A perpetual motion machine is a hypothetical device that repeats a certain motion indefinitely without an energy source. You might have seen a windmill-looking device in a physics book, which has bearing balls rolling around inside of the wheel or bearing balls swinging attached to the outer side of the wheel. That is called a “mass leverage” device, one of the most famous failures in the effort of inventing a perpetual motion machine. Since the Middle Ages, out of a desire to achieve an everlasting engine without burning fuel, countless efforts made by scientists to create this self-sustaining closed system have failed. The idea is impossible because it violates a couple of the laws of physics – the first or second law of thermodynamics. In simple words, it cannot close the loop because it loses energy gradually due to gravity and friction. The machine will eventually stop.
