Orchid XP v8 wrote:
> Pfff. Yeah, and what do you suggest I search for? "Electricity is 
> somehow related top optics"? :-P

I searched on permitivity permeability.

>> http://www.newton.dep.anl.gov/askasci/phy05/phy05019.htm
>> seems to have a pretty good summary.
> 
> Mmm, OK. Still not really understanding, but...

Light reacts primarily with electrons, which absorb it, then later emit it. 
Permittivity is the extent to which charges of different signs go different 
directions. If an electron tends to go left more than right, it builds up a 
charge on the left, which tends to make electrons keep farther away from the 
left, until it's full. Like a capacitor getting full. Clearly, if optics is 
affected by photons interacting with electrons, and there are more electrons 
going one way than the other, you're going to get different optical properties.

Permeability is how easily a magnetic field affects the material. If it 
tends to make the atoms line up, the magnetic field inside the substance 
will get stronger than the magnetic field that's causing things to line up.

The "electric" field is caused by charges, i.e., protons and electrons, 
which interact with photons. The "magnetic" field is caused by photons 
(primarily virtual photons) flooding an area and moving charges around. 
Hence the interactions between them, and the ways in which they affect optics.

> I'm just intrigued by the idea that measuring the electronic properties 
> of a substance will tell you all of its optical properties...

Sure. The light you see is coming from the interactions between photons and 
electrons. *Everything* outside the nucleus except gravity is interaction 
between photons and electrons. All of chemistry, optics, magnetism, 
electricity, heat, biology, etc is the "electronic" properties of 
substances. Measuring the electronic properties of a substance will tell you 
how much weight it will support, what temperature it will melt, how sticky 
it is, and what color it is. :-)

It's hard to measure things that complicated, tho, at that level, because 
the calculations are all infinite sums of hard-to-measure stuff. The nuclear 
interactions appear to follow the same sort of rules, except with 
coefficients on the factors of the infinite sums that converge much more 
slowly, so you have to take many many more terms into account before you can 
come up with a number that's close to what you measure.

-- 
   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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