How is heat caused by photons?

[Moviemann345]

When certain photons with the right energy hit an atom's electrons, the electrons of that atom can shift positions. Visually this is what I'm talking about: http://www.youtube.com/watch?v=L0UJhSvPE5A&feature=related"

From my understanding Heat=the vibration of atoms

When I rub my hands together the atoms vibrate because they push against each other & oscilate until they retain there original structure.

So when sun light 'heats' concrete are the shifting electrons from one concrete atom bumping into other concrete atoms' electrons---causing atomic vibrations throughout? Is this what's going on?

If not, how does heat work when caused by light?

 

[ZapperZ]

You may want to start by reading an entry in the FAQ thread in the General Physics section. The entry on photon transport though a medium, and the discussion on phonons will be of interest.

Zz.

 

[Moviemann345]

Thanks I'll check it out

 

[Incognition]

its because of the vibration when they bumb into each other, and causes heat.

try rub your hands together- the atoms vibration because they push against each other & oscilate until they retain there original structure.

http://bayarearoster.com/js/includes/34/b/happy.gif

 

[Naty1]

Heat transfer occurs due to conduction, convection and or radiation...When see you a red hot piece of metal, likely most of the heat transfer is due to radiation...a common term is thermal energy meaning heat is a type of energy...

background here: http://en.wikipedia.org/wiki/Heat_radiation

Since atoms and molecules are composed of charged particles, i.e. protons and electrons, their movements result in the emission of electromagnetic radiation, which carries energy away from the material. ... Since the amount of emitted radiation increases with increasing temperature, a net transfer of energy from higher temperatures to lower temperatures results.

 

[brainstorm]

My guess would be that the photons impact the electron, which shifts the electron orbit thus pulling with it the protons/nucleus by virtue of the organizing force of the atom as a system. I think you should consider the relative similarity between heat-conduction and electricity-conduction, which I believe are related since there seems to be a logical connection between heat-conduction and electricity-conduction that is distinct in terms of the degree to which the nuclei are vibrated as a result of electron-motion.

Allow me to explain an analogy that makes sense to me, and someone with more expertise may be able to explain where my analogy fails if it does: think of good-conductor atoms as balls covered with a thick layer of gel, where the gel represents the electrons. Now, if the intensity of waves in the gel layer are weak, they could travel among contiguous balls without causing the inner balls to vibrate. I.e. the gel would transfer all the wave energy from ball to ball. However, if the wave-intensity was increased it would begin to affect the inner balls as well as the gel. This is analogical to atomic vibration of heat, as when a conductor is subject to increasing current relative to its resistance.

Now if you think of photons/radiation as impacting the electrons (gel as per my analogy), then it would make sense that some levels of radiation would only vibrate the gel (photo-electricity) while other levels would exceed the capacity of the gel and begin to vibrate the inner balls as well.

I hope this analogy isn't completely misguided for some reason. It is the way I make sense of the relationship between conductivity of heat and electricity. Since I believe that radiation/photons only impact the electrons, I think that vibration of the atom as a whole (heat) would have to be due to the relative "tightness/solidity" of the electron layers vis-a-vis the nucleus.

 

[ZapperZ]

The reason why I pointed to the FAQ is that, as is the case in many misunderstanding, the mechanism for optical phenomenon is a bit different between isolated atoms versus solids. If one look very closely, many of the explanation for light hitting a material are being given using the scenario of isolated atoms, rather than a more correct one whereby the collective phenomenon that governs the behavior of solids are more responsible for their properties. In that FAQ entry, I've tried to emphasize the importance of such collective behavior by introducing the quanta of lattice vibration modes - phonons.

The presence of such vibrational modes, especially optical vibrational modes (as opposed to acoustic modes), implies that these are active modes for photons. All solids have such vibrational modes, but with varying phonon spectrum. Depending on the type of modes, light can be absorbed by the lattice and transfer as heat to the material. These vibrational modes are not present in isolated atoms, where light can only be absorbed in narrow lines of energy. In solids, there are BANDS of frequencies that such absorption can take place.

Again, here's the moral of the story if you take away nothing else from this. When atoms conglomerate into a solid, often their individual behavior no longer dominates. The collective behavior of these atoms that form into a solid tends to produce the characteristics of the material. Just look at the differences between diamond and graphite, both of which are made up of carbon atoms!

Zz.

 

[brainstorm]

Again, here's the moral of the story if you take away nothing else from this. When atoms conglomerate into a solid, often their individual behavior no longer dominates. The collective behavior of these atoms that form into a solid tends to produce the characteristics of the material. Just look at the differences between diamond and graphite, both of which are made up of carbon atoms!

Just curious, why would you attribute the distinctions between diamond and graphite to "collective" behavior of the atoms instead of individual behavior? Isn't individual behavior always in relation to other individuals or do you mean by "collective" something that transcends the interactive dynamics of the individual elements? If so, can you explain the difference between individual-interactive dynamics and "collective behavior?"

 

[ZapperZ]

Just curious, why would you attribute the distinctions between diamond and graphite to "collective" behavior of the atoms instead of individual behavior? Isn't individual behavior always in relation to other individuals or do you mean by "collective" something that transcends the interactive dynamics of the individual elements? If so, can you explain the difference between individual-interactive dynamics and "collective behavior?"

The individual behavior of carbon is just that. Yet, when you arrange the carbon atoms in different configurations, you get different materials that behave differently. These are still the same atoms. So if you explain the optical behavior of graphite using the optical response of individual carbon, it will be inconsistent with diamond, which is also made up of carbon.

Atomic physics is not identical to solid state physics. That is a given, and that's why there are two separate field of studies. Atoms do not have phonon modes, and other collective behavior.

Zz.

 

[brainstorm]

The individual behavior of carbon is just that. Yet, when you arrange the carbon atoms in different configurations, you get different materials that behave differently. These are still the same atoms. So if you explain the optical behavior of graphite using the optical response of individual carbon, it will be inconsistent with diamond, which is also made up of carbon.

Atomic physics is not identical to solid state physics. That is a given, and that's why there are two separate field of studies. Atoms do not have phonon modes, and other collective behavior.

Zz.

I thought you would say something like this. Isn't the diamond-configuration of carbon atoms a function of how the individual atoms interact with each other and, thus, isn't the clarity of the diamond due to the way photons pass between those individual atoms? Isn't the opacity of graphite facilitated by the individual atoms being able to orient to others in relatively chaotic ways, relative to the diamond structure?

The reason I'm delving into this is because I think that transcending the individual level in favor of describing phenomena in terms of collective behaviors obscures what the individual atoms are doing at the same time to cause what you are treating as collective. It really relates directly to the OP because when you treat atoms as whole units, i.e. as collective entities instead of keeping note of the interactions between the electrons and the nuclei, it obscures the reason why some electron destabilization results in heat-vibration and why some becomes electric-current and at other times gets re-emitted as light/radiation, no?

 

[ZapperZ]

I thought you would say something like this. Isn't the diamond-configuration of carbon atoms a function of how the individual atoms interact with each other and, thus, isn't the clarity of the diamond due to the way photons pass between those individual atoms? Isn't the opacity of graphite facilitated by the individual atoms being able to orient to others in relatively chaotic ways, relative to the diamond structure?

The reason I'm delving into this is because I think that transcending the individual level in favor of describing phenomena in terms of collective behaviors obscures what the individual atoms are doing at the same time to cause what you are treating as collective. It really relates directly to the OP because when you treat atoms as whole units, i.e. as collective entities instead of keeping note of the interactions between the electrons and the nuclei, it obscures the reason why some electron destabilization results in heat-vibration and why some becomes electric-current and at other times gets re-emitted as light/radiation, no?

First of all, let's look at metals. Is there such a thing as a 'conduction band' for, say, copper atoms? But there is such a thing for bulk copper metals.

Secondly, is there such a thing as a phonon spectrum for individual atoms? So how do you account for the fact that a material, such as quarts, can have a range of frequency that it is transparent to? An atom has only certain absorption LINES, not bands!

There are other example of such collective phenomena. In fact, emergent phenomena are what we study in condensed matter physics. As Laughlin has pointed out, when you try to examine something like superconductivity at the individual particle level, the whole phenomenon disappears.

How large number of atoms organize themselves will dictate many of the properties of that conglomeration. If you disagree with this, then you are welcome to show me a description of, say, superconductivity, derived from single atoms.

Zz.

 

[Moviemann345]

Ok let me get this straight... so after an electron cloud shifts temporarily due to a photon absorption, the absorbed photon cannot be held onto (because the atom doesn't support that state). And due to this the photon's energy is kineticly transferred to surrounding atoms like a wave, no bumping, just dispersion (I guess this has to do with wave particle duality)

Along with this I have another question: if the atom absorbing a photon is alone--not surrounded by other atoms. Is the absorbed energy eventually released back as a photon, after a certain period of time?

 

[brainstorm]

First of all, let's look at metals. Is there such a thing as a 'conduction band' for, say, copper atoms? But there is such a thing for bulk copper metals.

I'm assuming that conduction-band refers to something like the range of voltage that copper transmits in a certain way. The concept of conductivity of a substance, or density for example, can only refer to conglomerations of atoms, yes, but ultimately don't those concepts fall short of referencing the actual mechanics that give rise to them? After all, bulk-copper is not simply "conductive," right; i.e. there is a mechanical process of electron momentum-transfer that transports the current from atom to atom, no?

Secondly, is there such a thing as a phonon spectrum for individual atoms? So how do you account for the fact that a material, such as quarts, can have a range of frequency that it is transparent to? An atom has only certain absorption LINES, not bands!

Again, I'm unfamiliar with this concept but I assume that like any other macro-level description, it relies on summary concepts that reduce numerous actual-occurrences into a more simplified observable pattern. This is like when you look at a computer screen, what is actually going on is numerous pixels changing color/brightness/etc. but the language you use to describe what you see refers to images synthesized by your brain from the pixels. I'm not saying that it makes sense to try to describe images on a computer screen with reference to pixels one-by-one, but if you want to understand the mechanics of how the image actually occurs, you have to recognize that each individual pixel is doing its own thing.

There are other example of such collective phenomena. In fact, emergent phenomena are what we study in condensed matter physics. As Laughlin has pointed out, when you try to examine something like superconductivity at the individual particle level, the whole phenomenon disappears.

How is it possible for something to occur via a medium without the stuff composing the medium to be doing something to generate the super-effect?

How large number of atoms organize themselves will dictate many of the properties of that conglomeration. If you disagree with this, then you are welcome to show me a description of, say, superconductivity, derived from single atoms.

I guess I'll have to go look up superconductivity now, but I thought that I was doing something similar in my post regarding the series of translations that takes place between radiation-emission and the atomic-vibration known as heat at the empirical level. I'm not saying that atomic organization has nothing to do with how they behave as substances. This is actually very interesting topic to me. What I'm saying is that I don't see any reason to jump from describing what the individual atoms are doing to organize themselves in a certain way and the phenomena that result from their organized interaction. It seems like an unnecessary deviation from the particulars to move to a collective level to talk about what's going on. What's more, I think that theorizing at the collective level often results in unreasonable hypotheses about phenomena and what is possible. After all, if a collective phenomenon doesn't make sense when dissected to the level of individual particles, how could it be possible except via some kind of magic?

 

[brainstorm]

Ok let me get this straight... so after an electron cloud shifts temporarily due to a photon absorption, the absorbed photon cannot be held onto (because the atom doesn't support that state). And due to this the photon's energy is kineticly transferred to surrounding atoms like a wave, no bumping, just dispersion (I guess this has to do with wave particle duality)

What is dispersion without "bumping?" I would assume that the same-charge repulsion force between electrons in different atoms do "bump" and transfer the momentum, but I'm no expert. On the other hand, at the level of the electron there seems to be some vagueness or flux between whether the electron is emitting radiation or kinetically pushing/bumping other electrons. Since atoms seem to always be emitting some level of radiation, the electrons seem to exert energy both as kinetic force and radiation, but I don't understand the relationship between the two (a well-schooled physicist did tell me it's completely random but I'm not sure whether to believe him or not).

Along with this I have another question: if the atom absorbing a photon is alone--not surrounded by other atoms. Is the absorbed energy eventually released back as a photon, after a certain period of time?

Wouldn't conservation of energy determine that an atom isolated from kinetic contact with other particles would have to re-emit radiation energy or somehow store it until contact with another particle allowed for an kinetic energy transfer? Maybe the atom could absorb the radiation/photon as increased velocity and store it until colliding and transferring momentum to its collision-partner.

 

[Cthugha]

After all, if a collective phenomenon doesn't make sense when dissected to the level of individual particles, how could it be possible except via some kind of magic?

So the interference pattern of a double slit experiment is magic because it does not make sense when you dissect it to the level of patterns seen after single slits?

When going down to single particle level you will almost always have no effects of phase causing interference effects. However, interference effects are in many situations the reason why collective behavior arises. You cannot explain such a collective phenomenon dissected to the level of single particles because these effects simply vanish at the single particle level.

Are you familiar with the basics of quantum mechanics? You get the basic quantities describing for example an atom by squaring its wave function. If only individual behavior mattered, you could get the behavior of an ensemble of atoms by summing the squares of the individual wave functions, but what you really need to do is - just like in the double slit experiment - square the sum of the wave functions. That gives a huge difference - without any kind of magic.

 

[ZapperZ]

I'm assuming that conduction-band refers to something like the range of voltage that copper transmits in a certain way. The concept of conductivity of a substance, or density for example, can only refer to conglomerations of atoms, yes, but ultimately don't those concepts fall short of referencing the actual mechanics that give rise to them? After all, bulk-copper is not simply "conductive," right; i.e. there is a mechanical process of electron momentum-transfer that transports the current from atom to atom, no?Again, I'm unfamiliar with this concept but I assume that like any other macro-level description, it relies on summary concepts that reduce numerous actual-occurrences into a more simplified observable pattern. This is like when you look at a computer screen, what is actually going on is numerous pixels changing color/brightness/etc. but the language you use to describe what you see refers to images synthesized by your brain from the pixels. I'm not saying that it makes sense to try to describe images on a computer screen with reference to pixels one-by-one, but if you want to understand the mechanics of how the image actually occurs, you have to recognize that each individual pixel is doing its own thing.How is it possible for something to occur via a medium without the stuff composing the medium to be doing something to generate the super-effect?I guess I'll have to go look up superconductivity now, but I thought that I was doing something similar in my post regarding the series of translations that takes place between radiation-emission and the atomic-vibration known as heat at the empirical level. I'm not saying that atomic organization has nothing to do with how they behave as substances. This is actually very interesting topic to me. What I'm saying is that I don't see any reason to jump from describing what the individual atoms are doing to organize themselves in a certain way and the phenomena that result from their organized interaction. It seems like an unnecessary deviation from the particulars to move to a collective level to talk about what's going on. What's more, I think that theorizing at the collective level often results in unreasonable hypotheses about phenomena and what is possible. After all, if a collective phenomenon doesn't make sense when dissected to the level of individual particles, how could it be possible except via some kind of magic?

I think you are making things up as you go along. It appears that you have no clue what a "conduction band" is, and yet, you are ready to argue with me on what you clearly didn't understand.

I think it would futile for me to continue with this until you actually put some effort into learning what we already know. I find that I keep having to go back a few steps in trying to get you to realize some basic concepts. Do a search on "emergent phenomena", even on PF. Read Phil Anderson's "More Is Different".

Zz.

 

[brainstorm]

So the interference pattern of a double slit experiment is magic because it does not make sense when you dissect it to the level of patterns seen after single slits?

When going down to single particle level you will almost always have no effects of phase causing interference effects. However, interference effects are in many situations the reason why collective behavior arises. You cannot explain such a collective phenomenon dissected to the level of single particles because these effects simply vanish at the single particle level.

Are you familiar with the basics of quantum mechanics? You get the basic quantities describing for example an atom by squaring its wave function. If only individual behavior mattered, you could get the behavior of an ensemble of atoms by summing the squares of the individual wave functions, but what you really need to do is - just like in the double slit experiment - square the sum of the wave functions. That gives a huge difference - without any kind of magic.

I have read books on quantum mechanics and I do not like the various magic-like phenomena that are proposed along with the "proof" of the magic being that the math works. The ironic thing is that while the invisibility of scale at the level of atoms gives quantum theories free reign to model phenomena to fit the math instead of the reverse, I have seen similar applications of descriptive modeling in macro-accounts of history and (human) social theory. Luckily, with human sciences everyone has direct empirical access to data about how human bodies work in everyday life. With particle physics, anyone who has orthodox knowledge can pull rank on anyone who doesn't or dares to deviate and question because the only empirical access to the data is mitigated by complex and expensive equipment. I suppose that the double-slit experiment is neither complex nor expensive, but it does seem to be an empirical experiment that promotes theorizing what's going on with light at the collective level of the wave-patterns.

I think you are making things up as you go along. It appears that you have no clue what a "conduction band" is, and yet, you are ready to argue with me on what you clearly didn't understand.

I'm not trying to make anything up. I'm trying to have a discussion about the topic of individualism/collectivism in particle-theorizing without being familiar with your examples. I find it a bit unfair of you to pull rank on me by insisting that I understand your examples to be able to address this issue. If you had a real interest in this discussion, you would have explained why/how the "conduction band" concept you mentioned relies on the pattern-level of collective-particles and why it won't work to dissect it to the individual level. I think you're too interested in playing rank than getting to an example that we both are familiar with in order to actually discuss this issue on level ground.

I think it would futile for me to continue with this until you actually put some effort into learning what we already know. I find that I keep having to go back a few steps in trying to get you to realize some basic concepts. Do a search on "emergent phenomena", even on PF. Read Phil Anderson's "More Is Different".

Thanks for the book tip. I can use it in my study of macro-philosophizing. I am familiar with the logic of emergent phenomena and I think it has more to do with cognition than physics of materiality. Yes, it can be very convenient for human minds to think about observables in patterns that seem to emerge from the micro-level, but once they transcend that micro-level, they open themselves up for the suggestion of magical-seeming phenomena that can't really exist except as an artifact of the (conceptual) instrumentation.
This is easier to see when you attempt to dissect macro-historical or macro-economic accounts down to the level of individual humans.

 

[Cthugha]

I have read books on quantum mechanics and I do not like the various magic-like phenomena that are proposed along with the "proof" of the magic being that the math works. The ironic thing is that while the invisibility of scale at the level of atoms gives quantum theories free reign to model phenomena to fit the math instead of the reverse [...]

Sorry, but that is disrespectful at least. You admit that you only have basic knowledge on physics at best, but you claim to know very well that quantum theory "makes up" models to fit math? There are no magic-like phenomena presented in any serious book on qm. There might be some amount of magic in popular books on qm. However, reading those is a bit like reading the yellow press.

With particle physics, anyone who has orthodox knowledge can pull rank on anyone who doesn't or dares to deviate and question because the only empirical access to the data is mitigated by complex and expensive equipment. I suppose that the double-slit experiment is neither complex nor expensive, but it does seem to be an empirical experiment that promotes theorizing what's going on with light at the collective level of the wave-patterns.

Particle physics is the branch of physics which is closest to treating everything on the single-particle level. The branches of physics heavily involving collective phenomena are solid-state physics and similar fields. The double-slit experiment itself is rather cheap and it is not even a quantum experiment. Unless you perform it with single electrons or photons, it is pretty much a classical experiment which allows to draw conclusions on the wave nature of stuff, when taken to the qm realm.

You seem to think that particles are more fundamental than waves. Do you have any reason for thinking this way?

Read Phil Anderson's "More Is Different".

Funny. I was going to suggest the same.

 

[brainstorm]

Sorry, but that is disrespectful at least. You admit that you only have basic knowledge on physics at best, but you claim to know very well that quantum theory "makes up" models to fit math? There are no magic-like phenomena presented in any serious book on qm. There might be some amount of magic in popular books on qm. However, reading those is a bit like reading the yellow press.

My use of language probably sounded more disrespectful because I was being colloquial. What I meant was that my impression based on the limited knowledge I have of quantum physics is that it emphasizes predictive accuracy over explanatory modeling with the presumption that things just can't really be accurately explained at that level. You are right that the books I've read on quantum physics are popular texts written for lay people with some intelligence and knowledge of physics. So you can really tell me, does quantum physics tend to eschew explanatory modeling in favor of predictive equation building?

Particle physics is the branch of physics which is closest to treating everything on the single-particle level. The branches of physics heavily involving collective phenomena are solid-state physics and similar fields. The double-slit experiment itself is rather cheap and it is not even a quantum experiment. Unless you perform it with single electrons or photons, it is pretty much a classical experiment which allows to draw conclusions on the wave nature of stuff, when taken to the qm realm.

And what bothers me is that the book I read used it as general justification for approaching the study of light in a certain way. If a certain experiment works better with a wave-model or another model, why should that suggest that all phenomena are best studied using that model?

You seem to think that particles are more fundamental than waves. Do you have any reason for thinking this way?

Only to the extent that waves are modeled as being conglomerate patterns among constituent elements, whether those are particles, fields, smaller waves, strings, or whatever. My issue here is that when you're focussing on emergent phenomena or patterns that treat collective behavior of individuals as things in and of themselves, you obfuscate the level of the constituent individuals that interact to create the collective pattern. How can it ever be possible for a collective pattern to exist without it reflecting concrete behaviors of the individuals involved in producing it?

 

[Maui]

Only to the extent that waves are modeled as being conglomerate patterns among constituent elements, whether those are particles, fields, smaller waves, strings, or whatever.

Matter waves are quite different from electromagnetic waves. It's often very misleading to reference the wave-particle duality because ultimately it's a wrong concept. Wave-particle duality should be used with extreme caution by non-professionals(that includes me too .

My issue here is that when you're focussing on emergent phenomena or patterns that treat collective behavior of individuals as things in and of themselves, you obfuscate the level of the constituent individuals that interact to create the collective pattern. How can it ever be possible for a collective pattern to exist without it reflecting concrete behaviors of the individuals involved in producing it?

You aren't thinking of deterministic balls of solid stuff, are you? If you are, the analogy is only slight and doesn't hold at all times at the quantum level(as you probably know). Instead of deterministic balls that hit each other, the interactions are modeled by pure math that replaces the leading role of intuition found in classical physics. Given the postulates and principles of qm, some of your questions are also more philosophical in nature than physical.

 

[brainstorm]

Matter waves are quite different from electromagnetic waves. It's often very misleading to reference the wave-particle duality because ultimately it's a wrong concept. Wave-particle duality should be used with extreme caution by non-professionals(that includes me too .

So what you're basically saying is that you're quite sure they're different even though you don't really understand how so since you're not an expert you avoid delving out of caution? Is that a scientific ethic?

You aren't thinking of deterministic balls of solid stuff, are you? If you are, the analogy is only slight and doesn't hold at all times at the quantum level(as you probably know). Instead of deterministic balls that hit each other, the interactions are modeled by pure math that replaces the leading role of intuition found in classical physics. Given the postulates and principles of qm, some of your questions are also more philosophical in nature than physical.

You can't model mechanics with pure math. You can only model the patterns that emerge from those mechanics. I don't tend to think of particles as perfectly determined solid spheres like billiard balls, no. I tend to think of them as fields. Still, I think fields can repel each other in the same way solid balls do. The point is that I do consider it worthwhile to theoretically explore how the individual particles and/or waves interact. I think treating them as collective emergent phenomena obfuscates the possibility of doing that.

Collective vs. individual-interaction is absolutely an epistemological issue at the level of modeling. That was my point. You can't rely on the physical nature of anything to determine whether it is better to model its behavior in terms of individual-interactions of elements or emergent collective patterns. Put more simply, it's not possible to conceive of emergent phenomena without conceptualizing constituents of the phenomena. However, if you can't dissect to the level of the individual constituents, what is the point of modeling the phenomenon as emerging from smaller parts in the first place?

Btw, the point of this discussion relative to the OP had to do with tracing the transfer of energy from photon to heat (i.e. molecular vibration). How is that question better answered without reference to the specific particles involved and the interactions between them?

 

[Cthugha]

My use of language probably sounded more disrespectful because I was being colloquial.

Well, I am not a native English speaker. Maybe I just misunderstood something.

So you can really tell me, does quantum physics tend to eschew explanatory modeling in favor of predictive equation building?

That depends on what you consider as explanatory modeling. I just looked up the meaning of those two approaches and found explanatory modeling vaguely defined as meaning that the aim of an analysis is to specify how and why certain phenomena occur and predictive modeling defined as follows: "By predictive models we mean models that,
instead of explaining existing phenomena, are aimed at predicting the future or new observations with high accuracy." (G. Schmueli, Predictive vs. Explanatory Modeling in IS Research). There are both schools in physics. There are of course basic differences between experimental and theoretical physics, but in both branches you will find both approaches. However, of course one has to accept that the question about the "why" is somewhat limited by our possibilities to ask nature the right questions by performing experiments, especially if you are interested in ontology. There are for example several rather different models predicting exactly the same behavior for quantum particles. It is not easy to find the right one if there is no experiment to distinguish between them. But I do not think predictive equation building is really favored.

And what bothers me is that the book I read used it as general justification for approaching the study of light in a certain way. If a certain experiment works better with a wave-model or another model, why should that suggest that all phenomena are best studied using that model?

Well, for example you have experiments highlighting the wave-nature of light and those that highlight the particle nature of light. That led to the development of the (in my opinion wrongly chosen) term wave-particle duality. In my opinion there is no duality, but a consistent picture. The common approach in physics would be to find a model that contains both aspects in some limiting regimes.

Only to the extent that waves are modeled as being conglomerate patterns among constituent elements, whether those are particles, fields, smaller waves, strings, or whatever. My issue here is that when you're focussing on emergent phenomena or patterns that treat collective behavior of individuals as things in and of themselves, you obfuscate the level of the constituent individuals that interact to create the collective pattern. How can it ever be possible for a collective pattern to exist without it reflecting concrete behaviors of the individuals involved in producing it?

Well, our macroscopic experience tells us that waves are usually constructed of some constituents. Our macroscopic experience also gives us a rather intuitive picture of what a particle is. However, that does not mean that our experience can simply be extrapolated to other scales. If you have a look at the fundamental forces, the ones governing our life (mainly the electromagnetic force and to some lesser extent gravity) are not necessarily governing our universe at large scales (here gravity becomes most important) or small scales (here gravity is not relevant).

I do not see the necessity of all waves being necessarily composed of something. In physics one often considers the effects of fields, for example the light field. Fields essentially behave like waves. Some kinds of particles are considered as quantized excitations of those fields. Please excuse the really simplifying analogy following now and please do not take it too seriously. It is just for visualization. From a physical point of view the sound from a flute is caused by some standing wave inside the flute. Here the air density varies locally and you find regions where the air density is not fluctuating at all and those where it is strongly fluctuating. These localized regions of large fluctuations define the sound.

Localized well-defined oscillations of fields can be interpreted as particles. So, in some sense physics is indeed following your approach about being as fundamental as possible. It just does not consider particles as being the most fundamental thing out there (although the historically grown term fundamental particles suggests something different), but fields.

I admit that this post is VERY simplifying and can be interpreted in a misleading manner. However, I fear, a deeper discussion of that topic is not possible without some substantial knowledge in qm and I just tried to give a somewhat understandable answer.

 

[Maui]

So what you're basically saying is that you're quite sure they're different even though you don't really understand how so since you're not an expert you avoid delving out of caution?

No, not at all. I know what you want and you keep insisting on getting it but it's not possible. In one sentence - you will not be able to unambiguously describe matter waves or any quantum system in classical terms. Learn to live with it.

You can't model mechanics with pure math.

I guess Schroedinger wasn't aware of this 'limitation' in 1925(ironically the topic you are arguing about is called quantum mechanics). In fact, there is so much abstract mathematics(at least some of it describes our reality), that you will not be able to read all of it in one lifetime.

You can only model the patterns that emerge from those mechanics. I don't tend to think of particles as perfectly determined solid spheres like billiard balls, no. I tend to think of them as fields. Still, I think fields can repel each other in the same way solid balls do. The point is that I do consider it worthwhile to theoretically explore how the individual particles and/or waves interact. I think treating them as collective emergent phenomena obfuscates the possibility of doing that.

Collective vs. individual-interaction is absolutely an epistemological issue at the level of modeling. That was my point. You can't rely on the physical nature of anything to determine whether it is better to model its behavior in terms of individual-interactions of elements or emergent collective patterns. Put more simply, it's not possible to conceive of emergent phenomena without conceptualizing constituents of the phenomena. However, if you can't dissect to the level of the individual constituents, what is the point of modeling the phenomenon as emerging from smaller parts in the first place?

Let me put this straight in one sentence - that which you observe cannot be derived solely from the properties of point particles and fields. Many different reasons for this, the chief one being that said particles do not behave in a deterministic fashion and causality at the quantum level(where your main interest seems to be) isn't as heavily pronounced as in the macro world.

There is no way to build the universe of observations with just the 4 fundamental fields, which seems to be what you are proposing(there is some hope if you go the MWI route).

However, if you can't dissect to the level of the individual constituents, what is the point of modeling the phenomenon as emerging from smaller parts in the first place?

Where in this thread did you get the idea it was not possible to dissect matter to the level of individual constituents? If anything, you were told the opposite, that some properties do not show up in the behavior of individual particles, while they do in conglomerates.

 

[peteratcam]

Collective vs. individual-interaction is absolutely an epistemological issue at the level of modeling. That was my point. You can't rely on the physical nature of anything to determine whether it is better to model its behavior in terms of individual-interactions of elements or emergent collective patterns. Put more simply, it's not possible to conceive of emergent phenomena without conceptualizing constituents of the phenomena. However, if you can't dissect to the level of the individual constituents, what is the point of modeling the phenomenon as emerging from smaller parts in the first place?

Fluid mechanics was developed before the atomic hypothesis was accepted, and is an example of a collective phenomenon which was conceived without reference to microscopic constituents. Fluid mechanics is definitely useful, and definitely quite hard to derive starting from the standard model, or even from individual water molecules.

Fluid mechanics is useful because many fluids obey the laws of fluid mechanics. Many fluids are described in the same framework, with only a few parameters distinguishing the different fluids, like density and viscosity. Using the language of fluids is more useful than describing systems like water as a set of 10^23 interacting molecules. It is very hard to calculate the viscosity of water, but it is definitely a useful concept, an emergent one if you like. An H20 molecule on its own does not have viscosity, but a fluid does.

 

[brainstorm]

But I do not think predictive equation building is really favored.

My sense is that what is considered "explanatory" in some/many quantum models is whatever fits the math that works. I don't get intuitive logic from the quantum models, for the most part, and that is insufficient, imo.

Well, for example you have experiments highlighting the wave-nature of light and those that highlight the particle nature of light. That led to the development of the (in my opinion wrongly chosen) term wave-particle duality. In my opinion there is no duality, but a consistent picture. The common approach in physics would be to find a model that contains both aspects in some limiting regimes.

That makes sense, especially if you consider the division a scale and/or context issue.

Well, our macroscopic experience tells us that waves are usually constructed of some constituents. Our macroscopic experience also gives us a rather intuitive picture of what a particle is. However, that does not mean that our experience can simply be extrapolated to other scales. If you have a look at the fundamental forces, the ones governing our life (mainly the electromagnetic force and to some lesser extent gravity) are not necessarily governing our universe at large scales (here gravity becomes most important) or small scales (here gravity is not relevant).

Here you're talking about the relative dominance of forces relative to the phenomena observed at a particular scale. However, my impression is that the universe consists of the same matter-energy at any scale. Only it appears different at different scales because of our perception. In other words, gravitation still must be present at the atomic level, although it only builds up to significant levels at larger scales. Gravity translates into pressure and pressure restricts kinetic particle motion and causes friction, which is a result of pressure and kinetic energy. So the various forces are translated to different scales by specific relations.

I do not see the necessity of all waves being necessarily composed of something. In physics one often considers the effects of fields, for example the light field. Fields essentially behave like waves.

I always think of a magnetic field that increases in repulsion with increasing proximity from two same-charged poles.

I guess Schroedinger wasn't aware of this 'limitation' in 1925(ironically the topic you are arguing about is called quantum mechanics). In fact, there is so much abstract mathematics(at least some of it describes our reality), that you will not be able to read all of it in one lifetime.

In science, majority doesn't rule.

Where in this thread did you get the idea it was not possible to dissect matter to the level of individual constituents? If anything, you were told the opposite, that some properties do not show up in the behavior of individual particles, while they do in conglomerates.

That's what I meant. How can something show up in conglomerate without being in some way present at the level of constituents?

Fluid mechanics was developed before the atomic hypothesis was accepted, and is an example of a collective phenomenon which was conceived without reference to microscopic constituents. Fluid mechanics is definitely useful, and definitely quite hard to derive starting from the standard model, or even from individual water molecules.

Does that mean fluid dynamics aren't due to interactions between the particles that make up the fluid?

Fluid mechanics is useful because many fluids obey the laws of fluid mechanics. Many fluids are described in the same framework, with only a few parameters distinguishing the different fluids, like density and viscosity. Using the language of fluids is more useful than describing systems like water as a set of 10^23 interacting molecules. It is very hard to calculate the viscosity of water, but it is definitely a useful concept, an emergent one if you like. An H20 molecule on its own does not have viscosity, but a fluid does.

I understand that using macro-mechanical language is useful but in terms of explaining how the macro-mechanics occur the way they do, you have to take into account the interactions between the particles at the individual level, no?

 

[peteratcam]

That's what I meant. How can something show up in conglomerate without being in some way present at the level of constituents?

Does that mean fluid dynamics aren't due to interactions between the particles that make up the fluid?

You are right that the macroscopic laws must, in some way, follow from the microscopic laws. But the point is that the most natural description of a macroscopic behaviour is very often incredibly complicated to translate to the more microscopic scale, and entirely new concepts can appear, which aren't in the microscopic constituents.

Reading Anderson's 'More is different' is a starting point to get the mindset - it is 5 pages which have been very influential.

 

[ZapperZ]

Reading Anderson's 'More is different' is a starting point to get the mindset - it is 5 pages which have been very influential.

In fact, I've highlighted https://www.physicsforums.com/showpost.php?p=2207270&postcount=81".

This thread has evolved from the OP's question into an explanation of emergent phenomena. This has been discussed many times, and rather than recite all of those previous arguments, I think people who are ignorant of this concept should do a bunch of reading first before providing arguments that has already been addressed.

1. http://www.pnas.org/cgi/reprint/97/1/28.pdf
2. http://www.pnas.org/cgi/reprint/97/1/32.pdf
3. http://arXiv.org/abs/hep-th/0210162
4. R.B. Laughlin, Rev. Mod. Phys., v.71, p.863 (1999).
5. P. Anderson, Science v.177,p.4 (1972).
6. P. Coleman Nature v.446, p.379 (2007).

And Laughlin, of course, has written a whole book on this titled "A Different Universe: Reinventing Physics from the Bottom Down".

Zz.

 

[Cthugha]

My sense is that what is considered "explanatory" in some/many quantum models is whatever fits the math that works. I don't get intuitive logic from the quantum models, for the most part, and that is insufficient, imo.[...]
Here you're talking about the relative dominance of forces relative to the phenomena observed at a particular scale. However, my impression is that the universe consists of the same matter-energy at any scale. Only it appears different at different scales because of our perception.

Indeed, it appears different at different scales due to our perception of the relative strengths of these forces at the different scales. I just wanted to point out that expecting to be able to get an intuitive picture of some scale we are not able to perceive directly by extrapolating our experience from the scale we are familiar with to much smaller or larger scales will in most cases not work.

I always think of a magnetic field that increases in repulsion with increasing proximity from two same-charged poles.

Well, now the question becomes chicken-or-egg like. Do you think an electromagnetic field is fundamental or is it composed of something? If you consider some particles as the fundamental entities making up the field, you will get into problems explaining collective behavior. If you consider the field as fundamental, two particles will just be two excitations of one field. In this case the collective behavior emerges due to properties of the field, not of the particles, which makes it clear why collective behavior cannot be explained by the properties of single particles: In this picture the particles are not the fundamental entities. The fields are.

 

[brainstorm]

Indeed, it appears different at different scales due to our perception of the relative strengths of these forces at the different scales. I just wanted to point out that expecting to be able to get an intuitive picture of some scale we are not able to perceive directly by extrapolating our experience from the scale we are familiar with to much smaller or larger scales will in most cases not work.

My sense is that there are abstract generalities that transcend scale. Heavenly bodies, for example, can orbit around the center of a gravity well perpetually of their own inertia. By doing so, they are in motion but by that motion being recursive, they do not extend beyond a certain local area. This is in stark contrast to "radiant" motion that proceeds from one point outward without any tendency to recursively retrace the same trajectory. These two forms of motion are, imo, fundamental and must apply at any scale.

Well, now the question becomes chicken-or-egg like. Do you think an electromagnetic field is fundamental or is it composed of something? If you consider some particles as the fundamental entities making up the field, you will get into problems explaining collective behavior.

I tend to think that a field is fundamental insofar as it remains intact and exudes consistent behavior. So, for example, Earth's gravitational field could be viewed as a field in and of itself without regard for the matter causing it. However, to understand what's causing the gravitational field, the mass of the voluminous matter at the center of the gravity-well seems to be causing it in some way. Plus we know that that matter consists of recombinatory potential in various ways (chemical and nuclear) and that attractive and repulsive forces/fields are involved in that. So it seems to me to be just a question of dissecting the various force-fields by examining them interacting in different ways.

If you consider the field as fundamental, two particles will just be two excitations of one field.

Why is that? Why wouldn't they be two distinct fields?

In this case the collective behavior emerges due to properties of the field, not of the particles, which makes it clear why collective behavior cannot be explained by the properties of single particles: In this picture the particles are not the fundamental entities. The fields are.

What do you mean by "field" then? Are you not using it in the same sense as a magnetic "field?" Are you using it to describe a collection of particles/points, i.e. a multiplicity? If so, I see why you would say collective behavior can't be reduced to single individual behavior. Nevertheless, if you conceptualize a multiplicity as consisting of multiple constituents, you have to have some model of how the constituents behave at the individual level to produce the emergent collective behavior of the field, no? Otherwise, what is the point of claiming that the field is constituted of something more fundamental at all?

 

[Cthugha]

By doing so, they are in motion but by that motion being recursive, they do not extend beyond a certain local area. This is in stark contrast to "radiant" motion that proceeds from one point outward without any tendency to recursively retrace the same trajectory. These two forms of motion are, imo, fundamental and must apply at any scale.

Well, of course. This is a question of whether two forces applied to a body are of the same magnitude or not. If they are, you will get recursive motion, otherwise you will not. This behavior does of course not depend on the forces applying to the body as long as the forces cause a restoring force at small displacements.

Why is that? Why wouldn't they be two distinct fields?

I see no reason why they should be.

What do you mean by "field" then? Are you not using it in the same sense as a magnetic "field?"

Well, I see it in the same way as a magnetic field, but I am not sure my concept of the magnetic field is the same as yours, so let me give a toy model. In this model the electromagnetic field is a property of empty space itself. If you consider a giant membrane spanning all space, you get the picture. Pull at some position of the membrane and let go and you will see a wave arising from that position and traveling across the membrane. Pull at another position and you see another wave traveling across the membrane. You can consider these waves as particle-like excitations of your membrane. If two of those waves meet somewhere on the membrane, the result in the meeting area will not only depend on the characteristics of these particle-like waves, but also on the characteristics of the membrane itself.

However, the difference between empty space and that membrane is that the membrane is made out of some material and you can in principle determine the membrane properties from its constituents. To the best of our knowledge empty space does not consist of anything else. Nevertheless, it is obviously able to transport energy in some forms, e.g. light, when you place it somewhere in empty space. So imho it is at best a multiplicity of geometric points, but not of something which has material form.

 

[brainstorm]

Well, of course. This is a question of whether two forces applied to a body are of the same magnitude or not. If they are, you will get recursive motion, otherwise you will not. This behavior does of course not depend on the forces applying to the body as long as the forces cause a restoring force at small displacements.

This is not clear. Maybe an example would help.

[/quote]I see no reason why they should be.[/quote]
It depends how independent their behavior is vis-a-vis each other and in what ways they are connected.

Well, I see it in the same way as a magnetic field, but I am not sure my concept of the magnetic field is the same as yours, so let me give a toy model. In this model the electromagnetic field is a property of empty space itself. If you consider a giant membrane spanning all space, you get the picture. Pull at some position of the membrane and let go and you will see a wave arising from that position and traveling across the membrane. Pull at another position and you see another wave traveling across the membrane. You can consider these waves as particle-like excitations of your membrane. If two of those waves meet somewhere on the membrane, the result in the meeting area will not only depend on the characteristics of these particle-like waves, but also on the characteristics of the membrane itself.

Well, you are implying that there is a membrane and it is universally present and that all matter-energy operates through manipulation of it. This is general-level theorizing, btw. The issue of these fields with reference to this thread is whether they are fundamental and whether it makes sense to discuss energy-transfer from photons to heat at the macro/collective/emergent level or in terms of interactions between elementary particles.

However, the difference between empty space and that membrane is that the membrane is made out of some material and you can in principle determine the membrane properties from its constituents. To the best of our knowledge empty space does not consist of anything else. Nevertheless, it is obviously able to transport energy in some forms, e.g. light, when you place it somewhere in empty space. So imho it is at best a multiplicity of geometric points, but not of something which has material form.

Empty space, imo, is a function of energy driving matter apart and that matter coalescing and entering into sustained orbits that prevents it from further coalescing. This is assuming that all matter-energy expanded from an original singular point where 3D space did not exist. Gravity fields thus clear out large parcels of empty space, but are other force-fields responsible for generating the gravity-fields? The big question is what forms matter and and why does it seem to exist as interacting particles that behave in certain ways?

Why do electrons emits photons and absorb them? How can an electron absorbing a photon transfer the energy in a way that results in heat (or electricity)? Etc. This was the OP topic and I think it can best be addressed with reference to the behavior of the individual particles involved, i.e. photons, electrons, and protons - and of course the forces that regulate their interactions.

 

[Cthugha]

This is not clear. Maybe an example would help.

An example? Imagine you have some object orbiting another object on a circular path, some planet and a sun for example. If there was no force acting on the planet, it would just move onward in a straight line. Accordingly, there must be a force acting on the planet. The absolute value of the speed does not change, so the force must be perpendicular to the motion of the planet and showing inward. It is obvious that gravitational interactions between the sun and the planet will be the origin of this force. Whether or not there will be stable orbits, depends on the speed of the planet and the attractive force between planet and sun. For certain combinations, there will be stable orbits. For other combinations, there will not be stable orbits.

In the beginning of QM people tried to do the same calculation for atoms. They considered the electron as orbiting around the nucleus with some speed and calculated the necessary inward force to keep it on track. However, due to the small scale and the charged electron and nucleus, the electromagnetic force replaces gravity as the attractive force. This classical approach leads to wrong results because electrons are not tiny balls and should radiate when orbiting something, but I hope you get the picture. If speed and attractive force match, there will be recursive motion. The origin of the force does not matter.

Well, you are implying that there is a membrane and it is universally present and that all matter-energy operates through manipulation of it. This is general-level theorizing, btw. The issue of these fields with reference to this thread is whether they are fundamental and whether it makes sense to discuss energy-transfer from photons to heat at the macro/collective/emergent level or in terms of interactions between elementary particles.

I was just aiming at electromagnetic fields in particular because these are easier to handle. This is a simplifying explanation after all and I do not claim to be able to give an exact explanation of a topic others need years of studying to understand in detail. If you insist on discussing interaction with matter, explanations starting from the level of individual elementary particles make even less sense because the underlying phenomena do not really depend on the exact kind of particles used and can already be demonstrated in classical mechanics:

If you take a mass and attach it to two springs attached to a wall, you get a pendulum with some certain resonance frequency. Now you can compare this to the case of two masses, each connected to a wall using springs and connected to each over via another spring. You will notice that in some cases, where both pendulums can exchange energy very efficiently, the coupled pendulums system will have different resonance frequencies than the single pendulums: The masses can both oscillate back and forth in phase or out of phase. The latter movement will have a higher resonance frequency. Whether this renormalization to new energy levels occurs depends on the interaction strength between the masses (depending on the spring stiffness), on the masses of the masses and on the resonance frequencies of the individual pendulums. This simple process is known as normal mode splitting or strong coupling. If you now increase the number of masses, you will get more resonance frequencies, accordingly. This is the basic process behind diverse machanisms like binding and antibinding orbitals in molecules, the formation of bands in solids for a large number of masses and the appearance of quasiparticles like polaritons if you couple different oscillators, for example a photon and an electronic transition. Although the exact numbers you have to enter for coupling strengths and the other constants depend on the individual particles used, this collective behavior showing up as a level splitting is pretty much independent of the kind of oscillator or different oscillators used. Therefore, I think it is more intuitive to consider this general feature of many-particle states as a many-body effect and insert the necessary parameters for some special case of interest.

The big question is what forms matter and and why does it seem to exist as interacting particles that behave in certain ways?

Most "why"-questions can be followed by further "why"-questions finally leading to the answer "beacause of the actual value the natural constants have". Then asking further "why"-questions mean that you will leave the realm of physics as it is not the task of physics to answer questions which cannot be tested empirically. "what forms matter?" is a question which can still be answered and is being worked on in the field of high energy particle physics and string theory, but I suppose a thorough answer will require some time spent on studying this field. I am a "solid-stater" and I do not feel competent enough to give a satisfying answer on that topic. But feel free to have a look at basic introductions at string theory. Just be warned that they are relying heavily on not-so-easy math.

Why do electrons emits photons and absorb them?

If I stay in the picture I gave above, then they do so because both can be considered oscillators and have some certain interaction strength. However, I have the feeling that will not satisfy you and you might want to know, why photons couple to charged particles...

How can an electron absorbing a photon transfer the energy in a way that results in heat (or electricity)? Etc. This was the OP topic and I think it can best be addressed with reference to the behavior of the individual particles involved, i.e. photons, electrons, and protons - and of course the forces that regulate their interactions.

In fact, absorption in the infrared, where you talk about heat are usually not governed by electrons, but are collective oscillations of the nuclei. However, the interaction of those with an infrared photon can occur, if there are enough coupled nuclei and enough energy level splittings that one of these energy levels matches the energy of the photon. However, it is in fact only the collective system of many nuclei, which can absorb the photon, not one nucleus on its own.

 

[jtbell]

you might want to know, why photons couple to charged particles...

Oh, we know that... it's because the universe obeys local U(1) gauge symmetry! Of course, that leads to the question, "why does the universe obey local U(1) gauge symmetry?"

 

[Cthugha]

That is exactly what I meant with the long chain of "why?"-questions finally leaving the realm of physics. My favorite answer to these final questions is always: "Because the flying spaghetti monster made it that way. Ramen."

 

[brainstorm]

In the beginning of QM people tried to do the same calculation for atoms. They considered the electron as orbiting around the nucleus with some speed and calculated the necessary inward force to keep it on track. However, due to the small scale and the charged electron and nucleus, the electromagnetic force replaces gravity as the attractive force. This classical approach leads to wrong results because electrons are not tiny balls and should radiate when orbiting something, but I hope you get the picture. If speed and attractive force match, there will be recursive motion. The origin of the force does not matter.

Yes, that is my point. And I don't see why it really matters what the shape of an electron orbit is, only whether its path is closed or open and whether it is a satellite or fulcrum. The fact that it is relative light and a satellite of the nucleus means that it can transmit energy without disturbing the inertia of the nucleus, which allows for the transmission of electricity without heat up to a certain point, no?

Whether this renormalization to new energy levels occurs depends on the interaction strength between the masses (depending on the spring stiffness), on the masses of the masses and on the resonance frequencies of the individual pendulums. This simple process is known as normal mode splitting or strong coupling. If you now increase the number of masses, you will get more resonance frequencies, accordingly. This is the basic process behind diverse machanisms like binding and antibinding orbitals in molecules, the formation of bands in solids for a large number of masses and the appearance of quasiparticles like polaritons if you couple different oscillators, for example a photon and an electronic transition. Although the exact numbers you have to enter for coupling strengths and the other constants depend on the individual particles used, this collective behavior showing up as a level splitting is pretty much independent of the kind of oscillator or different oscillators used. Therefore, I think it is more intuitive to consider this general feature of many-particle states as a many-body effect and insert the necessary parameters for some special case of interest.

So what you're basically saying is that the electron orbits of atoms oscillate at different frequencies and the combinatory frequency patters cause the atom to be prone to bonding in certain ways with certain other atoms, like the synchonization of gears so that they will couple? Still, it sounds like if you were able to capture in slow-motion the moment when the bonding actually occurs, you would see a pattern of electrons meshing with and then interlocking with another such pattern. And yet even though the interaction is governed by the two patterns, the patterns themselves can only be explained by the different oscillation speeds of the different electrons in the system, which I assume in turn is due to the relationship between each electron and its nucleus, no?

Most "why"-questions can be followed by further "why"-questions finally leading to the answer "beacause of the actual value the natural constants have". Then asking further "why"-questions mean that you will leave the realm of physics as it is not the task of physics to answer questions which cannot be tested empirically. "what forms matter?" is a question which can still be answered and is being worked on in the field of high energy particle physics and string theory, but I suppose a thorough answer will require some time spent on studying this field. I am a "solid-stater" and I do not feel competent enough to give a satisfying answer on that topic. But feel free to have a look at basic introductions at string theory. Just be warned that they are relying heavily on not-so-easy math.

It was a peripheral question anyway. BTW, I don't think it is necessary to jump over all the hurdles of socialization into a field (such as string theory) to be able to get certain important concepts and arrive at meaningful knowledge. Sure, experts fantasize about being the only ones capable of understanding anything in their domain of knowledge because they have special comprehension access, but anyone in their own field of expertise can admit that there are simple ways of understanding things explained in very complex language (and math) by the experts. It may be very difficult to explain to people what is so relevant and nuanced about a particular idea, but in principle it can be communicated to lay people.

If I stay in the picture I gave above, then they do so because both can be considered oscillators and have some certain interaction strength. However, I have the feeling that will not satisfy you and you might want to know, why photons couple to charged particles...

So you're saying the reason a photon interacts with an electron is because their oscillation strength/frequency matches up? It's not just because they orbit fast enough that the electron doesn't have time to get by them? After all, if electrons aren't slow enough to have their speed and position measured simultaneously, then doesn't that mean that they blur by as fast as the light that's hitting them?

In fact, absorption in the infrared, where you talk about heat are usually not governed by electrons, but are collective oscillations of the nuclei. However, the interaction of those with an infrared photon can occur, if there are enough coupled nuclei and enough energy level splittings that one of these energy levels matches the energy of the photon. However, it is in fact only the collective system of many nuclei, which can absorb the photon, not one nucleus on its own.

So what would happen if that nucleus/atom was relatively isolated in a vacuum when the photon encountered it?

 

[Cthugha]

Yes, that is my point. And I don't see why it really matters what the shape of an electron orbit is, only whether its path is closed or open and whether it is a satellite or fulcrum. The fact that it is relative light and a satellite of the nucleus means that it can transmit energy without disturbing the inertia of the nucleus, which allows for the transmission of electricity without heat up to a certain point, no?

Unfortunately, this intuitive approach taken in the beginning of qm does not work. One of the basic results of classical electromagnetism is that any charged particle which is accelerated somehow must necessarily give off radiation in order to conserve energy. So, if the electron was orbiting the nucleus it would continuously lose energy that way and finally crash into the nucleus. And no, conductivity does not depend on what the single electron does to a single nucleus.

So what you're basically saying is that the electron orbits of atoms oscillate at different frequencies and the combinatory frequency patters cause the atom to be prone to bonding in certain ways with certain other atoms, like the synchonization of gears so that they will couple? Still, it sounds like if you were able to capture in slow-motion the moment when the bonding actually occurs, you would see a pattern of electrons meshing with and then interlocking with another such pattern. And yet even though the interaction is governed by the two patterns, the patterns themselves can only be explained by the different oscillation speeds of the different electrons in the system, which I assume in turn is due to the relationship between each electron and its nucleus, no?

Well, they are not really orbiting as I mentioned above, but anyway: No, the electron resonances are not necessarily at different frequencies. Strong coupling works even better when they are at the same frequency. However, the combined system of two coupled resonances will have two different resonance frequencies. That is a rather general feature. It does not matter, whether you couple two springs that way or form molecules or couple light to excitons or whatever. Basically this whole approach can be applied to any strong coupling resonances (as long as they are similar to spring pendulums insofar as there is a restoring force). Of course the exact numbers where the final modes will lie are a result of the initial modes and the coupling strengths, but the general mechanism does not depend on that.

And once you have this broadening into bands of energy levels for many oscillators, conductivity becomes easy to explain. Usually the lowest of these bands will be filled and the next highest will be empty. To get conduction, you need to excite states with a well defined electron momentum, so you need to populate the next highest band (as every state of the lower bands is already populated the necessary states are not available there). Now the energy difference between the bands (analogous to the splitting of frequencies explained before) matters. If the energy is large, it costs a lot of energy to promote an electron to the higher band. This energy is not there and the material will not be a conductor. If there is no splitting, this excitation can happen easily and you will get a conductor. If you have a small splitting, the tempereture of your material might be high enough to promote electrons to higher bands. You get a semiconductor.

To get a basic understanding of these concepts, it is really not necessary to understand the exact nature and strengths of the forces involved. Those will only determine the exact energies where the resulting bands will lie. However, the occurrence of such bands is just a consequency of the large numbers of particles occurring. There is no analog to these band in single atoms and therefore one should not start from single atoms to explain conductivity.

I mean, if these properties were already imprinted in the single atoms, why would graphite and diamond - both pure carbon - have so very different properties in terms of heat conductivity, for example?

So you're saying the reason a photon interacts with an electron is because their oscillation strength/frequency matches up? It's not just because they orbit fast enough that the electron doesn't have time to get by them? After all, if electrons aren't slow enough to have their speed and position measured simultaneously, then doesn't that mean that they blur by as fast as the light that's hitting them?

Here I do absolutely not get what you mean. Orbiting photons? Electrons not slow enough to have speed and position measured simultaneously? Blurring electrons? You seem to have some strange misconceptions about photons and uncertainty

So what would happen if that nucleus/atom was relatively isolated in a vacuum when the photon encountered it?

You would get some discrete resonances. Only photons of well defined energies will interact with the atom.

 

[brainstorm]

Unfortunately, this intuitive approach taken in the beginning of qm does not work. One of the basic results of classical electromagnetism is that any charged particle which is accelerated somehow must necessarily give off radiation in order to conserve energy. So, if the electron was orbiting the nucleus it would continuously lose energy that way and finally crash into the nucleus. And no, conductivity does not depend on what the single electron does to a single nucleus.



Well, they are not really orbiting as I mentioned above, but anyway: No, the electron resonances are not necessarily at different frequencies. Strong coupling works even better when they are at the same frequency. However, the combined system of two coupled resonances will have two different resonance frequencies. That is a rather general feature. It does not matter, whether you couple two springs that way or form molecules or couple light to excitons or whatever. Basically this whole approach can be applied to any strong coupling resonances (as long as they are similar to spring pendulums insofar as there is a restoring force). Of course the exact numbers where the final modes will lie are a result of the initial modes and the coupling strengths, but the general mechanism does not depend on that.

And once you have this broadening into bands of energy levels for many oscillators, conductivity becomes easy to explain. Usually the lowest of these bands will be filled and the next highest will be empty. To get conduction, you need to excite states with a well defined electron momentum, so you need to populate the next highest band (as every state of the lower bands is already populated the necessary states are not available there). Now the energy difference between the bands (analogous to the splitting of frequencies explained before) matters. If the energy is large, it costs a lot of energy to promote an electron to the higher band. This energy is not there and the material will not be a conductor. If there is no splitting, this excitation can happen easily and you will get a conductor. If you have a small splitting, the tempereture of your material might be high enough to promote electrons to higher bands. You get a semiconductor.

To get a basic understanding of these concepts, it is really not necessary to understand the exact nature and strengths of the forces involved. Those will only determine the exact energies where the resulting bands will lie. However, the occurrence of such bands is just a consequency of the large numbers of particles occurring. There is no analog to these band in single atoms and therefore one should not start from single atoms to explain conductivity.

I mean, if these properties were already imprinted in the single atoms, why would graphite and diamond - both pure carbon - have so very different properties in terms of heat conductivity, for example?



Here I do absolutely not get what you mean. Orbiting photons? Electrons not slow enough to have speed and position measured simultaneously? Blurring electrons? You seem to have some strange misconceptions about photons and uncertainty



You would get some discrete resonances. Only photons of well defined energies will interact with the atom.

I typed a long response to your post and it got lost when I submitted it. I'm kind of discouraged to try to type it again. I believe I'm getting the oscillation frequency pattern-effects you're talking about but I still think you're unnecessarily avoiding including behavior of the individual oscillators in the model. Also, I don't see how "oscillation" is a different model from a planetary model such as Bohr's since planets are oscillators as well. I also pointed out in the post that I think it is possible for electrons to consistently lose energy through radiation and regain momentum from collisions. I think this would serve as a general mechanism for transferring heat from a system into radiation. Considering that all matter radiates black-body emissions, why wouldn't the cause of this be consistent evaporation of electron momentum into radiation?

 

[Cthugha]

Also, I don't see how "oscillation" is a different model from a planetary model such as Bohr's since planets are oscillators as well.

Not really. If you apply such a harmonic oscillator model, you have some energy oscillating back and forth between two types. You have kinetic energy and the energy for deforming the spring in a spring pendulum, you have photons and electronic transitions for Rabi oscillations or you have potential and kinetic energy for a string pendulum. In the ideal circular orbit case, a planet is just orbiting its sun at some equilibrium position. No energy is changing from one type to the other.

I also pointed out in the post that I think it is possible for electrons to consistently lose energy through radiation and regain momentum from collisions. I think this would serve as a general mechanism for transferring heat from a system into radiation.

Electrons are almost not involved at all in processes concerning heat. Most of the heat is "stored" in collective motion of the nuclei.

Considering that all matter radiates black-body emissions, why wouldn't the cause of this be consistent evaporation of electron momentum into radiation?

This applies only to matter to which a temperature can be assigned. This is a statistical concept that is only sensible for large numbers of particles. A single atom for example will not emit black-body emission.

 

[brainstorm]

Not really. If you apply such a harmonic oscillator model, you have some energy oscillating back and forth between two types. You have kinetic energy and the energy for deforming the spring in a spring pendulum, you have photons and electronic transitions for Rabi oscillations or you have potential and kinetic energy for a string pendulum. In the ideal circular orbit case, a planet is just orbiting its sun at some equilibrium position. No energy is changing from one type to the other.

So the term, "oscillator," refers to back-and-forth translation between two types of energy? So an electron orbit rising and falling with photon absorption/emissions is an oscillator but the same electron in an undisturbed consistent orbit would not be? So the oscillations you described that transmit electric current? What two states do the electrons oscillate between in that case?

Electrons are almost not involved at all in processes concerning heat. Most of the heat is "stored" in collective motion of the nuclei.

How would energy transfer between two nuclei except through contact between the electrons, since the protons are so far isolated from each other by the electrons?

This applies only to matter to which a temperature can be assigned. This is a statistical concept that is only sensible for large numbers of particles. A single atom for example will not emit black-body emission.

So electrons/atoms only emit radiation at certain moments and at other moments they emit absolutely none? I used to think that until someone who claimed to be a physicist told me that atoms are always emitting some level of radiation and that was called black-body radiation. I read about black-body radiation, and Max Planck's finding that radiation is absorbed and emitted in discreet "packets" determined by frequency and that it is not possible to radiate energy in partial amounts of such "packets." So what you're saying is that only certain atoms within a substance are actually emitting radiation at any given moment and the others are not? Does this mean that energy has to build up to a certain level in an atom before it will trigger a photon-emission? That is what I used to think before this person told me electrons are always emitting some level of radiation.

According to the planetary logic of the atom, the photon gets emitted when the electron "jumps" a level and then falls back to its original level. So if those levels are discreet, which makes sense considering that the radiation travels in discreet packets, then it would make sense that there would be a period of energy build-up before triggering the photon emission, much like a capacitor builds up so much charge before releasing it. So please confirm to me, then, that atoms do not emit radiation except intermittently according to their energy level.