What happens in transparent materials? Do their molecules oscillate with the same frequency as the EM wave and then reemit in the same direction? Or the light goes through meshes in the bulk?
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1See https://en.wikipedia.org/wiki/Lorentz_oscillator_model for example. – Jon Custer May 11 '22 at 17:59
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1There is a good discussion here: https://physics.stackexchange.com/a/46897/195949 – Claudio Saspinski May 11 '22 at 21:52
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Also: https://en.m.wikipedia.org/wiki/Ewald%E2%80%93Oseen_extinction_theorem – Jono94 Feb 10 '24 at 11:45
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You’re basically right. In a transparent material, molecules/atoms oscillate with the same frequency as the incoming light, and they re-emit at the same frequency with little or no loss. The light beam ends up going the same direction as before because the collective action of all the emitters is like a phased array which destructively interferes any waves going the “wrong” way. There is also a slight time delay between absorbed and emitted light at each atom which gives the refractive index.
Gilbert
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Electromagnetic waves, light and all the frequencies above and below, are modeled by the classical electromagnetic theory of Maxwell.
In this article transparency of light is explained using the knowledge of the quantum mechanical frame of matter.
Electromagnetically induced transparency (EIT) is a coherent optical nonlinearity which renders a medium transparent within a narrow spectral range around an absorption line. Extreme dispersion is also created within this transparency "window" which leads to "slow light", described below. It is in essence a quantum interference effect that permits the propagation of light through an otherwise opaque atomic medium.
At the quantum level, light is composed by a great number of photons, ( see this interesting experiment) and the interaction of the photons with the material's molecular structure is what defines if it is transparent or not.
Hand waving, one can think of the photon scattering on the quantum molecular lattice of the material. If the material is transparent it means the photon+lattice scatter is elastic, the same frequency/energy and phase of the photon is retained, so that images can be transmitted. If the scattering Photon+lattice is inelastic the material is opaque.
anna v
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@Mercury if you looked at the single photon at a time link you will see that the direction of the photon changes, but the quantum mechanical wavefunction solution of the problem retains the phases as seen in the classical interference pattern on the right. Photons build up light but light is the quantum mechanical ensemble of many photons. – anna v May 12 '22 at 05:47
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@Mercury you mean it is not a regular lattice, it still has quantum mechanical points which can enter the quantum mechanical scatter "photon +glass". – anna v May 12 '22 at 18:29
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So in the end EM photons go through the meshes in a way undergoing some elastic statteing on the way because interference happens through slits. – Mercury May 13 '22 at 12:57
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@Mercury For the slits it is the quantum mechanical wavefunctions for "photons scattering on these specific two slits" , for transparency it is the wavefunction "photon scattering on the material"very complex mathematically but to the effect of keeping energies and phases. – anna v May 13 '22 at 13:11
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Whether the slits are two or 1002 physically it doesnt matter. Mathemathically is far more complex but there is no new physics? – Mercury May 13 '22 at 18:03
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@Mercury it is normal quantum mechanics, which was new when it was first proposed. – anna v May 13 '22 at 18:42