Born reciprocal relativity theory redefines the notion of mass: How massless photons appear massive in accelerated frames

Starting with a brief review of Born Reciprocal (non-inertial) Relativity Theory (BRRT), it is shown how massless photons in one frame of reference can appear massive in an accelerated frame. An immediate application can be found in the behavior of infalling/outgoing photons propagating in a black hole gravitational background where infalling and outgoing photons from the point of view of an accelerated frame of reference (with respect to a static spherically symmetric Schwarzschild black hole, for example) will appear massive and subluminal. In view of these novel findings, that massless particles can appear massive in accelerated frames, we believe they should have many important consequences in cosmology (dark energy, dark matter problem) and QFT.