The Big Band and the Age of the Universe
The Big Band and the Age of the Universe Astr 1010-100
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This 2 page Class Notes was uploaded by Alyssa Karounos on Friday February 27, 2015. The Class Notes belongs to Astr 1010-100 at University of Washington taught by Dr. Oliver Fraser in Winter2015. Since its upload, it has received 97 views. For similar materials see Introductory Astronomy 1 in Astronomy at University of Washington.
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Date Created: 02/27/15
22715 I II III IV Goals A Describe various methods for measuring cosmic distances standard candles cepheids main sequence tting Hubble s law B Relate measurements of galaxy recessional velocities to their distance C Relate the hubble plot to the age of the universe Magellanic Clouds A stars in a magellanic cloud varies in brightness as it ickers B How the changing stars reveal the changing universe 1 the longer the period the brighter the star 2 distance is greater than depth 3 Cepheid Variable Stars in the LMC get brighter and they pulse longer C stars are all a type of very massive giant stars red giants The Great Debate of 1920 A the spiral nebulae in the Milky Way local an island universe B the large debate are the spiral nebulae like our universe or are they in our galaxy 1 universe was synonymous with Milky Way Edwin Hubble in the 1940s A took repeated photograph of spiral nebulae B he nds variable stars in the Andromeda nebulae C D now we can start talking about galaxies in our universe absorption lines in a galaxy spectra spectra of millions of stars look like average stellar spectra but are almost always shifted to the red because the majority of detected stars will be red giants E galaxis must be moving away from us F the further away the galaxy is the faster it seems to be receding G measure recessional velocity to determine the distance Hubble s Law A v H 00 B Hubble discovered the expansion of the universe the expansion of the universe doesn39t look like an explosion how long have these galaxies traveled for quick age of the universe calculation 145 billion years 1 46 x1029km 39 10000kmS C D E FLUl rise age H o the assumption that we have been expanding at the same rate How come the universe hasn t collapse if gravity is pulling on everything Newton 7 1 either we live when the universe hasn t collapsed yet or the universe is in nite where there is the same amount on the right the left up and down H in nite in extent VI General Relativity almost disrupts this A Einstein stuck in a cosmological constant to create a static universe that isn t moving B calls this his greatest mistake VII Olbers Paradox A if the universe is in nite everywhere you look there should be a star If you follow this then the night sky should be as bright as the day lled with stars So why is the night sky dark 1 if the universe isn t in nitely old there may be a star in every space but not old enough to reach us