### Author Topic: magnetism is just electricity with relativity?  (Read 604 times)

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#### NiHaoMike

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##### magnetism is just electricity with relativity?
« on: June 15, 2018, 01:05:29 pm »

I'm not a quantum physicist so I have no way to verify if that's correct, but if it is, then magnetism is just an abstraction of the relativistic effects of moving charges?
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##### Re: magnetism is just electricity with relativity?
« Reply #1 on: June 15, 2018, 04:37:16 pm »
Well special relativity comes into play and keeps track of 'relative' motions, and how that determines the apparent magnetic field. A relativistic Lorentz force I guess?

And in some part of the math and Gauge theory, it works out just fine because...IDK anymore but it was something like u take the derivative of the (grad(of a scalar field)) and that is zero, and the velocity part of this is in that scalar field, so ....IDK the math details anymore but .....it worked out quite nice.

Look up Clifford algebra and electromagnetism .

Now why does nature act like that or mirror the math we humans us on this...no one knows.

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##### Re: magnetism is just electricity with relativity?
« Reply #2 on: June 15, 2018, 04:54:10 pm »
Something like in the 'vector potential field equations' that the velocity between the charge, there is a term whose derivative is always zero, and the velocity part was in that so math wise it also cancells out or balance's out or whatever.

I have to go learn this stuff again, it's been a while.

Wish I knew Lagrangian and Hamiltonian mechanics a lot more, but not yet, I have video games.
« Last Edit: June 15, 2018, 04:56:55 pm by lordvader88 »

#### TerraHertz

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##### Re: magnetism is just electricity with relativity?
« Reply #3 on: June 15, 2018, 07:06:34 pm »
... one can have magnetic field without flowing charges.

Care to explain how? Unless you're going to get pedantic about the difference between 'flowing' and 'moving'.
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#### T3sl4co1l

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##### Re: magnetism is just electricity with relativity?
« Reply #4 on: June 15, 2018, 08:29:44 pm »
Indeed, it generalizes: any field that has the same characteristics, also has a complementary magnetic equivalent.

So for example, gravitation comes with the gravitomagnetic effect and gravity waves.

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#### RoGeorge

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##### Re: magnetism is just electricity with relativity?
« Reply #5 on: June 16, 2018, 02:24:53 am »
... one can have magnetic field without flowing charges.

Care to explain how? Unless you're going to get pedantic about the difference between 'flowing' and 'moving'.

What I was thinking about initially was that the electron's spin (in permanent magnets) is not exactly a moving charge, but this is very debatable, and I realized that I don't have enough quantum physics knowledge/understanding in order to explain 'how'. Not sure if the 'how' answer exists as we speak (as in why there is charge, or spin, or if a distribution probability of an electron around nucleus can be viewed as a moving charge, and so on).

Long story short, I decided to take it back, and delete my previous message.
Thanks for the question.

#### rfeecs

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##### Re: magnetism is just electricity with relativity?
« Reply #6 on: June 16, 2018, 02:53:39 am »
This "problem" with Maxwell's Equations was pointed out by Einstein in the beginning of his original paper on special relativity "On the Electrodynamics of Moving Bodies":
http://hermes.ffn.ub.es/luisnavarro/nuevo_maletin/Einstein_1905_relativity.pdf

Quote
It is known that Maxwell’s electrodynamics—as usually understood at the
present time—when applied to moving bodies, leads to asymmetries which do
not appear to be inherent in the phenomena. Take, for example, the reciprocal
electrodynamic action of a magnet and a conductor. The observable phenomenon
here depends only on the relative motion of the conductor and the
magnet, whereas the customary view draws a sharp distinction between the two
cases in which either the one or the other of these bodies is in motion. For if the
magnet is in motion and the conductor at rest, there arises in the neighbourhood
of the magnet an electric field with a certain definite energy, producing
a current at the places where parts of the conductor are situated. But if the
magnet is stationary and the conductor in motion, no electric field arises in the
neighbourhood of the magnet. In the conductor, however, we find an electromotive
force, to which in itself there is no corresponding energy, but which gives
rise—assuming equality of relative motion in the two cases discussed—to electric
currents of the same path and intensity as those produced by the electric
forces in the former case.

The problem is in some situations whether you have a magnetic force or an electric force depends on your frame of reference.  Special relativity can explain this.

The problem is demonstrated in the first 5 minutes of this video:

« Last Edit: June 16, 2018, 08:01:09 am by rfeecs »

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