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A base-level question about electromagetism, magnetic fields, & conductors
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IanB:

--- Quote from: switchabl on October 01, 2023, 07:00:38 pm ---In classical field theory, it is really just a question of the coordinate system.
--- End quote ---

But according to the video I linked above, in classical field theory the equations for electromagnetism do not explain all observed phenomena and contain inherent contradictions. A change of reference frame can lead to problems.

Only when Einsteinian relativity and length contraction is included in the analysis it is possible to make sense of all observations.
switchabl:
What we call "classical" electrodynamics today already has special relativity baked in. It is understood that everything happens in a Minkowski space-time and that coordinate systems are related by Lorentz transforms (which convert between electric and magnetic fields and include effects such as length contraction and time dilation).

In modern physics, the word "classical" almost always just means "non-quantum". So I wasn't referring to pre-1900 electromagnetic theory; but I can see where that might be confusing.
RJSV:
   In my training, a pure beam of electrons will repel each other, (being 'like' charges), which are focused in the CRT case, to counter the tendency to spread out during travel.
Actually surprised, that similar situation, going down a wire, isn't the same, as far as the generated magnetic field, thinking the atoms etc. in a copper wire will have positive charges that balance the negative (moving) charges.  Or did I read previous posts wrong ?
(thanks)
RJSV:
...I've usually put up my own red flag, when a non-classical theory framework is discussed, (subjects like 'Quantum' physics are notorious, in other threads.)
   Listened, recently, to some 'medical' descriptions, blatent abuse of terms like 'frequency'...as in "Bad frequencies must be purged...by flooding the Patient's body, with cancellation waves...".
Those frequency cancelling effects seem to forget, about wave phase relations, in other material I've seen.

Just reminded me, as seen elsewhere.
SiliconWizard:
Although full of equations that must mean that it's all very serious stuff, admittedly a number of modern physics theories suspiciously look like dodgy alternative medical therapies.

That reminds me also of this user who was talking about aether and hugging photons and stuff. While the whole thing looked quite funky, it wasn't that much funkier than string theory. Oh well. Oh so little we know.
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