What are the Challenges in the Cosmic Distance Ladder?

Each method in the cosmic distance ladder has its limitations and sources of error. For example, parallax is limited by the accuracy of angle measurements, while standard candles require precise calibration of their intrinsic brightness. Additionally, the Tully-Fisher relation and SBF methods depend on the assumptions about galaxy properties. Redshift measurements are affected by local motions within clusters of galaxies, which can introduce uncertainties.