Reply to ‘‘Cosmological source of vacuum electromagnetic zero-point energy’’

In considering an Olbers-type radiation model for the source of vacuum electromagnetic zero-point energy (ZPE), we compare Wesson’s ‘‘time-of-formation’’ interpretation for the range of sources of the ZPE [preceding Comment, Phys. Rev. A 44, 3379 (1991)] with the Puthoff-Santos ‘‘optical depth’’ interpretation, and suggest that the latter may be more compatible with astrophysical constraints.