Early Universe Physics Insensitive and Uncalibrated Cosmic Standards: Constraints on Ω_m and Implications for the Hubble Tension

To further gain insight into whether pre-recombination models can resolve the Hubble tension, we explore constraints on evolution of cosmic background that are insensitive to early universe physics. The analysis CMB anisotropy has been thought highly rely However, show fact sound horizon at recombination being close end drag epoch is This allows us link absolute sizes two horizons and treat them as free parameters. Jointly, peak angular size, baryon acoustic oscillations, Type Ia supernovae be used physics uncalibrated standards, which measure history from today. They set strong robust post-recombination background, especially matter density parameter with Ωm = 0.302 ± 0.008 (68% C.L.), assuming a flat Λ cold dark after recombination. When combine these other nonlocal observations, obtain several H0 significantly reduced sensitivity These all more consistent Planck 2018 result than local measurement results such those based Cepheids. suggests tension between post-recombination, but nonlocal, measurements cannot resolved by modifying