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Cosmology

Explore the universe's origins in the big bang, galaxy evolution, dark matter mysteries, and the future fate of the universe. Learn about redshift, Hubble's Law, and the cosmic microwave background.

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Cosmology

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  1. Cosmology HNRT 227 Chapter 15 27 October 2015 Great Idea: The universe began billions of years ago in the big bang and it has been expanding ever since.

  2. Chapter Outline • Galaxies • The Redshift and Hubble’s Law • The Big Bang • The Evolution of the Universe • Dark Matter and Ripples at the Beginning of Time • The End of the Universe

  3. Galaxies

  4. The Nebula Debate • Nebulae • Cloud-like objects • Shapley vs. Curtis • Debate over distance of nebulae

  5. Edwin Hubble (with Milt Humason) and the Discovery of Galaxies • Hubble • Largest telescope in his day • Used Cepheid variable stars to measure distance to nebulae • Galaxies • Hubble examined a multitude of galaxies • Categorized and measured • Cosmology • All galaxies outside our Local Group are moving away from us • Doppler shift

  6. Kinds of Galaxies • Spiral • Elliptical • Irregular (& Dwarf) • Active galaxies • Blazars, Quasars, Radio, Seyfert

  7. Properties of Galaxies Property Spirals Ellipticals Irregulars Mass/M of Sun 109 to 4x1011 105 to 1013 108 to 3x1010 Luminosity/L of Sun 108 to 2x1010 3x105 to 1011 107 to 3x109 Diameter (light years) 16x103 to 8x105 3x103 to 7x105 3x103 to 3x104 % of galaxies 77% 20% 3% National Optical Astronomy Observatory images From this table, consider which galaxies are the most and least massive, most and least luminous, and largest and smallest in size.

  8. Active Galaxies

  9. Hubble Deep Field

  10. The Redshift and Hubble’s Law

  11. The Redshift and Hubble’s Law • Redshift • Hubble’s Law • The farther a galaxy, the faster it recedes • V=H x d

  12. The Big Bang

  13. The Big Bang • Big Bang • Best model of the formation of the universe • The universe began at a specific time in the past, and it has been expanding ever since

  14. The Large-Scale Structure of the Universe • The Local Group • Milky way, Andromeda galaxy, and others • Groups (smaller number), clusters, superclusters • Regular and irregular • Voids

  15. Some Useful Analogies Expanding Balloon Analogy Raisin-Bread Dough Analogy

  16. Evidence for the Big Bang • The Universal Expansion • Steady-state universe • The Cosmic Microwave Background • Penzias and Wilson • End of steady-state theory • The Abundance of Light Elements • Hydrogen, helium, very little lithium and beryllium

  17. The Evolution of the Universe

  18. Some General Characteristics of an Expanding Universe • All matter heats when compressed • Hot big bang • Freezings • Changes in universe

  19. 10-43 Second: The Freezing of All Forces • Two fundamental forces • Gravity • Strong-electroweak force • Limit of our knowledge of universe

  20. 10-35 Second: The Freezing of the Electroweak and Strong Forces • Three fundamental forces • The elimination of antimatter • Galaxy is ordinary matter • Why? • Leftover protons • Inflation • Short rapid expansion • Common temperature

  21. 10-10 Second: The Freezing of the Weak and Electromagnetic Forces • Four fundamental forces • Particle accelerators • Reproduce from here forward • Experimental evidence for evolution of universe

  22. 10-5 Second: The Freezing of Elementary Particles • Elementary particles formed • Prior • Quarks and leptons • After • Hadrons and leptons • Electrons, protons and neutrons

  23. Three Minutes: The Freezing of Nuclei • Nuclei become stable • Only nuclei of H, He, Li, Be • Plasma

  24. Before One Million Years:The Freezing of Atoms • Formation of Atoms • Radiation released • Cosmic microwave background • Galaxy problem

  25. Dark Matter and Ripples at the Beginning of Time • Dark Matter • Measure gravitational effects • Hydrogen atoms • Formation of dark matter (questions to be answered) • Before atoms formed? • Formed clumps? • Ripples at the beginning of time • Collection of luminous matter

  26. The End of the Universe • Open, closed or flat universe • Current data • Mass of universe • Open universe • Type Ia supernova • Dark Energy • 70% of universe’s mass • Future • Depends on dark energy • Big Rip

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