The entanglement of two macroscopic bodies, M1 and M2, consisting, each one, from many parts, is not a relation directly between the parts, but, first of all between the movements of the two bodies taken, each one, as a whole.

For instance, if M1 and M2 are two gaseous masses, the entanglement between them is not an entanglement between the molecules in the two gases, but between the global movement (center-of-mass movement) of the two gaseous masses.

Here begins the question. Is such an entanglement possible? The simplest entanglement is

Ψ = ψa φc + ψb φd ,

where the wave-packets ψ belong to M1 and φ to M2 . From the preparation region the wave-packets of M1 exit with velocities Va and Vb, whereas the wave-packets of M2 exit with velocities Vc and Vd.

Do macroscopic bodies have wave-packets? We know from Feynman's path integral that macroscopic objects have trajectories, not wave-functions, because for such objects the action function is huge in comparison with Planck's constant.

For illustrating simply the situation, assume that the two masses are equal, M = 1Kg, and |Va| = |Vb| = |Vc| = |Vd| = V. Let's require that the wavelength of the movement of each such wave-packet be at least as big as the nuclear radius, 10-12cm, and let's see how big is V. The well-known relation

λ = 2πh/MV => V = 2πh/Mλ

yields V = 6.28×10-27/(103×10-12) ≈ 6.28×10-18cm/s.

In short, the four wave-packets never leave the preparation region.

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