Probing Dark Energy And The Hubble Tension Through Multi-Probe Constraints From SNe Ia, CMB, And BAO

The current phase of precision cosmology is defined not only by increasingly accurate measurements, but by the need to interpret agreement and tension across fundamentally different probes. Type Ia supernovae (SNe Ia) trace the late-time luminosity distance relation, the cosmic microwave background (CMB) constrains the early-Universe acoustic scale and physical densities, and baryon acoustic oscillations (BAO) provide a robust standard ruler across a broad redshift range. The research problem addressed in this paper is whether the joint use of these probes strengthens the case for the baseline LambdaCDM model or instead points toward unresolved late-time physics, especially in relation to dark energy dynamics and the Hubble tension. This empirical conference paper develops a secondary-data synthesis of benchmark results from Pantheon+, Planck 2018, the completed SDSS/eBOSS analysis, DESI Year 1 BAO, and the SH0ES local distance-ladder determination. The analysis compares single-probe and joint constraints in flat LambdaCDM, wCDM, and w0waCDM, focusing on degeneracy breaking, uncertainty reduction, and residual inter-probe inconsistency. The findings show that multi-probe combinations sharply tighten constraints on Omegaₘ and w0 relative to supernova-only inference and continue to support flat LambdaCDM in the most precise CMB plus BAO combinations. However, the H0 tension remains unresolved, and recent DESI-era results indicate mild but not decisive pressure toward evolving dark energy when time variation is allowed. The paper argues that multi-probe cosmology is best understood as both a triumph of precision inference and a structured test of the limits of the standard model.