What is a perpetual motion machine?

Perpetual machine is an imaginary machine that can continuously move and do work without external input energy or only one heat source. Historically, people have been keen on developing various types of perpetual motion machines, including academic masters such as Da Vinci and Joule (Huang Wei, the general of the Chinese National Revolutionary Army, was engaged in the development of perpetual motion machines until his death after he was captured by the China People's Liberation Army), and some swindlers who wanted to be famous for perpetual motion machines and make money. After the establishment of the thermodynamic system, people proved that the perpetual motion machine violated the basic principles of thermodynamics through strict logic. Since then, there have been few researchers on perpetual motion machines. However, from one side, we can also think that human enthusiasm for perpetual motion machine and various practices of manufacturing perpetual motion machine have promoted the establishment of thermal system and the progress of mechanical manufacturing technology. 1775, the French Academy of Sciences in Paris passed a resolution declaring that perpetual motion machines would never be accepted. At present, the United States Patent and Trademark Office prohibits the application for granting patent certificates to perpetual motion machines. The word perpetual motion machine is now used as a rhetoric to describe those who are energetic and tireless. The first perpetual motion machine is the oldest concept of perpetual motion machine. This kind of perpetual motion machine tries to make the system continuously output energy to the outside world by mechanical means without obtaining energy. The most famous perpetual motion machine of the first kind in history is the "magic wheel" put forward by the Frenchman Henneckau in the 3rd century. The magic wheel can move forever through a series of movable cantilevers placed on the wheel. The downward cantilever will fall away from the center of the wheel under the action of gravity, which will increase the downward torque, while the upward cantilever will approach the center of the wheel under the action of gravity, which will reduce the torque and drive the magic wheel to rotate. /kloc-In the 5th century, the famous scholar Leonardo da Vinci also designed a similar device with the same principle. 1667, someone put Leonardo da Vinci's design into practice and made a huge machine with a diameter of 5 meters, but these devices ended in failure after being tested. In addition to the magic wheel that uses torque change, there are perpetual motion machines that use buoyancy and hydraulic principle, but after experiments, these perpetual motion machines are either proved to be failures or scams, and none of them are successful. 1842, the Dutch scientist Meyer put forward the law of energy conservation and transformation; 1843, British scientist Joule put forward the first law of thermodynamics, and they proved theoretically that the first perpetual motion machine that can generate energy out of thin air is impossible to realize. One of the expressions of the first law of thermodynamics is that the perpetual motion machine of the first kind cannot be realized. The second perpetual motion machine: after the first law of thermodynamics came out, people realized that energy could not be generated out of thin air, so someone proposed to design a device to absorb heat energy from the ocean, atmosphere and even the universe, and use these heat energy as the source of driving the perpetual motion machine to rotate and output power. This is the second perpetual motion machine. The first perpetual motion machine in history was the zero engine designed by American John Janji for the US Navy in 188 1 year. This device uses the heat of seawater to vaporize liquid ammonia and promote mechanical operation. But this device can't run continuously, because the vaporized liquid ammonia can't be liquefied again without a low-temperature heat source, so it can't complete the cycle. 1820s, French engineer Carnot designed an ideal heat engine-Carnot heat engine, which worked between two heat sources, and proved theoretically that the working efficiency of the heat engine was related to the temperature difference between the two heat sources. After studying Carnot cycle and the first law of thermodynamics, Clausius, a German, and Kelvin, an Englishman, put forward the second law of thermodynamics. This law points out that it is impossible to absorb heat from a single heat source and make it completely useful without other effects. The second law of thermodynamics condemned the death penalty of the second kind of perpetual motion machine, and one of the expressions of this law was that the second kind of perpetual motion machine could not be realized.