We show that the quantum statistical mechanics (QSM ) describing the quantum and thermal properties of objects only has the sense of a particular semiclassical approximation. We propose a more general microdescription than in QSM of objects in a thermal bath with the vacuum explicitly taken into account; we call it -k dynamics. We construct a qualitatively new model of the object environment, namely, a quantum thermal bath. We study its properties including the cases of a "cold" and a "thermal" vacuum. We introduce the stochastic action operator and show its fundamental role in the microdescription. We establish that the corresponding macroparameter, the effective action, plays just as significant a role in the macrodescription. The most important effective macroparameters of equilibrium quantum statistical thermodynamics-internal energy, temperature, and entropy-are expressed in terms of this macroparameter.
Keywords:-k dynamics, quantum thermal bath, cold vacuum, thermal vacuum, stochastic action operator, effective action, quantum-thermal entropy
Possible approaches to a consistent quantum-thermal description of natural objectsThe conviction that equilibrium quantum statistical mechanics (QSM) not only is an adequate description of microobjects in a thermal bath but also forms a basis for the corresponding macrodescription has predominated for a fairly long time. In other words, it is assumed that QSM allows obtaining thermodynamic macroparameters from the microdescription and establishing observable interrelations between them (thermodynamic laws, equations of state, etc.) [1]. At the same time, it is well known that there exist such macroparameters, temperature for example, whose analogues have not yet been studied on the microlevel. This leads to introducing the idea of the independence and equality of the micro-and macrodescriptions of nature with a certain interrelation between them [2], [3].We briefly analyze already revealed elements of the limitations of equilibrium QSM as a theory claiming to consistently describe all quantum and thermal phenomena. As is well known, QSM is based on the notion of the density matrix (operator), which in the energy representation has the form of the Gibbs-von Neumann quantum canonical distribution,where ε n is the spectrum of the object energy, F is the free energy determined by the normalization condition, and Θ is the inverse modulus of the distribution. It has the meaning of the Lagrange multiplier in the derivation of distribution (1) from the maximum entropy principle under thermal equilibrium conditions [4].