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How does the electron make a photon in an antenna?

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Rick Law:

--- Quote from: T3sl4co1l on February 07, 2017, 08:49:45 pm ---Quantum doesn't matter, because there are no quantum corrections necessary.

In the classical domain, the [average] electron flow in the wires, the electromagnetic fields in the transmission lines and in space: all of this is given by waves, or fluctuations over the norm if you prefer.

In QM, precisely the same is true.  If you wish to break it down to the lowest possible level (photon-electron interaction), that's fine, but you won't learn anything about it.  It's not a discrete, free-space, ballistic interaction, but even the faintest signal involves the coherent (or incoherent and noisy!) interaction of billions of photons and sextillions of electrons.  While the underlying mechanism remains true, there is nothing to learn from it -- the only useful knowledge to gain comes from the statistical ensemble, where the large scale QM behavior trends asymptotically towards the classical model; very accurately indeed, as it happens. :)

Tim

--- End quote ---

Absolutely!  Electronics is a macro concept.  Quantum mechanics in general doesn't come into play.

The only place quantum mechanics will begin to matter is when we continue the miniaturization.  Traces in a die are now down to ~30nm.  At 10nm, you are talking about 100 atoms abreast.  Electronic at that level will begin to get iffy.

T3sl4co1l:

--- Quote from: calexanian on February 07, 2017, 09:33:27 pm ---Perhaps this thought may help. Magnetic fields can exist completely independent of a particle carrier or medium. Particles can interact with the field, but they are not necessary for it to propagate.

--- End quote ---

In the classical, E&M, "no luminiferous aether" sense, yes.

QED takes a very different view, however.

Tim

T3sl4co1l:

--- Quote from: Rick Law on February 07, 2017, 09:52:18 pm ---Absolutely!  Electronics is a macro concept.  Quantum mechanics in general doesn't come into play.
--- End quote ---

Well... if "electronics" includes transistors, then... ;)

But yes, if you're only doing design on a bulk level, then a transistor looks like a transistor with characteristic curves, and you don't need to look at the quantum behavior directly.


--- Quote ---The only place quantum mechanics will begin to matter is when we continue the miniaturization.  Traces in a die are now down to ~30nm.  At 10nm, you are talking about 100 atoms abreast.  Electronic at that level will begin to get iffy.

--- End quote ---

You think RF is bad enough, where waves don't like to stay in wires?  At small enough scales, not even matter waves (at "DC") want to stay in wires! ;D

Tim

calexanian:

--- Quote from: Rick Law on February 07, 2017, 09:52:18 pm ---

Absolutely!  Electronics is a macro concept.  Quantum mechanics in general doesn't come into play.

The only place quantum mechanics will begin to matter is when we continue the miniaturization.  Traces in a die are now down to ~30nm.  At 10nm, you are talking about 100 atoms abreast.  Electronic at that level will begin to get iffy.

--- End quote ---

It's not iffy if you believe in it enough. hahahaha. The electrons know how you feel about them!

bson:
One of the classic Feynman lectures had a nice discussion of how magnetic fields and induction are required to preserve angular momentum... But I'll be damned if I can find the passage right now.  Anyone who hasn't seem these classic B&W lectures, absolutely should - the guy was a fantastic speaker.  Here's a collection of passages relating to the scientific method from the same talks... just brilliant. 

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