Ask any question you want about Physics

originally posted by: KrzYma
a reply to: mbkennel

...quantum phenomena like x-ray scattering.

What is so special about x-rays than the other frequencies... what do you mean exactly ?

Just that, the frequencies.

The frequencies are high and therefore the minimum energy for a photon is high and so the interactions tend to deal with low or single photon numbers (I was thinking of Compton scattering in particular which is only understandable with QM), whereas at optical or lower frequencies the effective photon number is very large and so everybody treats the problem classically because you get the same answers almost with much less effort. [i.e. it's hard vs insanely hard]

originally posted by: mbkennel

originally posted by: KrzYma
a reply to: mbkennel

...quantum phenomena like x-ray scattering.

What is so special about x-rays than the other frequencies... what do you mean exactly ?

Just that, the frequencies.

The frequencies are high and therefore the minimum energy for a photon is high and so the interactions tend to deal with low or single photon numbers (I was thinking of Compton scattering in particular which is only understandable with QM), whereas at optical or lower frequencies the effective photon number is very large and so everybody treats the problem classically because you get the same answers almost with much less effort. [i.e. it's hard vs insanely hard]

Agreed that's why we run computer simulations.

originally posted by: ImaFungi

Draw a point on a piece of paper, and then try and draw how you know the EM field is coupled to the electron, and then tell me what sort of substance the EM field you drew is composed of. Tell me how if it exists independently of charged particles, what it is composed of and how it has no rest mass. Tell me how the EM field, it exists as a dense
ocean of particular material energy which is coupled to charge particles, tell me why this dense ocean of particular material energy 'waves' away from the acceleration of a charge? And how it doesnt wave like other particles in mediums we are familiar with, tell me how the medium designates 2d lines only connected in certain spots of the imaginary 1d point, waves away in a certain 2d direction, without 3d/4dly rippling the entire local EM surroundings of the charge?

If the EM field exists everywhere, you need to admit that photons exist everywhere, the ones in which you refer to as 'flying around' or 'detected' are merely larger than average, or, not larger than average, but the rest mass of a portion of the EM field, with relative energy.

A perfect still bath tub of water, lets imagine as the EM field. You say there are no photons, I say the EM field is an energy dense medium composed entirely of energy/matter call them photons if youd like. I take a marble (charged particle) and touch it to the surface of the still tub of water, and ripples are created. You say photons are now flying around. or we say, the EM field has locally been excited due to an acceleration of mass coupled to it. I say it is all photons, just that relative areas of the photon field are now moving with relative motion, the average energy of a local area was increased.

The EM field does contain energy but another way to look at it is as a field of potentiality. It exists even if there are no charged particles. It is quantized so it's energy appears in bundles - photons. Electrons also have an electron field. Electrons disturb the EM field and sometimes the disturbance is known as virtual photons or virtual photon exchange.
There are also virtual electrons involved and other fields as well. It gets complicated and terminology varies.

originally posted by: mbkennel



No, it depends on the particular motion of the electron. sin^2 alpha = 0 for alpha = 0 and pi, so for some particular directions you wouldn't see any radiation. If, for instance, the electron oscillates in a small circle, then if you still look in that 2-d plane, there would indeed be radiation in all 360 degrees.

But if the electron is attached to the EM field 360 degrees; How when the electron is moved/accelerated at all; are the points of attachment 360 degrees; not also moved; the moving of which, is what EM radiation is; the EM field moving, is EM radiation; the electron moving; moves the EM field; which it is attached to on its 360 degrees?

So I think I see what you are saying, but we still dont know what the EM field is composed of, what the nature of that substance is; the picture you are painting is;

Imagine a baseball on the floor with 360 fishing lines attached around its perimeter which extend outwards and are attached to the walls; put your hand on top of the baseball and move it away from yourself and towards yourself, away from your self and towards yourself, away from yourself and towards yourself; notice how in the time and space dimensions the fishing lines perpendicular to you can be determined as 'a wave' or 'waves', while the fishing lines that are parallel with the directional axis you are moving the ball back and forward in, can not be said to be waving. Therefore 'em radiation' propagates away from the charge particle, in the direction perpendicular to the direction of acceleration.

Now, if that is a good enough analogy of what you mean, I further wish to ask; well for starters, you will notice in the analogy, that even with moving the ball towards and away from you, due to the nature of the substance 'fishing line' for this analogy, we would notice that the fishing line parallel to your direction of acceleration would be moving. What I want to ask is, in this analogy, before the ball/particle is accelerated, is it proper to analogize the fishing line as equal to stationary photons, and is stationary photons what you call virtual photons, and when i say EM field exists, am i saying stationary non 0 value photon exist?

Whatever you come up with as your answer to what in reality the fishing lines represent substantially, what is your answer as to why its substance is not propagated in the direction parallel to your hand and ball motion?

The full real theory is called 'quantum optics' and is the closest explanation of what a photon REALLY is

Can you just give me a sentence or two summary? let me guess, its a wave and a particle. Is a surfer a system of waves and particles that are composed of waves and particles living in a system of waves and particles on a giant particle made of particles made of waves and particles surfing on waves and particles that are made of waves and particles?

It's quite difficult to visualize. Perhaps there are simulators that help.

Its not difficult to visualize. Imagine a ball moving through a 3d substance medium, in such a way that other balls that go near it follow the enclosing hole made by the more massive ball moving through it.

The Lienard-Wiechert potentials can help you calculate the resulting fields from generalized motion of charges.

They integrate over the location of where charges used to be ("retarded time") at some distance away (propagating at 'c'), and then you take gradients and curl of these to get your electric and magnetic fields. See the section Equations here: en.wikipedia.org...

in the expressions for E() and B() there is a first term plus a second term. The first term is the 'near' contribution to the field, and in quantum mechanics might be assocaited with 'virtual photons', and the second is the radiation field which is associated with real photons which can propagate to infinity and carry energy & momentum.

You are offering all very practical and helpful information, but the reason i do not dedicate myself to studying all this useful tools and practicality, is because my interest lies in the absolutely most purest fundamental truths of reality, that I believe had to be and have to be glossed over, to have such things as civilization and science programs and technology. I am not interested in learning skills and pragmatism, I am interested as an intelligence which finds itself existing in a reality with the ultimate desire to comprehend exactly most intimately and fundamentally what the constructive and creative essence of the reality is, and how it functions on those most hidden levels.

originally posted by: ImaFungi


Whatever you come up with as your answer to what in reality the fishing lines represent substantially, what is your answer as to why its substance is not propagated in the direction parallel to your hand and ball motion?

a) There is an electric field in the direction of oscillation. It's vector direction is static (unchanging with time), so there is no *radiation* in the direction looking straight on the oscillation.

b) The dynamics of the electric and magnetic field are not the same as mechanical strings.

The field lines are partial representations of the vector field, which is a vector at every point in space, the same way that contour lines on a geophysical plot are representations of the scalar elevation field. They are graphical shortcuts, not physical objects.

The full real theory is called 'quantum optics' and is the closest explanation of what a photon REALLY is

Can you just give me a sentence or two summary? let me guess, its a wave and a particle.

The state of electromagnetism is a function (quantum mechanical wavefunction) of functions (the E&B fields), which has certain requirements imposed upon it which use Planck's constant such that when you make a modal expansion in some function basis you sum up elementary terms, each one of which, is called a 'photon', and if the photon has a definite frequency it has a proportional energy and momentum and there is a minimum non-zero amplitude.

Is a surfer a system of waves and particles that are composed of waves and particles living in a system of waves and particles on a giant particle made of particles made of waves and particles surfing on waves and particles that are made of waves and particles?

Everything is made out of stuff obeying laws of quantum field theory, as far as we can tell. Particles are the 'expansion' of the quantum fields in some useful quantum mechanical bases.

You are offering all very practical and helpful information, but the reason i do not dedicate myself to studying all this useful tools and practicality, is because my interest lies in the absolutely most purest fundamental truths of reality, that I believe had to be and have to be glossed over, to have such things as civilization and science programs and technology. I am not interested in learning skills and pragmatism, I am interested as an intelligence which finds itself existing in a reality with the ultimate desire to comprehend exactly most intimately and fundamentally what the constructive and creative essence of the reality is, and how it functions on those most hidden levels.

Physics used to be called Natural Philosophy, for good reason. I suggest you study it. The concepts and assertions of truth generally accepted cannot be adequately conveyed by linguistic means alone. The description of the photon above is pretty much jibberish unless you have experience with the mathematics and physics that it refers to.

I wonder if you're lazy.

a reply to: mbkennel

True if you dont understand the math involved you can never have a complete picture of Physics. That's why even I'm the age of computer simulations you still have students trudge through the math. You actually see the light click on as they gain a deeper Understanding of particle physics.

a reply to: Arbitrageur

All particles vibrate. That means that they have mass in motion. My question is this, are atoms or any particles for that matter perpetual motion machines, or are they subject to the laws of motion like everything else?

originally posted by: LibertyKrueger
a reply to: Arbitrageur

All particles vibrate.

That's sort of questionable. I don't know that ALL particles vibrate. I don't even know if MOST vibrate. A lot of them move around, though, under normal circumstances. If you are asking about the vibration of atoms within molecules, yes, they do, unless you're at absolute zero. The picture of whether electrons "vibrate" exactly or what's going on inside a nucleus or inside protons and neutrons is a bit less explicit, AFAIK. It's obvious there can be motion or you wouldn't get fission or have nuclear isomers. But "vibrate" to me is a term that describes a specific sort of thing. The atoms of a molecule often do this, due to QM.

That means that they have mass in motion. My question is this, are atoms or any particles for that matter perpetual motion machines, or are they subject to the laws of motion like everything else?

Yes. And it is not perpetual motion. Consider. Is the motion of the Earth around the Sun perpetual motion? No. There was energy imparted that causes it to move. That doesn't have anywhere to go...therefore it will stay in motion since nothing's acting against it.

This first law of motion is what you're looking at inside a molecule. The bonds between atoms in a molecule are not dissipative, therefore the motion of the atom typical of that bond will go on forever. If you remove energy from the system, the amplitudes will decrease until theoretically at absolute zero, they'll stop moving.

See also: IR spectroscopy

originally posted by: Bedlam

That's sort of questionable. I don't know that ALL particles vibrate.

delta p * delta x > c*hbar

If you sort of know where it is, then it's going to be moving around even at T=0.

Einstein & Stern even figured out something close to the right answer more than a decade before QM.

In addition to being the father of relativity, Einstein was the father of modern statistical mechanics.

originally posted by: Bedlam

originally posted by: LibertyKrueger
a reply to: Arbitrageur

All particles vibrate.

That's sort of questionable. I don't know that ALL particles vibrate. I don't even know if MOST vibrate. A lot of them move around, though, under normal circumstances. If you are asking about the vibration of atoms within molecules, yes, they do, unless you're at absolute zero. The picture of whether electrons "vibrate" exactly or what's going on inside a nucleus or inside protons and neutrons is a bit less explicit, AFAIK. It's obvious there can be motion or you wouldn't get fission or have nuclear isomers. But "vibrate" to me is a term that describes a specific sort of thing. The atoms of a molecule often do this, due to QM.

That means that they have mass in motion. My question is this, are atoms or any particles for that matter perpetual motion machines, or are they subject to the laws of motion like everything else?

Yes. And it is not perpetual motion. Consider. Is the motion of the Earth around the Sun perpetual motion? No. There was energy imparted that causes it to move. That doesn't have anywhere to go...therefore it will stay in motion since nothing's acting against it.

This first law of motion is what you're looking at inside a molecule. The bonds between atoms in a molecule are not dissipative, therefore the motion of the atom typical of that bond will go on forever. If you remove energy from the system, the amplitudes will decrease until theoretically at absolute zero, they'll stop moving.

See also: IR spectroscopy

No your not the first law of motion is not what causes molecules to move. It's contrary to every observation we have made. In your theory atoms wouldn't decay for one. Reason things move is energy doesn't matter if they are particles or atoms. You add energy through em radiation atoms are going to move. Particles are going to move faster causing the atom to move.

originally posted by: mbkennel

If you sort of know where it is, then it's going to be moving around even at T=0.

But what's going on inside the nucleus, and inside nucleons? I imagine there's motion, but I'm not sure it can be categorized as "vibration" in the sense you could say that about QM motions - scissoring, rocking, rotating etc.

originally posted by: dragonridr
No your not the first law of motion is not what causes molecules to move. It's contrary to every observation we have made.

Oh, sure it is, because it's NOT contrary to every observation we have made.

It's nearly Newtonian. QM vibrations in molecules is one of the few things that nearly makes sense, classically.

eta: instead of knee jerking, go back and actually look at IR spectroscopy, read a bit on QM motion in molecules. Then come back. The rocking, scissoring, rotating, flexing etc motions are all going on all the time and are NOT dissipative. They can dump energy by popping out photons (or phonons, depending) at a certain frequency but once in motion they stay in motion, because the bonds aren't dissipative. It's not like they can "run down". So it's not "perpetual motion" that they're always doing that, which was the original question. MBKennel says even at t=0.

originally posted by: mbkennel

If you sort of know where it is, then it's going to be moving around even at T=0.

So...can it emit phonons even in ground state/T=0?

originally posted by: Bedlam

originally posted by: mbkennel

If you sort of know where it is, then it's going to be moving around even at T=0.

So...can it emit phonons even in ground state/T=0?

A ground state is merely the lowest energy level an atom can have. Doesn't mean there is no energy. with an atom say we have an electron we add to much energy it flies off. This is what we call ionization. Now electron does not have to be in a particular place or energy level.An electron state is a superposition of states of definite energy level (energy eigenstates).Now even in a ground state an atom has potential energy. Let's say I set a glass of water in a cup and place it on the table. That water will sit there forever until something perturbed it such as us shaking the glass. Now the water is no longer in its lowest energy state.

Now atoms are the same way if nothing perturbs the electron in to excited energy eigenstate, then it simply will never decay it sits there becausr energy eigenstates are stationary; they do not evolve into anything other than themselves.But here's the catch being completely without external perturbation is actually impossible. The uncertainty principle provides the electromagnetic field with vacuum fluctuations. Meaning even our electron in our atom is constantly being shaken up even in its lowest energy state.

originally posted by: LibertyKrueger
a reply to: Arbitrageur

All particles vibrate. That means that they have mass in motion. My question is this, are atoms or any particles for that matter perpetual motion machines, or are they subject to the laws of motion like everything else?

"Laws of motion" is a classical concept.
Your question gets into quantum mechanics, which doesn't obey classical laws.
For example, we can prove pretty easily that the "orbits" of electrons around the nucleus can't possibly be following concepts of orbits in classical physics. Now we see the electron orbitals as something like a probability cloud without a definite position and momentum of the electron at any given time.

You should also consider that by adding the word "machine" to the words "perpetual motion" you have a new phrase which changes the meaning significantly.

"Perpetual motion" means motion that can persist indefinitely and we can certainly find examples of near perpetual motion with some astronomical objects which have very little friction to slow down their rotation. While technically the friction is only close to zero and not exactly zero, the motion can persist for billions of years so from the perspective of human time scales it would seem nearly perpetual.

"Perpetual motion machine" means "a hypothetical machine that can do work indefinitely without an energy source" as defined in Wikipedia. This definition is the main reason that astronomical objects rotating almost perpetually are not "perpetual motion machines", because they have a finite amount of angular momentum so work cannot be extracted from them indefinitely (though I admit we'd need an awful lot of tidal energy "farms" to extract enough energy from the Earth's rotation to change the length of a day from 24 hours to 25 hours). Likewise, vibrating particles are not perpetual motion machines because work cannot be extracted from vibrating particles indefinitely if there is no energy source.

a reply to: Bedlam

I'm more concerned about what's happening within the particle structure. For instance, if the particle structures movements that we see are caused by the internal deflection of the linear motion of the mass, it would explain what's realy driving the motions that we see. If that's the case, it would mean that quantum uncertainty isn't a driving force of quantum motions, but instead just related to the amount of environmental interactions something that small would be subject to. If particles are driven by internal deflections of its mass in motion, it would certainly explain their motions when they are pivoting on the chemical bonds as shown in the IR Spectroscopy page you referenced, and why those motions are continuous without an external energy input, with no need to invoke perpetual motion or a complete absence of external influences that could be acting against those driven motions.

originally posted by: Arbitrageur

originally posted by: LibertyKrueger
a reply to: Arbitrageur

All particles vibrate. That means that they have mass in motion. My question is this, are atoms or any particles for that matter perpetual motion machines, or are they subject to the laws of motion like everything else?

"Laws of motion" is a classical concept.
Your question gets into quantum mechanics, which doesn't obey classical laws.
For example, we can prove pretty easily that the "orbits" of electrons around the nucleus can't possibly be following concepts of orbits in classical physics. Now we see the electron orbitals as something like a probability cloud without a definite position and momentum of the electron at any given time.

You should also consider that by adding the word "machine" to the words "perpetual motion" you have a new phrase which changes the meaning significantly.

"Perpetual motion" means motion that can persist indefinitely and we can certainly find examples of near perpetual motion with some astronomical objects which have very little friction to slow down their rotation. While technically the friction is only close to zero and not exactly zero, the motion can persist for billions of years so from the perspective of human time scales it would seem nearly perpetual.

"Perpetual motion machine" means "a hypothetical machine that can do work indefinitely without an energy source" as defined in Wikipedia. This definition is the main reason that astronomical objects rotating almost perpetually are not "perpetual motion machines", because they have a finite amount of angular momentum so work cannot be extracted from them indefinitely (though I admit we'd need an awful lot of tidal energy "farms" to extract enough energy from the Earth's rotation to change the length of a day from 24 hours to 25 hours). Likewise, vibrating particles are not perpetual motion machines because work cannot be extracted from vibrating particles indefinitely if there is no energy source.

The reason for the question is due to an anomaly I came across in some published works that seem to indicate that the vibrational frequencies of matter are slowing very slightly over time. If that's the case, then it might need to be accounted for by changing or revising our assumptions about what is driving those motions. For instance, if the motions of the particle structure are caused by the internal deflection of linear motion of the mass, that deflection could be concidered useful work for which a tiny amount of that internal momentum would be conserved according to the Laws of Motion. That would slowly decrease the total sum of momentum energy of the mass contained within the particle structure, thereby decreasing the natural frequency of its motions over time.

originally posted by: dragonridr

originally posted by: Bedlam

originally posted by: mbkennel

If you sort of know where it is, then it's going to be moving around even at T=0.

So...can it emit phonons even in ground state/T=0?

A ground state is merely the lowest energy level an atom can have. Doesn't mean there is no energy. with an atom say we have an electron we add to much energy it flies off. This is what we call ionization. Now electron does not have to be in a particular place or energy level.An electron state is a superposition of states of definite energy level (energy eigenstates).Now even in a ground state an atom has potential energy. Let's say I set a glass of water in a cup and place it on the table. That water will sit there forever until something perturbed it such as us shaking the glass. Now the water is no longer in its lowest energy state.

Now atoms are the same way if nothing perturbs the electron in to excited energy eigenstate, then it simply will never decay it sits there becausr energy eigenstates are stationary; they do not evolve into anything other than themselves.But here's the catch being completely without external perturbation is actually impossible. The uncertainty principle provides the electromagnetic field with vacuum fluctuations. Meaning even our electron in our atom is constantly being shaken up even in its lowest energy state.

Actually, I think it's the other way around. That the vacuum fluctuations of the EM field are driven by the motions of matter rather than those fluctuations being primarily responsible for matters motions. The reason that I think that matters motions are primarily internally driven is because of the reported increase of internal frequency as the temperature of matter approaches absolute zero. As the outer structure of matter is being prevented from moving, it provides a more solid surface against which the internal deflections of the masses momentum take place. This increases the effective rebound energy of that internal deflection thereby increasing the frequency of those motions by eliminating the deflective losses that moving the external particle structure would impart.

originally posted by: Bedlam

originally posted by: mbkennel

If you sort of know where it is, then it's going to be moving around even at T=0.

But what's going on inside the nucleus, and inside nucleons? I imagine there's motion, but I'm not sure it can be categorized as "vibration" in the sense you could say that about QM motions - scissoring, rocking, rotating etc.

True, you aren't dynamically changing state.

originally posted by: Bedlam

originally posted by: mbkennel

If you sort of know where it is, then it's going to be moving around even at T=0.

So...can it emit phonons even in ground state/T=0?

No, not propagating ones which carry off energy to infinity. (it is in the ground state after all).