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/sci/ - Science & Math

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9322906 No.9322906 [Reply] [Original]

We've all been taught in our electrodynamics classes that fields can indeed be thought of as independent entities, meanwhile here comes this fucker

>https://www.quora.com/A-changing-electric-field-create-a-magnetic-field-and-also-the-other-way-around-What-is-meant-by-changing-and-does-the-changing-electric-field-become-a-magnetic-field-or-does-it-create-an-another-magnetic-field-Explain-with-some-pictures

who literally blows the fuck up general interpretation and with reference to the special relativity postulates gives a damn good explanation why every field can be traced to it's charge / current distribution and we should literally get rid of the view that E is instantaneously related to B through Maxwell's equations.

>https://en.wikipedia.org/wiki/Jefimenko's_equations

Why the fuck are we literally lied to most of our intro E&M, upper div electrodynamics classes?

>> No.9322921
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9322921

>>9322906
>quora

>> No.9322928

>>9322921
>le frogposting

Shut the fuck up and read it, unless of course you have no idea about the subject and then you should just get the fuck out of this thread.

>> No.9322931

>>9322928
>Shut the fuck up and read it, unless of course you have no idea about the subject and then you should just get the fuck out of this thread.
Why the vulgarities?

>> No.9322933

>>9322931
Because you're responding to an actual /sci/ thread with dumb frogposting and muh true scotsman fallacy.

>> No.9322934

>>9322906
If you know E you can find B and if you know B you can find E. They are two sides of the same coin.

In some sense B is just a superficial phenomenon arising from moving charges and relativity.

https://www.youtube.com/watch?v=1TKSfAkWWN0

>> No.9322937

>>9322934
Read the first Quora answer to understand the problem.

>> No.9322945

>>9322937
>Read the first Quora answer to understand the problem.
Give me a quick rundown, I don't open links to that trashcan of a website.

>> No.9322950

>>9322933
>Because you're responding to an actual /sci/ thread with dumb frogposting and muh true scotsman fallacy.
What's dumb about frogposting?

>> No.9322952

>>9322945
No, just read the whole first answer and the thread in it.

>> No.9322955

>>9322952
>No, just read the whole first answer and the thread in it.
"no"

>> No.9323034

>>9322906
>Why the fuck are we literally lied to most of our intro E&M, upper div electrodynamics classes?
But you aren't, just inspect Maxwell equations. It's all the guy in the answer does, too.

>> No.9323211

>>9323034
No, he actually gives a logically more consistent interpretation where we have to consider charge distribution as the primary entity and abolish the field~source equivalence interpretation given by Poisson equation

>> No.9323227

>>9322906
Your professor didn't tell you about it? What shitty school did you go to?

>> No.9323234

>>9322937
>>9322906
The dude is kinda right, but kinda retarded. When he's showing a Maxwell equation and complaining about "time lag", he doesn't understand that Maxwell equations are LOCAL equations linking LOCAL fields.

And obviously, freshman electrodynamics doesn't cover relativistic effects, because treating those require QED, which is a more advanced topic.

>> No.9323248
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9323248

>>9322906

"For Christ's sake, Soddy, don't call it transmutation. They'll have our heads off as alchemists."

>> No.9323259

>>9323211
>primary entity
this is physics, not philosophy
later in the same course you're taking now you'll learn about the vector potential. It could be regarded as more "fundamental" too

>> No.9323277

>>9322906
Fields are uniquely defined by charge distributions. If you know where the charges are, there's only one possible field that it corresponds to and vice versa.

This is taught in electrostatics and is the reason we can think of fields in the first place. What this guy says is true, but is a tautology.

>> No.9323291

>>9322934
>In some sense B is just a superficial phenomenon arising from moving charges and relativity.
This is false and can be easily disproven by looking at the invariants
itt anons that haven't studied EM beyond college-level shit, not even talking about qed

>> No.9323328

>>9323291
I think he just meant that B fields do no work. They exist but are the result of moving charge, which is where the forces /work actually exist. You do need qed to explain fully why B is a fictitious force.

>> No.9323350

>>9323328
>B doesnt do work

what the fuck am I reading? Whats fucking dipole??

>>9323259
You have no idea about what is the topic at hand
, this is not a matter of perspective and I advise you to reread the thread and the wiki page. Ive done classical electrodynamics three years ago, but nice projection.

>> No.9323402

>>9323350
>You have no idea about what is the topic at hand
I'm pretty sure I do lad.
Sure fields come from moving charges, but that doesn't allow you to say "we should literally get rid of the view that E is instantaneously related to B through Maxwell's equations." because they very well goddam are related.

Maybe you're troubled by the idea of local equations, but regardless they are equivalent to their integral forms.

>> No.9323549

>>9323350
Calm down sperglord.

Force is proportional to v x B.
So the force is always perpendicular to the motion of the particles.
Work is F •v dl
Since force and v are perpendicular, the dot product will always be 0. So the magnetic field does no work.

When you take an intro to modern physics, you'll see that the apparent discrepancy us resolved by qm.