The foundations of Relativity and Quantum theory are compromised by profound conceptual difficulties that have blocked unification of these 'twin pillars' of physical science and thus a fundamental understanding of gravity, light and physical phenomena generally. Current efforts to supersede these difficulties without directly addressing them, as exemplified by the approaches that go by the name of String Theory, are unlikely to lead to long term success. Moreover, it is found that quantization-of-action and Lorentz invariance are general, emergent properties of dynamical systems comprising periodic fluctuations in the underlying degrees of freedom. Therefore, mathematical models that "wire in" these attributes - instead of deriving them from the underlying model - do not furnish a theoretical foundation for their interpretation. With these considerations in view, a framework for a quantum theory of gravity and a new understanding of light is presented and discussed.