In everyday life, almost everything is at least somewhat reflective.

Metals are the best (or mirrors, which are covered with metals), next go plastics per say, then glass, painted/varnished wood, and even paper, clothes, or skin - all are relatively shiny.

So, my question is: does all shininess come from photon-electron reflective interaction?

Thus, the less things reflect, the more they absorb (or transmit).

Therefore, (I'm guessing) that's why we can't see our reflections on paper*, or skin: the more complicated chemical bonds within reflective materials are - the less wavelengths ending up in resulting reflection.

*I'm also guessing that it is roughness to blame - in case of white things like paper, since white is composition of all wavelengths.

...So, we do see our reflections inside almost any object: it's just that reflections are way too noisy, or lossy and/or monochromatic for us to recognize them, is that about right?

Edit: I realize that the question is a bit all-over-the-place :) So, the question is about electrons: is there any other phenomena aside from photon-electron scattering that produces macroscopic reflections? I.e., does any other scattering contribute as much as photon-electron to what we actually observe? Or is it just almost entirely mixture of photon-electron, polished surface and purity of chemical structure?


1 Answer 1


Let's start by considering only flat surfaces i.e. specular reflection. The reflection coefficient is related to the refractive index by the Fresnel equations, so how reflective a surface is depends only on the refractive index. Metal reflects more light than glass because its refractive index is different.

So your question:

Does all macro reflections caused by electrons?

really comes down to whether the refractive index is controlled by the electrons, and the answer is that yes it is. Light has an oscillating electric field, and in any medium containing electrons the field exerts a force on the electrons in the medium and makes them oscillate. It is this interaction between the light and the electrons in the medium that causes the light to slow down and hence the refractive index to be greater than one.

Finally you mention that surfaces like paper exhibit diffuse reflection not specular reflection, and you are quite correct that this is because the surfaces are uneven so they reflect the light in different directions depending on where the light hits the paper.

  • $\begingroup$ That's exactly the confirmation I hoped to receive to summarise my thoughts! Thank you! $\endgroup$ Commented Dec 2, 2019 at 16:50

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