Can Light Be Slowed or Even Stopped?

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Discussion Overview

The discussion revolves around the concept of whether light can be slowed or even stopped, exploring various theoretical and experimental perspectives. Participants examine the implications of light's behavior in different media and conditions, including gravitational effects and interactions with super-cooled atoms.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Experimental/applied

Main Points Raised

  • Some participants note that light can be slowed by passing through physical media such as glass, air, or water.
  • There is a claim that light can be slowed when emitted from a gravitational well, although this is contested regarding its effectiveness when light passes by a gravitational well, which is described as being blue shifted.
  • One participant mentions that shooting a laser through super-cooled sodium atoms can slow light to 34 mph.
  • Another participant questions whether the properties of light, particularly its wave-particle duality, are influenced by environmental conditions, suggesting that the particle nature might be more dominant in super-cooled states.
  • It is proposed that while light can be "stopped," this involves the conversion of photons to other excitations, which are then converted back to photons.
  • A later reply discusses the phenomenon of light appearing to freeze for a fraction of a second within a gas when a laser is turned off, before resuming after the laser is turned back on.

Areas of Agreement / Disagreement

Participants express multiple competing views regarding the slowing and stopping of light, with no clear consensus reached on the mechanisms or implications of these phenomena.

Contextual Notes

Some claims depend on specific definitions of "stopping" light and may involve unresolved assumptions about the nature of light in various states and conditions.

Tim13
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Has there been a previous thread that discusses how light can be slowed?

Thanks,
Tim13
 
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Light can be slowed by making it pass through a physical medium such as glass, air, water, etc.
 
Light can be slowed when emitted from a gravitational well. This is not effective for light passing by a gravitational well since it is blue shifted on the way in.
 
Chronos said:
Light can be slowed when emitted from a gravitational well. This is not effective for light passing by a gravitational well since it is blue shifted on the way in.

You mean it gets red shifted? [en.wikipedia.org]. Speed is the same I believe, unless you run it through anything other than vacuum/air.
 
Shooting a laser through super-cooled sodium atoms will slow the light to 34mph.
 
Brainiac2 said:
Shooting a laser through super-cooled sodium atoms will slow the light to 34mph.

If something can be slowed, then perhaps it may also be stopped? Perhaps the properties of light (its duality of wave and particle) are reactive based on environmental conditions? Is the particle nature more dominant in super cooled states and hence the light slows? Is the word "dominant" not the right choice?
 
Tim13 said:
If something can be slowed, then perhaps it may also be stopped? Perhaps the properties of light (its duality of wave and particle) are reactive based on environmental conditions? Is the particle nature more dominant in super cooled states and hence the light slows? Is the word "dominant" not the right choice?

You can think of light in the particle sense as an important man walking in a room. If he is just walking through an empty room, he is not really affected, as in, he is not bouncing around. If he just made an important speech, he will be shaking peoples hands a lot, just bouncing around, always going the speed of light, just in a zig-zag path. I don't think light will ever look like it is going completely at 0 speed relative to anyone else.
 
It is possible to "stop" light - but what really happens is that those photons are converted to other excitations, and back to photons afterwards.
 
Tim13 said:
If something can be slowed, then perhaps it may also be stopped? Perhaps the properties of light (its duality of wave and particle) are reactive based on environmental conditions? Is the particle nature more dominant in super cooled states and hence the light slows? Is the word "dominant" not the right choice?


When the laser is suddenly turned off the light freezes for a fraction of a second within the gas only to resume after the laser is turned back on .
 

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