Frequency Synchronization and Its Possible Role in Microworld Phenomena

We note the active interest of Yu.I. Neimark for research of frequency synchronization, as well as his substantial support for research in this area. In this work we discuss the main, not yet fully established, definitions and concepts of the theory of frequency synchronization. We consider significant differences between the phenomena of synchronization, self-synchronization, and entrainment. We emphasize that self-synchronization belongs to the class of self-organization phenomena, which is often ignored. We list some relevant unsolved problems of the theory of frequency synchronization, among them being the question of the possible fundamental role of synchronization in the microworld, which is discussed in detail. We express an opinion that it is advisable to attempt to describe physical reality by unified deterministic laws of physics, taking into account other new achievements in nonlinear dynamics listed in this work.