While playing around with magnets, as one sometimes does, we stumbled on a fun way to let the attraction create a stable equilibrium.
Steve the Squirrel plays with Magnets
Bring two magnets close, they start showing signs of attracting each other, then, like flipping a switch, they race towards each other and stick together, faster than you can see. They make a crash, everyone jumps. But the fun is over, the two are one, and all motion has stopped. Pull them apart and do it all again. I find something deeply biological, or maybe also spiritual about how the separate-and-attracting is the interesting thing to us. All this talk of “becoming one with…”, as if it is something we “truly” want in our “deepest” parts, and yet when the two magnets race together to become one, what is the first thing we do? We pull them apart.
How do we know if something is magnetic?
We can only measure the presence of a magnet with another magnet. This is so delightfully circular that is makes me smile each time I say it. How do you know the second thing is a magnet? How can you know if a musician has soul? You need to have some soul in yourself.
If you look closely at your favorite refrigerator magnet, you will see evidence for the “domain model”, see Fig 2. We imagine that tiny bits of magnetism are group together into regions, like little countries. The more overall alignment means a more strong magnet.
You can make a colloid mixture of magnetic materials, and the different directions of the magnetic force will reflect light differently. Beautiful patterns of opposites coexisting
Our explanation then has essentially applied the “atomic model” to magnetism, by saying that magnetism is composed of a huge number of very small magnets. But what are these “smallest magnets”?
When we look to individual Iron atoms, and we find that they behave like tiny magnets. How would a physicist prove that? They might shoot a very thin stream of Iron atoms through a strong magnet, and see if those individual Iron atoms are deflected. We could reduce the flow of the stream down to an iron atom per second, and see that they are still deflected by a magnet even though they are travelling alone. Hence we can say with confidence that individual Iron atoms are magnets.
But what is this force? Do we have any explanation for what makes the force?
But what makes an Iron atom a tiny magnet?
Here is where things get foggy.
There is no accepted theory for why Iron atoms are magnetic. The best we have done is postulate “protons & electrons have a magnetic moment”. Which, yes, is just inventing a name for an unknown, then pretending we have explained it. But much of physics works this way. If our made-up vocabulary lets us construct meaningful sentences, and make predictions, then we scientists will tend to run with that model.
But even after stating that protons & electrons have a “magnetic moment”, the devil is in the details how that ends up giving Iron, Cobalt, and Nickel naturally occurring magnetism. Last I checked there were nine theories, each of which explains different aspects of the available data. Your physics textbook will roll out one of these nine, probably the Heisenberg mean-field model, and call it a day, and the average physics student will feel secure that “this has all been explained”, and be able to sleep comfortably. But none of the nine theories explains all the data, and some data contradicts each of the nine theories.
We have not explained the force. The origins of forces are not explained in physics. Even the gauge theories only give us cool math to do better calculations & predictions, and the satisfaction of working with an elegant theory, etc. But the force itself remains a mystery, the “why does this thing pull on that thing even when they are not touching?” Newton famously explicitly avoided the whole issue in his physics. He said that he will not explain how it can be that there is force at a distance. He showed us the math to use “as if” there were forces acting at a distance.
The older I get the more I think we call it “force at a distance” because of our dimensional limitations. We can mostly only think and observe in 3 dimensions of space and one dimension of time. The magnetic force acts perpendicular to the flow of current. To me this so obviously screams that what is “really” going on is taking place in higher dimensions of space & time than we can perceive. Imagine that you push someone, and they move at a right angle to your push. Imagine hitting a baseball towards center field, and the ball heads directly to the first base dugout. This is in the very nature of the magnetic force: if you put an electric current into a magnetic field, the wire will feel a force perpendicular to both the direction of the current and the direction of the magnetic field.
Imagine we could only see in 2D, like we were beings stuck inside piece of paper. We might see a ball moving in a circle, and have to invent a mysterious force to explain this. In 3D the situation becomes obvious, that the ball is suspended by a string, and there is no need for a mystery force.
And why do the magnets not get tired? Steve the Squirrel has been hanging up there for several days now. The magnet over his head has been doing work for me for 5 years. Seems just as strong as when I bought it.
Incredibly ‘magnetic’ ideas! I always say that our ‘experts’ know far less FOR CERTAIN than they let on (typically) and than we think.
I also believe there’s something strangely spiritual/transcendental about magnets AND many other attractions, which occur in the natural world.
I find this kind of discussion so refreshing. “Experts” will tell you that magnets do not perform any work because there’s no movement, and all what they are doing when holding an object against gravity is maintaining the stored potential energy in the field.
Years ago I was reading an article on a journal of wastewater treatment that dealt with the use of a magnetic field to create a gradient of densities within a paramagnetic fluid that then can be used for separation of plastics of different kind by their different density which makes them buoyant at different depths within the liquid column. It’s a clever way to solve this problem but from reading this article my mind drifted towards and became way more interested in the idea of using this phenomena by means of a permanent magnet to create a permanent flow within a paramagnetic liquid. This was around 2006 and of course after reading a lot I have all sorts of reasons why my idea will never work, and I have “learnt” a lot about magnetism and magnetic fields, yet, if you ask me, I still don’t know why my silly idea can’t ever work.