vacuum media (I have written lengthy essays on this somewhere in here) and (iii) how we actually detect what is moving at what speed in anything.

Zz.
 
Zz, does this not get boring at times? It does for me. I get really tired of trying to explain the same thing over and over and over. If I had a theory-busting concept I would at least show the math. Pardon my disrespect for the math challenged.
 

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