This experiment reveals the nonlocal nature of quantum mechanics (QM) over large distances. It is predicted by quantum mechanics that this nonlocality will hold for the entire universe. The number of experiments of this kind, including experiments on photon tunneling[@Steinberg], appears to show that nonlocal correlations are a permanent feature of QM.

The counter-intuitive predictions of QM have puzzled physicists since the formulation of the theory. The peculiar nonlocal effects arise from particles in entangled states as predicted by the linear superposition principle of QM: $$\vert\psi\rangle=\frac{1}{\sqrt{2}}(\vert\alpha\rangle_1\vert\beta\rangle_2+\vert\gamma\rangle_1\vert\delta\rangle_2),$$ where $\vert\alpha\rangle_1$ and $\vert\gamma\rangle_1$$(\vert\beta\rangle_2$ and $\vert\delta\rangle_2)$ are orthonormal vectors in Hilbert space for particle 1 (particle 2).

Although QM agrees remarkably well over a wide range of experiments, there has been an on-going consistency problem with relativity theory. The standard point of view of “pragmatic" practitioners of QM is that there is no violation of causality in nonlocal QM measurements. It is stated that there is no “exchange of information" between the spacelike separated events associated with the entangled quantum states of the wave function, avoiding superluminal speeds of communication and a violation of special relativity.

The “orthodox" view is that the quantum state vector (wave function $\psi$) characterizes the individual system completely, a 