Exploring the Expanding Universe: Hubble Law & Cosmological Principle - Prof. Joseph J. Mo, Study notes of Astronomy

Download Exploring the Expanding Universe: Hubble Law & Cosmological Principle - Prof. Joseph J. Mo and more Study notes Astronomy in PDF only on Docsity! October 17, 2008 1 Models of an Expanding Universe A theoretical framework for understanding our expanding universe October 17, 2008 Astr 350 Lecture 17, Prof Mohr 2 Interpreting the Expansion !! The Hubble Law and its Interpretation !! Current Estimates of the Hubble Constant !! Models for an expanding Universe !! The cosmological principle October 17, 2008 Astr 350 Lecture 17, Prof Mohr 3 The Hubble Law speed distance Hubble parameter v1 d1 v2 d2 dHv 0 = October 17, 2008 Astr 350 Lecture 17, Prof Mohr 4 1d 2d Interpretations of Hubble Law Correct view: Space expanding everywhere with no center Galaxies carried along like “markers” 4d Consistent with the cosmological principle Observers throughout the universe would see galaxies around them receding from them October 17, 2008 Astr 350 Lecture 17, Prof Mohr 5 Hubble Parameter ! v(km /sec) = H0d(Mpc) "[H0 ] = km /sec/Mpc current estimate H0 = 72± 7 km/sec (Freedman et al. 2000) October 17, 2008 Astr 350 Lecture 17, Prof Mohr 6 History of H0 Measurements Freedman (1999) October 17, 2008 Astr 350 Lecture 17, Prof Mohr 7 Cosmological Principle !! Statement: !! The Universe is homogeneous and isotropic on large scales !! Homogeneous: !! the Universe is the same everywhere !! no special place (Copernican hypothesis) !! Isotropic: !! the Universe looks the same in every direction October 17, 2008 Astr 350 Lecture 17, Prof Mohr 8 Homogeneity vs Isotropy Homogeneous, isotropic Homogeneous, anisotropic Inhomogeneous, anisotropic Inhomogeneous, isotropic