Anyway, you tell your e-Friend Mr. Johnson that he does a marvelous job in creating these videos and the way they deliver the story.

Truly remarkable and entertaining and most important…educational.

I knew the science of course but still was entertained. Can’t be a bad thing.

If I were to have three thumbs I’d give you three thumbs up. Sadly for you and luckily for me I’m not a polydactylyst, so you’ll have to do with just the two!

And you get the rhyme from me for free.

cheers,
Rob

I want that music for as ring tone in my cell!

XD

For a mirrored surface what you have is an electron gas, where the outer electrons are free to wander from atom to atom, but still bound to the population. When an EM wave washes over the area each electron is shaken by the electric component of the wave, and as it shakes it emits its own waves into the EM field. That’s why you get the same frequencies; but quantum mechanically it’s still ultimately discrete excitations (photons) which are perturbing the electrons. The electrons are re-exciting the field and photons are being generated. At that level there is only a probability that any single photon will be emitted in any particular direction; but because of the way that the various paths interfere by phase, what you get on the large-scale is the classical behavior of light.

In all, this still amounts to reflected light being emitted light.

Some elaboration is called for on this. Even reflected light is emitted light, because a photon doesn’t simply glance off a surface. A photon is absorbed by an orbital electron, raising it to a higher orbital, and it eventually re-emits a new photon and reverts to an lower orbital. The property of reflected light to the effect that “angle of incidence equals angle of reflection” is a large-scale emergent process. At the scale of the individual atom, the re-emitted quantum of light has only a probability of propagating in any particular direction; but because of the way quantum mechanics works, energy & momentum on average tend to be conserved, and so a population of g’zillions of photons coming & going from a surface strongly tend to display the classical behavior of reflected light.

That seems … unlikely.

The angle-of-incidence case describes a mirror. With a mirror, you get not approximately but *exactly* the same light out as you put in; the wavelength doesn’t change, ane even the phase is completely predictable if it was so before. I have serious trouble believing you can do that with emergent behaviour from statistically scattered photons.

Now if you have a non-mirrorlike surface, it obviously gets slightly more complicated; yet again, only those wavelengths can come out that you put in in the first place – again something that does not seem to be possible with the process you propose.

In fact, what is observed strongly suggests that this may be a case of elastic collisions.

Or of course it may just be one of these things that are hard to explain looking at the particle side of things, and easier looking at the wave side – especially when it’s coupled with refraction in transparent material …

W00t! I learned something today! I can go home now, thanks…oh, I am home.

Actually, I probably re-learned it. I’m sure I must have gone through that in 3rd quarter physics.

- Jack

“We mostly see objects because they reflect light. Not because they emit it. ”

Some elaboration is called for on this. Even reflected light is emitted light, because a photon doesn’t simply glance off a surface. A photon is absorbed by an orbital electron, raising it to a higher orbital, and it eventually re-emits a new photon and reverts to an lower orbital. The property of reflected light to the effect that “angle of incidence equals angle of reflection” is a large-scale emergent process. At the scale of the individual atom, the re-emitted quantum of light has only a probability of propagating in any particular direction; but because of the way quantum mechanics works, energy & momentum on average tend to be conserved, and so a population of g’zillions of photons coming & going from a surface strongly tend to display the classical behavior of reflected light.

So what is the difference between, for example, the Sun & the Moon? We call the Sun a light source, the Moon a light reflector. Is there really an ultimate difference? The emission of light is due to an excited state; there’s a temperature difference between two regions. If one region is the Moon and the other the empty space surrounding it, the Moon is always found emitting a spectrum of EM radiation owing to its temperature; it has a store of heat energy and must lose it progressively to the space around it which has a lower temperature. The Sun also emits the same kind of radiation, and for the same reason: it has a store of energy which is being lost.

One may now say that the Sun generates its own heat and the Moon gets all its heat from the Sun. That’s true as far as it goes, but it still boils down to that a body emits light because its in an excited state. The Sun may be releasing its store of energy, but it’ll run out eventually. But this is exactly what the Moon has done: it was once in the process of collapsing under the weight of its own layers of planetary matter, going from excited to ground state, and as it did the potential energy of the settling geologic strata was converted to heat, which in due time was radiated away, just as the Sun is now doing.

What this all reduces to is that the difference between a source and a reflector is a convenience of classical physics, whereas the movie is illustrating a non-classical, quantum-mechanical process.

Also, that “molecule” fixation is annoying.

@10. Chris: yellow and blue photon girl should have worn a sports bra.

That film was terrific. Thanks!

The extra energy is dissipated as rotations et cetera (molecules), and eventually as heat.

Perhaps the electron exchange they depicted (but does it make sense within an orbital?) after the photon girl disappeared was to be some form of ‘rotation’ or sumthin’.

But my guess is that a molecule dance would have been closer.

I’ll let this link from Ben Goldacre speak for itself.

The p-orbitals have six electrons. No problem there.

But yeah, the fluorescence depiction was lacking in detail, which could be added easily. They should have used higher energy levels.

J/P=?