ASTRON 100 Lecture Notes - Galaxy Formation And Evolution, Before Present, Cosmological Principle
21 Jan 2014
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Document Summary
Using hubble"s law to determine the age of the universe. The expansion rate appears to be the same everywhere in space. The universe has no center and no edge (as far as we can tell). One example of something that expands but has no center or edge is the surface of a balloon. The universe looks the same no matter where you are within it. Matter is evenly distributed on very large scales in the universe. The cosmological principle has not been proven beyond a doubt, but it is consistent with. Hubble"s constant tells us the age of the universe because it relates the velocities and all observations to date. distances of all galaxies. Age = distance / velocity ~ 1/h0. Distance between far-away galaxies change while light travels. Astronomers think in terms of lookback time rather than distance, Lookback time: how long it takes light to reach us. Expansion stretches photon wavelengths, causing a cosmological redshift directly related.
