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Generating green light using a 510 nm AC current

J

Joop van der Velden

Jan 1, 1970
0
Bob said:
You can change "almost always" to "always" - it's just
that as you go lower and lower in frequency, the "launching"
of the EM waves becomes so inefficient as to be negligible.
Conversely, as you move to higher frequencies, it becomes
more and more dominant. Well before you get to "visible
light" frequencies, the "EM in space" path has become so dominant
that there is virtually nothing happening by what you think of
as ordinary conduction. Hence the early comment that
if you could "make electricity at 510 nm," you'd be making
green light already. Your problem all along has been that
you see "electricity" and "EM radiation" as two completely
separate phenomena, when in fact they're just two ways
of looking at what is basically one thing.

Maxwell explained it all 140 years ago.
http://en.wikipedia.org/wiki/Displacement_current

Any displacement of charge in a conductor *will* produce
electromagnetic waves. If the length of the displacement is more than
ca. 10% of the wavelength, an important part of the electrical energy
is radiated.

So yes, electrical current at 588THz (if you would be able to create
it) *will* produce EM radiation at 588THz, or green light.
 
Hi Mati,
Yes, I do understand that Einstein's model checks out while Newton's was
not quite right. But I was not talking about models, I was talking about
ontology's. And I do understand that Einstein's ontology was what must
be one of the most brilliant moves of the century. Even if Wolfgang
says, 'two such utterly different mathematical models', it can't be so
as the two models yield almost identical results. In context you can see
he means ontology's.
The difference between relativistic and Newtonian results is
proportional to (gamma -1) or to some power of this quantity,
depending on what it is we're talking about. I'm sitting right now on
the experimental floor of a synchrotron where the electrons are
circulating with gamma = 13700. The synchrotron radiation output is
proportional to gamma^2, thus the radiated power is nearly 9 orders of
magnitude higher than it would've been based on classical calculation.
Small difference? Yeah, sure.

So, no, it is simply *not true* that the two models yield "almost
identical results". This is an error, promoted by poorly written
popularizations. What is true is that within the narrow region of
physical parameters corresponding to our everyday experiences the
differences are small (as it is to be expected, once you think about
it). The further you get away from this region, the more the
differences grow, without limit.

To illustrate by example, the functions

f(x) = x/x_0
g(x) = sin(x/x_0)

are quite different in their behavior. One has a constant slope, the
other one doesn't. One grows (in absolute value) with no bound in
both directions of the X-axis, the other one is bounded. But, if you
would've only used a very narrow range of x values, say |x| < 0.001*x_0
then within this range the difference is negligible and may well go
unnoticed. And, you might've used f(x) for centuries, then, upon
learning that the more correct function is g(x), you could be
astonished at the thought that "two such different functions may yield
nearly the same results". But, they do not yield nearly the same
results, except within a narrow range of values of x.
Yes, I know.


Yes. And that was my point about interpretations of QM. It was
Wolfgang's point about the difference between the 'force of gravity' and
the 'curvature of space'.


Thanks for the credit, but I'll decline.
"Quantum electrodynamics "resolves" the wave-particle duality by saying
that light is made of particles, but the price of this great achievement
of science is a retreat by physics to a position of being able to
calculate only the probability that a photon will hit a detector,
without offering a good model of how it actually happens."
Feynman

Aha. And, is there anything in this passage about "little shiny
spheres"?

I'm not asking in jest. You keep harping on the term "particle".
Well, what is "particle"? You've to realize that lots of the physics
terminology was crafted in the "older, simpler times" when we dealt
with things directly accessible to the senses and could proceed with
no clear cut definitions, just some intuitively (here is this word
again) understood meanings. But by now we got far away from the
sandbox of science's childhood and those vague meanings are not good
enough. Clear definitions are needed. Absent a definition of what we
mean by "particle", an argument about whether photons are particles or
not is meaningless exercise. So, I suggest, try to define to yourself
what are the meanings you attach to the word "particle", then check
whether this agrees with the meaning used in QM.
There are many others.


Oh, I do know the quandary. Reading about QM has and still is a
wonderful experience. Bohm said it well:

"For example one may consider a water wave which causes a cork to bob.
The further the cork is from the center of the wave the less it will
move. But with the quantum field, it is as if the cork could bob with
full strength even far from the source of the wave."

I am not formally educated in the matter. I have read what I could on
the subject. hv is the quanta 'at transition'. We have, from what I
read, no observation that says light is otherwise corpuscular.
What do you mean "otherwise". Between interactions? I'll repeat
again, the only access we've to Mother Nature is through observations,
and observations mean interactions.

A repeated line in arguments here goes like "all you're telling me is
what it (where it can be light, gravity, heat, wave, whatever) does,
but I want to know what it *is*". Now, from the point of view of
physics, this is meaningless. From the point of view of physics, any
physical entity is fully characterized by the set of all its possible
interactions. That's the "is" for said entity and, as far as physics
is concerned, there is no other "is". Anything neyond the
interactions is metaphysics.

Mati Meron | "When you argue with a fool,
[email protected] | chances are he is doing just the same"
 
B

Bob Myers

Jan 1, 1970
0
Radium said:
Here are some things I have said to show that I know that electricity
has NO color what so ever:

"Light is electromagnetic radiation, yes. However, light is not
electricity. Electricity and electromagnetic radiation are two totally
different things."

I wouldn't be repeating such things if your aim is to show that
you understand this subject.
"The human eye cannot see electric current. It can see electromagnetic
radiation at the "visible light" range of frequencies. However,
electric current -- at any frequency -- is always invisible to the
human eye."

So what exactly IS "electric current," anyway? How rapidly
does it propagate?
"Think of a sound analogy. We can hear mechanical vibrations between
20-20K hz approx. However, we cannot hear electric current at any
frequency, can we."

Of course, that just MIGHT be because electromagnetic
radiation really IS a different phenomenon than pressure
waves in air - as opposed to being a "totally different thing"
than "electricity" - but we digress...

"Just like that, we can see electromagnetic radiation in the "visibile
light" frequencies but we cannot see their electrical equivalent."

"Electricity by itself is totally invisible and inaudible."

What IS the "electrical equivalent" of EM radiation, and again -
what is "electricity"?
So yes, I am well aware the electricity has no color at all.

If I wanted to start yet another extension of this thread, I would
note that in reality, NOTHING "has" any color at all, since color
is a perception, not a physical property. Ooops....looks like I've
gone and dont it. Darn. But I am at least confident that you
won't understand this one, either.

Bob M.
 
J

jasen

Jan 1, 1970
0
"Light is electromagnetic radiation, yes. However, light is not
electricity. Electricity and electromagnetic radiation are two totally
different things."

"The human eye cannot see electric current. It can see electromagnetic
radiation at the "visible light" range of frequencies. However,
electric current -- at any frequency -- is always invisible to the
human eye."

at 510 THz the electric current will be no more invisible than the
"conductor" carrying it.

visible in normal usage means not that our eyes sense the object, but
rather that they sense photons (or the absense thereof) coming from
the object.
"Think of a sound analogy. We can hear mechanical vibrations between
20-20K hz approx. However, we cannot hear electric current at any
frequency, can we."
"Just like that, we can see electromagnetic radiation in the "visibile
light" frequencies but we cannot see their electrical equivalent."

are you seriously suggesting we hear mechanical vibrations but can't see
electromagnetic ones?
So yes, I am well aware the electricity has no color at all.

looks kind of pink inside a neon tube :)
 
B

Bob May

Jan 1, 1970
0
Ah, but you did when you referred some light being generated as being blue
light!
 
D

Dan Bloomquist

Jan 1, 1970
0
The difference between relativistic and Newtonian results is
proportional to (gamma -1)...

Yes Mr. Meron, I know. But the above was about GR and Newtonian gravity,
not SR. I should have probably left this alone when you accused me of
building a straw man. Sorry to have troubled you.

Best, Dan.

--
"We need an energy policy that encourages consumption"
George W. Bush.

"Conservation may be a sign of personal virtue, but it is not a
sufficient basis for a sound, comprehensive energy policy."
Vice President Dick Cheney
 
R

Radium

Jan 1, 1970
0
Bob said:
I wouldn't be repeating such things if your aim is to show that
you understand this subject.
So what exactly IS "electric current," anyway?

Movement of electrons.
How rapidly
does it propagate?

Depends on resistance of conductor. In a vacuum it travels around
lightspeed.
Of course, that just MIGHT be because electromagnetic
radiation really IS a different phenomenon than pressure
waves in air - as opposed to being a "totally different thing"
than "electricity" - but we digress...
What IS the "electrical equivalent" of EM radiation,

Movement of electrons
and again -
what is "electricity"?

The type of energy that is negative in electrons/antiprotons and
positive in protons/positrons.
 
R

Radium

Jan 1, 1970
0
Bob said:
Ah, but you did when you referred some light being generated as being blue
light!

This "blue light" is incandescent and not directly caused by electric
current. Whereas my green light is generated directly by the electric
current.
 
T

Tim Ward

Jan 1, 1970
0
Radium said:
Movement of electrons.


Depends on resistance of conductor. In a vacuum it travels around
lightspeed.
<snippage of other stuff>

So, just how good a conductor is vacuum? Is that the best conductor?

Tim "always willing to learn" Ward
 
E

Eeyore

Jan 1, 1970
0
Radium said:
This "blue light" is incandescent and not directly caused by electric
current. Whereas my green light is generated directly by the electric
current.

I've some across 'purple light' in India when a medium voltage feed somehow
disentangled itself from a distribution box and ended up truly 'snaking' around
like a serpent alive ! Very dramatic indeed at night. It looked like a firework
display from a distance.

Graham
 
Yes Mr. Meron, I know. But the above was about GR and Newtonian gravity,
not SR. I should have probably left this alone when you accused me of
building a straw man. Sorry to have troubled you.
Well, the story is no different for GR, in this respect. Same as in
the previous case, it is not true, in general, that the difference
between the results of Newtonian gravity and GR is slight. It is only
true that the difference is slight in the "weak field" regime, which
is the one we're familiar with. Under other circumstances the
difference may be profound. And (again same as in the previous case)
it is not at all surprising that the difference is so slight within
the familiar regime, it can hardly be otherwise.

Mati Meron | "When you argue with a fool,
[email protected] | chances are he is doing just the same"
 
D

Duane C. Johnson

Jan 1, 1970
0
Hi Radium;

Radium said:
Bob Myers wrote:
Movement of electrons.

Not exactly.

In copper electrons move at about 1/2 cm per hour.
However, in a conductor the charge, not the electrons,
propagates at some large fraction of light speed.

As an analogy, water waves quite fast and to great
distances, but the water itself only moves in
circles and on average no distance.
Depends on resistance of conductor.
In a vacuum it travels around light speed.

Not possible as in a vacuum there would be
no electrons.
Movement of electrons

No, that would be photons.

Duane

--
Home of the $35 Solar Tracker Receiver
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R

Radium

Jan 1, 1970
0
jasen said:
at 510 THz the electric current will be no more invisible than the
"conductor" carrying it.

visible in normal usage means not that our eyes sense the object, but
rather that they sense photons (or the absense thereof) coming from
the object.
are you seriously suggesting we hear mechanical vibrations but can't see
electromagnetic ones?

We can see electromagnetic vibrations whose frequencies are around
384-769 THz.
 
D

Dan Bloomquist

Jan 1, 1970
0
Well, the story is no different for GR, in this respect. Same as in
the previous case, it is not true, in general, that the difference
between the results of Newtonian gravity and GR is slight. It is only
true that the difference is slight in the "weak field" regime, which
is the one we're familiar with. Under other circumstances the
difference may be profound.

Yes, I know. I got the Wolfgang quote from 'Exploring Black Holes',
Taylor, Wheeler. I read the book as diligently as I could more than
once. For all I recall you could have recommended it years ago.

But back to what you said, ''may' be profound'. We have barely tested
the deeper implication of GR.

Gravity Probe B
http://einstein.stanford.edu/
LIGO
http://www.ligo.caltech.edu/

Much less hands on with a black hole.
And (again same as in the previous case)
it is not at all surprising that the difference is so slight within
the familiar regime, it can hardly be otherwise.

But that is all we 'know' so far. And this is a quite a leap from the
discussion of ontology. So at that, it was the classical observations
between Newton's and Einstein's that I was addressing.

There are plenty of cranks on usenet, please don't treat me like one. I
started in this thread with:
"Has this is cross posted to sci.physics, corrections are welcome."
(Yea, shoulda been 'As')

It is you option to help me learn. If you choose to, I am grateful.

My present interest is QM. A wonderful mystery....
Mati Meron

Best, Dan.

--
"We need an energy policy that encourages consumption"
George W. Bush.

"Conservation may be a sign of personal virtue, but it is not a
sufficient basis for a sound, comprehensive energy policy."
Vice President Dick Cheney
 
Yes, I know. I got the Wolfgang quote from 'Exploring Black Holes',
Taylor, Wheeler. I read the book as diligently as I could more than
once. For all I recall you could have recommended it years ago.

Could be.
But back to what you said, ''may' be profound'. We have barely tested
the deeper implication of GR.
Yes, I agree.
Gravity Probe B
http://einstein.stanford.edu/
LIGO
http://www.ligo.caltech.edu/

Much less hands on with a black hole.

Most true. And it quite possible that, if we ever get to this point,
we'll find GR lacking too.
But that is all we 'know' so far. And this is a quite a leap from the
discussion of ontology. So at that, it was the classical observations
between Newton's and Einstein's that I was addressing.
If that's the whole scope (it wasn't clear from the original post)
then yes, within the realm we can lay our hands on, we're looking at
differences in the 7th decimal place or lower. The, potentially,
profound differences are extrapolations rather than observations.
There are plenty of cranks on usenet, please don't treat me like one.

Believe me, this was never my intention. Would've never mistaken you
for a crank. I know who are the sober minded people on this ng (since
there are quite few of these, it is not difficult to know). I was
just attempting to steer the discussion away from distinctions between
"what things are observed to be" and "what things intrinsically are",
because "this way are dragons".
It is you option to help me learn. If you choose to, I am grateful.

My present interest is QM. A wonderful mystery....
I fully agree. And, really, no less mysterious after nearly a century
of familiarity than it was at inception. We get used to it over time
but are never quite at ease with it.

Mati Meron | "When you argue with a fool,
[email protected] | chances are he is doing just the same"
 
D

Dan Bloomquist

Jan 1, 1970
0
Believe me, this was never my intention. Would've never mistaken you
for a crank. I know who are the sober minded people on this ng (since
there are quite few of these, it is not difficult to know). I was
just attempting to steer the discussion away from distinctions between
"what things are observed to be" and "what things intrinsically are",
because "this way are dragons".

Yes, thank you very much. And my intention if it seems otherwise.
I fully agree. And, really, no less mysterious after nearly a century
of familiarity than it was at inception. We get used to it over time
but are never quite at ease with it.

Yes. I may have no clue. I probably don't and don't realize this, (or I
do :)

I only want to explore the possibilities even if on the coattails of
great thinkers. Nature is such a great challenge, to interpret. I have
no predisposition. I mean that...

I do think that Einstein had it right, don't think inside a box...
Mati Meron

Thanks again, Dan.

--
"We need an energy policy that encourages consumption"
George W. Bush.

"Conservation may be a sign of personal virtue, but it is not a
sufficient basis for a sound, comprehensive energy policy."
Vice President Dick Cheney
 
Yes, thank you very much. And my intention if it seems otherwise.
Good, we agree then.

Yes. I may have no clue. I probably don't and don't realize this, (or I
do :)

This is one of the cases where, the more you know, the more you know
that you don't know.
I only want to explore the possibilities even if on the coattails of
great thinkers. Nature is such a great challenge, to interpret. I have
no predisposition. I mean that...

I do think that Einstein had it right, don't think inside a box...
The problem with thinking outside the box is, the box is there for a
reason. You know that you've to get out of the box to find a new
path, but you also know that most of the stuff outside the box is
garbage. It is like the lottery, you can't win without buying a
ticket, but chances are that you'll only lose if you buy one.

So, the trick is to find the right way out of the box. But there is
no recipe for this.

Mati Meron | "When you argue with a fool,
[email protected] | chances are he is doing just the same"
 
D

Don Klipstein

Jan 1, 1970
0
default wrote: said:
In theory it should work - build an oscillator that works at that
frequency and it would give off light. Hertz proved the connection
with his experiments with microwaves. The same techniques used to
reflect and refract light work with radio waves

Now for practical considerations . . . Think about how small 510
nanometers really is. The resonant cavity in a magnetron, as a way to
generate light, would have to be on the order of 510 nm. Not possible
with present technology and not likely to be in the near future.

Someday, perhaps a shortcut could be found - will it replace other
light sources?

There are semiconductor resonators that oscillate at optical
frequencies. These are laser diodes. The laser "cavity" is very small,
and the light-emitting aperture of the resonant "cavity" of a typical
laser diode is maybe a micrometer or two in one direction by a few
micrometers in the other.

- Don Klipstein ([email protected])
 
D

Don Klipstein

Jan 1, 1970
0
Is it practical to make synchrotron lasers? A synchrotron laser use a
synchrotron as the source that emits light. The synchrotron is inside
the laser. The laser has two mirrors on each end. One is a
full-reflective mirror, the other is a partial-silvered mirror that
partially reflects and partially lets light out. Light of a certain
wavelength is emitted from the synchrotron, this light hits both
mirrors thereby reflecting continuously, the coherent light then leaves
the partial-silvered mirror.

There is such a thing as a "free electron laser".

- Don Klipstein ([email protected])
 
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