This study exploits a historical gap in the evolution of metric systems that resulted from the incomplete implementation of the ‘rationalization’ concept published by Heaviside in 1893 and by ignoring the suggestion of Maxwell in 1873 to use the simplest form of Newton’s gravitational law expression with no proportionality constant. Bridging this gap required deriving an experimental Rationalized Metric System (RMS) and a corresponding Universal Planck Natural Unit System (UPNUS) in [ LT ] units. The described solution combines Heaviside’s rationalization of Newton’s law and makes the unit of mass dimensions [ L³T⁻² ], as suggested by Maxwell. Consequently, the modified Coulomb’s law, changes the unit of electric charge to the same dimensions as those of mass. The elimination of the kilogram and ampere has a disentangling effect on the dependencies among the constants of nature and opens new horizons. New systems have the potential to become powerful exploratory tools in fundamental research and education because of the simplification of the relationships among physical quantities. Some highlights from the analyzed examples are worth mentioning. The well-known expression for the Stoney mass (m _S ) when converted to RMS units is reduced to the electron charge quantity, whereas traditional metric systems entangle the charge, speed of light, and gravitational constant, forming an entity in the dimension of mass, as first presented by Stoney in 1874. Furthermore, a well-substantiated conjecture is proposed, wherein the Stoney energy E _S = m _S c ² is likely the long-sought, finite electric field energy of the electron, and the gravitational constant appears to be the limiting factor. In UPNUS, the most disentangled fundamental expression, apart from the Stoney mass, is the elementary charge e ̌ as the function of the fine structure constant α and the Planck mass m ̌ P , namely e ˇ = m ˇ P α ≈ 1.073476469 , with e ̌ and m ̌ P of the same [ L³T⁻² ] dimensions in Planck units, where m ̌ P = 4 π .

Motivated by Matsas et al. (2024), who demonstrated that time can serve as the sole fundamental dimension in place of traditional LMT dimensions, this study expands those results within the Minkowski and Tangherlini frameworks. Using a Lorentz transformation (LT) matrix approach, we validate the three-clock protocol, confirming that distance and newly discovered velocity expressions are derivable exclusively from proper times. The investigation is extended to Tangherlini's 4D spacetime to test whether absolute velocity is identifiable. While this resulted in velocity cancellation, a breakthrough was achieved by analysing the wave 4-vector geometric structure. By defining electromagnetic waves in transit as 'anonymous' — hosted by the ARF and unrelated to their original source frequency due to Doppler ambiguity at emission — we propose the Postulate of Anonymity, justified by the wave 4-vector structure in the Tangherlini framework. Using this concept, we successfully circumvented the "cancellation gap". We demonstrate that the ratio of spatial wave-vector components ky/kx (the tangent of the aberration angle) provides a direct, non-ambiguous measure of absolute velocity relative to the vacuum, reconciling with aberration methodologies utilised in the Planck 2013 mission. We prove that while the temporal component ω/c acts as a coordinate-dependent variable subject to sensor interaction, the spatial components tell the 'full truth' of the ARF. Consequently, we formally associate "peculiar velocity" with absolute velocity. The Andromeda Paradox is partially resolved as a coordinate artefact. We conclude that the wave 4-vector is a universal witness to an invariant, causal timeline anchored to the ARF.

Special Relativity holds that the relativity of simultaneity is an inescapable physical consequence of the Lorentz Transformation (LT). This study shows that the phenomenon disappears when a position 4-vector from the stationary frame S is transformed into a fully covariant form in the moving system S', which means the transformed 4-vector is not expressed by coordinates of S. This step is mandatory if S and S' are to be physically equivalent. Standard LT matrix multiplication yields a 'mixed-coordinate' representation in which the stationary time t remains the evolution parameter. An additional functional step is required to replace t with expressions in terms of the local time t'. When this procedure is applied to any two simultaneous events in S, the resulting time interval in S' is zero (Δt'=0). This demonstrates that the textbook claim of relative simultaneity is tied to the intermediate mixed-coordinate stage and does not reflect a physical effect once full coordinate homogeneity is enforced in the moving frame. The resulting physical effects’ predictions remain fully consistent with all observable consequences of special relativity and are equivalent to those obtained in the Tangherlini framework. We argue that absolute-like simultaneity emerges naturally as a formal necessity for the consistent transformation of the position 4-vector into a fully covariant form.