Keith F. Lynch:
Can anyone find an online copy of the original study that makes this claim? From the news coverage, I can't even tell whether they claim to have measured an effect, or whether this is entirely theoretical.
Theoretical. There are two papers in Springer's 'The European Physical Journal D'. Here are the abstracts: 1. The quantum vacuum as the origin of the speed of light: : "We show that the vacuum permeability and permittivity may originate from the magnetization and the polarization of continuously appearing and disappearing fermion pairs. We then show that if we simply model the propagation of the photon in vacuum as a series of transient captures within these ephemeral pairs, we can derive a finite photon velocity. Requiring that this velocity is equal to the speed of light constrains our model of vacuum. Within this approach, the propagation of a photon is a statistical process at scales much larger than the Planck scale. Therefore we expect its time of flight to fluctuate. We propose an experimental test of this prediction." 2. A sum rule for charged elementary particles: "There may be a link between the quantum properties of the vacuum and the parameters describing the properties of light propagation, culminating in a sum over all types of elementary particles existing in Nature weighted only by their squared charges and independent of their masses. The estimate for that sum is of the order of 100."