A Coherence Principle (CP) is proposed, a generalization and idealization of the virial theorem, stating that each well-defined phenomenon should be mono-frequency. When applied to the steady-state critical cosmology, characterized by the scale factor exp(t/T), this principle leads to three independent expressions for T compatible with the so-called Universe age TU ≈ 13.80(4) Gyr, as estimated by the recent Planck mission for the spatially-flat six parameters Λ-CDM model. The most precise formula is given by a c-free analysis of the “incredible” non-Doppler cosmic oscillation, implying tachyonic physics. This refutes (a) the primordial Big Bang model, (b) the cosmological anthropic principle and (c) the Multiverse theory, – in favor of the reconstructing Universe model with frequency about 10^103 Hz and pseudo-period T. This corresponds to critical condition Ω = 1, Hubble parameter H0 ≈ 70.8 km s^-1 Mpc^-1, matter density Ωm = 3/10, and baryonic one Ωb ≈ Ωm^2/2 = 0.045, with detailed predictions for astrophysics. The CP is connected with practical holography, which formalism is shown to be consistent with the basic quantum one, and holographic conservations are either demonstrated or observed, opening the way for further study. The CP is shown to apply also in atomic and stellar physics, together with biology, predicting the DNA chain to be a linear hologram.