Entanglement Relativity in the Foundations of The Open Quantum Systems Theory

Realistic many-particle systems dynamically exchange particles with their environments. In classical physics, small variations in the number of constituent particles are commonly considered practically irrelevant. However, in the quantum mechanical context, such and similar structural variations are generically taxed due to the so-called Entanglement Relativity. In this paper we point out difficulties in deriving master equation for a subsystem of an alternative partition of the closed quantum system. We find that the Nakajima-Zwanzig projection method cannot be straightforwardly used to solve the problem. The emerging tasks and prospects for the consistent foundations are examined.