Unfortunately, there is a law of nature that does not allow it: the second law of thermodynamics.
Can you imagine a world where euros are given at 90 cents? The second law of thermodynamics , one of the most fundamental laws of physics, is what prevents it from happening. What moves civilization is money, its exchange. In nature that role is played by energy . The exchange of energy between bodies, the business, is done in two ways: work and heat. Example of the first are all engines; of the second, to heat a cold room.
The second law of thermodynamics was obtained by pure observation of the processes where heat is involved. It is the expression of an essential asymmetry in nature: hot bodies cool down but cold ones do not heat up spontaneously; the vessels break but none of them recomposes itself. All these events conform to another fundamental law, the first law of thermodynamics or the principle of conservation of energy . That a glass could recompose itself is not against this first law, since the total energy remains the same from beginning to end; who does not allow it is the second because in this situation it is the distribution of that energy that changes in an irreversible way. In other words: the first law says that dealing with energy cannot make it disappear; the second law advises us of where these tricks should be directed.
If this were not the case, if we could jump to the bullfight the second law of thermodynamics , we would live in a universe where we would not know if we are watching a movie to the right or the other way around. It would be a world of free energy; the electric companies would go bankrupt. For example, it would not be necessary to plug in the refrigerator. In our normal world, energy does not pass naturally from a cold body to a warm one. If this happens, something else must happen somewhere else in the universe: the refrigerator cools the food because energy is released in a nuclear, thermal or hydroelectric power station . Ultimately, the second law defines a sense of natural processes and with it we can decide which are natural and which are not. If it were not like that, we would have problems heating a room , because the little heat it contained would go to the stove.
But there is a more subtle situation. The second law of thermodynamics assures us that there is no physical process whose sole purpose is the complete conversion of heat into work; some heat will always be lost. We can convert all work into heat (moving our hand back and forth over a piece of wool warms the hand) but we cannot convert all heat into work. If so, we would have a perpetual motive.
