Evolved general relativity directly proven by laboratories around the world, leads to proposals for accuracy improvement of the international system of units' second and meter

Einstein stated two dictums so that more experimental facts can replace the previously adopted hypotheses and general relativity (GR) can evolve to perfection. In the absence of experimental facts during the pre-Century-long Experience of Relativity-related Experiments on Physics, Astronomy and Celestial-mechanics (CEREPAC) era, Einstein found no “escape” from the consequence of non-Euclidean geometry, while keeping all frames permissible based on contemporary knowledge. Bergmann also stated in 1968 that the “principle of general-covariance” has brought about serious complications in GR. During CEREPAC, relativists and mathematical-astronomers invariably identified the appropriate “nature's preferred-frame,” which was later found to be essential for the operation of conservation laws. Based on CEREPAC, replacing the experimentally unverifiable hypotheses with experimentally proven principles and improving upon the GR astronomer model (developed by JPL-Jet Propulsion Laboratory, USA, as an evolved-version of the GR conventional model) in two successive stages, GR was remodeled to what became evident as evolved general relativity (EGR), after it enabled the elimination of all earlier-adopted “ad-hoc” methods or approaches, and of the problems, paradoxes, and anomalies, associated with the applications of GR, during CEREPAC, and after it unraveled the “general-relativistic nature of speed-of-light (c)” which links the variable c _r with F, the local gravitational red-shift-factor (as advocated by Einstein between 1911 and 1921). EGR enabled the first-time computation (over four astronomical-units) of c ₀ (the lower-limit in nature, for c _r ) to be 299 792 458.3 m/s, which links c _r with F. EGR predicted first-time, values of Δc, the “sought-after departure” of Space Time Asymmetry Research (STAR) mission (a US and Europe collaboration), having two baseline-objectives among those stated in National Aeronautics and Space Administration (NASA) Science-Plan (2007‐2016): To test the validity of GR and detect Δc that would have profound implications for cosmology, high-energy astrophysics, particle-astrophysics, and relativity [K.-X. Sun et al., in Astro 2010 White Paper for Technology Development for STAR mission (Stanford University, Stanford, CA, 2010), Paper No. 94305-4088]. EGR enabled the computation of an order-of-magnitude more accurate value of 1983-adopted terrestrial c, to be 299 792 458.5 m/s, directly proven independently by NIST (National Institute of Standards and Technology), USA, NPL (National Physical Laboratory), UK, and National Research Council of Canada, and the determined value is 299 792 458.6 ± 0.3 m/s. Five cases of Relativistic Geodesy at USA, France, and Japan verified the frequency shift due to the elevation difference between clocks in terrestrial Labs, providing direct experimental proof for EGR-computed (using relativistic-transformation factor) values: the most precise one in Japan, in the milliHz-domain and the largest shift in France, due to the elevation difference of about a km. Riehle stated in 2012 that optical transition in the ⁸⁸ Sr⁺ clock at a precision of 10 ^{− 17} supersedes that of the existing cesium standard and could lead to adoption of a new frequency standard for defining Système International (SI) second. Likewise, Nicholson et al. [Nat. Commun. 6, 6896 (2015)], NIST, stated in 2015 the improved accuracy of the ⁸⁷ Sr clock at 2.1 × 10⁻¹⁸. Keeping the “time-keeper” role of the primary Cs clock unhindered, a methodology is being proposed here, to improve upon the decimal digits of ν_Cs  = 9 192 631 770.0000000(27) at its 2017 accuracy of 3 × 10⁻¹⁶ since no constant-of-nature has so many consecutive zeroes. This methodology will make ν_Cs and ν_Sr(87&88) more accurate and compatible, leading to the accuracy improvement of SI second. Employing the newly adopted frequency standard (say ⁸⁷Sr) for the fresh determination of terrestrial c_r , will lead to 5 orders-of-magnitude improvement in accuracy of c and the SI meter.