A perpetual motion machine is a machine that, once it’s started, won’t stop and doesn’t need any additional energy to keep going. That means the machine could be used as a source of unlimited free energy. Which is great, so why don’t we just make one? Well, it isn’t because of some conspiracy theory by the energy sector. The reason none have ever been built is because they’re actually impossible to build since perpetual motion breaks the first two laws of thermodynamics. The first law is that energy is constant; it cannot be created or destroyed. The second is that entropy will either increase or remain the same. Essentially, you can never get a greater output of energy than inputted and energy will always decrease over time.