The microscopic expl. of how light is slowed in materials

In summary, the conversation discusses the concept of light being slowed down at the atomic scale in a material due to the disturbance created by the electric and magnetic fields. This results in the emission of similar photons from the shaken charges, potentially leading to light amplification in transparent materials. However, this effect is not observed in practice and can lead to a diffuse wavefront and absorption spectrum in isolated atoms. The standard models in Physics are generally reliable and should be followed. The thread is closed and attempting to re-open it is against the rules of the forum.
  • #1
DanMP
179
6
In wikipedia I found:
At the atomic scale, an electromagnetic wave's phase velocity is slowed in a material because the electric field creates a disturbance in the charges of each atom (primarily the electrons) proportional to the electric susceptibility of the medium. (Similarly, the magnetic field creates a disturbance proportional to the magnetic susceptibility.) As the electromagnetic fields oscillate in the wave, the charges in the material will be "shaken" back and forth at the same frequency.[1]:67 The charges thus radiate their own electromagnetic wave that is at the same frequency, but usually with a phase delay, as the charges may move out of phase with the force driving them (see sinusoidally driven harmonic oscillator). The light wave traveling in the medium is the macroscopic superposition (sum) of all such contributions in the material: the original wave plus the waves radiated by all the moving charges.

If what I underlined is correct, it means that from one incident photon we will get at the other end countless similar photons, as the "shaken" charges radiate "their own electromagnetic wave" (photons, right?). This sounds like light amplification, but the explanation is about any transparent material not about lasers. And the "amplification" would increase with the width/depth of the material (glass, water, etc.), because there are more atoms ready to "produce" new photons. We know that light doesn't get brighter when crossing through glass, water, etc. So what is wrong?

(I addressed this problem in another tread, but the answers I got from DrClaude were far from satisfactory. And then he closed the tread. Not so friendly forum ...)
 
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  • #2
DanMP said:
answers I got from DrClaude were far from satisfactory. And then he closed the tread. Not so friendly forum ...)
DanMP said:
If what I underlined is correct, it means that from one incident photon we will get at the other end countless similar photons, as the "shaken" charges radiate "their own electromagnetic wave" (photons, right?).
If it really were like that and if atoms absorb and re-emit photons, the path of light through a transparent medium wouldn't allow a coherent image to be formed because the absorption/emission process would introduce a variable phase and the wavefront would become diffuse. Optical instruments would just not work.

That effect does occur in gases with isolated atoms and the effect is to produce an absorption spectrum, consisting of dark lines in a normal white light continuous spectrum. The effect is not coherent; though.
DanMP said:
(I addressed this problem in another tread, but the answers I got ********** were far from satisfactory.
It strikes me that you're not satisfied because you didn't actually understand what was written. Frankly, although it can be fun to make up one's own Physics explanations, those explanations can easily be hopelessly wrong. This is not cutting edge Science and the standard models are usually pretty good. So why not stick to them?
 
  • #3
DanMP said:
(I addressed this problem in another tread, but the answers I got from DrClaude were far from satisfactory. And then he closed the tread. Not so friendly forum ...)
Attempting to re-open a locked thread is against the PF rules. Please check your PMs.

Thread is closed.
 

Related to The microscopic expl. of how light is slowed in materials

1. What is the microscopic explanation of how light is slowed in materials?

The microscopic explanation of how light is slowed in materials is based on the interaction between light and the electrons in the material. As light travels through a material, it causes the electrons to oscillate and create their own electromagnetic fields. These fields interact with the incoming light, causing it to slow down.

2. Why does light travel slower in materials compared to vacuum?

Light travels slower in materials because of the interaction between the light and the electrons in the material. In a vacuum, there are no electrons to interact with, allowing light to travel at its maximum speed. However, in materials, the presence of electrons causes the light to slow down.

3. How do different materials affect the speed of light?

The speed of light is affected by the properties of the material, such as its density, composition, and temperature. Materials with a higher density tend to slow down light more than materials with a lower density. Additionally, the composition of the material can also impact the speed of light, as different materials have different numbers of electrons that can interact with light.

4. Can light be slowed down to a complete stop in a material?

No, it is not possible to completely stop light in a material. However, it is possible to slow it down significantly. This is because the interaction between light and electrons in a material is not strong enough to completely halt the movement of light.

5. How does the speed of light in materials affect everyday life?

The speed of light in materials has a significant impact on everyday life. It allows us to see objects, as light travels through materials such as air and glass to reach our eyes. It also plays a crucial role in technologies such as fiber optics, which use materials with specific properties to transmit light signals for communication and data transfer.

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