TedEd: Why don't perpetual motion machines ever work?

A TedEd by Netta Schramm

In 1159 A.D., an Indian mathematician created one of the earliest designs for a perpetual motion machine. It consisted of a wheel with curved compartments full of mercury. When it turned, the mercury would always be at the bottom, making that side heavier and causing the wheel to turn forever. A perpetual motion machine is a machine that can generate energy forever without external assistance. For example, a lightbulb that produced enough energy to keep itself running, or a windmill that made its own wind. This is intriguing because such a machine could be used to support human life indefinitely. Unfortunately, these machines are currently impossible because of the Laws of Thermodynamics. The 1st law states that energy is neither created nor destroyed. That means the amount of energy coming out is the same as the energy going in. That means all practical uses of perpetual motion machines are gone because they could never produce more than enough energy needed to run itself. There would be no excess. So how about machines that just run forever? Many ideas for these have been variations on the wheel with weights as counterbalance. But the weights also shift the wheel's center of mass, causing it to just swing back and forth like a pendulum before stopping. Robert Boyle proposed the different idea of using capillary action that draws water up through tubes to make a self-watering pot. But the capillary action would also prevent the water from falling out of the tube, getting it stuck there forever. For all of these, they need extra energy to keep themselves moving, breaking the 1st law. If an engineer developed a machine that didn't violate the 1st Law of Thermodynamics, the 2nd law would thwart it. The 2nd law states that energy tends to spread out through forces like friction. Any moving machine would have parts to create friction and lose little bits of energy through heat over time, eventually stopping it. But we don't have to give up hope yet. There might still be a form of matter out there that can be perpetual.