Does this have anything to do with red look darker when there's less light?
https://en.wikipedia.org/wiki/Purkinje_effect
edit: maybe not. Looks like one is physiological, the other physical
Why are some things darker when wet?
81–90 of 171 posts
Re: Why are some things darker when wet?
#82Earlier quoted context omitted.
Except light is a wave and not a particle so reflection is explained when you consider that.
Light is not a wave. Photons are particles. Light as a wave is a convenient abstraction that explains a lot of light's behaviors, but not all of them. I recommend Feynman's QED lectures (or the book), where he explains this.
This debate is very old. Newton and Huygens fought long over it .. and eventually it was solved by: it is both or rather neither.
It is a quant.
https://en.wikipedia.org/wiki/Wave%E2%80%93particle_duality#...
Re: Why are some things darker when wet?
#83Earlier quoted context omitted.
I'm not convinced but even if we accept that explanation, why do all the atoms along the way emit the light in the direction it was travelling and then the ones at the surface suddenly emit it in a different direction?
I can recommend Hecht’s Optics textbook for this. I found it at my local library. I have had a number of electromagnetics courses over my life and none explained the unifying scattering principles of reflection, transmission, and refraction concept so clearly as that book
Hecht is an amazing author IMHO. Even his intro physics book is remarkable for introducing Emmy Noether at the outset of dynamics.
Re: Why are some things darker when wet?
#84This is a bit hand-wavey in its' description of light reflecting. One of the most mind blowing bits of physics I've ever learned is that photons do not actually "bounce" off of a surface like little balls. They are always absorbed and re-emitted. The actual photons that hit an object are not the same ones that eventually enter your eyes. The atoms in an object are stimulated by photons hitting them to then emit a new…
>Everything in this essay comes from this source. https://fermatslibrary.com/s/why-some-things-are-darker-when...
It's less hand-wavey. Also, the reflectivity of water is very low at low angles of incidence, rising to 100% at normal angles. Less light reaches the wetted material. https://en.wikipedia.org/wiki/File:Water_reflectivity.jpg
Re: Why are some things darker when wet?
#85Here are my own (much shorter) attempts to explain the same thing:
https://www.quora.com/Why-does-snow-appear-white-in-colour-w...
https://www.quora.com/Why-do-damp-items-such-as-fabrics-appe...
Re: Why are some things darker when wet?
#86This is a bit hand-wavey in its' description of light reflecting. One of the most mind blowing bits of physics I've ever learned is that photons do not actually "bounce" off of a surface like little balls. They are always absorbed and re-emitted. The actual photons that hit an object are not the same ones that eventually enter your eyes. The atoms in an object are stimulated by photons hitting them to then emit a new…
It doesn’t really make sense to talk about “the same” photon because photons don’t really have identity. Even in a vacuum you can send a photon in one end and see one on the other and not really know that the one going in was “the same” as the one going out. It can turn into other particles on its way and then recombine into a photon and there is no way to know this based on the observation that a photon came out of the end of your vacuum.
Re: Why are some things darker when wet?
#87Earlier quoted context omitted.
Yes, the water drops on the surface of the skin act as mini lens.
I am unconvinced by this argument. After all, the same light flux is hitting your body. Only thing a lens would do is make it focus in different spots than it otherwise would, but then you'd get spots with burns and spots without burns. This is not what I see happening at all.
It does happen, but due to inflammation and the fact that the “lens” wobbles since it is made out of water, you get enough consistency that it’s not noticeable without a detailed inspection.
It’s possibly still noticeable via the naked eye, but you’d have to compare and contrast to notice the slight mottling.
Re: Why are some things darker when wet?
#88Related Q/A on physics.SE: https://physics.stackexchange.com/questions/30366/why-do-wet...
This seems like a better explanation, because the effect is stronger for things that absorb water than for things where the water sits on top.
Re: Why are some things darker when wet?
#89If you find this kind of thing interesting, I strongly recommend the book [The Nature of Light and Colour in the Open Air](https://store.doverpublications.com/0486201961.html) by Marcel Minnaert. He discusses why wet things are darker, why shadows of leaves have little circular gaps, how to see the "green flash" that sometimes precedes a sunset, and dozens of others, some you might have noticed and wondered about, and some you won't realize you noticed until he points it out.
Re: Why are some things darker when wet?
#90If you find this kind of thing interesting, I strongly recommend the book [The Nature of Light and Colour in the Open Air]( https://store.doverpublications.com/0486201961.html ) by Marcel Minnaert. He discusses why wet things are darker, why shadows of leaves have little circular gaps, how to see the "green flash" that sometimes precedes a sunset, and dozens of others, some you might have noticed and wondered about,…
Sounds interesting! Thanks for the link!