 If the state of the hydrogen atom is represented by \(\Psi\) then the states of quantum subsystems \(C, R\) are not entangled but the states of quantum subsystems \(p, e\) are entangled. This illustrates the important point that one cannot draw metaphysical conclusions from a mathematical condition of quantum entanglement without first deciding which quantum systems are physical parts composing some physical whole. It may seem natural to take the physical parts of a hydrogen atom to be an electron and a proton. But note that the state of an isolated hydrogen atom is usually represented by \(\Psi_{R}\), and not by \(\Psi\) or \(\Psi_{e}\).