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Why does light exist as different wavelengths?!


FrankNBerry
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There are plenty of explanations as to why light exists in different colors due to existing as different wavelengths, but what I can't find is any explanation as to why light exists as a variance of wavelengths in the first place. What process/force/function/whatever is it that gives rise to a spectrum of wavelengths as opposed to there just simply existing one wavelength?

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5 minutes ago, FrankNBerry said:

There are plenty of explanations as to why light exists in different colors due to existing as different wavelengths, but what I can't find is any explanation as to why light exists as a variance of wavelengths in the first place. What process/force/function/whatever is it that gives rise to a spectrum of wavelengths as opposed to there just simply existing one wavelength?

There's no reason to not have the various wavelengths, i.e. there's no physical law requiring this.

Some sources of light are a continuum, like blackbody radiation. If you accelerate a charged particle you get radiation that's related to the acceleration, and a wide range of accelerations are possible.

Quantized sources depend on the nature of the bound system's energy levels, and these are all different, with many of these systems technically having an infinite number of transitions available.

Even if you started with one wavelength, scattering processes and conservation of energy and momentum would require different wavelengths, as recoil would "steal" some energy from a photon, requiring a different energy after the interaction.

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5 minutes ago, FrankNBerry said:

There are plenty of explanations as to why light exists in different colors due to existing as different wavelengths, but what I can't find is any explanation as to why light exists as a variance of wavelengths in the first place. What process/force/function/whatever is it that gives rise to a spectrum of wavelengths as opposed to there just simply existing one wavelength?

(My emphasis.)

This video is famous and has been going around these forums for quite a while. I think it's related to your problem:

Light has no fundamental length parameter characterizing it --unlike electrons, or protons, for example--. Why? There you are.

Electrons cannot come in wavelengths much smaller than their so-called Compton wavelength. If you try to do so, you don't get smaller-wavelength electrons; you get more electrons and positrons of larger wavelengths than the electron's Compton wavelength. But photons behave differently.

Adding to what Swansont has said, wavelength is a frame-dependent quantity. If you had a photon with a certain wavelength in one frame, it would have a different wavelength in another frame.

But then you can ask again, why?

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Saying there is no reason not to have various wavelengths is a non-answer. It's no different than saying there's no reason not to have just one wavelength. If there is no perceived reason not to then by association there would be no reason to, either. There being no perceived physical laws within scientific majorities agreeance of this particular aspect of nature to me is the equivalent of saying "nobody knows nor has a solid explanation as to why. It just is.". Would I be accurate in this translation? Does science have any explanations at this time as to why spectrums of wavelengths exist in such confined ways?

Rainbows would seem to demonstrate that what we call light does indeed have a length parameter characterizing it. Unless I'm mistaken as to what is meant by "length parameter". Purple to red, looping endlessly. 

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Originally, there was only one wavelength, a boring shade of green that everyone got tired of.  So a team at MIT found a way for things to emit different wavelengths and reduce what had become near-suicidal levels of boredom.  Many wept when orange was first unveiled, anticipating how it would be abused in carpet coloring.

Seriously, it relates to energy.  Some of the energy in the emitter is converted from, say, the kinetic energy of its atoms, to light.  An electron "orbiting" one of the atoms at a high energy level plummets to a much lower energy state and a photon of light is emitted.  Due to the big drop in the electron's energy state, that photon carries off a lot of energy, which is expressed as a higher frequency and a shorter wavelength.   If the electron had only been a little bit excited, and then had a lesser drop in energy state, then the resulting photon would be less energetic, and you'd have lower frequency and longer wavelength.  One way to think of it is as jiggling a length of rope.  Vigorous jiggling (high energy) gives you lots of waves closely spaced, while listless shaking might just give a couple waves along a given length. 

 

Edited by TheVat
I just get off on editing. Sue me.
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2 hours ago, joigus said:

wavelength is a frame-dependent quantity. If you had a photon with a certain wavelength in one frame, it would have a different wavelength in another frame.

An excellent point. This shown up as Doppler broadening in spectroscopy. You broaden the resonance owing to the motion of e.g. a gas, so even though a particular transition might emit a narrow frequency band, the overall light for the sample covers a larger range, since various atoms have different Doppler shifts. 

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3 hours ago, FrankNBerry said:

Saying there is no reason not to have various wavelengths is a non-answer. It's no different than saying there's no reason not to have just one wavelength. If there is no perceived reason not to then by association there would be no reason to, either. There being no perceived physical laws within scientific majorities agreeance of this particular aspect of nature to me is the equivalent of saying "nobody knows nor has a solid explanation as to why. It just is.". Would I be accurate in this translation? Does science have any explanations at this time as to why spectrums of wavelengths exist in such confined ways?

Rainbows would seem to demonstrate that what we call light does indeed have a length parameter characterizing it. Unless I'm mistaken as to what is meant by "length parameter". Purple to red, looping endlessly. 

The thing you need to keep in mind is that light is always emitted by a source. The wavelength (frequency) is determined by the source that emits it. For example the famous sodium D lines, which make street lamps yellow, are due to sodium atoms emitting a pair of frequencies in the yellow region of the spectrum because the emission is due to electrons in sodium atoms dropping from a pair of levels in the atom to the ground state. But if you look at the tungsten filament in a lightbulb, that emits a continuous spectrum, because this is due to radiation due to thermal motion, rather than transitions between specific energy levels in the atom.  Alternatively a radio antenna emits radiation of far longer wavelength (lower frequency), corresponding to the frequency of the oscillation of electrons in the antenna. 

So it's all to do with the source of the light.

 

Edited by exchemist
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3 hours ago, FrankNBerry said:

Saying there is no reason not to have various wavelengths is a non-answer. It's no different than saying there's no reason not to have just one wavelength.

No, actually. Not in a physics context. There’s a concept in particle physics: that which is not forbidden is mandatory.

One frequency is a narrow constraint would require some physical law to be in place, such as conservation laws, and there aren’t any. 

It would be one thing to see that there were such laws, and one might ask why - and we start down the rabbit hole in the Feynman video joigus posted. Ultimately you hit a wall where you can’t explain why.

But contemplating why a physical law doesn’t exist is really a non-starter. You hit that wall immediately. You would need to explain why that law should exist.

 

Quote

If there is no perceived reason not to then by association there would be no reason to, either. There being no perceived physical laws within scientific majorities agreeance of this particular aspect of nature to me is the equivalent of saying "nobody knows nor has a solid explanation as to why. It just is.". Would I be accurate in this translation? Does science have any explanations at this time as to why spectrums of wavelengths exist in such confined ways?

 

Basically, science ultimately does not explain why. It explains how nature behaves.

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7 hours ago, TheVat said:

Originally, there was only one wavelength, a boring shade of green that everyone got tired of.  So a team at MIT found a way for things to emit different wavelengths and reduce what had become near-suicidal levels of boredom.  Many wept when orange was first unveiled, anticipating how it would be abused in carpet coloring.

Seriously, it relates to energy.  Some of the energy in the emitter is converted from, say, the kinetic energy of its atoms, to light.  An electron "orbiting" one of the atoms at a high energy level plummets to a much lower energy state and a photon of light is emitted.  Due to the big drop in the electron's energy state, that photon carries off a lot of energy, which is expressed as a higher frequency and a shorter wavelength.   If the electron had only been a little bit excited, and then had a lesser drop in energy state, then the resulting photon would be less energetic, and you'd have lower frequency and longer wavelength.  One way to think of it is as jiggling a length of rope.  Vigorous jiggling (high energy) gives you lots of waves closely spaced, while listless shaking might just give a couple waves along a given length. 

 

That explanation just rephrases my question from "why does light exist as different wavelengths?" to "why does light exist as different energy levels?" The wording changes, but the question still remains unanswered. These "energy" states vary for a reason. Is there an explanation as to why?

You jest about their once being one wavelength of green, yet it is possible that the entire color spectrum exists as only two "colors". 

The reason I'm asking is that I've reached a conclusion as to why there are varied wavelengths in light that results in a spectrum. I'm curious if anyone within the scientific fields have already reached any such conclusion themselves. 

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7 hours ago, FrankNBerry said:

That explanation just rephrases my question from "why does light exist as different wavelengths?" to "why does light exist as different energy levels?" The wording changes, but the question still remains unanswered. These "energy" states vary for a reason. Is there an explanation as to why?

You jest about their once being one wavelength of green, yet it is possible that the entire color spectrum exists as only two "colors". 

The reason I'm asking is that I've reached a conclusion as to why there are varied wavelengths in light that results in a spectrum. I'm curious if anyone within the scientific fields have already reached any such conclusion themselves. 

Yes, there are well understood reasons for why these energy states are what they are. This is what Quantum Mechanics tells us. QM also tells us how it is that electrons moving between states, or molecules moving between vibration or rotation states, or whatever it may be, can emit (and absorb) EM radiation. This was all sorted out in the 1920s and 1930s, actually, when QM was being originally developed.

So it has been widely known for about a century and is taught to all physics and chemistry undergraduates - and even in simplified form in schools, in the 6th form. You really need to read a bit about this before coming forward with ideas of your own. Otherwise you risk trying to reinvent the wheel, from a position of ignorance, which is obviously going to be asking for trouble. 

Edited by exchemist
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8 hours ago, FrankNBerry said:

These "energy" states vary for a reason. Is there an explanation as to why?

There are different elements and isotopes, each with a different electron energy structure, owing to the variation in the charges and charge distributions in the nucleus. The differences in the electrostatic interaction strength have a direct effect on the energy levels. (e.g. two protons have twice the force on an electron as compared to one proton, all else being the same)

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17 hours ago, joigus said:

Electrons cannot come in wavelengths much smaller than their so-called Compton wavelength. If you try to do so, you don't get smaller-wavelength electrons; you get more electrons and positrons of larger wavelengths than the electron's Compton wavelength. But photons behave differently.

This argument is incorrect because I was in a hurry. I will try to add the proper disclaimer later. Electrons cannot be probed with collision energies corresponding to wavelengths smaller than their Compton wavelength --I think that's the correct argument.

Edited by joigus
correction
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17 hours ago, FrankNBerry said:

There are plenty of explanations as to why light exists in different colors due to existing as different wavelengths, but what I can't find is any explanation as to why light exists as a variance of wavelengths in the first place. What process/force/function/whatever is it that gives rise to a spectrum of wavelengths as opposed to there just simply existing one wavelength?

Hello, Frank and welcome.

I wonder if you are asking your question in this way because you have placed it in the Physics section and been looking at Physics sources, which all refer to wavelength ?

But are you really interested in the colour theory itself, and the reason we have so many colours and how they all arise?

Please confirm whether you are really interested in wavelengths  - which is just a simple piece of Mathematics.

or

You are really interested on colours  - which is an interesting blend of Biology, Chemistry and Physics ?

Edited by studiot
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On 8/14/2021 at 5:03 AM, exchemist said:

Yes, there are well understood reasons for why these energy states are what they are. This is what Quantum Mechanics tells us. QM also tells us how it is that electrons moving between states, or molecules moving between vibration or rotation states, or whatever it may be, can emit (and absorb) EM radiation. This was all sorted out in the 1920s and 1930s, actually, when QM was being originally developed.

So it has been widely known for about a century and is taught to all physics and chemistry undergraduates - and even in simplified form in schools, in the 6th form. You really need to read a bit about this before coming forward with ideas of your own. Otherwise you risk trying to reinvent the wheel, from a position of ignorance, which is obviously going to be asking for trouble. 

It is ignorant comments like this, representative of a blind faith mimicked by followers, that makes so many people pull away from the construct of science. Every day more and  more people lose faith in science because it's just a bunch of repetitive nonsense. People claiming answers and intelligence yet never actually answer anything. They talk in circles when attempting to explain. QM doesn't tell us squat because it is a construct. Constructs can't tell us anything. You demonstrate ignorance yet refer to others as demonstrating ignorance. Shame on you. Stop mimicking others and actually think for yourself. 

On 8/14/2021 at 6:51 AM, studiot said:

Hello, Frank and welcome.

I wonder if you are asking your question in this way because you have placed it in the Physics section and been looking at Physics sources, which all refer to wavelength ?

But are you really interested in the colour theory itself, and the reason we have so many colours and how they all arise?

Please confirm whether you are really interested in wavelengths  - which is just a simple piece of Mathematics.

or

You are really interested on colours  - which is an interesting blend of Biology, Chemistry and Physics ?

Biology, Chemistry, and Physics are all representations of the same thing. Varied perceptions of just one behavior/force. What we call "color" exist as another representation of that force. You can't categorize my question as my question revolves around the very nature to which all categories exist.

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16 minutes ago, FrankNBerry said:

It is ignorant comments like this, representative of a blind faith mimicked by followers, that makes so many people pull away from the construct of science. Every day more and  more people lose faith in science because it's just a bunch of repetitive nonsense. People claiming answers and intelligence yet never actually answer anything. They talk in circles when attempting to explain. QM doesn't tell us squat because it is a construct. Constructs can't tell us anything. You demonstrate ignorance yet refer to others as demonstrating ignorance. Shame on you. Stop mimicking others and actually think for yourself. 

Biology, Chemistry, and Physics are all representations of the same thing. Varied perceptions of just one behavior/force. What we call "color" exist as another representation of that force. You can't categorize my question as my question revolves around the very nature to which all categories exist.

!

Moderator Note

If you make claims outside of established science, it is on you to explain how your model (or construct as you call it) has a better explanatory power than existing explanations. Just making claims without support and attacking established sciences, which actually do work, just does not cut it here.

 
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23 minutes ago, FrankNBerry said:

Biology, Chemistry, and Physics are all representations of the same thing. Varied perceptions of just one behavior/force. What we call "color" exist as another representation of that force. You can't categorize my question as my question revolves around the very nature to which all categories exist.

I am quite taken aback by this adverse reaction to my genuine attempt to draw out the meaning of your question, whatever it actually might be.

I don't know what your question is or what you mean by your original post so I asked, politely, for clarification.

As I don't know what your question is, no 'categorisation' was attempted.

 

I do however know that the quoted post makes a bold assertion, quite at variance with Physics, ancient and modern.

I hope this is not a back door attempt to introduce religous preaching about 'one force' .

So I ask you again, do you wish to discuss wavelength or do you wish to discuss colour ?

They are quite different things.

Perhaps you might like to think about the fact that the colour of an object is not always the same.
What colour do you think a red post office box appears under the light from a sodium lamp ?
 

Edited by studiot
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6 minutes ago, FrankNBerry said:

It is ignorant comments like this, representative of a blind faith mimicked by followers, that makes so many people pull away from the construct of science. Every day more and  more people lose faith in science because it's just a bunch of repetitive nonsense. People claiming answers and intelligence yet never actually answer anything. They talk in circles when attempting to explain. QM doesn't tell us squat because it is a construct. Constructs can't tell us anything. You demonstrate ignorance yet refer to others as demonstrating ignorance. Shame on you. Stop mimicking others and actually think for yourself. 

Biology, Chemistry, and Physics are all representations of the same thing. Varied perceptions of just one behavior/force. What we call "color" exist as another representation of that force. You can't categorize my question as my question revolves around the very nature to which all categories exist.

Aha. Good to see you run up the Jolly Roger at last: now we know what we are dealing with.  

Quantum Mechanics is a "construct" in the same sense as Newton's Laws. All theories are constructs, in that they extrapolate from observations to make general inferences - which are then tested against further observation. It is not "blind faith", because these theories are based on observation and tested against observation. So we know they work. That is the polar opposite of "blind faith". 

You appear to be attacking something here, without first taking the trouble to try to understand it. Is this wise?     

And, if you think such "constructs" can't tell us anything, I'll be intrigued to see you put forward a theory that is not a "construct" in this sense. 

 

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17 hours ago, FrankNBerry said:

It is ignorant comments like this, representative of a blind faith mimicked by followers, that makes so many people pull away from the construct of science. Every day more and  more people lose faith in science because it's just a bunch of repetitive nonsense. People claiming answers and intelligence yet never actually answer anything. They talk in circles when attempting to explain. QM doesn't tell us squat because it is a construct. Constructs can't tell us anything. You demonstrate ignorance yet refer to others as demonstrating ignorance. Shame on you. Stop mimicking others and actually think for yourself. 

And yet much of modern electronic technology is heavily reliant on QM. Integrated circuits and lasers — devices needed to make a computer/smart phone and a network run, allowing you to post this. Atomic clocks and GPS, which has become ubiquitous in much of the world. Medical technology like MRI. Quite a happy accident that they all work, despite constructs not being able to tell us anything.

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