The isotropic Cosmic Microwave Background Radiation (CMBR) is reinterpreted as emission from the geometric structure of spacetime. This is postulated to occur in the context of the Wheeler/Feynman transactional radiation law, extended to include the dynamics of spacetime topology in a framework of continuous state Spacetime Cavity-QED (STCQED) where the Planck Blackbody spectrum is described as an equilibrium condition of cosmic redshift as absorption and CMBR as emission. The continuous state spin-exchange compactification dynamics of the Dirac vacuum hyperstructure is shown to gives rise naturally to a 2.735° K Hawking type radiation from the topology of Planck scale micro-black hole hypersurfaces. This process arises from the richer open Kaluza-Klein dimensional structure of a post Bigbang continuous state cosmology.