Itoero Posted October 23, 2017 Author Posted October 23, 2017 38 minutes ago, Strange said: 1. A wave can. A wave isn't made of particles. So light does not exist out of photons(particles)? That's new. You contradict yourself. 44 minutes ago, Strange said: . Scattering is not the cause of refraction. Scattering causes light to be scattered in multiple directions Yes and when the scattering happens coherently, you can get refraction. 49 minutes ago, Strange said: Yes, because that defines how the light interacts with the particle. So, yes, scattering is affected by refractive index. But refraction is not scattering. It's not the same but scattering can cause refraction. Refraction and Raleigh scattering are both affected by the refractive index... Refraction is due to elastic coherent scattering, but you deny this? What happens with photons when light-propagation bends?
Strange Posted October 23, 2017 Posted October 23, 2017 (edited) 17 minutes ago, Itoero said: So light does not exist out of photons(particles)? I said a wave isn't made of particles. I even highlighted the words to make sure you didn't misunderstand. But you could win a gold medal for misunderstanding. 17 minutes ago, Itoero said: Yes and when the scattering happens coherently, you can get refraction. Really? Can you give an example? I haven't heard of that. Edited October 23, 2017 by Strange
swansont Posted October 24, 2017 Posted October 24, 2017 11 hours ago, Itoero said: That's true, if you don't like wave particle duality... It's true even if you do. Refraction has a classical explanation which does not involve scattering.
Itoero Posted October 24, 2017 Author Posted October 24, 2017 20 hours ago, Strange said: I said a wave isn't made of particles. I even highlighted the words to make sure you didn't misunderstand. But you could win a gold medal for misunderstanding. Yes of course. What do you mean when you say a wave isn't made of particles? Light is an electromagnetic wave and is made of photons. 20 hours ago, Strange said: Really? Can you give an example? I haven't heard of that. Get a grip, when photons don't scatter coherently then the intensity of light is normally speaking to low to be observed. The fact that we can see things means that observable light scatters coherently. Can you plz answer on this? What happens with photons when light-propagation bends? 11 hours ago, swansont said: It's true even if you do. Refraction has a classical explanation which does not involve scattering. Refraction is the classical explanation of a kind of scattering. The way light behaves in our atmosphere is basically described via Rayleigh scattering. There is water vapor in our atmosphere. So the interaction photons-watermolecules concern Rayleigh (elastic, coherent) scattering. When light enters liquid water (river, lake,...) it still scatters and it refracts. This shows that refraction is a kind of scattering. Do you deny this?
dimreepr Posted October 24, 2017 Posted October 24, 2017 A good rule of thumb is, read first then challenge. 27 minutes ago, Itoero said: Light is an electromagnetic wave and is made of photons. Nope, it's neither and both. Quote It expresses the inability of the classical concepts "particle" or "wave" to fully describe the behavior of quantum-scale objects. 36 minutes ago, Itoero said: The fact that we can see things means that observable light scatters coherently. Nope. https://www.google.co.uk/search?q=how+do+we+see&oq=how+do+we+&gs_l=psy-ab.1.0.0l10.3492.9034.0.11599.10.10.0.0.0.0.99.901.10.10.0....0...1.1.64.psy-ab..0.10.900...35i39k1j0i131k1j0i67k1.0.4BjEETkLP7k Take your pick, or read this. My point is, even I know this and I know almost nothing compared to the other contributors in this thread.
Itoero Posted October 24, 2017 Author Posted October 24, 2017 (edited) 58 minutes ago, dimreepr said: Nope, it's neither and both. What does that matter? The properties of observable light change because the interacting of photons with other particles. Is this not true perhaps? 58 minutes ago, dimreepr said: Nope. https://www.google.co.uk/search?q=how+do+we+see&oq=how+do+we+&gs_l=psy-ab.1.0.0l10.3492.9034.0.11599.10.10.0.0.0.0.99.901.10.10.0....0...1.1.64.psy-ab..0.10.900...35i39k1j0i131k1j0i67k1.0.4BjEETkLP7k Take your pick, or read this. That doesn't 'prove' anything. Why do people never answer on things that matter? Edited October 24, 2017 by Itoero -1
dimreepr Posted October 24, 2017 Posted October 24, 2017 I'm just going to follow your lead, downvote without reading. 30 minutes ago, Itoero said: Why do people never answer on things that matter? They have you just don't listen -1
studiot Posted October 24, 2017 Posted October 24, 2017 40 minutes ago, Itoero said: The properties of observable light change because the interacting of photons with other particles. Is this not true perhaps? Yes this can be true, but where is the guarantee that the photons will interact, they may not. What about the other circumstances that can change the properties of observable light, such as relative velocity? Quote A wave cannot change course without scattering of its particles. I am concerned about this assertion as it suggests you mean something different from the rest of us by the word 'scattering' Would you please explain what you mean.
Strange Posted October 24, 2017 Posted October 24, 2017 2 hours ago, Itoero said: Light is an electromagnetic wave and is made of photons. Not “and” but “or”. It can be describes bed either as a wave or in terms of photons. 2 hours ago, Itoero said: What happens with photons when light-propagation bends? I suggest you read Feynman’s book, QED. It is ver readable and explains how refraction, reflection and diffraction work. 2 hours ago, Itoero said: When light enters liquid water (river, lake,...) it still scatters and it refracts. Those are two different effects. You can have either one without the other. 59 minutes ago, Itoero said: The properties of observable light change because the interacting of photons with other particles. Is this not true perhaps? Are you confusing scattering with interaction? It is true that it is one possible description. But it also possible to describe most properties in terms of waves (without using photons). 1
swansont Posted October 25, 2017 Posted October 25, 2017 13 hours ago, Itoero said: Refraction is the classical explanation of a kind of scattering. The way light behaves in our atmosphere is basically described via Rayleigh scattering. There is water vapor in our atmosphere. So the interaction photons-watermolecules concern Rayleigh (elastic, coherent) scattering. When light enters liquid water (river, lake,...) it still scatters and it refracts. This shows that refraction is a kind of scattering. Do you deny this? Light scattering and refracting does not make refraction scattering. Rayleigh scattering is not refraction. Mie scattering is not refraction. Raman scattering is not refraction. Compton scattering is not refraction. Notice a pattern? All of the scattering processes have "scattering" in the name. If you Google scattering, refraction is not listed. It's not even in the "see also " section.
Itoero Posted October 25, 2017 Author Posted October 25, 2017 10 hours ago, swansont said: Light scattering and refracting does not make refraction scattering. Rayleigh scattering is not refraction. Mie scattering is not refraction. Raman scattering is not refraction. Compton scattering is not refraction. Notice a pattern? All of the scattering processes have "scattering" in the name. If you Google scattering, refraction is not listed. It's not even in the "see also " section. Scattering is not refraction. Depending on the medium, scattering causes refraction but it can cause a lot of other things so it's normal it's not mentioned in Wikipedia. I've read a couple discussions and papers and its pretty clear refractions has it origins in scattering. What happens with photons when light is refracted? When light enters an ocean, it tends to filter out red light (low energy) There are other factors but the radiation energy decides the penetration depth. (blue goes deeper then red) Photons in oceans eventually get absorbed by opaque particles. Scattering is interacting with a change in direction. How can photons behave like that in the ocean without scattering? 21 hours ago, Strange said: It is true that it is one possible description. But it also possible to describe most properties in terms of waves (without using photons). True, but in order to change the properties you need to interact with the wave....you can't really interact with a wave, you can only interact with its particles. 22 hours ago, studiot said: Yes this can be true, but where is the guarantee that the photons will interact, they may not. What about the other circumstances that can change the properties of observable light, such as relative velocity Can the properties of a wave be changed without interacting with its particles? Is that (relative velocity) because of the observer effect? 22 hours ago, studiot said: am concerned about this assertion as it suggests you mean something different from the rest of us by the word 'scattering' Would you please explain what you mean. Scattering imo means a change in direction due to a form of interaction. 'A form of interaction' can mean anything. 22 hours ago, dimreepr said: I'm just going to follow your lead, downvote without reading. 23 hours ago, Itoero said: Why do people never answer on things that matter? They have you just don't listen I'm giving down votes because I find your comments irrelevant and I don't like your tone. -1
dimreepr Posted October 25, 2017 Posted October 25, 2017 39 minutes ago, Itoero said: I'm giving down votes because I find your comments irrelevant 1 Perhaps you should read them first. 41 minutes ago, Itoero said: and I don't like your tone. Should I go an octave higher or lower? -1
studiot Posted October 25, 2017 Posted October 25, 2017 35 minutes ago, Itoero said: 22 hours ago, studiot said: Yes this can be true, but where is the guarantee that the photons will interact, they may not. What about the other circumstances that can change the properties of observable light, such as relative velocity Can the properties of a wave be changed without interacting with its particles? Is that (relative velocity) because of the observer effect? 22 hours ago, studiot said: am concerned about this assertion as it suggests you mean something different from the rest of us by the word 'scattering' Would you please explain what you mean. Scattering imo means a change in direction due to a form of interaction. 'A form of interaction' can mean anything. Frequency would be one such property. I had in mind the Doppler effect. That is too wide a definition. Yes scattering is a deflection of path. But scattering is a random effect. From a particle point of view it means that every particle is scattered a different variable amount in a different variable direction. From a wave/geometric point of view the same applies to rays. For light of a given frequency The turning of all particles or rays by a fixed or set amount within a single transmission medium is called reflection. The turning of all particles or rays by a fixed or set amount when passing from one medium to another is called refraction. Light of different frequencies may be separated by refraction as the turning is frequency dependent. Concentrating waves into regions of high and low intensity within a single medium or widening a geometric beam past obstacles within a single medium is called diffraction. 1
Strange Posted October 25, 2017 Posted October 25, 2017 5 hours ago, Itoero said: I've read a couple discussions and papers and its pretty clear refractions has it origins in scattering. Then you should be able to provide a reference. 5 hours ago, Itoero said: Scattering is interacting with a change in direction. So is refraction and reflection and diffraction. It doesn't mean they are all the same thing though. They are different interactions. 5 hours ago, Itoero said: True, but in order to change the properties you need to interact with the wave....you can't really interact with a wave, you can only interact with its particles. So you mean the study of optics and electromagnetic waves was impossible before photons were understood? We can explain the behaviour of waves without needing to resort to photons. The photon description is unnecessarily complicated in most cases. 5 hours ago, Itoero said: Scattering imo means a change in direction due to a form of interaction. 'A form of interaction' can mean anything. Sounds like you are stretching the meaning of "scattering" to mean "any interaction of light with an object". If you do that, then yes your "scattering" is the cause of refraction. But you will now need to invent a new word for the process of scattering, which is different from refraction (even though it is caused by your "scattering"). But trying to win an argument by redefining well-understood terms is a bit silly.
Itoero Posted October 28, 2017 Author Posted October 28, 2017 (edited) On 25-10-2017 at 9:59 PM, Strange said: Sounds like you are stretching the meaning of "scattering" to mean "any interaction of light with an object". If you do that, then yes your "scattering" is the cause of refraction. I did not say anything that points in that direction. Don't make such silly assumptions. I'm not stretching anything, scattering is a change in direction due to a form of interaction.https://en.wikipedia.org/wiki/Scattering Photons travel at c but observable light only in vacuum. In a medium (with particles) the light is absorbed and re-emitted by the particles of the medium. Between re-emitting/absorption events it travels at c, but its overall speed through the medium is slowed. The re-emitting can also change the direction (rayleigh, compton...) which also slows the speed or it can cause a sort of filtering effect. Scattering is about particle behavior while diffraction, reflection and refraction are about waves that exist out of many particles. This is of course very relative. You can treat waves as particles, like in this paper.https://arxiv.org/pdf/1502.05722.pdf "Radio-wave scattering in the turbulent interstellar medium (ISM) produces familiar e ects: scintillation in frequency,time, and position. This scintillation has two distinct branches: di ractive and refractive." Light scatters in the atmosphere and in water so refraction is due to scattering.https://en.wikipedia.org/wiki/Color_of_water (this shows that light scatters in water)The atmosphere and water have a different refractive index...which causes refraction. The refractive index is a number that describes how light propagates through a medium...propagation works via the interacting of the photons with the particles of that medium...this implies scattering. Edited October 28, 2017 by Itoero
Strange Posted October 28, 2017 Posted October 28, 2017 (edited) 47 minutes ago, Itoero said: The refractive index is a number that describes how light propagates through a medium...propagation works via the interacting of the photons with the particles of that medium...this implies scattering. No. Because not all interactions are scattering. Scattering is one specific type of interaction. (Or class, as there are several types of scattering. But none of them are refraction.) Edited October 28, 2017 by Strange
interested Posted October 29, 2017 Posted October 29, 2017 (edited) - Edited October 29, 2017 by interested posted on wrong thread
studiot Posted October 29, 2017 Posted October 29, 2017 Sorry you don't seem to have read my last post which answered the questions you posed in your previous reply.
swansont Posted October 29, 2017 Posted October 29, 2017 Scattering has a fixed angular variation which depends on the type of target. That is lacking with refraction — you can change the density of a gas and its index will change, affecting the angle of refraction. That doesn't happen with scattering — the number of targets affects the scattering rate, not the angle. One scatter per photon off of a target. The bottom line is that physics consensus is that refraction is not scattering.
studiot Posted October 29, 2017 Posted October 29, 2017 27 minutes ago, swansont said: Scattering has a fixed angular variation which depends on the type of target. That is lacking with refraction — you can change the density of a gas and its index will change, affecting the angle of refraction. That doesn't happen with scattering — the number of targets affects the scattering rate, not the angle. One scatter per photon off of a target. Would you like to explain further please? Quote Brittanica The preferred conversion reaction for the direct detection of fast neutrons tends to be the elastic-scattering interaction. The resulting recoil nuclei can absorb a significant fraction of the original neutron energy in a single scattering and then deposit that energy in a manner similar to that of any other charged particle. The scattered neutron, now with a lower energy, may either escape from the detector or possibly interact again elsewhere in its volume. The most common scattering target is hydrogen, and a fast neutron can transfer up to all its energy in a single collision with a hydrogen nucleus. The amount of energy transferred varies with the scattering angle, which in hydrogen covers a continuum from zero (corresponding to grazing-angle scattering) up to the full neutron energy (corresponding to a head-on collision). Thus, when monoenergetic fast neutrons strike a material containing hydrogen, a spectrum of recoil protons is produced that ranges in energy between these limits. Some information about the original energy of the neutrons can be deduced by recording the pulse height-spectrum from a hydrogen-containing detector. This process generally involves applying a computer-based deconvolution code to the measured spectrum and is one of the few methods generally available to experimentally measure fast-neutron energy spectra.
Itoero Posted October 29, 2017 Author Posted October 29, 2017 (edited) 17 hours ago, Strange said: No. Because not all interactions are scattering. Scattering is one specific type of interaction. (Or class, as there are several types of scattering. But none of them are refraction.) Scattering is indeed a kind of interacting...interacting that implies a change in direction. In order to change the direction of the wave propagation due to a change in transmission(refracting) then the wave interacts with the particles of the new transmission medium. According to wave function collapse, photons interact with the particles of the new medium. Refraction implies a change in direction of wave propagation so the interacting photons must also change direction. Interacting with a change in direction is scattering. =>wave function collapse states you can't refract without scattering. 2 hours ago, swansont said: Scattering has a fixed angular variation which depends on the type of target. That is lacking with refraction — you can change the density of a gas and its index will change, affecting the angle of refraction. That doesn't happen with scattering — the number of targets affects the scattering rate, not the angle. One scatter per photon off of a target. The bottom line is that physics consensus is that refraction is not scattering. Doesn't this depend if the scattering is elastic or inelastic? Inelastic scattering changes the energy, which changes the angle. On 25-10-2017 at 4:53 PM, studiot said: Frequency would be one such property. I had in mind the Doppler effect. Yes but the doppler effect is about observable light/waves. It does not state you can change the frequency without interacting. The energy is proportional to the frequency...can you change the energy of light without any interaction??? Their is definitely an interaction, else conservation of energy is wrong. On 25-10-2017 at 4:53 PM, studiot said: That is too wide a definition. Yes scattering is a deflection of path. But scattering is a random effect. From a particle point of view it means that every particle is scattered a different variable amount in a different variable direction. From a wave/geometric point of view the same applies to rays. For light of a given frequency The turning of all particles or rays by a fixed or set amount within a single transmission medium is called reflection. The turning of all particles or rays by a fixed or set amount when passing from one medium to another is called refraction. Light of different frequencies may be separated by refraction as the turning is frequency dependent. Concentrating waves into regions of high and low intensity within a single medium or widening a geometric beam past obstacles within a single medium is called diffraction. How do you refract a wave without interacting with its particles? Edited October 29, 2017 by Itoero 1
studiot Posted October 29, 2017 Posted October 29, 2017 2 hours ago, Itoero said: 1) Yes but the doppler effect is about observable light/waves. It does not state you can change the frequency without interacting. The energy is proportional to the frequency...can you change the energy of light without any interaction??? Their is definitely an interaction, else conservation of energy is wrong. 2) How do you refract a wave without interacting with its particles? I am going to put the your obstinacy down to the fact that English is not your first language. I also see that (at least) two others are frustrated about this because of the downvotes, but I think that excessive. So I am going to reverse one of them and try one last time to hold a discussion where each of us reads the other's post properly. 1) Yes observable light waves, but the observer has no power whasoever to alter the frequency of the oncoming light waves. I actually said that it was the circumstances which change the frequency and identified these circumstances as being relative velocity in the case of the Doppler effect. Consider two observers, Observer A is not in relative velocity vis-a-vis the source and sees particularly frequency light, Observer B is in relative velocity and observes a different frequency. Both measure frequency by the same method so interact with the light in identical fashion, so it is the circumstances not the interaction that matters. 2) I said nothing whatsoever about there being no interaction. I offered a list of different terms describing different effects following interaction. Why else do you think we have different terms? Note I was commenting on your definition/use of a single word - scattering - when I did this. And scattering was one of the terms I offered a description of. How else can we help overcome the language barrier and make your diiscussions in English more productive?
Strange Posted October 29, 2017 Posted October 29, 2017 3 hours ago, Itoero said: Scattering is indeed a kind of interacting Correct. 3 hours ago, Itoero said: Interacting with a change in direction is scattering. Incorrect. 38 minutes ago, studiot said: I am going to put the your obstinacy down to the fact that English is not your first language. You would think that with multiple native speakers telling him that "interaction" and "scattering" are not synonyms (not in common use and especially not in physics) he might get the idea. But apparently not. Obstinate is being kind. 3 hours ago, Itoero said: Yes but the doppler effect is about observable light/waves. It does not state you can change the frequency without interacting. The energy is proportional to the frequency...can you change the energy of light without any interaction??? Their is definitely an interaction, else conservation of energy is wrong. Doppler shift doesn't involve any interaction with the wave. It s not conservation of energy that is wrong but your understanding. 3 hours ago, Itoero said: How do you refract a wave without interacting with its particles? Straw man. The point is not that there is no interaction but this interaction is NOT scattering.
swansont Posted October 29, 2017 Posted October 29, 2017 6 hours ago, Itoero said: Doesn't this depend if the scattering is elastic or inelastic? Inelastic scattering changes the energy, which changes the angle. Rayleigh scattering is elastic.
Itoero Posted October 30, 2017 Author Posted October 30, 2017 21 hours ago, Strange said: Incorrect. Then what is scattering according to your opinion?https://en.wikipedia.org/wiki/Scattering Is Wikipedia wrong? 21 hours ago, Strange said: You would think that with multiple native speakers telling him that "interaction" and "scattering" are not synonyms (not in common use and especially not in physics) he might get the idea. But apparently not. Obstinate is being kind. Interaction can lead to scattering...they are obviously not the same thing. 19 hours ago, swansont said: Rayleigh scattering is elastic. There is rayleigh scattering in our atmosphere and oceans but that doesn't mean the moment of refraction is due to rayleigh scattering. And that doesn't matter since scattering implies being forced to deviate from a straight trajectory.https://en.wikipedia.org/wiki/Scattering Scattering implies a change in direction. (Do you deny this?) 22 hours ago, Strange said: raw man. The point is not that there is no interaction but this interaction is NOT scattering. This is just a question, no straw man, how do you refract a wave without interacting with its particles? (you just said there is no interaction) 22 hours ago, studiot said: Yes observable light waves, but the observer has no power whasoever to alter the frequency of the oncoming light waves. I actually said that it was the circumstances which change the frequency and identified these circumstances as being relative velocity in the case of the Doppler effect. Consider two observers, Observer A is not in relative velocity vis-a-vis the source and sees particularly frequency light, Observer B is in relative velocity and observes a different frequency. Both measure frequency by the same method so interact with the light in identical fashion, so it is the circumstances not the interaction that matters. indirectly caused E=hf So observer A sees different energy of light then observer B yet at the source the light is evenly distributed.....You can describe those thing 'classically' but in order to explain it you need to study the particle behavior. Quantum mechanical collapse states that when light does not travel trough vacuum, the photons interact with particles of the transmission medium they are in. On 25-10-2017 at 4:53 PM, studiot said: That is too wide a definition. Yes scattering is a deflection of path. But scattering is a random effect. From a particle point of view it means that every particle is scattered a different variable amount in a different variable direction How can anything deflect from its path without an interaction? What do you mean with this: "that every particle is scattered a different variable amount in a different variable direction" The momentum decides how the photon is scattered, how is that random?
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