Astronomy 2022A/B Lecture Notes - Lecture 6: Cosmological Constant, Anisotropy, Cosmic Microwave Background
Document Summary
Large-scale structure in the universe and dark energy. Steady-state model: the universe is uniform and infinite in time/space and essentially unchanging (popular in. Even if universe is infinite, our observable universe is finite (cid:449)e ca(cid:374)(cid:859)t see things more than 14 billion light years a(cid:449)ay, so does(cid:374)(cid:859)t (cid:373)atter if it is i(cid:374)fi(cid:374)ite, it(cid:859)s fi(cid:374)ite for us. Considering the largest scales in the universe, we make the following fundamental assumptions: homogeneity: on the largest scales, the universe has the same physical properties errywhere. Isotropy: on the largest scales, the local universe looks the same in any direction: universality: laws of physics are the same errywhere and throughout time. Initial measurements of galaxy distributions revealed a surprising amount of asymmetry: on large surveys, it shows filaments and walls of galaxy super-clusters, and voids (empty space, but on very large scales seems the uni is h and i. Superclusters clusters of clusters of galaxies align along filaments.