Quantum-mechanical cases

Partha Ghose

In spite of its popularity, it has not been possible to vindicate the conventional wisdom that classical mechanics is a limiting case of quantum mechanics. The purpose of the present paper is to offer an alternative point of view in which quantum mechanics emerges as a limiting case of classical mechanics in which the classical system is decoupled from its environment.

Malin Premaratne, Govind Prasad Agrawal

Lev Sakhnovich

We present some basic inequalities between the classical and quantum values of free energy, entropy and mean energy. We investigate the transition from the deterministic case (classical mechanics) to the probabilistic case (quantum mechanics). In the first part of the paper, we assume that the reduced Planck constant $\hbar$, the absolute temperature $T$, the frequency of an oscillator $ω$, and the degree of freedom of a system $N$ are fixed. This approach to the problem of comparing quantum and classical mechanics is new (see [35]--[37]). In the second part of the paper, we simultaneously derive the semiclassical limits for four cases, that is, for $\hbar{\to}0$, $T{\to}\infty$, $ω{\to}0$, and $N{\to}\infty$. We note that only the case $\hbar{\to}0$ is usually considered in quantum mechanics (see [21]). The cases $T{\to}\infty$ and $ω{\to}0$ in quantum mechanics were initially studied by M. Planck and by A. Einstein, respectively.

L. L. J. Vick

Qinghai Wang, Song-zhi Chia, Jie-hong Zhang

The Hilbert space in -symmetric quantum mechanics is formulated as a linear vector space with a dynamic inner product. The most general -symmetric matrix Hamiltonians are constructed for the 2 × 2 and 3 × 3 cases. In the former case, the -symmetric Hamiltonian represents the most general matrix Hamiltonian with a real spectrum. In both cases, Hermitian matrices are shown to be special cases of -symmetric matrices. This finding confirms and strengthens the early belief that the -symmetric quantum mechanics is a generalization of the conventional Hermitian quantum mechanics.

Tianrong Zhang