St. wrote:

>     (Anyway, I'm looking for loops for my old Copycat now... That's damn 
> good too...)   ;)

My dad buys them from ebay.

In fact, no - he bought a reel of tape from ebay, and then bought a 
splicing kit and some tape from ebay too.

(He bought the Copycat from ebay, but the tape loop it came with was 
worn to hell. Using it results in thunderous echoy booming sounds not 
unlike Forbidden Planet...)

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Darren New wrote:
> Invisible wrote:
>> However, it's really damn unusual for a material's electrical or 
>> magnetic properties to have any bearing at all on its optical properties.
> 
> That's why mirrors made out of wood work so well, after all. :-)

Well, you know, there are conductive materials that are reflective, and 
ones that aren't. There are insulators that are reflective, and ones 
that aren't. There seems to be little correlation here.

>> * Iron is highly magnetic, while aluminium isn't. Good luck telling 
>> the two metals apart by their appearence!
> 
> Magnetism is a field of photons at a frequency you just can't see.

What an interesting concept...

>> * Electricity does not, under any remotely "normal" conditions, 
>> produce light or affect it in any way. (E.g., you can't bend light 
>> using electricity.) The same goes for magnetism.
> 
> Except for photoelectric effects, LEDs, solar cells, florescent light 
> bulbs, all that sort of thing.

Solar cells work by using strange chemistry rather than directly turning 
light into electricity. (Presumably that's why they're so inefficient.)

Florescent light bulbs work by stimulating atoms to release photons, not 
by directly turning electric oscilations into light.

I have no clue why LEDs work. But apparently they do. ;-)

> Don't you use a computer? What do you think you're looking at?

Electricity can be used to excite atoms in such a way that they release 
photons. So can heat energy, chemical energy, and all kinds of other 
energy. It's hardly unique to electricity. Basically if you get atoms 
excited enough, they glow.

>> (I still can't figure out why you can use an oscilator to make radio 
>> waves, but not light rays...)
> 
> You can. It just has to osscilate a lot faster.

I think I've found an answer for this one.

   frequency = velocity / wavelength

For light, the velocity varies a little, but it's roughly 300,000 km/s. 
That means that even if each wave is 1 km long (pretty damn long wave!), 
it's going to have a frequency of 300 kHz. If you make that wave 1 m 
long, that becomes 300 MHz, and by the time you get down to an utterly 
*microscopic* wavelength, you're well above the THz range.

AFAIK, nobody has ever made an oscilator that goes that fast... (Indeed, 
maybe there's even a quantum-mechanical reason why you *can't* do this? 
Don't electrons have a "frequency" after all?)

So it seems that unless you can find a material with an index of 
refraction of several thousand, you aren't going to make light with an 
electric oscilator.

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Darren New wrote:
> Invisible wrote:
>> bizare that electronic properties should actually affect optical ones, 
>> but there we are.)
> 
> Actually, the only interactions that take place outside the nucleus are 
> between electrons (and antielectrons, I guess) and photons, so it seems 
> pretty *necessary* more than *bizarre*. :-)

Well, sure, at quantum scales perhaps. At macroscopic scales? Well, 
let's put it this way: there's no simple, easily observable correlation 
between these variables in everyday life. I'm not denying that whoever 
wrote this thing knew what they were talking about...

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> For light, the velocity varies a little, but it's roughly 300,000 km/s. 
> That means that even if each wave is 1 km long (pretty damn long wave!), 
> it's going to have a frequency of 300 kHz. If you make that wave 1 m 
> long, that becomes 300 MHz, and by the time you get down to an utterly 
> *microscopic* wavelength, you're well above the THz range.

Wikipedia article on "color" has a list of wavelengths and frequencies 

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"Invisible" <voi### [at] devnull> wrote in message
news:47342cbb$1@news.povray.org...
> For light, the velocity varies a little, but it's roughly 300,000 km/s.

Ur, no. The speed of light in a vacuum doesn't vary at all. It's a universal
constant.

299 792 458 m.s^-1

Post a reply to this message

> "Invisible" <voi### [at] devnull> wrote in message
> news:47342cbb$1@news.povray.org...
>> For light, the velocity varies a little, but it's roughly 300,000 km/s.
> 
> Ur, no. The speed of light in a vacuum doesn't vary at all. It's a universal
> constant.
> 
> 299 792 458 m.s^-1

...

How the HECK did they measure that o_O

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Gail Shaw wrote:
> "Invisible" <voi### [at] devnull> wrote in message
> news:47342cbb$1@news.povray.org...
>> For light, the velocity varies a little, but it's roughly 300,000 km/s.
> 
> Ur, no. The speed of light in a vacuum doesn't vary at all. It's a universal
> constant.
> 
> 299 792 458 m.s^-1

Yes, the speed of light *in a vacuum* doesn't vary.

The speed of light in other mediums varies though. ;-)

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Nicolas Alvarez wrote:

>> 299 792 458 m.s^-1
> 
> ...
> 
> How the HECK did they measure that o_O

With lots of mirrors, as a guess...

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Invisible wrote:
> It's a phenomenon that has something to do with electricity, magnetism, 
> waves and particles, but nobody really understands what exactly. ;-)

	Actually, I'm sure physicists believe they understand electricity and 
magnetism to the letter. They consider the theory to be complete (and 
have for ages). So they'd probably disagree with you there.

> Specifically, light is an electromagnetic wave (or is it a subatomic 
> particle?) in a particular frequency range (or is that particle energy?) 
> that registers in our eyes due to the chemical transformations it 
> induces in certain protein groups.

	For a single photon, frequency is proportional to energy. A photon has 
both wave and particle properties, as does your finger, and just about 
anything else in the world. May be hard to fathom, but it's not unique 
to light.

> (I still can't figure out why you can use an oscilator to make radio 
> waves, but not light rays...)

	Just needs to oscillate at the frequency of light - I have no idea if 
it's practical, though.

-- 
Sarchasm: The gulf between the author of sarcastic wit and the person 
who doesn't get it.


                     /\  /\               /\  /
                    /  \/  \ u e e n     /  \/  a w a z
                        >>>>>>mue### [at] nawazorg<<<<<<
                                    anl

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Darren New wrote:
> Magnetism is a field of photons at a frequency you just can't see.

???

-- 
Sarchasm: The gulf between the author of sarcastic wit and the person 
who doesn't get it.


                     /\  /\               /\  /
                    /  \/  \ u e e n     /  \/  a w a z
                        >>>>>>mue### [at] nawazorg<<<<<<
                                    anl

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