COMMENT ON ZERO-POINT FLUCTUATIONS AND THE COSMOLOGICAL CONSTANT

An interesting concept, vacuum zero-point fields (ZPF), has become, in some circles, an uncritically accepted idea. Attempts have been made link it with a nonzero cosmological constant (Lambda), and a number of cosmology papers now treat Lambda as a free variable to be determined by observation. Recent work has claimed relevance of ZPF to cosmic vo ids. The ZPF view is that space is filled with an infinite energy dens ity of undetectable photons, which, mysteriously, do not gravitate, bu t which are claimed to lead to all sorts of interesting physical effec ts. However, the ZPF seem largely to be a computational trick, in whic h case the vacuum can be considered as simply empty. Even if one adopt ed ZPF as having some sort of existence, any connection to Lambda is f raught with difficulties (despite allegations to the contrary, the ZPF is not Lorentz invariant). If this were not enough, Einstein's choice of sign for Lambda is noted to be unphysical in the sense that it cor responds to an imaginary graviton mass.