Richard Feynman unravels the mystery behind why magnets attract or repel each other by exploring the fundamental nature of electromagnetic forces. He explains how these forces are the foundation of chemistry, biology, and everyday objects, and reveals the role of electron spins and virtual photons in magnetism. Feynman emphasizes that electromagnetism is a fundamental force, not explained by anything else, and highlights Maxwell's unification of electricity and magnetism.
You pick up two magnets, push them together, and there's this invisible something pushing back. Flip one around, and snap, they slam together so hard they almost take your finger off. What is that? What's actually happening there?
When you ask why about anything, you need a place to stand. You need things you already accept as true. Otherwise, you're just falling forever with why, why, why. It never ends.
For example, why is your Aunt Minnie in the hospital? She slipped on ice and broke her hip. But why did she slip? Because ice is slippery. But why is ice slippery? When you stand on ice, the pressure melts a tiny layer on top, so you're really sliding on water. But then why does pressure melt ice? Because water expands when it freezes, and pressure wants to un-expand it. And why did she fall when she slipped? Because of gravity.
Every answer opens more questions. You have to stop somewhere or you'll be asking why until you collapse.
People often want explanations in terms of something familiar, like rubber bands connecting magnets. But that just pushes the mystery back one step: why do rubber bands pull back? Because of electrical forces between molecules, which is the same force we're trying to explain. This is running in circles, using the mystery to explain the mystery.
Electrical and magnetic forces are fundamental. They are the bedrock of physics. We don't explain them in terms of something else; instead, we explain everything else in terms of them.
It's everywhere. It runs everything.
You don't think it's strange that you can't put your hand through a table. When you push on it, it pushes back. But your hand never actually touches the table. The atoms get close, and the electrons start repelling each other. That's what you feel as solid. That's what touching is. The exact same force as the magnets.
So, why is the table obvious and the magnet mysterious? Just because you grew up pushing on tables and not pushing magnets together every day. The table is just as strange; you just stopped wondering about it.
Electrical forces aren't just strong; they're monstrously strong. Compared to gravity, electromagnetism is stronger by something like 10^40 times. It's incomprehensibly stronger.
Why don't we notice? Because atoms are balanced. Positive charges in the middle, negative charges around the outside, plus and minus, everything neutralizes. The most powerful force in nature hides in plain sight because it cancels itself out.
When you comb your hair and pick up bits of paper, you rub off a few electrons. Just a few, but the force is so gigantic that even that tiny imbalance creates something you can see across the room.
Magnets are special because of what happens in iron. Electrons spin. In most materials, they spin every which way, canceling out. But in iron, they line up, all spinning the same direction. When they cooperate like that, all those tiny magnetic effects add up and amplify.
That's why iron is magnetic and copper isn't. Copper has the same physics, same electrons, same forces, but the spins point randomly. In iron, they work together.
It's like a stadium full of people: if everyone talks at once, you hear noise, nothing. But if everyone chants the same word, you hear it miles away.
At the most fundamental level, it's about particles being exchanged. Electrons don't just sit there; they're constantly throwing things at each other called photons, little packets of light.
These aren't visible light photons but virtual photons, which exist only during the interaction. You can never catch one and look at it directly.
One electron throws a photon, another electron catches it, and that exchange is what we experience as the electromagnetic field.
Every time you feel a magnet push against another magnet, trillions upon trillions of these virtual photons are being exchanged between the electrons in both pieces of metal.
Everything electromagnetic comes from just three simple actions:
From these three actions, you get all of chemistry, all of light, all of magnetism, all of electricity, radio waves, the colors you see, and the fact that your hand stops at the table instead of going through it.
There are no gears underneath, no hidden mechanism. This is how it really works.
In 1873, James Clerk Maxwell wrote down the equations that unified electricity and magnetism. This was probably the most fundamental transformation in human history.
Once you understand that electrical and magnetic forces are connected, that they're really two aspects of the same phenomenon, you can do incredible things:
Electricity and magnetism dance together.
Think about a dam somewhere with waterfalls turning a big wheel. That wheel is connected to copper wire spinning near some iron. Because the copper moves near the iron, electrons start moving in the wire. That movement travels through thin copper lines spread across the whole city.
At the other end, another piece of copper and iron turns that electron movement back into spinning motion. All the wheels in the city turn because one wheel at the dam turns.
Magnets work because of fundamental electromagnetic forces, which are the foundation of the physical world. The mysterious push and pull you feel when handling magnets is the result of electron spins aligning and exchanging virtual photons. This fundamental understanding not only explains magnetism but also underpins all of chemistry, biology, and the technology that powers our modern world.
Understanding electromagnetism is understanding the very fabric of reality, as Richard Feynman beautifully elucidates.
