(And thanks to Joel for the earlier explanation, too)

Why can’t we stick two cats together?

You should try briskly rubbing them together first.

If you want a perfect explanation of magnetism, you’ll have to cover a lot of physics. Here is a link to a chart showing particles described by the Standard Model of particle physics:
http://bccp.lbl.gov/Academy/workshop08/08%20PDFs/chart_2006_4.jpg

Protons and Neutrons are types of baryons. Electric charge comes from combinations of quarks. The smallest of the familiar sub-atomic particles, the Electron, is a type of Lepton. Technically, the photon is also a type of particle (a boson)… but most people don’t think of ‘photons’ when they list sub-atomic particles.

So if rubbing a magnet on a nail from top to bottom causes a bunch of electrons to switch to a counter-clockwise spin, what happens when I rub the magnet perpendicular to the main, making one “side” of the nail north, as opposed to one “end.”

This is why it made more sense to me to suggest that we are just changing the tilt of the (not-really) spinning teacups, instead of saying we were flipping their spin. But it seems that the spin is, in fact, changing direction.

So I’m still confused. This may be the problem with analogies.

Plasmas are made of atoms where some (or all) of the electrons are free to move independently of the nuclei. Some of the teacups have come off the carousel, in other words. But it’s still made up of positively charged proton-neutron balls and electrons.

The same thing happens in metals; some of the electrons in a bulk metal can freely flow from one nucleus to another. That’s why metal conducts electricity.

So while plasma doesn’t really fit the ponies-on-a-carousel model, it’s still made up of the same stuff as everything else, just arranged a bit differently. At the level of ‘everything is made of atoms!’ I think it’s misleading to say plasma is any different.

What are they and why are they and why do they have a so much stronger magnetic force?

Basically, a ferromagnet (ferro = iron) is a permanent magnet that is dependent on the electron interactions mentioned in the article. By getting the domains to line up in the same direction, we can produce a strong magnetic field. The domains tend to reinforce each other and maintain “order” as long as stuff stays relatively undisturbed (heating ferromagnets past the “Curie temperature” of the magnet starts to jostle the domains out of synch).

An electromagnet is the result of current flowing through a wire. This phenomenon is actually related to another deep truth in physics: electricity and magnetism are basically the same thing; which one you experience depends on your frame of reference. Basically, when electricity moves/flows, it produces a magnetic field. When magnets move or change strength, it produces an electric field. In an electromagnet, the flow of electricity around a coil of wire produces a magnet. In the ferromagnet, the “spin” of the electrons produces a magnet. Either way, we have electron motion producing the field.

TL;DR – Motion of electrons produces a magnetic field. If you turn off the current/flow, then the magnet turns off too.

The whole point of that song is “…fuck science because I don’t want to know how shit works.” It’s a fundamentally incurious mindset, and we don’t owe them any kind of apology for wearing their ignorance with pride.

Why do electrons have spin? What is it about that particular triplet of quarks gives it to them?

Course it does.

If you take the electron’s velocity as ‘c’ (as you do) it happens when

r(m_e)(c)/hbar = 1/2

or

radius of orbit = hbar / 2(m_e)c = 1.9e-13 m. ’bout a hundred times thicker than a proton.

See: http://en.wikipedia.org/wiki/Electron_magnetic_dipole_moment

Every electron has an intrinsic magnetic moment which is the result of this quantity we call “spin”. As mentioned in the article, this cannot possible be actual, physical spin, because the calculations of its velocity produce values higher than the speed of light. Even so, the magnetic properties of the electron are very similar to a charged object that is spinning in place: it has a magnetic moment (strength and orientation) that is measurable in the lab.

In most materials, the valid orbitals for electrons to fill produce electron pairs whose spins are opposed. That is, their magnetic moments cancel each other out, leaving the effective amount of magnetism at zero. However, the way electrons fill orbitals is not as simple as filling a bookshelf. Electrons always fill the lowest energy level first, and due to orbital interactions this produces some unexpected results. In iron, cobalt, and nickel (mostly iron), there is an unpaired electron that results in a small net magnetic field. Also, in order to produce strong magnetic fields overall, the individual atoms must be highly organized, crystalline in structure, like iron and some iron compounds.

so i think it just confuses and discourages people when they ask “how do they work” and we physicists start going on about electron spin.

so, i wrote a post about it explaining how magnets work in terms of awesome fans:

http://paleocave.sciencesortof.com/2010/11/fcking-magnets-how-do-they-work/

yeah.

If you take attraction and repulsion of electric charges for granted, though, magnetism automatically shows up as what that looks like when they move. Something sitting in place is on a path through time, and something moving is one one through time and space. By relativity, though those are just different directions; you can do a space-time rotation to turn one into the other.

What we find is that the field a charge generates also has a direction through space-time. If a charge is sitting there, only moving through time, that field will also point straight into time. A second stationary charge will only feel a push or pull based on that same component, which is what we’ve named the electric potential.

The situation where they’re moving is the same, but rotated. Now the charge is going through time and space, so besides the part of the field pointing into time there are extra space parts. And a second charge also moving through space and time is going to feel forces based on them, because rotate back to its perspective and they become time again.

Those extra components are what we call magnetism; you get them straight out of rotating Coulomb’s Law. Unfortunately the math is hard to follow intuitively, because these aren’t ordinary Euclidean rotations. Even so, I hope that gives some idea why there should be an extra force associated with currents and spins. Relativity actually gives similar results for gravity, but most of the time you never see anything both heavy and fast enough to notice it.

Gravity bloody well is something to philosophize over, and ‘because objects move in straight paths in curved space’ is as good as it gets.

Magnetism occurs when charged particles move. Yeah, okay, Feynman meant that he could describe how electric and magnetic fields were exchangeable, describe how replacing the normal concept of energy (schrodinger) with relativistic energy (dirac) can be approximated as spin, and finally describe the difference between electric and magnetic fields in QED–and the average listener wouldn’t follow.

But please understand. The point is that the explanation is one that YOU WOULDN’T UNDERSTAND, not one that DOESN’T EXIST.

Electrons actually aren’t made of quarks. They are leptons, which like quarks are considered “fundamental” particles. String theory posits that electrons and quarks are actually loops of energy vibrating away, but we haven’t proven this yet.

Spin is a “quantum number”. A value that we assign to particles of different types that helps us distinguish them. Asking “What is spin?” is like asking “what is mass?” My point is that it’s a good, nay, GREAT question, but one that I don’t think I can really give you an answer to.

What I CAN say, is that we call it spin for a few reasons. Angular momentum is a measurable value related to objects which are spinning in place. Through extensive experimentation, physicists discovered that individual electrons seem to have a specific amount of intrinsic angular momentum. Also, they’ve shown that electrons have a magnetic moment (related to the discussion above) that would be characteristic of a charged object that is spinning around an axis. Unfortunately, calculating how fast the electron would have to be spinning in order to produce the values we find in the lab (based on it’s mass and distinguishable size) produces numbers in excess of the speed of light. This doesn’t mesh with our understanding of relativity, so at this point we just say that it has spin 1/2 and move on. Other particles have spin too: photons are spin 1, neutrons are spin 1/2, quarks are spin 1/2. In fact, we can separate all particles into 2 groups, bosons who have integer spin, and fermions who have spin 1/2.

It’s a very good explanation though, probably better than the explanation our science teacher in high school gave us and had us gasping for air after the first 5 minutes…

Magnetic field lines, I was told, are thought of as a static ‘circuit’ of photons. Based an above description of spin, it doesn’t seem wrong to thing of this ‘circuit’ as inexhaustible, as it’s not a transfer of something from one place to another. It seems like it’s more a static wave.

These circuits desire to be as short as they can, but that depends on the permeability of the material they’re passing through. Materials with high permeability will allow the field to pass through in a more concentrated fashion, which allows a particular path parallel to the shape of the field to be shorter.

I expect that it’s the attraction of two opposite magnetic poles which causes a pull between all electrons in the field. Think about an electric circuit. Any two points in the circuit have a potential relative to each other, but you can take your voltage source and simplify your view of the circuit by collapsing components directly attached to it into your unitary view of it (assuming there are no other components directly attached to it).

If you take that integration of components and consider each particle on the magnetic circuit to be a component of that circuit, then you can think of of any group of particles as a single one, and think of each group of particles attracting the next group along the circuit.

As these particles get closer to each other, their pull on each other increases (hiya, inverse square law!). As their pull increases, they tend to get closer, so it’s a self-reinforcing.

Where does the initial movement come from, though? At a guess, I might point at temperature vibration, or possibly this ‘vibration’ that is described by string theory. Anything that causes things to be non-static in a static frame of reference might suffice. (Which is curious, actually…if a vibration is perpendicular to the direction of the magnetic field, it wouldn’t have an effect in bringing the component closer or farther away. If it were in any component parallel (my geometry terminology is almost gone, sorry), the magnetic field might represent a resistance or inertia against movement away, but not towards, and thus the actual force viewed would be the aggregation of the vibrating energy)

Feynman acknowledges that any explanation he gave would be a lie-to-children.

It upsets me when people mistake this for saying that there is no answer.

These make for especially strong magnets because the particular crystal structure of the rare-earth alloys makes it possible to lock more of the domains pointing in the same direction than in other materials. In Joel’s metaphor, the “squabbling city states”, once aligned by a strong leader, are especially resistant to post-revolutionary political change.

Since more of the domains align together, they add up to larger macroscopic magnetic field.

Rare earth magnets are alloys of iron and one of the elements from the “rare earth” group on the periodic table. Most of the time, if you have a rare earth magnet, it is a combination of iron and neodymium, and boron. Some of these rare earth elements make good ferromagnets, but only at temperatures much colder than people usually live at. By combining them with other ferromagnetic elements, they produce extra strong permanent magnets. I guess you can think of it like a “magnetic alloy” that is a stronger magnet than its parts alone.

[I find it very strange to be speaking about non-rhetorical questions while only using rhetorical questions. My head is beginning to hurt, I think I'll go and have a lie-down before I find myself thinking about recursion and thinking about thinking about recursion.]