Statistical Mechanics of Light in Free Space

The consequences of Bose’s statistical theory with regard to the possible existence of zero-energy photons are discussed. It is pointed out that Einstein’s mass dilation formula leaves open the distinct possibility that photons with zero energy can move with speed v<c. On this basis it is argued that the spontaneous radiative emission observed for atoms and molecules can be explained in a straightforward manner on the basis of the principle of conservation of energy, without invoking the assumption of quantum electrodynamics (QED) that vacuum fluctuations of the electromagnetic field are responsible. It is also shown that the quantization of electronic states can be explained by insisting that transitions resulting from photon interactions must obey the principle of conservation of momentum. Consideration of the spontaneous decay of positronium also opens up the possibility that the product is a zero-energy photon, thereby circumventing the requirement that the constituent electron and positron are destroyed in the transition and providing a possible description of the photon as a strongly bound (diatomic) state of an electron and positron. The ubiquitous use of the assumption that matter can be destroyed or annihilated in physical processes is therefore questioned on this basis.