in the book in the narrow sense of this concept, from the point of view of classical and quantum mechanics of the many-particle systems. More exactly, physical economics here is a study of the formal agent-based physical models of the market economic systems. Finally, I define physical economics here primarily as the science of the agent-based physical modeling of the market economic systems, with the aid of methods and approaches worked out earlier in classical and quantum mechanics. When applying ideas of quantum mechanics to the many-agent economic systems, we inevitably obtain probabilistic economic theory which is understood in this book as most of physical economics. Note that all the physical economic models here are also agent-based ones. I think that there is great advantage to applying the agent-based approach of physical modeling because it makes it possible at the micro level, i.e., at the level of separate agents, to find a basis for explaining economic phenomena at the macro level, i.e., at the level of the whole economy. Analogously, quantum mechanics first explained the behavior of the separate electron in the deep pit. At the time, it undertook the explanation of the macro effects and calculation of macro quantities on the basis of the knowledge obtained there.
In essence, a new physical economic picture of the market world is drawn in the book. There is a huge number of formulas in it, and practically none of them are borrowed from economic literature. However, they all have their analogues in the picture of the physical world, expressed in theoretical physics or, even more accurately, in classical and quantum mechanics.
Physical economics is a proper economic discipline, since, in contrast to physics, the objects of its studies are the actions of real subjects of the economy but not the real subjects themselves. It addresses actions of real people in the real economic world, first of all; of buyers and sellers on the markets, focused on battling for their material interests and simultaneously achieving mutually advantageous cooperation. I follow the idea of classical economic theory in which the economy is simultaneously both the product and the process of human action. Moreover, in contrast to the physical world, both the structure of the economy as well as forms and methods of human action continuously and rapidly vary with time as a result of the general human evolution, as well as scientific and technical progress. Therefore, the economic laws should be derived from the study of practical human activities, but in no way by means of fitting of the known physical laws to the economic world. But the situation is reversed if we want to use theoretical methods of physics in search of the economic laws and to develop quantitative economic theories. The point is that physics has elaborated the enormous number of mathematical methods and apparatuses that describe the structure and dynamics of diverse physical systems, from the simple to the complex. And, there is nothing that would forbid us fruitfully applying these formal mathematical methods in economics.