What is a magnetic field made from?

I have found this, from a person called "coolmagnetman", a name which does not inspire me with confidence:


So, how does one magnet feel the presence of another magnet when they approach each other? I don't think physicists really know the answer to that. They know that the electromagnetic field is actually made of an enormous number of photons, but do virtual, massless photons make up the magnetic field, and how does one field affect other magnetic fields at a distance, and does the magnetic field travel at the speed of light like gravitational waves? Perhaps you will be the one to discover some of these answers.

http://www.coolmagnetman.com/magfield.htm

So is coolmagnetman cool, or not?

 

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He's definitely not cool.

 

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The interaction between two magnets is "felt" by the magnetic dipoles of the magnetized material, which (at least on a superficial level) is well understood.

You could ask the same question at the molecular level: how does hydrogen "feel" like bonding to nearly everything? Why does a dipole moment exist at all?

So there is an elementary force involved. The coulomb force would be equivalent, the electrostatic complement of the force between magnets.

Remember also, just as there is an electric circuit, there is a magnetic circuit. Magnetism is a little less intuitive than electricity, only because we (common people) have so much real-life experience with electricity... but who has ever seen a magnetic arc? It just doesn't manifest itself the same way.

As far as how the field propagates, and what particles are involved, there certainly is a lot of physics to delve into, so if that's where this thread is headed, I'll kick back and listen.

However, I will challenge any contributor to explain, in their analysis, the nature of the intrinsic impedance of free space, which is imposes both electric permittivity and magnetic permeability constraints and this is the underlying cause of the field propagation and its constraint to expand at the speed of light.

 

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Impedance is like resistance, but for alternating current rather than direct current. The impedance of free space is given as Z[sub]0[/sub] = √(μ[sub]0[/sub]/ε[sub]0[/sub]), where μ[sub]0[/sub] is permeability and ε[sub]0[/sub] is permittivity. The speed of light is c = √(1/ε[sub]0[/sub]μ[sub]0[/sub]). In mechanics a transverse wave travels at a speed determined by the stiffness and density of the medium, and the expression for this is v = √(G/ρ), where G is the shear modulus of elasticity and ρ is density. Permittivity and permeability are the electromagnetic equivalent of these, but note the reciprocal on permittivity. They aren't exactly like "stretchability" and "density" because space isn't a medium in the usual sense. But an electromagnetic wave is said to be a transverse wave, so there is a parallel. Have a read of displacement current, and note that it is not an electric current of moving charges, but a time-varying electric field. Have a look at electromagnetic four-potential too. It's really interesting is electromagnetism.

 

Is Empty Space a substance in its own rights. So it has these properties like other substances.
That is just an "out of the Blue" answer. Just to make a noise and accept your challenge.

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I thought that this question would have an answer.
I didn't realise that physicists had no idea either.

 

AFAIK the (electro)magnetic field is made of photons.

 

I am tending to think a magnetic field is the combined effect of very large number of aligned atoms, so that the field lines that were present at the atomic level now combine and show their effect beyond the material itself.
So it is an attribute of a magnetic molecule intensified becuase of the alignemnt of many.
So it is an atomic scale thing. If this is so is there something happening at the atomic scale that explains it?

Is a single atom a magnet in its own right?

 

Yes! A single hydrogen atom, since it has a charged particle which (in a sense) spins around the nucleus, has a very strong magnetic moment. However, most hydrogen is in the form H2 (two hydrogen atoms) and since their spins cancel they don't have much of a magnetic moment.

 

No, magnetism is very well understood in terms of the mathematical properties of photons. What's not understood is why photons have those properties. You should try looking up some of Feynman's interviews on Youtube, there's a really good one where he talks about electromagnetism as a force that simply can't be explained in terms of more primitive analogies- essentially, it just is, like every other fundamental law of nature.

 

So (usually) it's photons traveling through free space, and electrons through a conductor. (Obviously an electron in emission is a different situation).

The first, the photon, we usually associate with the EM wave, and the electron we usually associate with EM field.

Except: once I set electrons in motion on an antenna (under the right design), inducing a field, I will also launch a wave, due to coupling. And if that antenna is out in space, it will.... couple? With what, you ask: particles - substance? I say no, it couples with space itself, dumping energy across the "load" introduced by the intrinsic impedance of space.

I'm taking this opportunity to say this here because I have read a lot of opinions from some of you that space has a "substance" or "ether" or (some even say) "particles".

I say no, it's the intrinsic impedance, something that is very fundamental to the definition of reality, because it establishes the relation between space and time, insofar as light speed and relativity are concerned. Intrinsic impedance, I'm saying, is the "ether" some of you are seeking.

And yes, as noted above, impedance is like a resistance, only at "AC" in other words, the load changes its value according to frequency.

Remember also, there are time varying fields (which usually launch waves) and static fields, such as in the magnets you are discussing.

And what gave them their "power"? They were subjected to a static magnetic field just as they were cooling from liquid to solid state. So their dipoles were aligned that way, and froze. They chain together in part of a magnetic circuit that can be completed by "shorting" it with a ferromagnetic material connected from pole to pole, just like shorting a wire across a battery from negative to positive.

For the relativity debaters, another perspective I find interesting is to eliminate "c" in the Lorentz transformation altogether, replacing it with intrinsic impedance. It's just another way of attributing time and space warps to something fundamental in the universe, that seems "arbitrarily chosen" to have these particular values.

 

Not sure if this post is relevant however there seem to be three distinct structures when considering magnetism.
1) Material displaying magnetic properties
2) Material (copper) does not display magnetic properties but is (electric current) affected by moving magnets.
3) Non-magnetic material (insulators!)

Are the electrons in Non-magnetic material affected by magnets or not? Perhaps a quick check with MRI scanner results is needed.

 

Definitely. All moving electrical charges (of which electrons count) are affected by magnets. They are affected in a great many ways - some are attracted (paramagnetism) some are repelled (diamagnetism) some pick up permanent magnetic fields (ferromagnetism.) Others see effects like the Hall effect.

 

Is that change in direction of motion of the electron the way the magnetic force is activated?

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from http://www.google.co.uk/imgres?q=ma...bnw=184&start=30&ndsp=17&ved=1t:429,r:13,s:30

So these photons flow from the north pole to the south.
Would the magnet eventually discharge itself if you left it long enough?
Or would it happen forever?

 

Nothing flows in an open circuit.
The lines are lines of force, potential, the potential to flow.

 

Is it possible for the photons to be in the visible range of wavelengths and be seen as light?

 

Sort of. The Lorentz force is the term used for the force applied to a moving electron by a magnetic field, and it is the most direct measure of magnetic field. Conversely, moving electrons (i.e. an electric current) can generate magnetic fields.

 

When electricity moves through a wire, are photons involved in that as well?

 

Definitely. But again, it has to be a _moving_ magnetic/electric field to generate photons with nonzero energy. To generate light by moving a magnet you'd have to move it insanely fast, almost a quadrillion times a second.