The Disappearing Magnetic Field

[MSimon]

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http://www.edn.com/article/CA6632376.ht ... 1806982773


With diagrams:
http://www.edn.com/contents/images/6632376.pdf

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In this experiment, the choice of reference frame modulates the existence of the magnetic force. You can turn it on or off depending upon where you stand or sit. It is therefore not a “real” force. It is nothing more and nothing less than a direct consequence of Einstein’s theory of relativity.

[blaisepascal]

In this experiment, the choice of reference frame modulates the existence of the magnetic force. You can turn it on or off depending upon where you stand or sit. It is therefore not a “real” force. It is nothing more and nothing less than a direct consequence of Einstein’s theory of relativity.

That particular gedanken experiment is unfamiliar to me, but I learned the idea (and math) of magnetism being a relativistic effect from a 1st year undergraduate physics text from the early 1960's.

[D Tibbets]

I'm to lazy to research it, so I'll ask instead. Can the relativistic model cover perminate magnets, non-moving particles / objects in magnetic fields (magnet stuck on a refrigerater door)? Can the Left hand rule be explained on this basis? And, just to demonstrate my ignorance, what does this view have to say about the possibility of magnetic monopoles and thier apparent nonexistance?


Dan Tibbets

[blaisepascal]

I'm to lazy to research it, so I'll ask instead. Can the relativistic model cover perminate magnets, non-moving particles / objects in magnetic fields (magnet stuck on a refrigerater door)? Can the Left hand rule be explained on this basis? And, just to demonstrate my ignorance, what does this view have to say about the possibility of magnetic monopoles and thier apparent nonexistance?

Exactly everything the Maxwellian model of EM has to say about it.

When you write Maxwell's equations in the language of special relativity, the electric and magnetic fields combine to form a tensor (an antisymmetric tensor, if I recall correctly) field, from which the E and B components are easily recovered. A Lorentz boost doesn't change the form of the tensor, nor its physical results, but it does change the values of the specific field components. By choosing the appropriate Lorentz boost, one can make the B-field components 0.

A description of the EM tensor, its properties, derivation, and relation to Maxwell's laws can be found at http://en.wikipedia.org/wiki/Electromagnetic_tensor