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This time, the URL really *does* say it all!
http://en.wikipedia.org/wiki/Negative_refractive_index
Mmm, I wonder if POV-Ray can do this?
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Invisible escribió:
> This time, the URL really *does* say it all!
>
> http://en.wikipedia.org/wiki/Negative_refractive_index
>
> Mmm, I wonder if POV-Ray can do this?
I remember somebody who was involved in the development of such
materials, and was asking on these newsgroups if POV-Ray could simulate
it. People weren't even sure what a negative index would look like, and
POV didn't either :)
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Nicolas Alvarez wrote:
> Invisible escribió:
>> This time, the URL really *does* say it all!
>>
>> http://en.wikipedia.org/wiki/Negative_refractive_index
>>
>> Mmm, I wonder if POV-Ray can do this?
>
> I remember somebody who was involved in the development of such
> materials, and was asking on these newsgroups if POV-Ray could simulate
> it. People weren't even sure what a negative index would look like, and
> POV didn't either :)
Yeah, I would think this is likely to freak POV-Ray out a bit...
According to Wikipedia's diagrams, such a material "reflects" light, but
with the angle of reflection NOT equal to the angle of incidence (as in
normal reflection), but computed by Snell's law instead (as per normal
refraction).
Damn weird if you ask me...
Also, apparently some materials have an IOR of less than 1. (E.g.,
0.98.) But not for optical wavelengths.
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Invisible <voi### [at] dev null> wrote:
> Mmm, I wonder if POV-Ray can do this?
Probably not. AFAIK povray has a very specific refraction formula, which
it converts to total internal reflection when needed. I'm all but certain
that this formula does not support the concept of negative IOR.
--
- Warp
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Invisible nous apporta ses lumieres en ce 2007/11/07 10:59:
> Nicolas Alvarez wrote:
>> Invisible escribió:
>>> This time, the URL really *does* say it all!
>>>
>>> http://en.wikipedia.org/wiki/Negative_refractive_index
>>>
>>> Mmm, I wonder if POV-Ray can do this?
>>
>> I remember somebody who was involved in the development of such
>> materials, and was asking on these newsgroups if POV-Ray could
>> simulate it. People weren't even sure what a negative index would look
>> like, and POV didn't either :)
>
> Yeah, I would think this is likely to freak POV-Ray out a bit...
>
> According to Wikipedia's diagrams, such a material "reflects" light, but
> with the angle of reflection NOT equal to the angle of incidence (as in
> normal reflection), but computed by Snell's law instead (as per normal
> refraction).
>
> Damn weird if you ask me...
>
> Also, apparently some materials have an IOR of less than 1. (E.g.,
> 0.98.) But not for optical wavelengths.
A wave guide have ior <1 for radio waves. You can't find the equivalent for IR
and visible light.
POV-Ray accept dispersion <0, but render the object as a mirror.
Try ior = -1.5 VS. 1.5... and the result is: (At least, it don't choke on this.)
Strange looking, unintuitive, but it work. I realy can't say if what I get is
physicaly acurate, as I don't have anything to compare to.
--
Alain
-------------------------------------------------
My wife likes to talk on the phone during sex; she called me from Chicago
last night.
Rodney Dangerfield
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Invisible wrote:
> This time, the URL really *does* say it all!
>
> http://en.wikipedia.org/wiki/Negative_refractive_index
>
> Mmm, I wonder if POV-Ray can do this?
I think I remember someone doing it a few years ago. It did produce
something like fur or so. Or am I mixing things up? ...
In p.b.i. there is a thread about 'fur and negative ior' of Swen Heinzel
dated march 21st 2002. Seems like I am indeed confusing some things. ;)
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Warp wrote:
> Invisible <voi### [at] devnull> wrote:
>> Mmm, I wonder if POV-Ray can do this?
>
> Probably not. AFAIK povray has a very specific refraction formula, which
> it converts to total internal reflection when needed. I'm all but certain
> that this formula does not support the concept of negative IOR.
That was more or less my diagnosis, yes. ;-)
It's not something any typical implementation would support unless the
designer purposely had this in mind, I would think.
Now negative light sources........ ;-)
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Orchid XP v7 escribió:
> Now negative light sources........ ;-)
You never tried it? It's fun. The shadows are brighter than the lit areas :)
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> This time, the URL really *does* say it all!
>
> http://en.wikipedia.org/wiki/Negative_refractive_index
>
> Mmm, I wonder if POV-Ray can do this?
Wow that's something to think about. It was only a few years ago I learned
that the refractive index is actually a complex number, useful when working
with things like polarisers and (liquid) crystals that do funky things to
the light.
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Invisible <voi### [at] devnull> wrote:
> This time, the URL really *does* say it all!
>
> http://en.wikipedia.org/wiki/Negative_refractive_index
>
> Mmm, I wonder if POV-Ray can do this?
sure:
http://www.opticsexpress.org/abstract.cfm?id=88325
Christoph Hormann, long contributor to povray, is one of the authors.
http://www.imagico.de/
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"nemesis" <nam### [at] gmailcom> wrote:
> Invisible <voi### [at] devnull> wrote:
> > This time, the URL really *does* say it all!
> >
> > http://en.wikipedia.org/wiki/Negative_refractive_index
> >
> > Mmm, I wonder if POV-Ray can do this?
>
> sure:
> http://www.opticsexpress.org/abstract.cfm?id=88325
>
> Christoph Hormann, long contributor to povray, is one of the authors.
> http://www.imagico.de/
a more direct link in his own site:
http://www.imagico.de/pov/metamaterials.html
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nemesis wrote:
> a more direct link in his own site:
> http://www.imagico.de/pov/metamaterials.html
Woah - so you mean POV-Ray already does this *now*?
Now suddenly the subject line seems even more appropriate. ;-)
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scott wrote:
>> This time, the URL really *does* say it all!
>>
>> http://en.wikipedia.org/wiki/Negative_refractive_index
>>
>> Mmm, I wonder if POV-Ray can do this?
>
> Wow that's something to think about. It was only a few years ago I
> learned that the refractive index is actually a complex number, useful
> when working with things like polarisers and (liquid) crystals that do
> funky things to the light.
Yeah, freaky isn't it?
(IIRC, the imaginary part of the complex number you speak of is just the
amount of absorption in the material, but yeah... it's derived from the
electronic permitivity and permeability or something. I find it rather
bizare that electronic properties should actually affect optical ones,
but there we are.)
BTW, did you know that there exist materials with an IOR even higher
than diamond? And there exist materials with a (positive) IOR < 1?
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> I find it rather
> bizare that electronic properties should actually affect optical ones,
> but there we are.)
Well yeh, what's light?
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And lo on Thu, 08 Nov 2007 10:50:34 -0000, scott <sco### [at] laptopcom> did
spake, saying:
>> I find it rather bizare that electronic properties should actually
>> affect optical ones, but there we are.)
>
> Well yeh, what's light?
Feathers, balloons, air :-P
--
Phil Cook
--
I once tried to be apathetic, but I just couldn't be bothered
http://flipc.blogspot.com
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"scott" <sco### [at] laptopcom> wrote in message news:4732e9fc@news.povray.org...
>> I find it rather
>> bizare that electronic properties should actually affect optical ones,
>> but there we are.)
>
> Well yeh, what's light?
Feathers are light. :-P
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"Phil Cook" <phi### [at] nospamrocainfreeservecouk> wrote in message
news:op.t1gz8td6c3xi7v@news.povray.org...
> And lo on Thu, 08 Nov 2007 10:50:34 -0000, scott <sco### [at] laptopcom> did
> spake, saying:
>
>>> I find it rather bizare that electronic properties should actually
>>> affect optical ones, but there we are.)
>>
>> Well yeh, what's light?
>
> Feathers, balloons, air :-P
Oh bugger, I didn't see your reply seemingly 25 minutes before mine and I
said much the same thing.
I could swear I refreshed the list before posting.
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And lo on Thu, 08 Nov 2007 11:43:01 -0000, Brian Elliott
<NotForSpam@AskIfUWant> did spake, saying:
> "Phil Cook" <phi### [at] nospamrocainfreeservecouk> wrote in message
> news:op.t1gz8td6c3xi7v@news.povray.org...
>> And lo on Thu, 08 Nov 2007 10:50:34 -0000, scott <sco### [at] laptopcom> did
>> spake, saying:
>>
>>>> I find it rather bizare that electronic properties should actually
>>>> affect optical ones, but there we are.)
>>>
>>> Well yeh, what's light?
>>
>> Feathers, balloons, air :-P
>
> Oh bugger, I didn't see your reply seemingly 25 minutes before mine and
> I said much the same thing.
>
> I could swear I refreshed the list before posting.
Great minds post alike.
--
Phil Cook
--
I once tried to be apathetic, but I just couldn't be bothered
http://flipc.blogspot.com
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scott wrote:
>> I find it rather bizare that electronic properties should actually
>> affect optical ones, but there we are.)
>
> Well yeh, what's light?
It's a phenomenon that has something to do with electricity, magnetism,
waves and particles, but nobody really understands what exactly. ;-)
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.
However, it's really damn unusual for a material's electrical or
magnetic properties to have any bearing at all on its optical properties.
* Impure water is an excellent conductor, while pure water is a very
good insulator. Yet both substances have almost identical optical
properties.
* Iron is highly magnetic, while aluminium isn't. Good luck telling the
two metals apart by their appearence!
* 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.
Sure, theoretically they're related. But it's not something you see in
the real world very often. ;-)
(I still can't figure out why you can use an oscilator to make radio
waves, but not light rays...)
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Invisible <voi### [at] devnull> wrote:
>
> * 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.
>
I thought lightning was normal at least in a storm.
> (I still can't figure out why you can use an oscilator to make radio
> waves, but not light rays...)
If you oscillate something fast enough it will heat up and emit light.
Stephen
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"Invisible" <voi### [at] devnull> a écrit dans le message de news:
4733016b$1@news.povray.org...
> (I still can't figure out why you can use an oscilator to make radio
> waves, but not light rays...)
Is not a laser an excitated resonant optical cavity eg a oscillator?
Marc
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Stephen wrote:
> Invisible <voi### [at] devnull> wrote:
>
>> * 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.
>
> I thought lightning was normal at least in a storm.
Oh, sure, if you make stuff hot it will give off light. (And other
frequencies, for that matter.) But you don't need to use electricity to
make things hot; you can use *anything* to make it hot, and it will
glow. So it's not really an electrical effect.
>> (I still can't figure out why you can use an oscilator to make radio
>> waves, but not light rays...)
>
> If you oscillate something fast enough it will heat up and emit light.
More to the point, presumably if you shine a light on some kind of
conductor, it will induce a current... (And yet nobody has found a way
to use this to convert sunlight to electricity yet. They all rely on
obscure chemical and physical properties to try to do the job.)
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M_a_r_c wrote:
>> (I still can't figure out why you can use an oscilator to make radio
>> waves, but not light rays...)
>
> Is not a laser an excitated resonant optical cavity eg a oscillator?
Actually, I thought it was a tube full of extremely hot gas with some
mirrors at the ends? (I don't know a huge amount about lasers.)
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Invisible <voi### [at] devnull> wrote:
> Stephen wrote:
> > Invisible <voi### [at] devnull> wrote:
> >
> >> * 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.
> >
> > I thought lightning was normal at least in a storm.
>
> Oh, sure, if you make stuff hot it will give off light. (And other
> frequencies, for that matter.) But you don't need to use electricity to
> make things hot; you can use *anything* to make it hot, and it will
> glow. So it's not really an electrical effect.
>
> >> (I still can't figure out why you can use an oscilator to make radio
> >> waves, but not light rays...)
> >
> > If you oscillate something fast enough it will heat up and emit light.
>
> More to the point, presumably if you shine a light on some kind of
> conductor, it will induce a current... (And yet nobody has found a way
> to use this to convert sunlight to electricity yet. They all rely on
> obscure chemical and physical properties to try to do the job.)
You’re nearer to school age than I am so you have a better chance of knowing
than I. I thought that you could not separate electricity and magnetism. Also
Light is part of the Electro magnetic spectrum and to my simple mind that
implies some sort of relationship.
Stephen
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> However, it's really damn unusual for a material's electrical or magnetic
> properties to have any bearing at all on its optical properties.
I thought it was quite common, eg nearly all electrical conductors are
opaque.
> * Impure water is an excellent conductor, while pure water is a very good
> insulator. Yet both substances have almost identical optical properties.
I wouldn't exactly call impure water an "excellent" conductor, but more
conductive than pure water yes...
> (I still can't figure out why you can use an oscilator to make radio
> waves, but not light rays...)
Lasers?
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scott 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.
>
> I thought it was quite common, eg nearly all electrical conductors are
> opaque.
...which the obvious exception of water, liquid NaCl, various kinds of
crystals... ;-)
>> * Impure water is an excellent conductor, while pure water is a very
>> good insulator. Yet both substances have almost identical optical
>> properties.
>
> I wouldn't exactly call impure water an "excellent" conductor, but more
> conductive than pure water yes...
Depends what the impurities are and how much. ;-)
>> (I still can't figure out why you can use an oscilator to make radio
>> waves, but not light rays...)
>
> Lasers?
I don't actually know how those work. I was under the impression that it
works by exciting atoms so that they emit photons - much the same way a
lump of iron glows if you put it in a hot fire. (But with some mirrors
in there to ensure the light only travels in one direction...)
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Invisible a écrit :
> scott wrote:
>> Lasers?
>
> I don't actually know how those work. I was under the impression that it
> works by exciting atoms so that they emit photons - much the same way a
> lump of iron glows if you put it in a hot fire. (But with some mirrors
> in there to ensure the light only travels in one direction...)
It's not the same thing at all. Laser light is very coherent, i.e. all
the photons in it have almost the same wavelength. When you just heat
iron you don't get that at all... And what makes it work is that the
mirrors build a resonant optical cavity, they are not there just to give
the direction.
--
Vincent
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"Invisible" <voi### [at] devnull> a écrit dans le message de news:
473326a7$1@news.povray.org...
>
> I don't actually know how those work. I was under the impression that it
> works by exciting atoms so that they emit photons - much the same way a
> lump of iron glows if you put it in a hot fire. (But with some mirrors in
> there to ensure the light only travels in one direction...)
AFAIK The optical cavity between the 2 mirrors works as a resonator or as an
amplifier with an amount (one of the mirrors is semi-reflective to allow
output) of reinjection of output into input.
Marc
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And lo on Thu, 08 Nov 2007 10:50:34 -0000, scott <sco### [at] laptopcom> did
spake, saying:
>> I find it rather bizare that electronic properties should actually
>> affect optical ones, but there we are.)
>
> Well yeh, what's light?
On a more serious note can anyone explain refraction in terms of
particles. To put it another way fit a standard double-slit experiment in
front of a transparent block set at an angle and then detect which slit
the photon is passing through then examine the terminus of the photon
through the block.
--
Phil Cook
--
I once tried to be apathetic, but I just couldn't be bothered
http://flipc.blogspot.com
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Invisible escribió:
> nemesis wrote:
>
>> a more direct link in his own site:
>> http://www.imagico.de/pov/metamaterials.html
>
> Woah - so you mean POV-Ray already does this *now*?
>
> Now suddenly the subject line seems even more appropriate. ;-)
WOAH
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Nicolas Alvarez <nic### [at] gmailisthebestcom> wrote:
> Invisible escribió:
> > nemesis wrote:
> >
> >> a more direct link in his own site:
> >> http://www.imagico.de/pov/metamaterials.html
> >
> > Woah - so you mean POV-Ray already does this *now*?
> >
> > Now suddenly the subject line seems even more appropriate. ;-)
>
> WOAH
updated the "External links" section in the wikipedia article to point to the
very handy visual presentation by Hormann...
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"Stephen" <mcavoys_AT_aolDOT.com> wrote in message
news:web.473305e34b19b3ff726bd13c0@news.povray.org...
> Invisible <voi### [at] devnull> wrote:
>
>>
>> * 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.
>>
> I thought lightning was normal at least in a storm.
>
>> (I still can't figure out why you can use an oscilator to make radio
>> waves, but not light rays...)
>
> If you oscillate something fast enough it will heat up and emit light.
Oh wow! When I was about 20('83), I remember borrowing a friends
German-made echo box for my (then horrible) lecky guitar, (it was a
*fantastic* echo box, but I can't remember what it was called), and it had
two lime green flourescent 'beams' that met in the middle when you hit the
sweet notes. Is that what you mean?
(Anyway, I'm looking for loops for my old Copycat now... That's damn
good too...) ;)
Sorry, just reminiscing... ;)
~Steve~
>
> Stephen
>
>
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> It's a phenomenon that has something to do with electricity, magnetism,
> waves and particles, but nobody really understands what exactly. ;-)
>
> 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.
E=MC^2
All matter is both mass and energy.
Photons are "packets" of energy that fluxuate between
electical potential and magnetic potential at a certain frequency,
a.k.a. an electromagnetic wave.
They have more energy than an electron.
> However, it's really damn unusual for a material's electrical or magnetic
> properties to have any bearing at all on its optical properties.
This is a common misconception.
The color of normal objects IS an electrical property,
it is the variation in electrical conductivity at optical frequencies.
> * Impure water is an excellent conductor, while pure water is a very good
> insulator. Yet both substances have almost identical optical properties.
Resistance in materials varies by frequency.
Both salt-water and pure water are conductive at optical frequencies.
> * Iron is highly magnetic, while aluminium isn't. Good luck telling the
> two metals apart by their appearence!
>
> * 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.
Because photons are in high frequency flux, they have both positive
and negative charge, or no DC charge (depending on
how you look at it).
> Sure, theoretically they're related. But it's not something you see in the
> real world very often. ;-)
>
> (I still can't figure out why you can use an oscilator to make radio
> waves, but not light rays...)
Imagine three arrow vectors sitting at the origin, they point X,Y,Z,
this represents mass, electical, and magnetic.
The arrows must maintain the same overall vector length
X+Y+Z = k. However, they can fluctuate.
If a photon collides with something it regains its mass, so the
electrical and magnetic portions are gone, if the photon then
reflects it again has no mass, but electical and magnetic.
In a solar panel the photon collides, gains mass, but then at
lower frequencies it's conduductive, so only a portion is
reflected as radiation, an electron sized chunk of the energy
goes off down the wires.
As an electron is excited to high frequencies by equipment,
many of the components (like wires) have high resistance to
high frequencies. That is why lasers use rubies, or gas tubes,
they are controlable high frequency oscilators that are still
conductive at optical frequencies.
That is also why you can fit more information down a fiber-
optic line than a copper line, fiber can operate at higher frequencies.
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Alain wrote:
> A wave guide have ior <1 for radio waves. You can't find the equivalent
> for IR and visible light.
Huh. Why not? Just because of the size of the atoms you'd have to build
it from or something?
--
Darren New / San Diego, CA, USA (PST)
Remember the good old days, when we
used to complain about cryptography
being export-restricted?
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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*. :-)
--
Darren New / San Diego, CA, USA (PST)
Remember the good old days, when we
used to complain about cryptography
being export-restricted?
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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. :-)
> * 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.
> * 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.
> Sure, theoretically they're related. But it's not something you see in
> the real world very often. ;-)
Don't you use a computer? What do you think you're looking at?
> (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.
--
Darren New / San Diego, CA, USA (PST)
Remember the good old days, when we
used to complain about cryptography
being export-restricted?
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M_a_r_c wrote:
> Is not a laser an excitated resonant optical cavity eg a oscillator?
No. You have to pump up the electrons into higher valences, and then
when one photon hits, it causes the excited atom to drop the next photon
at the same frequency and phase, because that's how the math comes out
for photons. (It's the opposite for electrons, which is why you can't
have more than two electrons in the same place and phase and all.)
The resonance comes from putting a mirror at each end to get the photons
crossing the substrate more than once, so they have a better chance of
hitting more atoms. But in theory, it would work if you just made a
sufficiently long tube, or you could keep the atoms pumped up without
interfering with the emmision. (The latter is what laser LEDs do, I think.)
--
Darren New / San Diego, CA, USA (PST)
Remember the good old days, when we
used to complain about cryptography
being export-restricted?
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Vincent Le Chevalier wrote:
> And what makes it work is that the mirrors build a resonant optical cavity,
I'm pretty sure that's not fundamental to getting the photons in phase.
--
Darren New / San Diego, CA, USA (PST)
Remember the good old days, when we
used to complain about cryptography
being export-restricted?
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Phil Cook wrote:
> On a more serious note can anyone explain refraction in terms of
> particles.
Yes.
http://www.amazon.com/QED-Strange-Princeton-Science-Library/dp/0691125759/ref=pd_bbs_1
--
Darren New / San Diego, CA, USA (PST)
Remember the good old days, when we
used to complain about cryptography
being export-restricted?
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And lo on Fri, 09 Nov 2007 00:41:46 -0000, Darren New <dne### [at] sanrrcom>
did spake, saying:
> Phil Cook wrote:
>> On a more serious note can anyone explain refraction in terms of
>> particles.
>
> Yes.
>
> http://www.amazon.com/QED-Strange-Princeton-Science-Library/dp/0691125
759/ref=pd_bbs_1
Thanks, though I note one commentator said "The problem is that we never
get an explanation for why the vectors point the way the do, are rotated
just so, etc. Without that it's simply voodoo, and nothing has been
explained." never mind. Amazon UK stocks it, but I'll check out my local
store first.
--
Phil Cook
--
I once tried to be apathetic, but I just couldn't be bothered
http://flipc.blogspot.com
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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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Invisible escribió:
> 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
for the different colors. Red is ~630–700 nm, ~480–430 THz.
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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
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Gail Shaw escribió:
> "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:
> Gail Shaw escribió:
>> 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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