Antony Lewis - Understanding Acoustic Scale Observations: The One-Sided Fight Against Λ

Parallel Talk | Cosmology from Home 2025 https://www.cosmologyfromhome.com/ Abstract: This talk explores how cosmic microwave background (CMB) and baryon acoustic oscillation (BAO) measurements constrain cosmological models. The CMB angular scale provides robust constraints on the ratio of sound horizon to angular diameter distance, limiting possible deviations from the standard ΛCDM model. We demonstrate that the null energy condition for dark energy imposes strict inequalities on BAO observables relative to ΛCDM predictions, restricting the freedom to fit new data within standard cosmological frameworks. I’ll discuss what this means for latest BAO results.