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A little bit of background information: I'm planning to write a little booklet or web page about CPU/computer architecture, basically for my own education, because we didn't cover it in depth in college. I feel like I should be learning a lot more about the fundamentals about how computers work, if I want to be a better programmer.

The idea is to present the workings of a CPU by describing it from the ground up. Starting at simple electrical circuits, then semiconductors, transistors etc. From my school physics class I remember that I was very often left with a lot of gaps about how different concepts are linked together. I want to avoid this.

So here's my question: How does an electrical field really work? How come that an electron can exert a force on another electron without physical contact? What is it in an electron that creates the field, where does the energy for doing the work come from?

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If it is the case that the electric field and the electron are fundamental constituents of nature, is it possible to describe "how they work"? If they are truly fundamental, in what "more fundamental" terms could they be described? –  Alfred Centauri Dec 24 '12 at 1:46
Just for Fun, I googled Feynman electricity and got a pretty good answer to your question. (I later looked at the link in Dave's answer but I prefer the one I stumbled on). Part of Feynman's genius was that he understood (from his father I think) that giving things a name didn't explain them. He could answer these sorts of questions without saying "it happens because of so-and-so's law". –  RedGrittyBrick Dec 24 '12 at 22:00
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2 Answers

up vote 2 down vote accepted

How does an electrical field really work?

There are two formulations that describe the known data on electric and magnetic fields.

a) The classical electromagnetic theory ruled by Maxwell's equations . This works well in describing the macroscopic data, of which the electric field is a component.

b)The quantum mechanical formulation that leads to an explanation of how fields are built up, which is necessary to explain effects like the "photelectric effect", the behavior of atoms and molecules, the internals of atoms and molecules.

For a) the electric field is a fundamental component of the behavior of matter.

For b) the electric field is built up coherently by innumerable virtual particle exchanges, mainly virtual photons, between the generators of the field and the detectors of its existence, so it is not fundamental. Charge is fundamental in this framework, and charge is quantized (+/-1/3, +/-2/3,+/-1)in absolute value electron charge units. That is why it is a quantized theory of the world.

How come that an electron can exert a force on another electron without physical contact?

For a) it is an action at a distance , the field of the electron exerts a force on other charged matter; similar to classical newtonian gravity, where the masses exert a force on each other.

What is it in an electron that creates the field, where does the energy for doing the work come from?

It is the charge of the electron. When we are talking of electrons we are really in the realm of b), quantum mechanics, because its size is of the size where quantum mechanics has to be used to understand the data.

In QM language the electron, when looked at individually, is continually exchanging virtual photons with the boundaries of its containment. Virtual means that energy and momentum are not conserved because nothing real is exchanged with the other electrons/ions except an information "I am here". When many electrons are involved, the surface of a charged metal sphere for example, the collective electric field is built up out of those exchanges.

The energy was supplied in this case by the experimenter who provided work to separate the electrons from the rest of the molecules, turning them into ions.Either by the triboelectric effect or the classical generators of electricity, using magnetic fields and providing a current of electrons in metals. Ultimately it is kinetic energy turned into electric energy. ( actually sun energy stored in fuels or water works, turned into kinetic energy ...)

Now magnetic fields, used to generate most of our electricity, are a bit of a different story, but similar and again needing quantum mechanics to be understood. In scenario a) they also are fundamental.

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v nice summary. –  Art Brown Dec 24 '12 at 5:30
Thanks for this elaborate answer. –  alexraasch Dec 24 '12 at 14:18
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I'm going to paraphrase a response by Feynmann who was asked to explain electromagnetic forces. He (correctly) interpreted the questioners intent as "explain E&M in terms of the force between your behind and the chair." The problem is that E&M just is a fundamental interaction between particles and it is the fundamental microscopic description of most of the macroscopic forces that we deal with on a day to day basis.


I suggest reading QED: The Strange Theory of Light and Matter by Dr. Feynmann and see if you can condense it to meet your requirements.

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If anyone has the corresponding link w/o the ICP references please let me know. –  Dave Dec 24 '12 at 1:48
So are you saying that there is no more fundamental explanation or that we don't know yet? –  alexraasch Dec 24 '12 at 2:09
@Dave Without the added ICP bits: youtube.com/watch?v=wMFPe-DwULM –  Nathaniel Dec 24 '12 at 2:15
@alexraasch I'd say that any "more fundamental" description would get well outside of the question's stated scope, requiring getting into quantum field theory, the gauge symmetry model of forces and so on. –  Dave Dec 24 '12 at 2:43
Well, if I have to dive into that I will. There's no rush. The level of electronics that they teach you in computer science is rather superficial. I've always been dissatisfied with that.In that video of Feynman, he actually doesn't say that it's fundamental and that there is no deeper explanation. He just says that he can't explain it to an ordinary person. That's a lot different from what you told me. –  alexraasch Dec 24 '12 at 2:49
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