[First draft – comments welcomed]
In one of my school shows I ask my audience to tell me their ideas for how my magic tricks are achieved. Invariably I’ll get the answer of “magnets”; regardless of how practical their use would be. Primary school pupils have a fixation with them. Part of this is because of their limited knowledge of scientific principles and also that the magnet solution is more tangible than momentum, conservation of energy, buoyancy etc. However I think the main reason for this fixation is that magnets are magical.
Whilst I was still active in physics research I worked in two different fields. The first was in superconductivity. The Meissner effect that leads to magnetic levitation being one of strangest phenomena in physics. During that time I had the privilege to spend two weeks running experiments at the European High Field Magnetic Laboratory in Grenoble. Working with a 30 Tesla monster magnet comes with a few dangers. Tools will literally be pulled out of your hands even from a couple of metres away and if you forget to remove your wallet before entering the lab (like me on the last day) you can have your credit cards wiped. There’s almost a supernatural quality to magnets; they’re a little scary and unworldly. You only have to be holding two strong magnets in your hands to feel the force between them. I find the repulsive force of two opposite magnetic poles to be weirder than the attractive force – like there’s an entity in the ether between them. And like my credit cards found out, a magnetic encounter can leave behind a nasty footprint.
I later switched from condensed matter to atomic physics research. My Ph.D at Durham University was on using pulsed magnetic fields to manipulate laser cooled atom clouds. I was effectively designing the magnetic equivalent of an optical lens. (If you want to join an exclusive club of readers, here’s a link to my thesis LINK.) Even though I worked with the mathematical equations that describe both the magnetic field and how matter interacts with the field, there was a disconnect between the maths and the intuitive understanding of how magnets work. A common question from children is “how do magnets work?” and truthfully it’s one of the areas in science I struggle to explain even though I became a Dr from making and using them.
Gravity is a fairly easy concept to grasp: ‘things attract’. Simples. Initially it’s: ‘things fall down’ but as science schooling progresses the pupils will learn the bigger picture that all objects have a gravitational attraction (usually from studying the solar system). And when much later they start putting equations to the forces, the mathematics makes intuitive sense. Heavier objects have a larger pull. Closer objects have a larger pull. There’s not much more you need to know until you get to the extremes and have to start making corrections for General Relativity.
The classical equation for the force between two magnetic poles has essentially the same form as the gravitational (and electrostatic) equation. However, the understanding is far from straight forward. I think the main reason for this is the wide range of magnets, magnetic phenomena and that not all materials are affected. It’s not universal like gravity or based on a few simple rules like electrostatics. Furthermore, the strength of the magnetic force dominates most other forces. Magnets are both mysterious and complicated. So when my audience are trying to form an understanding of a strange trick, I think magnets are a natural (or should I say supernatural) explanation.
One of my favourite stories from magic history is the time the magician Eugene Robert-Houdin was sent by the French government to help quash a revolt in Algeria. The local tribes were superstitious and he used magic tricks to convince the locals that French magic was stronger than their own witchcraft. The fearful Algerians soon quietened down in the face of French ‘superiority’. One of the tricks Robert-Houdin used was called The Light and Heavy Chest. He’d get a small child to lift a wooden box to prove how light it was. Then he’d summon the strongest man in the village. After the man had gone through a mock hypnosis he found he was unable to shift the box that minutes earlier a boy had moved. Unbeknownst to the strong man he was the victim of a metal plate in the bottom of the box and an electromagnet concealed in the floor. Magnets are magical.