A theory of science stands on and falls with its conceptual foundations.  The relativity edifice was erected on freak foundations. Einstein made no secret of his unclarity about the nature of light yet got away with replacing the physical medium (ether) for light-wave with non-existent 4-D spacetime continuum, creating thereby the greatest confusion in science. For Unified Theory all spacetime continua are mere mathematical constructs bereft of physical existence. Observed inter-convertibility of various forms of energy among themselves and/or with mass along with Einstein equation E = mc² inescapably enforces the suggestion for the existence in real Nature of a Basic Substance composing all forms of energy and mass, otherwise the E & m could NOT interconvert. The electron-positron pair inter-converts with light, which is also a wave hence composed by its propagating medium. The light propagating sharmon medium composed by the new particle �sharmon� as a kinetic gas thus, emerges as the all-composing �basic substance�. Sharmon comprises two elementary cosminos, the +ve positrino and �ve negatrino. The effective �origin� of the light-wave is NOT the light source but the 0-spin sharmon in the sharmon medium which is the first to receive the wave energy quantum and rise to its 1-spin state. Similarly the effective �terminus� of the light wave is NOT the target but the last propagating 1-spin sharmon in the sharmon medium that transfers the wave energy quantum to the target and falls to its 0-spin state. Due to creative beginning of the light-wave at the origin the light velocity is independent of the motion of the source. And because of the vanishing end of the light-wave at the terminus the light velocity is invariant to the target motion. From origin to terminus the light wave energy quantum is propagated along the transverse electromagnetic wave as a wave-quantum UNITY via 1-spin sharmons which do not move about the mean positions yet provide a physical carrier. The light velocity c in the sharmon medium remains constant and invariant to the source-observer motion. This explains the Michelson-Morley & Sagnac experiments without the formulae for the unrealistic �contraction of space� and �dilatation of time� given by Lorentz and/or Einstein.   Thus light propagating sharmon medium emerges as the absolute reference frame and light propagation as a non-relative absolute motion. Since the spin of the source does not fall by 1 and that of the target does not rise by 1, the 1-spin photon or energized 1-spin sharmon as a whole is neither emitted or absorbed or propagated. Instead, it is the wave energy composed by 0-spin sharmons that is emitted, absorbed and propagated. Unified Theory gives six reasons for the non-existence of the conventional 1-spin �photon�, which is now replaced by energized 1-spin sharmon, but the name �photon� is retained in deference to usage. The photon or energized 1-spin sharmon of energy hn = h/t  (n= frequency, t= cycle) is a pulse of one cycle (t) duration and one wavelength (L) long. Approximating it as a sphere of closely packed cosminos of radius rc its radius becomes r = r_c.(2hc/l)^1/3 . Unified Theory explains the photoelectric effect for which Einstein got the 1921 Nobel prize. It explains Maxwell equations and bending of light under gravity which Relativity also did. The Relativity did not but UT explains Compton effect and interference of light. Besides explaining the constancy and invariance to source-observer motion of light velocity c, which Special Relativity used as its two axiomatic postulates without explanation, the Unified Theory also explains the observed variability and superluminality that invalidate both Special and General Relativity. Unified Theory thus provides an alternative replacement for both Special & General Relativity Theories.