clipka wrote:
> You can polish stone or plastic though to get mirror-like reflections.

You'll get recognisable reflections. You won't get a reflection like a 
mirror gives. That's more what I meant. You'll get "polished" rather than 
"shiny", if that makes sense.

> That's pure nonsense. If you deal with fluorescence you'll see that *all*
> re-emitted light is *undirected* (at least with relation to the direction of
> the absorbed light).

Of course this is true with flourescence, because you're emitting a 
different frequency than you absorbed. It's not true in general. See, for 
example, a laser, where all re-emitted light is specifically in the same 
direction and phase as the absorbed photon that triggers the re-emission.

> in order to comply with Maxwell's equations.

Maxwell's equations are a statistical summarization of the actual behavior.

> It can't work with absorption and re-emission - because the "incoming angle =
> outgoing angle" law of specular reflection is a result of a light wave's
> interference with itself. 

Sort of. What would keep interference from working between an absorbed 
photon and a re-emitted photon?

> But as soon as a photon is absorbed by an electron,
> the photon's probability wave collapses, 

This is incorrect, as far as I understand it. OK, well, for the kind of 
"absorb" you're talking about, where the photon turns into a higher energy 
band of electron "orbit", that might be right. But not for simple "change of 
direction" kind of absorption.

> so the re-emitted light's probability wave has no way of interferencing with it, 

Also incorrect. You can get interference between two photons that aren't 
even in the same light cone any more.

> It also can't work with absorption and re-emission

Perhaps my reference to florescence has made the rest of my statements mean 
something to you different than what I intended. When I say "absorption and 
re-emission", i'm talking at the level of individual photons interacting 
with individual electrons in a QED sort of way. I'm not talking about 
absorption and then re-emission some (theoretically) measurable time later, 
like you get with fluorescence.

> because both are limited to certain wavelengths for many materials, 

I think we're talking about different types of absorption and re-emission. 
I'm talking individual photons interacting with individual electrons. I.e., 
I'm talking about the scale where it's nonsensical to argue whether it's the 
"same" photon or a "different" photon.

> Note however that quite a lot of instances of diffuse reflection are still
> "bouncing" light. 

Light "bounces" off the electrons of an atom. Whether you want to call it 
"absorb and re-emit" or whether you want to call it "bounce" simply depends 
on whether you want to think of it as the same photon or a different photon, 
which is a question that makes no sense.

> You also typically get re-emissions at different (usually longer) wavelengths
> than the absorbed photons (if only because of the principle of entropy).

Yes. I confused you with my mention of fluorescence. Sorry about that.

-- 
   Darren New, San Diego CA, USA (PST)
   The NFL should go international. I'd pay to
   see the Detroit Lions vs the Roman Catholics.

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