Chapter 16 Dark Matter Dark Energy and the Fate of the Universe Copyright 2009 Pearson Education Inc End of Term Final midterm 8am 16 Dec Essay due 16 Dec on Turnitin com Final homework is extra credit It will replace your worse or missed homework It has been fun teaching you I hope you have enjoyed this review of astronomy Copyright 2009 Pearson Education Inc 17 3 The Big Bang and Inflation Our goals for learning What aspects of the universe were originally unexplained by the Big Bang theory How does inflation explain these features of the universe How can we test the idea of inflation Copyright 2009 Pearson Education Inc What aspects of the universe were originally unexplained by the Big Bang theory Copyright 2009 Pearson Education Inc Mysteries Needing Explanation 1 Where does structure come from 2 Why is the overall distribution of matter so uniform 3 Why is the density of the universe so close to the critical density 4 Why are there no magnetic monopoles Copyright 2009 Pearson Education Inc Mysteries Needing Explanation 1 Where does structure come from 2 Why is the overall distribution of matter so uniform 3 Why is the density of the universe so close to the critical density An early episode of rapid inflation can solve all three mysteries Copyright 2009 Pearson Education Inc How does inflation explain these features of the universe Copyright 2009 Pearson Education Inc Inflation can make structure by stretching tiny quantum ripples to enormous sizes These ripples in density then become the seeds for all structure in the universe Copyright 2009 Pearson Education Inc How can microwave temperature be nearly identical on opposite sides of the sky Copyright 2009 Pearson Education Inc Regions now on opposite sides of the sky were close together before inflation pushed them far apart Copyright 2009 Pearson Education Inc Density Critical Density Critical Density Critical Copyright 2009 Pearson Education Inc The overall geometry of the universe is closely related to total density of matter and energy The inflation of the universe flattens the overall geometry like the inflation of a balloon causing overall density of matter plus energy to be very close to critical density Copyright 2009 Pearson Education Inc How can we test the idea of inflation Copyright 2009 Pearson Education Inc Patterns of structure observed by WMAP show us the seeds of the universe Copyright 2009 Pearson Education Inc Observed patterns of structure in the universe agree so far with the seeds that inflation would produce Copyright 2009 Pearson Education Inc Seeds Inferred from CMB Overall geometry is flat Total mass energy has critical density Ordinary matter 4 6 of total Total matter is 28 of total Dark matter is 23 of total Dark energy is 72 of total Age of 13 7 billion years Copyright 2009 Pearson Education Inc Seeds Inferred from CMB Overall geometry is flat Total mass energy has critical density Ordinary matter 4 6 of total Total matter is 28 of total Dark matter is 23 of total Dark energy is 72 of total Age of 13 7 billion years In excellent agreement with observations of present day universe and models involving inflation and WIMPs Copyright 2009 Pearson Education Inc What have we learned What aspects of the universe were originally unexplained by the Big Bang theory The origin of structure the smoothness of the universe on large scales the nearly critical density of the universe How does inflation explain these features of the universe Structure comes from inflated quantum ripples Observable universe became smooth before inflation when it was very tiny Inflation flattened the curvature of space bringing the expansion rate into balance with the overall density of mass energy Copyright 2009 Pearson Education Inc What have we learned How can we test the idea of inflation We can compare the structures we see in detailed observations of the microwave background with predictions for the seeds that should have been planted by inflation So far our observations of the universe agree well with models in which inflation planted the seeds Copyright 2009 Pearson Education Inc 17 4 Observing the Big Bang for Yourself Our goals for learning Why is the darkness of the night sky evidence for the Big Bang Copyright 2009 Pearson Education Inc Why is the darkness of the night sky evidence for the Big Bang Copyright 2009 Pearson Education Inc Olbers Paradox If the universe were 1 infinite 2 unchanging 3 everywhere the same then stars would cover the night sky Copyright 2009 Pearson Education Inc Olbers Paradox If the universe were 1 infinite 2 unchanging 3 everywhere the same then stars would cover the night sky Copyright 2009 Pearson Education Inc The night sky is dark because the universe changes with time As we look out in space we can look back to a time when there were no stars Copyright 2009 Pearson Education Inc The night sky is dark because the universe changes with time As we look out in space we can look back to a time when there were no stars Copyright 2009 Pearson Education Inc What have we learned Why is the darkness of the night sky evidence for the Big Bang If the universe were eternal unchanging and everywhere the same the entire night sky would be covered with stars The night sky is dark because we can see back to a time when there were no stars Copyright 2009 Pearson Education Inc Some Final Thoughts Is there a beginning to time Is the Universe compactified String Theory Copyright 2009 Pearson Education Inc String Theory lots of handwaving here Copyright 2009 Pearson Education Inc String Theory I Copyright 2009 Pearson Education Inc String Theory II 11 dimensions 6 compactified 5 dimensions 4 dimensional branes in a 5 D universe Forces are little loops 100500 universes the landscape Copyright 2009 Pearson Education Inc Chapter 18 Life in the Universe Copyright 2009 Pearson Education Inc Do you believe there is life elsewhere in the Universe A Yes B No C For me there is not even life in College Station Copyright 2009 Pearson Education Inc Earliest Life Forms Life probably arose on Earth more than 3 85 billion years ago shortly after the end of heavy bombardment Evidence comes from fossils and carbon isotopes Copyright 2009 Pearson Education Inc Fossils in Sedimentary Rock Relative ages deeper layers formed earlier Absolute ages radiometric dating Copyright 2009 Pearson Education Inc Fossils in Sedimentary Rock Rock layers of the Grand Canyon record 2 billion years of Earth s history Copyright 2009 Pearson
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