On hybrid dynamics of the Copenhagen dichotomic world

In the Copenhagen viewpoint, part of the world is quantized and the complementary part remains classical. From a formal dynamic aspect, standard theory is incomplete since it does never account for the so-called 'back-reaction' of quantized systems on classical systems except for the highly idealized system-detector interaction. To resolve this formal issue, a certain 'hybrid dynamics' can be constructed to account for the generic interaction between classical and quantized parts. Hybrid dynamics incorporates standard quantum theory, including collapse of the wave function during system-detector interaction. Measurable predictions are robust against shifting the classical-quantum boundary (von Neumann-cut).