Can Magnetic Fields Exist in a Perfect Vacuum?

[cjameshuff]

Well, I quess that's where I get confused.
A magnetic field can extend into a vacuum. This is widely accepted, and I accept it.
But HOW does it do this?

It just does...your question assumes that there's something special required for it to do so. Saying "virtual particles" doesn't answer the question, it just shifts it...how do those virtual particles move through empty space? Why are they emitted? Virtual particles serve to fit these fields into the mathematical framework of quantum mechanics and allow their behavior to be described in a systematic way, not to answer the question of why things work the way they do.

Magnetism is not fully emissive like a photon, in the sense that a photon of light can be emitted and never return to it's source, yet magnetism currently requires a return to source. No "magnetic laser" so-to-speak can be constructed(at this time) without the discovery and manipulation of "monopoles"... if they exist.

It has nothing to do with magnetism being emissive or not. Magnetism does not "return to its source"...field lines are described as closed loops, but this is a way of visualizing certain characteristics of the field, there's nothing actually traveling in loops away from and back to the magnet. Magnetic monopoles would be the magnetic equivalent of charged particles like electrons and positrons...these particles certainly exist, and don't have looped "field lines", but electrostatic fields aren't any more or less "emissive" than magnetic ones. There's no "electrical laser" either.

Really, it's foolish to try to treat them as separate forces...they are both aspects of electromagnetism. One may dominate in a given situation, but you can't have one without the other. Accelerate an electron and you see a magnetic component to the field. Accelerate a permanent magnet and you see an electrical component to the field. Do either of these and you will produce electromagnetic radiation, which always has both components.

I am under the impression that the extension of a magnetic field in a vacuum requires the idea of "virtual particles" as a transport medium/assist, since magnetism is not fully emissive.

Again, I don't know. I could be spouting BS for all I know.

Why would a wave packet be any more able to cross vacuum than a continuous field? Or why would the field be less able?

Virtual particles aren't a medium, they're a mechanism used to describe fields in the quantum mechanical description of things. Relativity is a field theory, and does not involve virtual particles in its description of the behavior of fields. Neither description is complete or final.

 

[mrspeedybob]

Well, I quess that's where I get confused.
A magnetic field can extend into a vacuum. This is widely accepted, and I accept it.
But HOW does it do this?

Magnetism is not fully emissive like a photon, in the sense that a photon of light can be emitted and never return to it's source, yet magnetism currently requires a return to source. No "magnetic laser" so-to-speak can be constructed(at this time) without the discovery and manipulation of "monopoles"... if they exist.

This is all so confusing to me.

I am under the impression that the extension of a magnetic field in a vacuum requires the idea of "virtual particles" as a transport medium/assist, since magnetism is not fully emissive.

Again, I don't know. I could be spouting BS for all I know.

I find it helpful to think of a magnetic field as an illusion created by the combination on an electric field and special relativity. Here's a link to an explanation of how that works...
http://physics.weber.edu/schroeder/mrr/MRRtalk.html

This isn't to say that electric fields are fundamental and magnetic fields are derived, it could just as well be the other way around, bu this is the way I have found it easy to think about.