This document is a foundation-level reconstruction of msf: 47650. The earlier version attempted to unify optical color, propagation loss, coherence, material broadening, black appearance, and redshift through a universal frequency-dependent decay law. It proposed expressions such as: Delta f (x) = Delta f0 exp-alpha (f) x alpha (f) proportional to 1/f squared and w (f) proportional to 1/f. Those relations are not retained as foundation laws in version 2. 0. The reconstructed framework explicitly rejects intrinsic loss of photon frequency, energy, amplitude, or coherence caused only by travel through otherwise empty vacuum. In a stationary source-free vacuum, monochromatic components accumulate phase while preserving frequency. Irradiance may decrease through geometric spreading, but this does not mean that individual photons lose energy. Version 2. 0 instead begins from the established optical transfer chain: source to propagation path to material or interface to spectral redistribution to detector or observer. A measured color or spectrum is therefore not treated as one intrinsic state of a freely propagating photon. It is the detector-resolved outcome of: the emitted source spectrum, angular distribution, polarization, timing, vacuum phase and geometry, interfaces, material absorption, material scattering, reflection, transmission, prompt re-emission, delayed re-emission, thermal radiation, and the detector response kernel. The canonical measurement architecture is: Sdetector (f, t) equals the detector-kernel integral of path-transmitted source radiation plus scattered radiation plus re-emission plus thermal radiation plus detector noise. The source term may be supplied by atomic, molecular, lattice, laser, lamp, or thermal-emission models. The document synchronizes this source layer with msf: 52350, which supplies the upstream three-dimensional atomic-emission and detector-kernel language. The present document begins after emission and focuses on local propagation, interaction, redistribution, and measurement. The retained USP contribution is narrow and operational. For a measured material mode j, define: Delta fᵢnteraction, j = fᵢncident - fⱼ and the normalized compatibility coordinate: chiⱼ = absolute value of Delta fᵢnteraction, j divided by Gammaⱼ. Here: fⱼ is a measured material resonance or transition frequency. Gammaⱼ is a measured linewidth or declared response bandwidth. The interpretation is: chiⱼ much smaller than 1: the incident frequency lies near the measured interaction window. chiⱼ approximately 1: the incident frequency lies near the edge of the response window. chiⱼ much larger than 1: direct coupling to that specific mode is weak. This compatibility coordinate does not replace: transition matrix elements, oscillator strengths, selection rules, polarization dependence, complex refractive index, density of states, momentum constraints, material geometry, or optical cross-sections. It organizes measured detuning and becomes scientifically useful only if parameters inferred from independent spectroscopy predict withheld optical behavior without retuning. Version 2. 0 also corrects the earlier blue-versus-red interpretation. Blue and red are frequency regions, not universal coherence or decay classes. For equal photon number, higher-frequency blue light carries more energy because: E = hf. For equal optical power, lower-frequency red light contains a larger photon flux. These comparisons must therefore declare whether power, photon number, irradiance, radiance, or detector counts are held fixed. In a Rayleigh-like scattering regime, shorter wavelengths scatter more strongly: sigmaRayleigh proportional to lambda to the power minus 4. This can produce: redder direct transmission and bluer side scattering at the same time. The blue energy has been redistributed in angle. It has not universally decayed into red light. The document also reconstructs the meaning of black, gray, and white. White is an observer- and detector-dependent achromatic response to a spectral distribution. Gray is a lower-luminance achromatic response under specified illumination and adaptation. Black means low detected radiance or reflectance within a declared spectral band, geometry, illumination, and detector kernel. Black does not mean: Delta f equals zero, absence of field activity, absence of matter, absence of internal modes, absence of stored energy, or absence of thermal and quantum dynamics. A material that appears black in visible light may remain detectable through: infrared reflection, thermal imaging, fluorescence, delayed emission, transmission, or another measurement band. Version 2. 0 introduces one optical energy ledger. Incident optical power must be partitioned into: reflection, transmission, elastic scattering, inelastic scattering, prompt re-emission, delayed re-emission, thermalization, chemical storage, electrical output, structural or field-energy storage, and bounded unmeasured loss. A possible USP residual is defined only after these standard channels and their uncertainties are closed. The null hypothesis is: PUSP, residual = 0 within declared measurement and model uncertainty. A nonzero remainder is first treated as evidence of incomplete accounting, calibration error, collection loss, detector nonlinearity, uncertain emissivity, chemical change, or an omitted standard channel. It is not automatically evidence of new physics. The operational experimental program includes: calibrated source–surface–detector mapping, turbid-medium angular redistribution, near-black excitation and delayed-emission tests, coherence-specific comparisons between ordered and disordered samples, detector-kernel invariance tests, matched absorbed-energy controls, time-resolved spectral measurements, complete power and energy closure, and prediction on withheld datasets. The document requires a preregistered hierarchy of null models: instrument noise and drift, geometric collection error, standard reflection and transmission, Rayleigh, Mie, and radiative-transfer models, fluorescence and phosphorescence, Raman and recombination channels, thermal radiation and heat transfer, trap and defect behavior, photochemistry and structural change, and only then a bounded USP residual. The main scientific question is no longer whether one universal decay law explains color. It is: Can an independently calibrated resonance-compatibility coordinate improve prediction of how structured matter accepts, redirects, stores, or releases optical energy after established optics, spectroscopy, materials physics, thermal physics, and detector response have been applied? Non-replacement statement This work does not replace quantum electrodynamics, Maxwell electrodynamics, wave optics, geometric optics, radiometry, photometry, quantum optics, spectroscopy, complex refractive-index theory, Fresnel equations, Rayleigh or Mie scattering, radiative transfer, Beer–Lambert attenuation, fluorescence or phosphorescence theory, thermal radiation, semiconductor optics, detector calibration, CIE colorimetry, or standard cosmological redshift. These remain the quantitative baseline. USP Field Theory is used here only as a guarded interpretation of independently measured resonance-compatibility windows and possible bounded residuals.
Sadegh Sepehri (Mon,) studied this question.