Collective Electrodynamics

What Hacker News says

1. bsderApr 2025
   I'm pretty sure this is what you want:

   "Collective Electrodynamics: Quantum Foundations of Electromagnetism" https://www.amazon.com/Collective-Electrodynamics-Quantum-Fo...

   thread
2. bsderJan 2024
   Maxwell's theory is not hard to understand--once you have the proper tools.

   The problem is that because of trying to cram a degree into 4 years, you wind up having a class on electromagnetics without any understanding of vector fields.

   Electrical engineering is particularly bad about this. You never get exposed to the Hamiltonian formulations of classical mechanics, and you never get exposed to vector analysis. Consequently, you are stuck with the Heaviside-Hertz pedagogy with silly things like "displacement current" and stupid, weird-ass integration contours (which don't work in motors, LOL)--and the attendant difficulty in understanding Maxwell's theory.

   However, if you have vector analysis and fields, then you can understand formulations like Carver Mead's "Collective Electrodynamics": https://www.amazon.com/Collective-Electrodynamics-Quantum-Fo...

   Suddenly, emag is a whole lot more straightforward to understand. It's not EASY as it's very math heavy, but it has a lot fewer weird things that are just "we say it works."

   Show morethread
3. bsderAug 2019
   > The realm of electrodynamics is pretty interesting, and it's where seemingly basic concepts like electric potential begin to fail -- it becomes path-dependent!

   Not really. The problem is that we have sort of an "electron abstraction" which is incorrect in the Heaviside-Hertz pedagogy when fields start to store energy. I recommend "Collective Electrodynamics" by Carver Mead as a modern formulation without the silliness of an Aether: https://www.amazon.com/Collective-Electrodynamics-Quantum-Fo...

   > I only brought up ground (in the Earth ground sense) because I've heard people think that antennas in general work by using the Earth as a second conductor, with EM radiation as the first.

   Really? Most of the time I describe antennas as sort of really long range transformers. And, while you need each side of the transformer to be a circuit, the two sides of the transformer don't have to interact other than through a field.

   > My previous comment was written out of a reasonably common conception of a closed circuit being a loop with constant current flow, but capacitors break such a circuit.

   Yes and no. Capacitors have the hand wavy notion of "displacement current" in classical electrodynamics--but most of the issue is with the fact that we use the Heaviside-Hertz pedagogy which was formulated back when everybody believed in the Aether.

   The real issue is that to deal with capacitors you must deal with fields rather than just the notion of electrons. However, if we kind of squint and wave our hands the "electron formulation" can be kinda sorta made to work. (Side note: Capacitive dividers are even more annoying and you have to be really careful.)

   Classical Heaviside-Hertz electrodynamics also has a lot of issues dealing with motors and generators, as well. Again, the key is that an "electron formulation" isn't really enough when fields start holding an appreciable amount of energy.

   Show morethread
4. KoshkinDec 2017
   Most useful link, thanks.

   So, the idea seems to be that an electron that has crossed ("excited") into the conduction band may, instead of recombining with a hole it (or some other electron) left behind, it may, as the article puts it, "pair up" with the hole and thus form a bosonic quasi-particle.

   One of the interesting aspects of this is that unlike Cooper pairing (of two electrons), the pairing of an electron with a hole is a collective effect, i.e. one that requires the participation of many electrons (as well as the atom's nucleus that accounts for the hole's positive charge).

   Those who want to learn more about "collective electrodynamics" may consult a book by Carver Mead.

   Show morethread
5. bsderApr 2017
   And it doesn't work very well for certain systems. Motors are notoriously annoying to attempt to use "displacement current" on.

   Remember, the Heaviside-Hertz pedagogy existed in a time when the "Ether" was assumed to exist.

   What works nicely for things that "displacement current" fails badly is a "field based" representation. See "Collective Electrodynamics" for such a pedagogy.

   https://mitpress.mit.edu/books/collective-electrodynamics

   (Edit: Misspoke a bit: Field based works well for all systems. It just doesn't give nice, textbook, closed-form solutions for certain problems that are "simple".)

   Show morethread
6. bsderNov 2016
   > You would have to go back to James Clerk Maxwell's original 20 equations to see what it's all about. Okey, quaternions are kind of hard, I'll admit to that, but all in all it makes much more sense.

   Not ... really. The problem is that we teach electromagnetics using a 19th century pedagogy that assumes the existence of the Ether.

   This works well for some things and makes them nicely closed form and simple. Of course, it breaks down for other things (motors are one of the big ones) where you really want a field description.

   Of course, a field description makes nothing simple and closed form. So, it isn't good for making exams out of.

   If you can deal with 4-vectors, "Collective Electrodynamics" is a really good book.

   Show morethread