Speaker wires don't carry any energy (power).

[Raindog123]

I've literally begged:

But please, let's do not discuss the meaning of E=mc²

...but, no, here it comes:

Yeah, or the energy of the rest mass of a stool. Right? What energy is that? Do you mean the mass of such particles? Do you mean the equivalent energy of the particle that can be calculated with E=mc²?

MUCH MORE IMPORTANT: Can someone teach me how to do super- and subscript on ASR? Like in @xaviescacs' "E=mc²"? Please?

 

[Andrew s]

Maybe we can discuss mc2 audio products https://www.mc2-audio.co.uk/

 

[Cbdb2]

So you feel comfortable saying that energy doesn't go through the wire but around the wire? I was only trying to put that assertion in perspective.

What perspective, the wrong one? Pyhsics dosnt care about your comfort, intuition or understanding. The energy transfered to the load travels around the wire. This is not a guess its shown in every beginner EM textbook. If you still believe your intuition after dozens of post showing otherwise I give up.

As Neil deGrasse Tyson puts it.
The Universe is under no obligation to make sense to you.

 

[Cbdb2]

I am not (and I do not want to) saying anything. I have just reported what Feynman says in its famous lectures in Physics. If you think that what Feynman said is not correct or/and that wikipedia is more correct, then fine with me.

My intention was to focus on what Feynman was saying in general about the Poyinting vector (and I have reported the related sentences). I have found that very brilliant and wanted to share with you that idea. Nothing more, nothing less.

There both correct and they mean the same thing. What you showed was only part of what Feynman said. Last time. The energy flowing into the load is the part of the Poyting vector parallel to the wire and towards the load, the energy flowing into the wire and never reaching the load (the resistive losses in the wire) is the part of the Poyting vector perpendicular (into) to the wire. These 2 vectors sum to the Poyting vector. Its direction shows where all the energy is going, some to the load some is burned up in the wire.

 

[giuppo77]

There both correct and they mean the same thing. What you showed was only part of what Feynman said. Last time. The energy flowing into the load is the part of the Poyting vector parallel to the wire and towards the load, the energy flowing into the wire and never reaching the load (the resistive losses in the wire) is the part of the Poyting vector perpendicular (into) to the wire. These 2 vectors sum to the Poyting vector. Its direction shows where all the energy is going, some to the load some is burned up in the wire.

Could you please report the Feynman's words stating that the Poynting vector in that specific example (a simple wire, no coax cables, no other similar cases, that specific one only) has a component parallel to the wire? Because it seems to me clearly stated that there is no component of the Poyting vector parallel to the wire (being it radial and orthogonal to both E and B).

I may have mis-read and/or misunderstood the Faynman's words (I am not english-native); glad to learn what I have mistaken.

 

[giuppo77]

The above is wrong. The boson that mediates the EM interactions is the photon. The W and Z bosons mediate the weak nuclear force.

To be formally correct, there is a unique force, the electro-weak one described by the SU(2) x U(1) simmetry group. SU(2) brings three generators, U(1) brings a single generator. The gauge theory behind that foresees mass-less generators; a simmetry breaking mechanism (the famous Higgs mechanism) brings masses to the game and leads to: three massive bosons W+, W- and Z, and one mass-less boson, the photon.

I am not completely precise, just to give an idea of what is behind that.

 

[xaviescacs]

MUCH MORE IMPORTANT: Can someone teach me how to do super- and subscript on ASR? Like in @xaviescacs' "E=mc²"? Please?

Hmmmm I haven't done anything special. K³ See? I just write K ^ 3, but without hitting space after the ^.

By the way, I've asked more than once to enable LaTeX here in ASR, so we can write formulas properly. EM and electronics formulas of course. H|x>

 

[xaviescacs]

What perspective, the wrong one? Pyhsics dosnt care about your comfort, intuition or understanding. The energy transfered to the load travels around the wire. This is not a guess its shown in every beginner EM textbook. If you still believe your intuition after dozens of post showing otherwise I give up.

Other people is telling me what is intuitive or not, or what I will find more intuitive. They tell me if I don't accept that fact that EM tells, it's because I don't find it intuitive. When have I said that?

 

[xaviescacs]

(But please, let's do not discuss the meaning of E=mc²):

Sorry, I missed that. But we can start a fresh thread on this if you like....

 

[xaviescacs]

So are you saying W and Z bosons are moving electron to electron in a wire? ... Are they what moves in a transformer and capacitor too?

EM interaction, as any other interaction, is carried by some particles (photons at large distances), going from one place to another, from one interaction to the other, they get emitted and then absorbed, and that creates the effect that a force has acted upon some particle. The fact that I don't remember what particle does what doesn't change anything (well, it explains why I don't have any reputation). Electrons need some energy to start moving, and they don't care about vectors, they start moving when they absorb some energy. And this is, ridiculously simply stated, the mechanism by which a transformer works. There is nothing strange or controversial about it.

Why this is important? Well, not much really, as no one is his mind will try to model a transformer using the standard model. My only intention was to add some arguments to put in perspective this assertion that energy doesn't go though the conductor, by contrasting EM model with the particle model.

It seems I haven't achieved much though... perhaps just add some energy into the system (thread).

 

[Andrew s]

To be formally correct, there is a unique force, the electro-weak one described by the SU(2) x U(1) simmetry group. SU(2) brings three generators, U(1) brings a single generator. The gauge theory behind that foresees mass-less generators; a simmetry breaking mechanism (the famous Higgs mechanism) brings masses to the game and leads to: three massive bosons W+, W- and Z, and one mass-less boson, the photon.

I am not completely precise, just to give an idea of what is behind that.

Indeed but they decouple at about 10^15 K so for describing physics of audio circuits they are effectivly separate. Regards Andrew

 

[Raindog123]

It seems I haven't achieved much though... perhaps just add some energy into the system (thread).

Energy? - I doubt it. Some entropy, maybe.

 

[Raindog123]

I haven't done anything special. K³ See? I just write K ^ 3, but without hitting space after the ^.

Does not work for me. Must be your browser…

 

[samsa]

EM interaction, as any other interaction, is carried by some particles (photons at large distances), going from one place to another, from one interaction to the other, they get emitted and then absorbed, and that creates the effect that a force has acted upon some particle. Electrons need some energy to start moving, and they don't care about vectors, they start moving when they absorb some energy. And this is, ridiculously simply stated, the mechanism by which a transformer works. There is nothing strange or controversial about it.

Why this is important? Well, not much really, as no one is his mind will try to model a transformer using the standard model. My only intention was to add some arguments to put in perspective this assertion that energy doesn't go though the conductor, by contrasting EM model with the particle model.

That's an extremely naive (and deceptive) description of how QED works. A better one, suitable for laymen is Feynman's book, "QED". Suffice to say that classical E&M is not a "contrasting model"; it emerges from QED in the limit of large occupation-numbers for some state of the photon field.

MUCH MORE IMPORTANT: Can someone teach me how to do super- and subscript on ASR? Like in @xaviescacs' "E=mc²"? Please?

Unicode? U+00B2 = ² ; U+2082 = ₂ .

 

[JustAnandaDourEyedDude]

It strikes me that the short Section 27-4 "The ambiguity of the field energy" of the same chapter of the Feynman Lectures linked to in Post #322 is quite relevant to this discussion of the path of the energy flow.
https://www.feynmanlectures.caltech.edu/II_27.html

I quote Feynman from that section: "There are, in fact, an infinite number of different possibilities for u and S, and so far no one has thought of an experimental way to tell which one is right! People have guessed that the simplest one is probably the correct one, but we must say that we do not know for certain what is the actual location in space of the electromagnetic field energy." And also he says: "Anyway, everyone always accepts the simple expressions we have found for the location of electromagnetic energy and its flow. And although sometimes the results obtained from using them seem strange, nobody has ever found anything wrong with them—that is, no disagreement with experiment. So we will follow the rest of the world—besides, we believe that it is probably perfectly right." Meaning to say that Feynman believed that the location and direction of field energy given by the Poynting vector is probably perfectly right. And as previously quoted in this thread, at the end of Section 27-5, Feynman concludes by saying "You no doubt begin to get the impression that the Poynting theory at least partially violates your intuition as to where energy is located in an electromagnetic field. ... but it is clear that our ordinary intuitions are quite wrong."

Wikipedia quotes Feynman from Vol. I of the same Lectures, on the topic of fields: "The fact that the electromagnetic field can possess momentum and energy makes it very real ... a particle makes a field, and a field acts on another particle, and the field has such familiar properties as energy content and momentum, just as particles can have." The History section of the same Wikipedia page on Fields makes this interesting statement: "... was soon followed by the realization (following the work of Pascual Jordan, Eugene Wigner, Werner Heisenberg, and Wolfgang Pauli) that all particles, including electrons and protons, could be understood as the quanta of some quantum field, elevating fields to the status of the most fundamental objects in nature."
https://en.wikipedia.org/wiki/Field_(physics)

 

[samsa]

It strikes me that the short Section 27-4 "The ambiguity of the field energy" of the same chapter of the Feynman Lectures linked to in Post #322 is quite relevant to this discussion of the path of the energy flow.
https://www.feynmanlectures.caltech.edu/II_27.html

I quote Feynman from that section: "There are, in fact, an infinite number of different possibilities for u and S, and so far no one has thought of an experimental way to tell which one is right! People have guessed that the simplest one is probably the correct one, but we must say that we do not know for certain what is the actual location in space of the electromagnetic field energy."

Feynman is referring to the fact that the canonical stress-energy tensor (the one derived via Noether's Theorem) for electromagnetism is not gauge-invariant. By a gauge-transformation, we can change where in spacetime it is supported.

The "improved" stress-energy tensor is gauge-invariant and hence unambiguous. (FWIW, the improved stress-energy tensor is symmetric (unlike the canonical one) and it's the thing that couples to gravity. This last point, while not directly relevant to the experiment at hand, is the "real reason" there can't really be an ambiguity about where the energy in the electromagnetic field is located. Energy-momentum is the source for the gravitational field. So it can't be gauge-variant or otherwise ambiguous.)

The "0-i" component of the "improved" stress-energy tensor is the Poynting vector.

 

[giuppo77]

The History section of the same Wikipedia page on Fields makes this interesting statement: "... was soon followed by the realization (following the work of Pascual Jordan, Eugene Wigner, Werner Heisenberg, and Wolfgang Pauli) that all particles, including electrons and protons, could be understood as the quanta of some quantum field, elevating fields to the status of the most fundamental objects in nature."
https://en.wikipedia.org/wiki/Field_(physics)

Indeed, that is known as "second quantization".

 

[Spkrdctr]

This is how it starts:

"In discussions on the internet (including a number of Wikipedia pages) and in books and articles for non-experts in particle physics, there is considerable confusion about various notions around the concept of particles of subatomic size, and in particular about the notion of a virtual particle. This is partly due to misunderstandings in the terminology used, and partly due to the fact that subatomic particles manifest themselves only indirectly, thus leaving a lot of leeway for the imagination to equip these invisible particles with properties, some of which sound very magical"

Regards Andrew

All they had to do was ask me. I specialize in that field of science, as quoted "equipping invisible particles and properties, some of which sound very magical".

 

[Cbdb2]

I don't think @Cbdb2 is disagreeing with Feynman.

What I am perceiving is a misunderstanding of the Poynting vector. It is a cross-product of the E&B fields, calculated at a point is space, or perhaps integrated over a space if one so desires. So close to a source it will point out from the source, but not necessarily towards the load at that point in space, and it will point in towards a load if the point is close to the load, etc. When we say the Poynting vector points from source to load, we mean if we take a cut in space between the two and integrate the cross product. Localize direction will be different.

Man, all I wanted to do was show people that the energy doesn't transfer thru the copper,
Maybe I over simplified to make the point. Of course the vector points in various directions if the field is not homogeneous and isotropic but the "average" (integrated over the surface perpendicular to the conductor) points to where the energy goes. Take an infinite surface perpendicular to the wire and from the energy that flows thru it figure out the difference in energy that flows into the wire, compared with the load, these are the wire R losses (only if it has resistance, otherwise theres no E field (voltage) in the wire). That will give you the angle of the "average" Poyting vector. Which seems a more useful concept than saying the vector is straight into the wire at the wire surface and parallel to the wire at a distance, and all the angles in between. When the wire has resistance its a load and it changes the direction of the vector.
Wikipedia
"If a conductor has significant resistance, then, near the surface of that conductor, the Poynting vector would be tilted toward and impinge upon the conductor. Once the Poynting vector enters the conductor, it is bent to a direction that is almost perpendicular to the surface.[13]: 61  This is a consequence of Snell's law and the very slow speed of light inside a conductor. The definition and computation of the speed of light in a conductor can be given.[14]: 402  Inside the conductor, the Poynting vector represents energy flow from the electromagnetic field into the wire, producing resistive Joule heating in the wire. For a derivation that starts with Snell's law see Reitz page 454.[15]: 454 "

And in a real cable:
From https://www.chemeurope.com/en/encyclopedia/Poynting_vector.html
"For example, the Poynting vector within the dielectric insulator of a coaxial cable is nearly parallel to the wire axis (assuming no fields outside the cable) - so electric energy is flowing through the dielectric between the conductors. If the core conductor was replaced by a wire having significant resistance, then the Poynting vector would become tilted toward that wire, indicating that (some) energy flows from the e/m field into the wire, producing resistive Joule heating in the wire."

Are we done yet?

 

[Spkrdctr]

Are we done yet?

I seriously doubt it. This is ASR after all!