Mirrors, Atoms and Light Question

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Discussion Overview

The discussion revolves around the nature of light reflection from mirrors, particularly focusing on the atomic and microscopic properties that contribute to this phenomenon. Participants explore the implications of atomic structure on the smoothness of reflective surfaces and the mechanisms behind reflection at the atomic level.

Discussion Character

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

Main Points Raised

  • One participant suggests that mirrors reflect light perfectly due to their uniform flatness, questioning the role of atomic structure in this reflection.
  • Another participant proposes that the imperfections in glass are much smaller than the wavelength of visible light, which may explain the observed reflection.
  • A different viewpoint emphasizes that surfaces reflect light well because they do not transmit or absorb it, with various mechanisms such as interference effects or conductivity being relevant.
  • It is noted that if the phase error from surface roughness is smaller than the wavelength, the surface can still appear smooth, with typical optical elements having roughness on the order of wavelength/8.
  • Discussion includes the idea that in metals, the distribution of electrons contributes to a nearly homogeneous structure that facilitates reflection.
  • One participant raises a question about the fundamental nature of reflection, likening it to scattering processes involving light and matter interactions.
  • Another suggests that understanding reflection may require deeper study, recommending resources on quantum optics.
  • One participant describes a conceptual model where incident light causes surface electrons to oscillate, leading to the emission of reflected light.

Areas of Agreement / Disagreement

Participants express various hypotheses regarding the mechanisms of reflection and the role of atomic structure, with no consensus reached on a singular explanation. Multiple competing views remain regarding the nature of reflection at the atomic level.

Contextual Notes

Limitations include the dependence on definitions of smoothness and reflection, as well as the unresolved nature of the mechanisms involved in light-matter interactions.

cl-ml
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According to my knowledge and understanding of things, mirrors reflect light perfectly because they are almost perfectly flat, or at least uniformly flat at most places.
(\ and / are light rays)

__\/__

But if all matter is composed of atoms, then a mirror would not be flat and would look like this (_ and \ are light rays)
)
)_
)\
therefore light would not reflect perfectly, and mirrors would just look like a white surface.
But this is obviously not the case. Why? What am I misunderstanding?
Thanks in advance.
 
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My guess is that the imperfections in the glass are much smaller than the wavelength of visible light, which is 390 to 750 nm.
 
cl-ml said:
According to my knowledge and understanding of things, mirrors reflect light perfectly because they are almost perfectly flat, or at least uniformly flat at most places.
<snip>

No, surfaces are good reflectors because they don't transmit or absorb. Specifically 'why' depends on the nature of the reflecting surface- it can be an interference effect (thin film bragg reflectors) or because the material is conductive (metallic reflectors), it can be total internal reflection, or perhaps some other effect.

'good' mirrors are flat, yes- or rather, smooth on the scale of the wavelength. Atoms are much smaller than a wavelength.
 
If the phase "error" induced by a rough surface is much smaller than the wavelength, then the surface will still appear smooth. The surface roughness of a typical optical element for example is the wavelength/8.

Claude.
 
Andy Resnick said:
No, surfaces are good reflectors because they don't transmit or absorb. Specifically 'why' depends on the nature of the reflecting surface- it can be an interference effect (thin film bragg reflectors) or because the material is conductive (metallic reflectors), it can be total internal reflection, or perhaps some other effect.

On the atomic scale, what causes reflection? how does it work?
 
In metals the electrons are not localized but distributed over the whole piece of metal. As the electronic structure is "smoothed" out the light waves are reflected by a nearly homogeneous structure, not by localized structures.
 
GT1 said:
On the atomic scale, what causes reflection? how does it work?

That's a very open-ended question, and generally leads to a never-ending series of "but what caused that?" type questions.

Fundamentally, reflection is like any other scattering process, involving the interaction of light and matter.
 
GT1 said:
On the atomic scale, what causes reflection? how does it work?

Maybe get a book on quantum optics or feynmans book - QED: The Strange Theory of Light and Matter
 
GT1 said:
On the atomic scale, what causes reflection? how does it work?
The way I think of it is, the incident light wave causes electrons near the material surface to oscillate at the same frequency as the light. The oscillating electrons emit waves of the same frequency, and that is seen as outgoing, reflected light ... as well as transmitted (refracted) light if the material is transparent.
 

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