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Offline Pmb

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Is Electromagnetic Energy Quantized?
« Reply #25 on: 03/04/2011 04:31:54 »
In chemistry we learned, E=hν which means energy equals planks constant times frequency. Our professor (and our book) then suggests that this means that energy can only exist in certain quantized amounts that are integers of planks constant. Is this true? The way I see it, assuming this equation is correct (which I am) this in no way suggests that electromagnetic energy is quantized. because ν, frequency, is not an integer. It can be any possible value, and any possible value times a constant can be anything. And if energy can be anything, that is the opposite of quantized. But that is not at all how it is being represented to us in class or in our literature. Am I missing something?
EM energy is quantized *fixing the frequency*. If frequency is free, then you can have whatever energy you want.
Not sure what that means.

To be precise, the EM field is quantized by quantizing the fiel into photons. I don't see where the frequency of these photons are fixed. What about a static electric field?
 

Offline JP

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Is Electromagnetic Energy Quantized?
« Reply #26 on: 03/04/2011 05:07:30 »
In chemistry we learned, E=hν which means energy equals planks constant times frequency. Our professor (and our book) then suggests that this means that energy can only exist in certain quantized amounts that are integers of planks constant. Is this true? The way I see it, assuming this equation is correct (which I am) this in no way suggests that electromagnetic energy is quantized. because ν, frequency, is not an integer. It can be any possible value, and any possible value times a constant can be anything. And if energy can be anything, that is the opposite of quantized. But that is not at all how it is being represented to us in class or in our literature. Am I missing something?
EM energy is quantized *fixing the frequency*. If frequency is free, then you can have whatever energy you want.
Not sure what that means.

To be precise, the EM field is quantized by quantizing the fiel into photons. I don't see where the frequency of these photons are fixed. What about a static electric field?

If you fix the frequency of the field, say for example making it perfectly green light of a given frequency, then the absolute smallest packet of energy you can see is 1 photon of that green light.  You can't subdivide the field into any smaller energy packets than that one photon.  You're free, of course, to choose any frequency you want, so those tiniest packets can be of different sizes if you choose a different frequency, but in all cases, there is a smallest packet of energy for your field and it is 1 photon.
 

Offline Heikki Rinnemaa

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Is Electromagnetic Energy Quantized?
« Reply #27 on: 03/04/2011 07:23:05 »
:)

http://en.wikipedia.org/wiki/Newton%27s_laws_of_motion#Newton.27s_second_law

Energy,,what is it?,, and what need to be exist,, that we can calculate energy?

F=ma,, m=mass,,m=matter

So,,we need matter, and therefore Energy is matter-motion result.

Without matter, mathematical calculated and technical system measured energy, cannot exist.


http://en.wikipedia.org/wiki/Planck_constant

I dont see that E=hv formula any m=matter,,so it cannot be nature thruth?

- Wave cannot made energy without matter-motion.
- Wave cannot exist without matter=m.

That is my thought,,can be wrong or right,,but that is my thought how i see this nature-situation with mathematical formulaes.

All physics theoretical stuff is not describe of nature-world,, i think,,:)






 

Offline syhprum

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Is Electromagnetic Energy Quantized?
« Reply #28 on: 03/04/2011 07:40:10 »
JP

"You're free, of course, to choose any frequency you want,"

In my opinion your are not free to choose any frequency you want I believe that the wavelength can only changed in discreate multiples of the Planck unit of length 1.6*10-35 m.
This has no practical effect now but may have been a factor during the 'big bang'
« Last Edit: 03/04/2011 10:37:45 by syhprum »
 

Offline Geezer

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Is Electromagnetic Energy Quantized?
« Reply #29 on: 03/04/2011 08:08:43 »
JP

"You're free, of course, to choose any frequency you want,"

In my opinion your are not free to choose any frequency you want I believe that the wavelength can only changed in discreate lengths of 1.6*10-35 m the Planck unit of length.
This has no practical effect now but may have been a factor during the 'big bang'

That's interesting. We should be able to detect those steps in frequency/wavelength. I always assumed the spectrum was continuous, but this would suggest it is not.
 

Offline lightarrow

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« Reply #30 on: 03/04/2011 13:20:33 »
Not sure what that means.
To be precise, the EM field is quantized by quantizing the fiel into photons. I don't see where the frequency of these photons are fixed. What about a static electric field?
I have not written that the frequency of these photons are fixed. As JP wrote, what I mean is that if you let the frequency f be as free as you want, you will never find a smallest packet of energy:
lim hf = 0.
f→0
« Last Edit: 03/04/2011 13:23:36 by lightarrow »
 

Offline lightarrow

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« Reply #31 on: 03/04/2011 13:41:59 »
JP

"You're free, of course, to choose any frequency you want,"

In my opinion your are not free to choose any frequency you want I believe that the wavelength can only changed in discreate lengths of 1.6*10-35 m the Planck unit of length.
This has no practical effect now but may have been a factor during the 'big bang'

That's interesting. We should be able to detect those steps in frequency/wavelength. I always assumed the spectrum was continuous, but this would suggest it is not.
Do you have in mind the separation between the two lines of the sodium's doublet? (one line of the doublet is at 589.0 nm, the other at 589.6 nm) You have 4*1025 possible lines between them. Are them enough for you?  :)
 

Offline syhprum

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« Reply #32 on: 03/04/2011 14:58:25 »
The question posed is 'Is Electromagnetic Energy Quantized' I agree that Quantization is not very apparent at optical frequencies but in the high temperature era early in the big bang it may well of had a part to play
 

Offline JP

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Is Electromagnetic Energy Quantized?
« Reply #33 on: 03/04/2011 17:25:43 »
The question posed is 'Is Electromagnetic Energy Quantized' I agree that Quantization is not very apparent at optical frequencies but in the high temperature era early in the big bang it may well of had a part to play

Interesting point, though I'm not sure if there's any way to test the idea that EM.  My feeling on the Planck units is that they're just an issue with our current theories, i.e. the standard model would need to account for quantum gravity at sub-Planck scales, which it doesn't currently do.  Therefore we can't reasonably make predictions in that region, but the Planck length might not have fundamental physical meaning other than us needing a better theory at those distances.  If string theory turns out to be right, from what I understand it does explain some sub-Planck structure.  Then again, the Planck length might be something extremely significant, but we just don't know yet.

By the way, if we're going to talk about Planck units, there is one thing that's bugged me with the explanation that they're special or in some way signify a breakdown of our laws of physics.  The Planck mass is huge compared to the other units: roughly 20 micrograms.  We can see things under a microscope with masses less than this...

 

Offline Pmb

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Is Electromagnetic Energy Quantized?
« Reply #34 on: 03/04/2011 17:37:26 »
If you fix the frequency of the field, say for example making it perfectly green light of a given frequency, then the absolute smallest packet of energy you can see is 1 photon of that green light.  You can't subdivide the field into any smaller energy packets than that one photon.  You're free, of course, to choose any frequency you want, so those tiniest packets can be of different sizes if you choose a different frequency, but in all cases, there is a smallest packet of energy for your field and it is 1 photon.
That was not what I was referring to. I was addressing the more general question regarding quantum field heory and the photons that make up the field. Those photons are, of course, virtual.

Regarding quantinization - Quantum mechanics doesn't imply that energy is always equantized. E.g. consider of a free particle. The quantum state has a continuum of energy states. The energy is only quantized when certain conditions hold true, e.g. when a particle is moving in a potential well.
 

Offline JP

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« Reply #35 on: 03/04/2011 17:52:01 »
Ah, I did misunderstand you.  I do agree that the physical process determines what frequencies of photons you can get.  Since these processes can vary, there is no rule saying that you can only get certain frequencies of photons in the universe.

However, quantization of light usually refers to the fact that each photon, no matter how it's been generated, cannot be sub-divided in energy.  It also refers to the fact that classical monochromatic light is in what's called a coherent state, and in that state, it is made up of only one kind of photon, so that there is a minimal packet of energy for that kind of light.
 

Offline Geezer

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« Reply #36 on: 03/04/2011 18:24:12 »
JP

"You're free, of course, to choose any frequency you want,"

In my opinion your are not free to choose any frequency you want I believe that the wavelength can only changed in discreate lengths of 1.6*10-35 m the Planck unit of length.
This has no practical effect now but may have been a factor during the 'big bang'



That's interesting. We should be able to detect those steps in frequency/wavelength. I always assumed the spectrum was continuous, but this would suggest it is not.
Do you have in mind the separation between the two lines of the sodium's doublet? (one line of the doublet is at 589.0 nm, the other at 589.6 nm) You have 4*1025 possible lines between them. Are them enough for you?  :)

I suppose it would! Thanks!
 

Offline Pmb

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« Reply #37 on: 03/04/2011 19:53:29 »
However, quantization of light usually refers to the fact that each photon, no matter how it's been generated, cannot be sub-divided in energy. etc.
Exactly! :)
 

Offline lightarrow

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« Reply #38 on: 03/04/2011 21:57:03 »
By the way, if we're going to talk about Planck units, there is one thing that's bugged me with the explanation that they're special or in some way signify a breakdown of our laws of physics.  The Planck mass is huge compared to the other units: roughly 20 micrograms.  We can see things under a microscope with masses less than this...

But you should confine those 20 micrograms in a 10-35 m radius black hole:

http://en.wikipedia.org/wiki/Planck_mass
Quote
The Planck mass is the mass of the Planck particle, a hypothetical minuscule black hole whose Schwarzschild radius equals the Planck length.

 

Offline yor_on

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« Reply #39 on: 04/04/2011 20:18:15 »
There are several tings I wonder about there :) But let's take Planck mass fist.

"The Planck mass is the mass a point particle would need to have for its classical Schwarzschild radius (the size of its event horizon, if you like) to be the same size as its quantum-mechanical Compton wavelength (or the spread of its wave-function, if you like). That mass is 1019 GeV/c2, or about 10-8 kilograms." So the concept of a plank mass being important to physics seems to be that it is at the relative size where general relativity and quantum gravity effects both can act on it. And that way the Planck length gets defined by that point particles possible mass.

If you compress that particle any more (Schwarzschild radius) you will get a black hole as Lightarrow pointed out. And if you look at the Compton wavelength you will find that it is what seems to define the border for where Quantum mechanical effects take over. Combining those two formulas "and solve for m, we find that at a mass of (hc/G)1/2 (about 10-5 g) the Schwarzschild radius and the Compton length are equal. This mass is called the Plank mass. The length at which the Schwarzschild radius and the Compton length are equal is called the Plank length. At the Plank length, both relativistic and quantum affects are equally dominant."

The Schwarzschild radius is given by Gm/c2 and the Compton length by h/mc. Then one also have to remember that 'point particles' is assumed to have no spatial size what so ever. Like a electron, and that seems to be proved by scattering experiments where they act different from what you can expect of particles of a definite size. And as we know, they can also become superimposed, in this case being in two locations at the same time, which is another excellent reason for calling their orbitals orbitals, instead of orbits which we use macroscopically.

But then we come to light. In the particle definition of photons we find that it is its frequency (the amount of waves passing a given point in time) that will define the energy. But if we instead look at waves the definition seems to be its amplitude (think of that as the highest and lowest points of a wave. Or as a 'length/measure' made of its vibrations up and down.)

So a waves amplitude is a photons frequency? If we now think of a wave getting 'expanded/red shifted' in space by a 'expansion'. How do I describe that as photons? As fewer passing some certain point in time? But a photon can also be sent one and one, as we define it? Or should I consider it as its 'frequency' changing by the expansion'? How can there be a frequency in one photon, quantized 'energy' is easier to accept for me that any frequency. To me it seems that all this started with assuming waves studying 'black body radiation'?
==

And what about a relative blue-shift as observed between two spacecrafts meeting? If looked at as waves it will then be the amplitude, but not the frequency changing? Well, not entirely true as you will see both a Lorentz contraction and Doppler Effect, but I should still have to define the energy increasing as having deeper troughs and higher crests?
« Last Edit: 04/04/2011 20:33:17 by yor_on »
 

Offline yor_on

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Is Electromagnetic Energy Quantized?
« Reply #40 on: 07/04/2011 13:02:08 »
If I got this correctly a single photon can't be 'red shifted'. The only thing that can red shift here is its position relative its companions (other photons) But that becomes weird to me. Easier to see it as a 'continuous' wave although that too becomes weird as we then will define energy as the (length too?) heights and troughs passing in that 'expansion'. But why would that decrease the height of it? Why couldn't it as easily be seen as just 'lengthening it' but staying on that 'height' when looked at purely as geometry? To assume that it 'sinks' is the same as having two poles with the wave as a slack rope in the middle, hanging in a bow. Then the 'expansion' would be the poles moving in opposite directions tensing that rope and stretching it, making the bow shrink into a line at some point, as it seems to me?

The other way is to assume it as something magnifying all positions. In that case any point of your wave will be added too, in three dimensions simultaneously, but there will be no bow 'shrinking' instead the wave will only get 'enlarged' in each point, begetting more points.

Well?
As I (naively) think of it.
 

Offline thebrain13

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« Reply #41 on: 08/04/2011 00:55:25 »
I agree with what most of you guys are saying now, we are coming together a bit. However, I do think that most people think quantized energy levels for photons means something completely different than basically, "light is carried by photons".

Anyways, Yor on, I think you bring up a very good point, and I never thought about that before. I have an answer for you, but its based upon my own (completely anti-particle) stuff, not modern physics.

However figuring out all the little nuances for how a "group" of things creates quantized objects, with "sometimes" quantized forces takes a ridiculous amount of work. It's not simple, to change directions from an all particle theory, like we are basically using now, to a completely divisible one like I am using, requires an enormous amount of new logic. You can't say anything without it appearing to have a million problems. I'll post my basic conceptual picture of what I think "particles" are.



 

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