0 Members and 1 Guest are viewing this topic.
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 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 It's energy changes by J, which is times the photon's energy. The reflected photon's wavelength is increased by a factor of ). This is generally considered insignificant.
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 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.
why even consider a mechanism where the photon's wave-length is increased by a factor of , 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 ?
http://www3.uji.es/~planelle/APUNTS/ESPECTROS/jce/JCEphoto.html [Links inactive - To make links active and clickable, login or click here to register] - This is a very thorough explanation of absorption of photons with quicktime videos.http://madsci.org/posts/archives/2004-04/1082128751.Ph.r.html [Links inactive - To make links active and clickable, login or click here to register] - This is a more direct answer to your question.http://webpages.ursinus.edu/lriley/courses/p212/lectures/node40.html [Links inactive - To make links active and clickable, login or click here to register] - 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.
Why have a separate process for reflection and a separate process for scattering, when patently, there is absolutely no sane reason for it ?
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...)
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.
The oscillations that occur in the electron wave function during a transition exactly match the oscillations of the incoming or outgoing photon.
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.
What is the difference between the scattering of photons and the reflection of photons.
What are these Photons you speak of?
In respect to a Photon, a Photon travels a linear path at the speed of the light (c) .
chiralSPOQuote 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.
TheboxQuote What are these Photons you speak of?Quote 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.
QuoteReflection 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.
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.
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.
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.
Relatively no observer, observes the existence of a single photon, neither does the observer, observe such as photon packets.
Quote from: Thebox on 19/03/2016 15:36:25Relatively 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. https://en.wikipedia.org/wiki/Photomultiplier#High_sensitivity_applications [Links inactive - To make links active and clickable, login or click here to register]"For smaller photon fluxes, the photomultiplier can be operated in photon counting or https://en.wikipedia.org/wiki/Geiger_counter [Links inactive - To make links active and clickable, login or click here to register] mode (see also: https://en.wikipedia.org/wiki/Single-Photon_Avalanche_Diode [Links inactive - To make links active and clickable, login or click here to register]). 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.
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.
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.
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, ....
On the subject of the multiple Dimensions arising from Schrodinger’s equation Max Born had this to say:“ We have two possibilities. Either we use waves in space of more than three dimensions…………..or we remain in three dimensional space, but give up the simple picture of the wave amplitude as an ordinary physical magnitude , and replace it with a purely mathematical concept into which we cannot enter.”
This is especially so when the Lamb shift has proven through solid, reproducible experimental evidence, the existence of virtual photons and especially when the emission and absorption of virtual particles automatically means that the need for an electron following the physical pattern of wave/particle duality no longer exists.
Virtual particles cannot and do not exist outside of quantum field theories like Quantum Electrodynamics. In general they are described as excitations of the underlying quantum fields that aren't stable enough to be real particles.
It is obvious that you do not read anything properly before replying.
I have stated that there is solid, verifiable and reproducible experimental evidence that 'virtual' particles do exist, in the form of the Lamb shift.
(You will be surprised to learn that until a very short time ago Quantum Mechanics supporters were claiming with equal fervour, that there were no such things as 'virtual' particles. )
That being so, how can you claim that virtual particles exist only in quantum mechanics ?
Or that they do not exist outside of the quantum field? This is like saying the moon can only be seen from your window!
You may claim that they are excitations of the underlying quantum fields. That doesn't mean that you are right.
It is perfectly reasonable to accept that there are really small interactions in the sub-atomic world that we cannot see or measure, and that being impossible to measure on our scale that they do not violate the conservation of energy laws.
This does not mean that they are evanescent waves or that they have to be evanescent waves. This will bring you full circle through the Schrodinger wave equation, to the question of how a wave, cloud or whatever, can absorb or emit a particle. Or does it emit a wave that turns into a particle. OR does this wave/particle entity have super powers that means it has to be neither and can interact with either ? Or that it is a particle when being measure and a wave when it is propagating. I repeat my Question WHY? WHY? WHY? when it is no longer necessary ?
Even more important and something that tells us a lot about what Quantum Mechanics is is the fact that if you except 'virtual' photons as being excitations of the field that the electron interacts with, then why is it still necessary to have the cloud theory. A dog in the manger is a veritable angel when compared to Quantum mechanics which just seems to want to hoard and hoard, everything it has ever thought of, even when thos ideas are obsolete.
No one that actually understands quantum field theory would ever make that claim. Also, theoretical understanding in science evolves over time. You cannot dismiss an entire domain of thought because it has gradually progressed through dedicated study and comparison to observation. To do so would be to deny the very concept of science itself and at that point the entire discussion becomes meaningless.
You cannot dismiss an entire domain of thought because it has gradually progressed through dedicated study and comparison to observation.
When one thing is made of something else that first thing can't exist without the second thing. Virtual particles are made from quantum fields and thus don't exist without quantum fields.
This a new theories forum so you can't relate everything back to quantum mechanics, saying things like , "Oh QM says it's not like that it's like this.". Immediately the whole concept of a New Theories forum becomes obsolete and it becomes instead a forum where Quantum Mechanics is literally forced down everyone's throats, regardless of any points or discrepancies that might be raised.
That is precisely why I am dismissing it, why have a wave/particle duality when there is no reason for it ,then again remember there is no reality in the sub-atomic world so how can you refer to it :
Look at this quote from QM once again: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. Firstly it is obvious that the whole raison d'etre of the 'electron as cloud' theory is because if it was not a cloud it would radiate energy and fall into the nucleus. Look in particular at the last sentence which is the justification: "There's no reason for it to radiate.". Well if the electron interacts with 'virtual' particles, whether they are fluctuations of the field or whatever there is an absolutely verifiable theory as to why it does not spiral into the nucleus, i.e., it mediates its energy through emission and absorption of 'virtual particles'. How come you now have two theories for why electrons do not fall into the nucleus? One because it interacts with 'virtual particles' and one because it is a wave or cloud? Notice I do not say , two reasons why electrons do not radiate, because the statement would not be supported by the facts. AND please do not try to brush this aside!
Look at the prejudice, first you are absolutely sure that the wave/particle duality has to be true because otherwise the electron would radiate away energy and fall into the nucleus , and then when a new discovery is made,namely 'virtual particles' you are equally certain that only the quantum mechanics theory of why they exist is true. How in the Big Bang do you account for the 100 or more fields that quantum mechanics postulate? Maybe each of these particles had its own associated field as a preordained prerequisite of the Big Bang? Your interpretation of QM sounds more like a h...'s a's the more I hear of it.