R. L. Jaffe of MIT published a paper in PHYSICAL REVIEW D 72, 21301(R) (2005) presenting his rebuttal that the Casimir effects can be reformulated without any reference to the existence of quantum fluctuations of zero-point energies. On the contrary, he argued that the effects are simply relativistic quantum forces between charges and currents. Furthermore, he contended that the Casimir force is dependent on the fine structure constant and as the constant approaches zero in the lower bound limit the force simply disappears while the standard result which appears independent actually corresponds to the limit as the constant approaches infinity.

In his conclusion, starting from the second paragraph he summarized as follow: “The deeper question remains: Do the zero-point energies of quantum fields contribute to the energy density of the vacuum and, mutatis mutandis, to the cosmological constant? Certainly there is no experimental evidence for the reality of zero-point energies in quantum field theory (without gravity). Perhaps there is a consistent formulation of relativistic quantum mechanics in which zero-point energies never appear. I doubt it. Schwinger intended source theory to provide such a formulation. However, to my knowledge no one has shown that source theory or another S-matrix based approach can provide a complete description of QED to all orders. In QCD confinement would seem to prevent an insuperable challenge to an S-matrix based approach, since quarks and gluons do not appear in the physical S matrix. Even if one could argue any quantum zero-point contributions to the vacuum energy, the problem of spontaneous symmetry breaking remains: condensates that carry energy appear at many energy scales in the standard model. So there is good reason to be skeptical of attempts to avoid the standard formulation of quantum field theory and the zero-point energies it brings with it. Still, no known phenomenon, including the Casimir effect, demonstrates that zero-point energies are real.”

The phenomenon of nonzero magnetic dipole moments could hold the key for proving the reality of zero-point energies and the associated quantum vacuum fluctuations. See the upcoming thread on zero magnetic dipole moment.