N ov 2 00 4 Has Dark Energy really been discovered in the Lab ?

We show that Dark Energy contributions can not be determined from noise measurements of Josephson junctions, as was recently suggested in a paper by C. Beck and M.C. Mackey. Zero-point energies and non-gravitational effects In a recent paper [1] of C. Beck and M.C. Mackey the possibility was suggested that part of the zero-point energy of the radiation field that is gravitationally active can be determined from noise measurements of Josephson junctions. We are convinced that there is no basis for this. The reason being that the absolute value of the zero-point energy of a quantum mechanical system has no physical meaning when gravitational coupling is ignored. All that is measurable are changes of the zero-point energy under variations of system parameters or of external couplings, like an applied voltage. This was nicely illustrated some time ago by C. Enz and A. Thellung in a paper [2] contained in the memorial volume of Helv. Phys. Acta for W. Pauli. Beside the Casimir effect, these authors considered the sublimation pressure of isotopes. Contrary to earlier beliefs of O. Stern and W. Pauli [3], the latter is independent of whether the zero-point energies of the lattice vibrations of the solid are included or not, as long as the total Hamiltonian is symmetric in all the atoms (in the solid and vapor phases). The simplest example which illustrates our point is the following caricature for the van der Waals force. Consider two identical harmonic oscillators