Why a perpetual magnet engines do not work?


A sample of this motor:


In: 87



Energy can’t be created or destroyed only change form.

Even if you could get a contraption like this to spin in perpetuity (spoiler, not possible) as soon as you try to draw energy out of the system it will slow to a stop because there is no source for the energy.

Imagine a gravity powered generator. You lift up a big heavy object, then release it and let it slowly wind out a pulley and a series of gears to “fall” slowly and spin your motor to turn that action into energy.

That’s not a perpetual motion machine. Once the weight hits the bottom, that’s it. You have to put energy back into the system to lift the weight up again and reset it.

And the amount of energy you put in is always going to be more than you get back out.

Magnet ‘perpetual motion machines’ work exactly the same way, but you’re ‘dropping’ the weight into a magnetic field instead of gravity. To get any energy out of it, you first have to put *more* energy into it by pulling the object away from the magnet again so it can “fall” back towards the magnet again.

Magnets don’t add energy to the system, the same way gravity doesn’t add energy. They just define the lowest energy state that you then have to pull the other part of the generator away from, so that you can then recapture *some* of that energy as it reverts back to the lowest energy state.

That’s exactly what’s happening in the video. The person is putting all the energy into the system, not the magnets, by pulling the arms *out* of their lowest energy state, essentially winding it up, giving it potential energy, and then releasing it to ‘fall’ back into the lowest energy state over a few spins before it eventually stops and has to be pulled back again.

Think of magnets like hills. You can roll a tire down a hill to gain momentum, but it loses it when rolling up the next hill. You can’t arrange a series of hills in such a way, that a tire both gains speed and at the end is back to the baseline height. (You can throw a tire down a well, it will go superfast, but it will end up at the bottom of a well, which isn’t useful)

Magnets have a potential around them, just like hills – you can use that once to do something when you are on top, but you can’t roll down the same hill twice. The potential alone can’t add energy to the system.