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Author Topic: What is the difference between scattering and reflection of photons ?  (Read 2756 times)

Offline McQueen

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What is the difference between the scattering of photons and the reflection of photons. According to present wisdom, reflection of photons means that they ( bounce ?? ) of surfaces without any alteration in energy, frequency or wave-length while scattering constitutes absorption and emission of the photon with  a possible change in frequency, wave-length and energy.  If it is  possible to come up with a more absurd idea, I would like to be the first to hear it ? How, using whatsoever means of logic available is it possible for such an anomaly to take place? The discovery of the Balmer, Rydberg and Lyman series clearly demonstrates that light of specific wavelength is due to the absorption and emission of certain photon energies. How then is it possible for light ( any light) to just bounce off some surface and still preserve its original energy ! Surely it goes against the Laws of the Conservation of Energy, to even consider such a phenomenon ? Fortunately, it is possible to determine by experimentation whether the reflected light has the same frequency and wavelength as the  incident light. It is common knowledge that the reflected light and frequencies, barring any anomalies in the conditions in which the reading takes place such as interference with other matter, has the same frequency and wave length as the incident light. This is a physical impossibility precisely because even though a photon might be a mass-less particle it does possess energy on which depend both its frequency and wave-length, to assume that such a photon can bounce of an object without any change in its energy and a resultant change in frequency and wavelength is absolutely absurd.
I have emphasised over and over again in my posts that the old quantum mechanics view of photon emission and absorption as a one off process, a photon being absorbed and after a suitable interval being emitted and after another wait another interaction is a virtual dinosaur, that is NOT how things work. Instead photon absorption and emission should be viewed as taking place at the same frequency with which the electron is being irradiated, the electron oscillating rapidly back and forth between its rest state and excited state, giving rise to a steady stream of photons being emitted at the frequency and wave length needed to maintain the atom's equilibrium.  Two processes, one for scattering and one for reflection are not involved.

What does this mean ? It calls into question the whole ethos of the Big Bang that assumes that the process of multiple scattering changes the distribution of photon energies  from the gamma rays and optical photons to a black body spectrum that is characteristic of the core temperature, in a process known as thermalisation. the overall effect is that the energy that was generated by a small number of high energy photons  is now in the form of a large number of low energy photons whose energies are distributed according to a black body curve.   Leaving for the moment the issue of whether this change was due to the scattering or reflection of photons, (it doesn't really make much difference until it is applied in a different sense.).

According to the Big Bang Theory The Photon Epoch (or Radiation Domination),lasted  from 3 minutes to 240,000 years:

During this long period of gradual cooling, the universe is filled with plasma, a hot, opaque soup of atomic nuclei and electrons. After most of the leptons and antileptons had annihilated each other at the end of the Lepton Epoch, the energy of the universe is dominated by photons, which continue to interact frequently with the charged protons, electrons and nuclei.

The next stage in the Big Bang theory is the Recombination/Decoupling, lasting from 240,000 to 300,000 years:

As the temperature of the universe falls to around 3,000 degrees (about the same heat as the surface of the Sun) and its density also continues to fall, ionized hydrogen and helium atoms capture electrons (known as “recombination”), thus neutralizing their electric charge. With the electrons now bound to atoms, the universe finally becomes transparent to light, making this the earliest epoch observable today. It also releases the photons in the universe which have up till this time been interacting with electrons and protons in an opaque photon-baryon fluid (known as “decoupling”), and these photons (the same ones we see in today’s cosmic background radiation) can now travel freely. By the end of this period, the universe consists of a fog of about 75% hydrogen and 25% helium, with just traces of lithium.

It is time to pose the question and to honestly respond to it. Does this correspond in ANY WAY to what is known of photon emission and absorption.  The answer is that it does not, it is well known that photons mediate the energies of electrons as such any slight change in the electrons state will result in the emission and absorption of photons. It is impossible to even contemplate the number of photons that must have been created in this span of 240,000 years (approx.) certainly more than enough photons to fill the Universe . According to the Big Bang theory matter constitutes only 4% of the total matter in the Universe, how is it possible for that 4% of matter to absorb the numbers of photons produced during a period lasting 240,000 years. It is not possible, even taking into account thermalisation, it doesn't make sense. What does make sense is that as the photons permeated the whole of the Universe without possibility of interaction with matter, the energy was distributed in the same manner as thermalisation, but at such low energies as to create a 'virtual photon aether' allowing light to propagate. And setting the speed of light. 

Light any light does not occur in the form of individual photons, it occurs in the form of trillions and trillions of photons per second, imagine that process going on for 240,000 years (-3 minutes) and it is possible to see a Universe filled with light, which eventually, in the absence of any interaction with matter to renew their energies, faded to extremely low energies that constitute the 'virtual photon aether'.


 

Offline Phractality

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Energy and momentum are conserved. If one photon enters one side of an atom and only one photon exits the other side, then either the exit photon has the same energy and momentum as the entry photon (including exactly the same direction), or some momentum and energy are left behind in the atom, perhaps in the form of lifting an electron to a higher orbital.

A photon's energy is E = hc/λ = hf. Its momentum is p = E/c.

A visible photon's energy is roughly 4 x 10-19 J.
It's momentum is roughly 10-27 Newton second. 

A photon reflecting perpendicularly off of a massive mirror surface reverses its direction. This imparts very slightly less than twice the photon's initial momentum to the mirror, and the photon rebounds with very slightly less momentum than it had.

If the mirror's mass is 1 kg, its velocity changes by Δv = Δp/M = 2 x 10-27 Ns / kg = 2 x 10-27 m/s. It's energy changes by 1 x 10-54 J, which is 2.5 x 10-34 times the photon's energy. The reflected photon's wavelength is increased by a factor of 1 + (2.5 x 10-34). This is generally considered insignificant.

If the mirror's mass is 1 yoctogram, the factor becomes 1 + (2.5 x 10-7), which is still negligible, unless your searching for gravity waves.
[A proton's mass is 1.67 yoctogram.]

Until now, I've been tacitly using the mirror's own coordinate system. In another system with significant velocity relative to the mirror, there is a Doppler shift. If the mirror's motion is parallel to that of the incoming photon, the reflected photon will be redshifted; anti-parallel, blueshifted.
« Last Edit: 18/03/2016 18:53:23 by Phractality »
 

Offline McQueen

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Energy and momentum are conserved. If one photon enters one side of an atom and only one photon exits the other side, then either the exit photon has the same energy and momentum as the entry photon (including exactly the same direction), or some momentum and energy are left behind in the atom, perhaps in the form of lifting an electron to a higher orbital.

My point is this, is it really necessary to insist that a photon's frequency, which in any other sense, even  when a photon is considered as a radio wave, is a function of its periodicity, should in the case of optical photons be treated as a separate and distinctive property having nothing to do with periodicity but existing instead as some kind of abstract property with no physical meaning ? Surely that is ridiculous ? Bear with me for a moment, consider for instance the emission spectrum of hydrogen, can we assume that the hydrogen atom possesses only one electron ? If so how do you explain the emission spectrum of hydrogen which contains blue , green blue, red etc light each having distinctive frequencies. If it were an atom with multiple electrons there might be latitude for some confusion, however since there is only one electron involved, it follows ( indeed if any attempt is to be made to be logical, it must follow) that, if for instance the excited hydrogen atom is emitting blue light at 500 nm and  a frequency of 6 x 10 14  Hz, it follows that this must be due to that single electron oscillating back and forth at just those frequencies(i.e., at the rate of 6480ce1ba268927e3741d7e21420b161.gif times a second)?  Following this line of reasoning further if the electron in the hydrogen atom can oscillate at such frequencies isn't it possible that electrons in more complicated atoms possessing multiple electrons, have the same capability?  Now before you state that the frequency of the photon has nothing at all to do with it. Consider for instance the generation of Microwaves with frequencies   of  10 13 Hz, if it is possible for a man made device to create oscillations at 10 13 Hz , what makes it so impossible for an electron within an atom to oscillate at frequencies of 10 14 Hz. In fact to deny such a possibility, which is apparently what you are doing if I am not mistaken, is  totally unreasonable. Would you agree with this statement ?  In spite of the fact that it might be claimed that gravity waves have been found, there still seems to be some confusion on the mechanism of photon emission and the one off scenario that your post seems to imply apparently has widespread support. 

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A photon reflecting perpendicularly off of a massive mirror surface reverses its direction. This imparts very slightly less than twice the photon's initial momentum to the mirror, and the photon rebounds with very slightly less momentum than it had.
If the mirror's mass is 1 kg, its velocity changes by 7eece7ead9d0f6e2f87a73e8084ba9d7.gif It's energy changes by d06675394ddcde2b33c367288e210304.gif J, which is 3c3b84690231f4575bbdea7951346d2a.gif times the photon's energy. The reflected photon's wavelength is increased by a factor of 9be7e69c16e8f0e4007b51be8d6e4d9b.gif). This is generally considered insignificant.

Too true but there is nothing in the realm of physics that states that it is in fact reflection that is taking place, in the example given above ( see first paragraph above) it is shown that photon emissions do take place at fantastic frequencies, the electrons oscillating trillions of times a second, why even consider a mechanism where the photon's wave-length is increased by a factor of 1dbe4d83d553385d677fa9ea15079443.gif , when in the first place such an insignificant (to us) difference, might be considerable for a photon and in the second place is totally unnecessary, a competent working mechanism of absorption and emission being already in place.   Why have a separate process for reflection and a separate process for scattering, when patently, there is absolutely no sane reason for it ?
 

Offline chiralSPO

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Bear with me for a moment, consider for instance the emission spectrum of hydrogen, can we assume that the hydrogen atom possesses only one electron ? If so how do you explain the emission spectrum of hydrogen which contains blue , green blue, red etc light each having distinctive frequencies. If it were an atom with multiple electrons there might be latitude for some confusion, however since there is only one electron involved,

A single hydrogen atom will only emit one photon at a time. The different frequencies available can be explained by there being multiple energy levels available, between which the electron can move. The reason the emission spectrum of hydrogen has multiple lines is because the samples used always have many atoms (I would be surprised if there were many measurements made on collections of fewer than 1010 atoms, and therefore 1010 electrons involved...)

it follows ( indeed if any attempt is to be made to be logical, it must follow) that, if for instance the excited hydrogen atom is emitting blue light at 500 nm and  a frequency of 6 x 10 14  Hz, it follows that this must be due to that single electron oscillating back and forth at just those frequencies(i.e., at the rate of 6480ce1ba268927e3741d7e21420b161.gif times a second)?  Following this line of reasoning further if the electron in the hydrogen atom can oscillate at such frequencies isn't it possible that electrons in more complicated atoms possessing multiple electrons, have the same capability?  Now before you state that the frequency of the photon has nothing at all to do with it. Consider for instance the generation of Microwaves with frequencies   of  10 13 Hz, if it is possible for a man made device to create oscillations at 10 13 Hz , what makes it so impossible for an electron within an atom to oscillate at frequencies of 10 14 Hz. In fact to deny such a possibility, which is apparently what you are doing if I am not mistaken, is  totally unreasonable. Would you agree with this statement ?  In spite of the fact that it might be claimed that gravity waves have been found, there still seems to be some confusion on the mechanism of photon emission and the one off scenario that your post seems to imply apparently has widespread support. 

Is it perhaps possible that there are multiple mechanisms of photon formation? Yes, we can make radio waves and microwaves by oscillating currents in wires. But what about systems that contain no electrons? For instance the gamma rays produced by annihilation of a proton and an antiproton, or gamma rays produced by transitions in nuclei, or x-rays produced by accelerating protons (cyclotron radiation)...

why even consider a mechanism where the photon's wave-length is increased by a factor of 1dbe4d83d553385d677fa9ea15079443.gif , when in the first place such an insignificant (to us) difference, might be considerable for a photon and in the second place is totally unnecessary, a competent working mechanism of absorption and emission being already in place.   Why have a separate process for reflection and a separate process for scattering, when patently, there is absolutely no sane reason for it ?

Maybe there are different models for the different processes because people have observed two distinct processes... That sounds sane to me.
 

Offline agyejy

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I'm going to quote another post that I wrote awhile ago. It has good information on what happens during absorption and emission of a photon:

http://www3.uji.es/~planelle/APUNTS/ESPECTROS/jce/JCEphoto.html - This is a very thorough explanation of absorption of photons with quicktime videos.

http://madsci.org/posts/archives/2004-04/1082128751.Ph.r.html - This is a more direct answer to your question.

http://webpages.ursinus.edu/lriley/courses/p212/lectures/node40.html - This is another explination of the absorption process.

The gist of the above is that in order for an electron to transition from one state to another it has to enter a supposition of the initial and final state. The resulting supposition is no longer time independent and evolves over a finite amount of time from being more initial state to being more final state with significant oscillations. The result for an electron in an atom is that the electron cloud changes shape in an oscillatory manner with a frequency that matches the light being emitted or absorbed.

The reason most physics courses don't talk about this processes is because it requires some pretty complicated mathematics (even by Quantum standards) and in general you can calculate everything you are likely to need to know about the absorption of a photon without ever detailing the processes. Most physical observables of interest like the energy of the photon can be calculated from the time independent stationary states so there is no reason to bother with the more complicated stuff.

The oscillations that occur in the electron wave function during a transition exactly match the oscillations of the incoming or outgoing photon.

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Why have a separate process for reflection and a separate process for scattering, when patently, there is absolutely no sane reason for it ?

Reflection and scattering are precisely the same thing. Reflection is just scattering from a lot of atoms all arranged in a very uniform way such that the resulting scattering is also very uniform and reinforces itself.
 

Offline Phractality

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A mirror's silver layer provides a constant-voltage surface. When a photon hits that surface, the outer electrons of the silver atoms move about in such a way that their combined electric fields together with the incoming photon add up to a constant-voltage surface. Subtracting the electric field of the incoming photon yields the electric field of a virtual photon continuing along the incoming photon's path and disappearing into the depths of the mirror's virtual image. When the electrons rebound to their equilibrium positions, they emit a real photon; and angle of incidence equals angle of reflection.

Total internal reflection, like in a glass prism, works on a different principle. I'll let you look that up, yourself.

The blue sky is caused by Rayleigh scattering. You can look that up, too.
 

Offline McQueen

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chiralSPO
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A single hydrogen atom will only emit one photon at a time. The different frequencies available can be explained by there being multiple energy levels available, between which the electron can move. The reason the emission spectrum of hydrogen has multiple lines is because the samples used always have many atoms (I would be surprised if there were many measurements made on collections of fewer than 1010atoms, and therefore 1010 electrons involved...)
May I request you, just for a moment to take your nose out of your books and say, take a walk around the garden or to sit and admire a favourite piece of furniture, its shape its colour and so on. Or even just look around at the clutter on your desk, the pens, the covers of books, maybe the mouse pad.  Try to imagine that all this wonderful, terrific wealth of information is being delivered to your senses by one atom, emitting one photon at a time, if you can succeed in doing this you are truly a magi of Quantum Mechanics, one of the consecrated !  If after this exercise you still feel that your impossible to ascertain statement is true, then well and good, my reasoning must be at fault and I will have to re-think my ideas.
 

Offline McQueen

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A mirror's silver layer provides a constant-voltage surface. When a photon hits that surface, the outer electrons of the silver atoms move about in such a way that their combined electric fields together with the incoming photon add up to a constant-voltage surface. Subtracting the electric field of the incoming photon yields the electric field of a virtual photon continuing along the incoming photon's path and disappearing into the depths of the mirror's virtual image. When the electrons rebound to their equilibrium positions, they emit a real photon; and angle of incidence equals angle of reflection. 

Unless my powers of observation are sadly lacking it seems to me that in order to justify the above statement there should be many more metallic surfaces present than occur naturally. In fact there appear to be more matte surfaces than reflective ones, yet they are also clearly visible. So your reasoning is that those surfaces, like mirrors that have a shiny metallic surface, reflect photons, while matte surfaces like woolen scarves or carpets or clothing absorb and re-emit photons to convey information. Doesn't this seem redundant to you, isn't it possible that metallic surfaces have so many suitable electrons at the surface  that they are able to absorb and re-emit a far greater range of photon energies than matte surfaces ?
 

Offline McQueen

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agyejy
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The oscillations that occur in the electron wave function during a transition exactly match the oscillations of the incoming or outgoing photon.
The above seems to be closer to the gist of what I have been saying and the links also seem to bear this out.
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Reflection and scattering are precisely the same thing. Reflection is just scattering from a lot of atoms all arranged in a very uniform way such that the resulting scattering is also very uniform and reinforces itself.

The above statement is not supported, according to present thinking, scattering and reflection are two different and separate processes.

 

Offline Thebox

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What is the difference between the scattering of photons and the reflection of photons.

What are these Photons you speak of?


 

Offline McQueen

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Thebox
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What are these Photons you speak of?
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In respect to a Photon, a Photon travels a linear path at the speed of the light (c)   .

The above is taken from your post The Theory of Realistic! . The photons I am referring to are the same photons ( apparently) that you are referring to in your post.
 

Offline chiralSPO

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A single hydrogen atom will only emit one photon at a time. The different frequencies available can be explained by there being multiple energy levels available, between which the electron can move. The reason the emission spectrum of hydrogen has multiple lines is because the samples used always have many atoms (I would be surprised if there were many measurements made on collections of fewer than 1010atoms, and therefore 1010 electrons involved...)
May I request you, just for a moment to take your nose out of your books and say, take a walk around the garden or to sit and admire a favourite piece of furniture, its shape its colour and so on. Or even just look around at the clutter on your desk, the pens, the covers of books, maybe the mouse pad.  Try to imagine that all this wonderful, terrific wealth of information is being delivered to your senses by one atom, emitting one photon at a time, if you can succeed in doing this you are truly a magi of Quantum Mechanics, one of the consecrated !  If after this exercise you still feel that your impossible to ascertain statement is true, then well and good, my reasoning must be at fault and I will have to re-think my ideas.

Please re-read my comment. I thought it was very clear that I was stating that our observations are of MANY atoms, and that therefore we must consider what happens in huge collections of atoms when trying to comprehend the world around us. Thus (relatively) simple treatment of single atom phenomena, when considered en mass yields the complex and beautiful world around us.
 

Offline Thebox

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Thebox
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What are these Photons you speak of?
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In respect to a Photon, a Photon travels a linear path at the speed of the light (c)   .

The above is taken from your post The Theory of Realistic! . The photons I am referring to are the same photons ( apparently) that you are referring to in your post.

ar, but if you had read further .

7. Understanding the constant-'constant of light propagating through space.


Light in a vacuum travels at 299 792 458 m / s and is a constant.   Space  is a near perfect vacuum and is ''transparent'' to light, meaning that space allows light to propagate through space unchanging in the constant speed.  Ourselves,  observe a clarity of space in that relatively we can observe distant objects reflecting light and the space between ourselves and the observed object  is not opaque, it is relatively perceived to be  ''see through''.  This observation is relatively constant to all visual observers in any frame of reference that is not in darkness. 

Let us consider the difference of  three dimensional objects relative to the surrounding relativity of the space and the observable effect of spectral colour.    When we are observing an object we observe three dimensional  light at the objects exact location, we see this three dimensional state of light as spectral colours.  We observe the ''tips'' of a length of light  to be different to that of the clarity of length of space.

 There is some ''truth'' in that the light propagating through space is observed as a dimensional singularity relative to sight,  thus proposing the matter reflecting or emitting light  are three dimensional  light singularities observed in  a one dimension singularity of light which is perceived to be a clarity in reactive observation.

Thus leading us to the proposition of the Box singularity, which we shall discuss in length in the next chapter.
In continuation of understanding the constant-'constant  let us look at the consistency of the
relativity of the observation of the  one dimensional whole of light propagating through space.

In imagination let us imagine the ''invisible man'' standing but only 10 feet away from us.  It would be a conclusion that it would be impossible to define the dimensions of the ''invisible man''.
In regards to this we can consider that the ''invisible man'' has no dimensions of width , height or length to reflect light at a greater ''band-width'' than the singularity whole .  In any direction of observing a length between eye and object  there is a ''truth'' in that we observe a singularity whole which has no apparent dimensions.
   
There is no lie's relatively that while submerged in a swimming pool we observe the length of water  before our eyes.   

Thus leading us to enquire about the nature of light and the existence of the said single particle namely the Photon.  Relatively no observer, observes the existence of a single photon, neither does the observer, observe such as photon packets.  Relatively all observers , observe the singularity whole to be not opaque. 

There is certainty a ''truth'' that we observe dust particles or the falling of rain or snow, but there is no ''truths'' in the relativity of us observing Photons. 
This does not  conclude that our eyes do not detect Photons, it concludes the relativity to observation.

 

Offline agyejy

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Reflection and scattering are precisely the same thing. Reflection is just scattering from a lot of atoms all arranged in a very uniform way such that the resulting scattering is also very uniform and reinforces itself.

The above statement is not supported, according to present thinking, scattering and reflection are two different and separate processes.

No reflection is just coherent scattering. They are not different processes.
 

Offline McQueen

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No reflection is just coherent scattering. They are not different processes.

Here is an account of the present wisdom on the phenomena of scattering and reflection, I do not  necessarily hold the same views:

What is the difference between Reflection and Scattering?

• Scattering is a wave property of matter whereas reflection is a particle property.
• Scattering requires a total absorption and emission of a particle or a photon, whereas reflection only bounces back the incident particle or wave.
• The wavelength of the incident wave can change due to scattering, but it cannot change due to reflection.
• Reflection is easily observable, whereas observation of scattering requires advanced equipment.
• The law of reflection holds to any reflective material whereas the equations for scattering is dependent on the materials and conditions used.
 
A radical shift is needed away from the  present  static treatment of  the phenomenon of the absorption  and emission of photons , it should be replaced with a dynamic model in which every object in the universe in thermal equilibrium  absorbs and emits radiation continuously. Why is this important ? It is important because this simple but important fact completely changes, or more accurately gives a new slant to ideas that were previously overshadowed by the considering of the emission and absorption of photons by looking at atomic models that give a one off description of the process but do not extend it to the everyday level where it would be obvious that each electron is absorbing and emitting photons at the photon frequency of the incident light. Any practitioner of Quantum Mechanics reading this will immediately state "What baloney!", frequency is an abstract property of the photon, it has no physical existence in reality.  If due consideration is paid to the fact that the frequency of photons was calculated in exactly the same manner that the frequency of radio waves or sound waves is calculated, namely by dividing the speed of the wave by the wave- length.   The wave-length of light can be calculated using an interferometer , since the speed of light is constant it is possible to calculate the frequency of that particular light ( if it is monochromatic).  It is therefore clear that the frequency of light does actually have some physical basis.  This being so it follows that electrons must be absorbing and emitting ( at least where reflection is concerned) photons at the same frequency as the incident radiation. However, Quantum Mechanics cannot agree to this as they do not believe there is a physical basis to the frequency of light precisely because of wave/particle duality. In Quantum Mechanics, at least as far as the emission and absorption of photons are concerned, the frequency of light is an abstract concept.  IF on the other hand we ignore wave/particle duality and view light as a synthesis of light and particle ( i.e., not light as either particle or wave but as both together)  rather like the  hypersound used in lipotripsy, which is most definitely a wave but whose effect are particle like, the concept of frequency of light as a physical quantity begins to make sense. This is the point I am trying to convey to chiralSPO, to theBox, and Phractality  who continue to evade or pretend not to see  the issue. Wave/particle duality is absolute bunkum and should be scrubbed. 

 

Offline agyejy

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Here is an account of the present wisdom on the phenomena of scattering and reflection, I do not  necessarily hold the same views:

What is the difference between Reflection and Scattering?

• Scattering is a wave property of matter whereas reflection is a particle property.
• Scattering requires a total absorption and emission of a particle or a photon, whereas reflection only bounces back the incident particle or wave.
• The wavelength of the incident wave can change due to scattering, but it cannot change due to reflection.
• Reflection is easily observable, whereas observation of scattering requires advanced equipment.
• The law of reflection holds to any reflective material whereas the equations for scattering is dependent on the materials and conditions used.

What exactly is your source for these statements?

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A radical shift is needed away from the  present  static treatment of  the phenomenon of the absorption  and emission of photons , it should be replaced with a dynamic model in which every object in the universe in thermal equilibrium  absorbs and emits radiation continuously.

That's exactly how the interactions between light and matter are modeled. The energy comes in quantized discrete packets but the processes are always continuous. Further an object in thermal equilibrium is always in the process of emitting and absorbing infrared photons. It is in fact emitting exactly as much as it is absorbing which is why it is in thermal equilibrium in the first place.

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Why is this important ? It is important because this simple but important fact completely changes, or more accurately gives a new slant to ideas that were previously overshadowed by the considering of the emission and absorption of photons by looking at atomic models that give a one off description of the process but do not extend it to the everyday level where it would be obvious that each electron is absorbing and emitting photons at the photon frequency of the incident light.

In no way do the current models of the atom prevent the atom from responding to light with a frequency that is not exactly matched to its energy level differences. To assert that the electrons of an atom would not respond to changing electric and magnetic fields would be absurd. Regardless of the frequency of the photon the electrons of an atom will be driven into a forced oscillation (a point made in at least one of my previous links if I recall correctly). If those oscillations resonate with a particular transition between energy levels there is a chance (and it isn't completely certain) the photon will be absorbed by the atom and the transition will occur. Once that transition occurs there is another chance the atom will return to its ground state by emitting an identical in frequency photon but there are other ways for the atom to give up that energy that doesn't require the emission of a photon. They are called non-radiative transitions. Resonate effects always cause large increases in intensity so when they occur they stand out against the background of non-resonant effects. Now if the forced oscillations do not resonate with a particular transition (and usually they don't) the electric and magnetic fields that are always produced by the oscillations of electrons (even during resonance) interact with but do not cancel the incoming electric and magnetic fields (the resonance during an absorption event causes a cancellation while resonance during emission as per stimulated emission and lasers causes reinforcement). The two fields interfere and the result is that the incoming photon is altered. This is called scattering. When a lot of atoms in a very regular arrangement do this the scattered waves all interfere with each other resulting in the observed macroscopic laws of reflection. If the surface doing the scattering is rough on a scale that is much much larger than the atoms but much much smaller than humans we get what is called a diffuse reflection. Most reflections are diffuse. All scattering and reflection of photons comes down to forced oscillations of electrons due to incident light that produce electromagnetic oscillations that cause the outgoing light to be slightly different.

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Any practitioner of Quantum Mechanics reading this will immediately state "What baloney!", frequency is an abstract property of the photon, it has no physical existence in reality.

Not unless this so called practitioner had absolutely no idea what they were talking about and was in fact just pretending to be scientifically literate.

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If due consideration is paid to the fact that the frequency of photons was calculated in exactly the same manner that the frequency of radio waves or sound waves is calculated, namely by dividing the speed of the wave by the wave- length.   The wave-length of light can be calculated using an interferometer , since the speed of light is constant it is possible to calculate the frequency of that particular light ( if it is monochromatic).  It is therefore clear that the frequency of light does actually have some physical basis.

No one versed in the science of electromagnetism would ever argue against this point.

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This being so it follows that electrons must be absorbing and emitting ( at least where reflection is concerned) photons at the same frequency as the incident radiation. However, Quantum Mechanics cannot agree to this as they do not believe there is a physical basis to the frequency of light precisely because of wave/particle duality.

This was all covered above. Atoms and their electrons must respond to any electric and magnetic fields that they encounter. There is no way around this. Absorption happens due to resonances and emission sometimes happens when an atom with a little too much energy gives it up. For all non-resonant cases the atom and its electrons still respond to the incoming photon and the result is an alteration of the photon. It is all considered under the heading of scattering kind of like all squares are rectangles.

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In Quantum Mechanics, at least as far as the emission and absorption of photons are concerned, the frequency of light is an abstract concept.  IF on the other hand we ignore wave/particle duality and view light as a synthesis of light and particle ( i.e., not light as either particle or wave but as both together)  rather like the  hypersound used in lipotripsy, which is most definitely a wave but whose effect are particle like, the concept of frequency of light as a physical quantity begins to make sense.

This is nothing but a failure to understand quantum mechanics and an apparent inability to accept verifiable experimental results.
 

Offline McQueen

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The two fields interfere and the result is that the incoming photon is altered. This is called scattering. When a lot of atoms in a very regular arrangement do this the scattered waves all interfere with each other resulting in the observed macroscopic laws of reflection. If the surface doing the scattering is rough on a scale that is much much larger than the atoms but much much smaller than humans we get what is called a diffuse reflection. Most reflections are diffuse. All scattering and reflection of photons comes down to forced oscillations of electrons due to incident light that produce electromagnetic oscillations that cause the outgoing light to be slightly different.

Here again you talk about fields rather than photon absorption and emission, so according to  you, [The two fields interfere and the result is that the incoming photon is altered.]  scattering is where the incoming light (electromagnetic field) behaves like a wave and interacts with the electron; is altered by the interaction and scattered.  Yet this is not what experiment shows occurs. The very definition of a  field(s) is that its energies are diffuse and spread out , experiment has shown that every electron reaction with incoming light is with a definite quanta of energy that reacts (or not)  with the electron.  You go onto say that if the material of the substance on which the light is impinging is smooth ( relative to the size of the atom) reflection results, if the surface is rough (relative to the size of the atom) a more diffuse form of reflection results. The point is (AND THIS IS SOMETHING THAT FIELDS CANNOT DO ) is that every photon/electron reaction requires a definite quanta of energy. How then can you put forward a wave theory as an explanation? OR is that the whole point of your post namely that reflection and scattering involve wave phenomena while absorption and emission require particle phenomena ?

How does sight work, is it the wave or particle nature or light that transmits the information. How do the various frequencies of light prior to being reflected effect what we see? Since the perception of color depends on the firing of these three types of nerve cells, do you suppose that it is fair to assume that sight actually involves the absorption of photons and the resultant (very specific) energy and not mere interaction with a wave, since it has to result in the firing of nerve receptors, a wave would be diffuse, how would it convey the exact energy needed. If you disagree with this supposition please give your reasons. If on the other hand you agree with that statement, just look around, try and calculate how many things you are seeing and how many photons those objects might represent and explain why sight works with emission and absorption but that a different mechanism is needed ( electromagnetic fields) when talking about reflection and scattering.
« Last Edit: 20/03/2016 10:42:58 by McQueen »
 

Offline Phractality

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Relatively no observer, observes the existence of a single photon, neither does the observer, observe such as photon packets. 

Human eyes may not be sensitive enough to observe a single photon, but our power of observation is not limited to our eyes.

Photo multiplier:
"For smaller photon fluxes, the photomultiplier can be operated in photon counting or Geiger mode (see also: single-photon avalanche diode). In Geiger mode the photomultiplier gain is set so high (using high voltage) that a single photo-electron resulting from a single photon incident on the primary surface generates a very large current at the output circuit."
 

Offline Thebox

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Relatively no observer, observes the existence of a single photon, neither does the observer, observe such as photon packets. 

Human eyes may not be sensitive enough to observe a single photon, but our power of observation is not limited to our eyes.

Photo multiplier:
"For smaller photon fluxes, the photomultiplier can be operated in photon counting or Geiger mode (see also: single-photon avalanche diode). In Geiger mode the photomultiplier gain is set so high (using high voltage) that a single photo-electron resulting from a single photon incident on the primary surface generates a very large current at the output circuit."

You are wrong sir, observation is limited to the eyes, I think you are referring to detection which is distinguishable from observation. In observation with your eyes you do not see directly individual photons, your eyes may detect single photons but your eyes certainty do not see them.
ANY act of measurement or detection is observer affect, to release a single drip of water from a tap is not the same as a flowing river. Let us imagine light is made up of tiny little particles called photons, IMAGINE giving the game away. 

Let us imagine light is not made of single particles and is a whole, now that is more realistic.


 

Offline McQueen

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Quantum Mechanics can certainly be very confusing. Here are some examples of questions and   answers . ( Questions In red, answers in blue)

Why don't atoms emit radio waves if  their electrons are in continuous motion? Since electrons are moving charges, shouldn't they be producing, at least, some tiny amount of radiation?

Congratulations!
Wondering about this was one of the questions that led to the development of quantum mechanics. You're asking about atomic orbitals.
You're quite right. IF the electrons were orbiting the nucleus like little planets around a sun, THEN they would emit radiation due to accelerating. The fact that they don't shows that model is wrong. Instead, we use the atomic orbital model.
Electrons act as both particles, and as waves. The reason they don't spiral into the nucleus and hit it, emitting radiation as they go, is because the model of the atom that describes electrons acting as little planets orbiting a nucleus sun is wrong. That model only accounts for their particle nature. Instead, you can think of electrons as existing both as particles, and as standing waves.


Here is another quote:
The electron is present as a cloud. Averaged over the cloud, the positive kinetic energy is half as big as the negative potential energy.
More importantly, the cloud really is the state of the electron. It's not a picture of where some dot-like particle probably is. It isn't anywhere in particular. It also doesn't have any particular velocity.  In a hydrogen atom, it's certainly not going in a circle. The cloud doesn't go anywhere at all. There's no reason for it to radiate.
The world at a small scale cannot be put together out of anything like the pictures we're used to at a large scale.
 


These were the problems that gripped quantum mechanics almost a hundred years ago when it first came into being. TODAY the answer might go something like this:

The electron is constantly emitting and absorbing 'virtual' photons which enable it to maintain its equilibrium around the nucleus. Hence (theoretically) no need for wave/particle duality.

Here is an extract from a book : Atoms, Molecules and Photons: An Introduction to Atomic-, Molecular- and quantum physics.
By Wolfgang Demtröder

"An atom can absorb or emit electromagnetic radiation. The correction description has to take into account the interaction of this atom with the radiation field. This interaction is not only present during the absorption and emission of photons, but also for the so called 'virtual interactions' where the atomic electron in the Coulomb field of the nucleus can absorb and then emit a photon of energy 0f9925457a8362dfbd541adaef71e405.gif during a time interval 7858770def844cb6504cba0cb2a8c6c7.gif. The uncertainty relation dab3651a8561d92b4e836b3acf3ae33c.gif allows such processes without violating the energy conservation law.
This interaction leads to a small shift of the energy levels (Lamb shift), which depends on the spatial probability distribution of the electron in the Coulomb field of the nucleus and therefore on the quantum number n and l.
The Lamb Shift can be understood at least qualitatively by an illustrative simple model. Because of the photon recoil, the statistical virtual absorption and emission of photons results in a shaky movement of the electron in the Coulomb field of the nucleus. "


The above experiment demonstrates empirically that electrons constantly emit and absorb 'virtual' photons. Since this is the case, why still consider wave/particle duality ?

When two answers are available to a problem , why keep both ?
« Last Edit: 20/03/2016 15:50:46 by McQueen »
 

Offline Phractality

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You are wrong sir, observation is limited to the eyes, I think you are referring to detection which is distinguishable from observation.

Observation
is the active acquisition of information from a primary source. In living beings, observation employs the senses. In science, observation can also involve the recording of data via the use of instruments. The term may also refer to any data collected during the scientific activity. Observations can be qualitative, that is, only the absence or presence of a property is noted, or quantitative if a numerical value is attached to the observed phenomenon by counting or measuring.
 

Offline McQueen

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Just an addition to my last post; You do see the difference between a hundred years ago and today, right. But for Quantum Mechanics apparently not. Theories, some of them pretty flaky, thought up a hundred years ago, when classical physics had nothing better to offer are still strictly followed today, even though alternative theories are available. In fact today's Quantum Mechanics is as close to an aether theory as it is possible to get without actually saying it. In giving explanations like :

The electron is present as a cloud. Averaged over the cloud, the positive kinetic energy is half as big as the negative potential energy.
More importantly, the cloud really is the state of the electron. It's not a picture of where some dot-like particle probably is. It isn't anywhere in particular. It also doesn't have any particular velocity.  In a hydrogen atom, it's certainly not going in a circle. The cloud doesn't go anywhere at all. There's no reason for it to radiate.
The world at a small scale cannot be put together out of anything like the pictures we're used to at a large scale.


Quantum Mechanics seems to completely ignore the fact that an electron has mass, yet often tries to justify this view point on the grounds that the electron is a charged particle.  So according to Quantum Mechanics a particle possessing mass can possess a diffused form and exist as a wave or cloud AND a mass less photon can be a particle. There is in reality no justification for eithjer statement except that at the time there seemed to be a need for this to be true.


 
« Last Edit: 20/03/2016 23:52:45 by McQueen »
 

Offline agyejy

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Here again you talk about fields rather than photon absorption and emission, so according to  you, [The two fields interfere and the result is that the incoming photon is altered.]  scattering is where the incoming light (electromagnetic field) behaves like a wave and interacts with the electron; is altered by the interaction and scattered.  Yet this is not what experiment shows occurs. The very definition of a  field(s) is that its energies are diffuse and spread out , experiment has shown that every electron reaction with incoming light is with a definite quanta of energy that reacts (or not)  with the electron.  You go onto say that if the material of the substance on which the light is impinging is smooth ( relative to the size of the atom) reflection results, if the surface is rough (relative to the size of the atom) a more diffuse form of reflection results. The point is (AND THIS IS SOMETHING THAT FIELDS CANNOT DO ) is that every photon/electron reaction requires a definite quanta of energy. How then can you put forward a wave theory as an explanation? OR is that the whole point of your post namely that reflection and scattering involve wave phenomena while absorption and emission require particle phenomena ?

The first thing you have to keep in mind is that nothing is ever completely particle like or completely wave like in quantum mechanics. Sometimes you get more of one than the other but there is always some properties we associate with waves and always some properties we normally associate with particles. Quantum mechanics and more specifically the radically successful relativistic quantum field theories like quantum electrodynamics are specifically about the existence of quantized excitations of fields and how those excitations behave. The notion that excitations of fields cannot have a definite quanta of energy is a classical one that is very wrong. Quantum mechanics is in general a wave theory but the waves aren't exactly classical waves.

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How does sight work, is it the wave or particle nature or light that transmits the information. How do the various frequencies of light prior to being reflected effect what we see? Since the perception of color depends on the firing of these three types of nerve cells, do you suppose that it is fair to assume that sight actually involves the absorption of photons and the resultant (very specific) energy and not mere interaction with a wave, since it has to result in the firing of nerve receptors, a wave would be diffuse, how would it convey the exact energy needed. If you disagree with this supposition please give your reasons. If on the other hand you agree with that statement, just look around, try and calculate how many things you are seeing and how many photons those objects might represent and explain why sight works with emission and absorption but that a different mechanism is needed ( electromagnetic fields) when talking about reflection and scattering.

You are making a rigid distinction that doesn't exist anywhere in quantum mechanics. Nothing ever behaves completely as a classical wave or completely as a classical particle. The true behavior always has elements of both. Sometimes when writing scientists take shortcuts with their explanations and say things behaved like a particle or like a wave when they really mean the behavior was more like a particle than a wave or more like a wave than a particle. The rigid distinction you are trying to make between particle and wave does not exists in quantum mechanics and it doesn't exist in nature.

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But for Quantum Mechanics apparently not. Theories, some of them pretty flaky, thought up a hundred years ago, when classical physics had nothing better to offer are still strictly followed today, even though alternative theories are available. In fact today's Quantum Mechanics is as close to an aether theory as it is possible to get without actually saying it.

Yeah that isn't remotely true. Any decent historical account of quantum mechanics will give a pretty good account of how it has evolved over time.
 

Offline agyejy

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In giving explanations like :

The electron is present as a cloud. Averaged over the cloud, the positive kinetic energy is half as big as the negative potential energy.
More importantly, the cloud really is the state of the electron. It's not a picture of where some dot-like particle probably is. It isn't anywhere in particular. It also doesn't have any particular velocity.  In a hydrogen atom, it's certainly not going in a circle. The cloud doesn't go anywhere at all. There's no reason for it to radiate.
The world at a small scale cannot be put together out of anything like the pictures we're used to at a large scale.

Quantum Mechanics seems to completely ignore the fact that an electron has mass, yet often tries to justify this view point on the grounds that the electron is a charged particle.  So according to Quantum Mechanics a particle possessing mass can possess a diffused form and exist as a wave or cloud AND a mass less photon can be a particle. There is in reality no justification for eithjer statement except that at the time there seemed to be a need for this to be true.

Strange that you'd choose to edit a post after a reply. In any event the addition changes nothing. For starters nothing in the explanation you quoted implies any sort of aether. Secondly the mass of the electron is present in absolutely every equation that describes how electrons behave. It is far from ignored. Finally we have direct experimental confirmation of the electron cloud.

Here is an news article: http://io9.gizmodo.com/the-first-image-ever-of-a-hydrogen-atoms-orbital-struc-509684901

and here is the scientific paper: https://physics.aps.org/featured-article-pdf/10.1103/PhysRevLett.110.213001
 

Offline Phractality

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The electron is present as a cloud.
Yes; that is a useful simplification of reality. Treating electrons as probability clouds results in simpler maths than models that dare to consider the paths of electrons around individual circuits of their orbits, even below the Planck time scale.

Analogous models, i.e., models that are analogous to familiar mechanical systems, may offer a deeper and more psychologically satisfying reality. Some of us, who have not yet fully outgrown the "Why?" phase of our childhood development, are not fully satisfied with that electron cloud analogy. We need to know why the clouds is shaped as it is. Such quests for a deeper understanding, when not proven to have economic benefits, are considered frivolous, if not heretical, by all "serious" scientists. That has always been the case, hasn't it? Copernicus, Galileo, ....

Some such models are falsifiable by simulating the Planck-scale mechanics of virtual molecules. Then, integrating the locations of the virtual electrons should yield the known probability cloud for each Bohr orbital. Unfortunately, it may be necessary to renormalize a laundry list of parameters to yield the one combination that matches our universe. Come to think of it, my own model suffers from that malady. Too many unknown parameters; beginning with inertial density and hardness of the aether.
 

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