The cosmic distance ladder is a hierarchical methodological framework that determines extragalactic distances by sequentially linking local geometric measurements (stellar parallax) to astrophysical standardizable proxies, including main-sequence fitting and Cepheid variable period-luminosity relations, ultimately utilizing Hubble's Law for remote cosmology. This theory operates on the fundamental assumption of physical uniformity across space and time, allowing absolute brightness derived from intrinsic properties or spectral analysis to infer distance via inverse-square flux attenuation in conjunction with redshift measurements as an indicator of recessional velocity due to cosmic expansion.
The cosmic distance ladder is a hierarchical methodological framework that determines extragalactic distances by sequentially linking local geometric measurements (stellar parallax) to astrophysical …