Lecture22 - Quiz 13: Signature Course UGS 303 (Fall 2009)...

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1 Q: You have just heard about cold and hot dark matter. Cosmologists sometimes also consider “warm dark matter”. Can you guess what the “warm” is referring to? Quiz 13: A: The particles are moving with speeds that are intermediate between hot (almost the speed of light) and cold (with very sluggish speeds) dark matter! The History and Philosophy of Astronomy (Lecture 22: The Dark Side II: Dark Energy) Instructor: Volker Bromm The University of Texas at Austin Department of Astronomy Signature Course UGS 303 (Fall 2009) The Dark Side of the Universe • Big Q: What is the universe made of? • consensus view of early 21 st century (WMAP): - 4% normal matter (`baryons ʼ ) (stars, gas, people…) - 23% dark matter - 73% dark energy ``Deep into the darkness peering, long I stand there wondering, fearing. ʼʼ (E.A. Poe, The Raven ) • We don ʼ t know what > 90% of universe is made of !!! Einstein ʼ s Cosmological Constant • 1917: Einstein constructs model of the universe that is eternal and static • Fnite but without boundary (spatially closed) • balance between attractive gravity and repulsive cosmological constant (“anti-gravity”)
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2 Einstein ʼ s “Greatest Blunder” !? • 1929: Hubble discovers that the Universe is
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This note was uploaded on 12/18/2010 for the course UGS 303 taught by Professor Foster during the Spring '08 term at University of Texas at Austin.

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Lecture22 - Quiz 13: Signature Course UGS 303 (Fall 2009)...

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