Chapter 18

Chapter 18 - Note that the following lectures include...

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Unformatted text preview: Note that the following lectures include animations and PowerPoint effects such as fly ins and transitions that require you to be in PowerPoint's Slide Show mode (presentation mode). Cosmology in the 21 st Century Chapter 18 This chapter marks a watershed in our study of astronomy. Since Chapter 1, our discussion has focused on learning to understand the universe. Our outward journey has discussed the appearance of the night sky, the birth and death of stars, and the interactions of the galaxies. Now we reach the limit of our journey in space and time, the origin and evolution of the universe as a whole. The ideas in this chapter are the biggest and the most difficult in all of science. Our imaginations can hardly grasp such ideas as the edge of the universe and the first instant of time. Perhaps it is fitting that the biggest questions are the most challenging. But this chapter is not an end to our story. Once we complete it, we will have a grasp of the nature of the universe, and we will be ready to focus on our place in that universethe subject of the rest of this book. Guidepost I. Introduction to the Universe A. The Edge-Center Problem B. The Necessity of a Beginning C. Cosmic Expansion D. The Necessity of a Big Bang E. The Cosmic Background Radiation F. The Story of the Big Bang II. The Shape of Space and Time A. Looking at the Universe B. The Shape of the Expanding Universe C. Model Universes D. Dark Matter in Cosmology Outline III. 21st-Century Cosmology A. Inflation B. The Acceleration of the Universe C. The Origin of Structure and the Curvature of the Universe Outline (continued) Olberss Paradox Why is the sky dark at night? If the universe is infinite, then every line of sight should end on the surface of a star at some point. The night sky should be as bright as the surface of stars! Solution to Olberss Paradox: If the universe had a beginning, then we can only see light from galaxies that has had time to travel to us since the beginning of the universe. The visible universe is finite! Hubbles Law Distant galaxies are receding from us with a speed proportional to distance The Expanding Universe On large scales, galaxies are moving apart, with velocity proportional to distance. Its not galaxies moving through space. Space is expanding , carrying the galaxies along! The galaxies themselves are not expanding! Expanding Space Analogy: A loaf of raisin bread where the dough is rising and expanding, taking the raisins with it. Raisin Bread (SLIDESHOW MODE ONLY) The Expanding Universe (2) You have the same impression from any other galaxy as well. This does not mean that we are at the center of the universe! Finite, But Without Edge?...
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Chapter 18 - Note that the following lectures include...

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