121–130 of 171 posts
This is the theme of Bon Jovi's ill-fated concept album "Dark When Wet", the followup to their smash hit "Slippery When Wet". Such commercial success must have gone to their heads to attempt such an audacious second project as a sequel based on Quantum Electrodynamics. It was doomed to failure. Re-interpretations of their classics, such as "Wanted, Dead or Alive - Schrödinger Redux" failed to capture the live animal…
I'm sorry what
Why are some things not darker when wet?
It feels like the fact that water is absorbed has to matter here--wood, dirt, cloth and sand all darken when they absorb water but not when the water remains in a bubble on the surface (as it does on cloth/sand/wood treated with a hydrophobic coating).
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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…
That's one of the things, that annoys me with questions about physics, which me might not know well enough yet: When someone asks about whether something "is", people answer with what we can in general know at our current level of understanding and then make it seem as though that is the same, as answering the question, what really "is". > Even in a vacuum you can send a photon in one end and see one on the other and…
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One constant in quantum electrodynamics is that it doesn't look right to me, but it seems to work! Richard Feynman's "QED" is a great read on this.
You can also watch the original lecture. This is one of my very favorite explanations of anything: http://www.vega.org.uk/video/programme/46 This explanation starts at about 30 minutes, but I highly recommend watching from the beginning.
http://www.vega.org.uk/video/subseries/8
1. A gentle lead-in to the subject, Feynman starts by discussing photons and their properties. 2. What are reflection and transmission, and how do they work? 3. Feynman diagrams and the intricacies of particle interaction. 4. What does it mean, and where is it all leading?
The site has many other science videos too:
On a related note, I find it fascinating that modern CGI cannot quite simulate wet fabric. I watched Frozen 2 and the rendering is absolutely breathtaking on most materials. Water, fabric, hair, etc. All impeccable. But the minute fabric gets wet, it looks so unrealistic. It looks plastic-y or greasy. I can only assume this is an active area of research, but we’re clearly not there yet.
Well, we may well be able to simulate it perfectly, but it might not fit into Frozen 2's limited budget for rendering.
If 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,…
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This is the question that should be higher up in the thread. This whole discussion makes no sense. Photons carry no hidden identity.
A photon doesn't need to carry a UUID for people to conceptualize a difference between a photon going through free space and being absorbed and re emitted. The parent comment asks the right question, what is being meant by "the same" is required to know before being able to say the discussion makes no sense. Taking your first literal interpretation as the only way the discussion could have value is no more helpful th…
Yeah but hot dogs belong to classical mechanics, while photons to quantum mechanics, and in quantum mechanics you can actually have the same hot dogs in different places, until you observe them
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This is the question that should be higher up in the thread. This whole discussion makes no sense. Photons carry no hidden identity.
Who knows, maybe they actually do, but we do not know it yet. I mean, how do you know they do not?
We may not know but we can only know what we can see and what we can see is explained by what we know.
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> They are not the same photons. How do you define "the same" for two photons?
it's all the same photon
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A photon doesn't need to carry a UUID for people to conceptualize a difference between a photon going through free space and being absorbed and re emitted. The parent comment asks the right question, what is being meant by "the same" is required to know before being able to say the discussion makes no sense. Taking your first literal interpretation as the only way the discussion could have value is no more helpful th…
> "I'm going to the store, do you want the same hot dogs we have in the fridge?" "That doesn't make sense, the store can't have the same hot dogs we have in the fridge" Yeah but hot dogs belong to classical mechanics, while photons to quantum mechanics, and in quantum mechanics you can actually have the same hot dogs in different places, until you observe them