# How can magnets defy entropy?

52 views

So. Heavy iron thing wants to fall to the ground, but magnet keeps it up against gravity… How can this happen seemingly against entropy? Without input of energy?

In: 0

>So. Heavy iron thing wants to fall to the ground, but magnet keeps it up against gravity… How can this happen seemingly against entropy? Without input of energy?

There is no work being done. There is no difference between a table preventing the thing from falling and a magnet at the ceiling preventing the thing from falling.

You could ask the same thing of gravity working against the magnet. Or electrons being held in place near an atom’s nucleus. If anything, these are examples of a stable equilibrium that entropy leads you to rather than work being exerted to go against the equilibrium. The iron going towards the magnet rather than the Earth’s centre of gravity just happens to be the path of least resistance. Going against this path is what requires energy and reversing entropy.

There *is* an input of energy. When you lift a weight (a.k.a. heavy iron thing) against gravity you must spend energy to do so. That energy doesn’t just flutter off into the void, it is stored in the object as potential energy. When you let go of the object, it falls to the ground, transforming that potential energy into kinetic energy. The energy is transformed again when the magnetically conductive object travels through a magnetic field, inducing an electric current in the object. Because the current has no where to go, it is again transformed into heat that radiates from the object. But wait… where does all of this current and heat come from!? It comes from the kinetic energy, the object’s motion as it’s falling! So the object is losing kinetic energy as it falls through the magnetic field and thus slowing down in the presence of that field.

> So. Heavy iron thing wants to fall to the ground ~~, but magnet keeps it up against gravity…~~ How can this happen seemingly against entropy? Without input of energy?

Things will move to states where potential energy is minimized. That’s why gravity pulls things down. It’s the same reason why magnets pull things up, away from gravity. As long as the magnetic field is present, and stronger than the force of gravity, the lowest possible energy state is up close to the magnet, not down close to the ground.

If you’re using an electromagnet, then there *is* an input of energy going on here. The electromagnet heats up, and requires a source of electric current to maintain its pull. But if it’s a permanent magnet, the heavy iron thing will just “fall” up towards the magnet and stay there.