Causal Physics: Photons by Non Interactions of Waves redefines the mathematical Superposition Principle as an operational Superposition Effect; which is the measurable physical transformation experienced by a detector due to stimulations induced by multiple waves simultaneously acting on the detecting dipoles. This light-matter interaction process driven model emerges naturally by incorporating the observed properties, Non-Interaction of Waves (NIW) and quantized photo detectors needing to fill up their “quantum-cups” with the required quantity of energy from all the stimulating waves around it. By not incorporating this NIW-property explicitly, quantum mechanics failed to extract various embedded realities in the theory while incorporated unnecessary hypotheses like wave-particle duality. The book utilizes this NIW-property to explain all the major optical phenomena (diffraction, spectrometry, coherence.) without using any self-contradictory hypotheses that are prevalent now. The book redefines the old ether (constituting the space) as a stationary Complex Tension Field (CTF), holding all the energy of the universe (no need for Dark Energy of Dark Matter). CTF sustains perpetually propagating EM waves as its linear excitations and the particles as self-looped localized resonant non-linear excitations. Tensions are identified by Maxwell, then the velocities of emitting and detecting atoms through the CTF contribute to the Doppler shifts separately. This calls for re-visiting physical processes behind Hubble Redshift and hence Expanding Universe. The success of the book derives from a novel thinking strategy of visualizing the invisible interaction processes, named as Interaction Process Mapping Epistemology (IPM-E). This is over and above the prevailing strategy of Measurable Data Modeling Epistemology (MDM-E). The approach inspires the next generation of physicists to recognizing that the “foundation of the edifice of physics” has not yet been finaliz …