1. Cosmology Tim Arlen UCLA Physics Department Fall 2006 Image Credit: NASA, ESA, and The Hubble Heritage Team (STScI/AURA)

2. Pleiades Star Cluster. Image Credit: Robert Gendler. Cosmology- study of the overall structure and properties of the universe as a whole.

3. Image Credit: NASA, ESA, and Martino Romaniello (European Southern Observatory, Germany) Topics to Explore Highlight history of human thought Overview of our current theory Do we believe our theory is correct?

4. Image Credit: NASA, ESA, HEIC, and The Hubble Heritage Team (STScI/AURA) Cat’s Eye Nebula Greek Cosmology ~ 400 B.C. Plato and Aristotle 5 Elements of the universe: Earth, Air, Fire, Water, and Quintessence. Earth-stationary, everything revolved around it in circles.

5. Greek Cosmology Image Credit: NASA,ESA, M. Robberto (Space Telescope Science Institute/ESA) and the Hubble Space Telescope Orion Treasury Project Team

6. Image Credit: NASA, NOAO, ESA, the Hubble Helix Nebula Team, M. Meixner (STScI), and T.A. Rector (NRAO) More Greek Cosmology Ptolemy ~ 200 A.D, “geocentric model”, Earth is very small compared to heavens Based on mathematics; planets move in “Epicycles” Taught throughout Middle Ages. Image credit: http://math-ed.com /Resources/GIS/Geometry_In_Space/

7. Pre-20 th Century Cosmology Copernicus, Kepler, and Galileo –“Heliocentric Model” Advancement of telescope, galaxies discovered By end of 19 th Century: belief in infinite, static, homogeneous universe. Image Credit: Credit: NASA, ESA, S. Beckwith (STScI) and the HUDF Team Hubble Ultra Deep Field

8. Image Credit: NASA, ESA, and The Hubble Heritage Team (STScI/AURA) Einstein bursts onto the scene! Formulated General Relativity by 1915 Equations showed that the universe is expanding. He didn’t like this! Birth of Modern Cosmology

9. Pleiades Star Cluster. Image Credit: Robert Gendler. Some Gravity Concepts Mass affects space by bending it. Imagine space in 2D, like a trampoline.

10. Image Credit: NASA, ESA, HEIC, and The Hubble Heritage Team (STScI/AURA) Cat’s Eye Nebula Dramatic Comfirmation of GR Bending of starlight. Confirmed with eclipse in 1916. Image: http://astro.physics.sc.edu /selfpacedunits/Unit57.html Image Credit: (Cover) Spacetime and Geometry: An Introduction to General Relativity by Sean Carroll, published by Addison-Wesley.

11. Expansion of Space Some Time T Some Time Later T +  T

12. Image Credit: NASA,ESA, M. Robberto (Space Telescope Science Institute/ESA) and the Hubble Space Telescope Orion Treasury Project Team Hubble and Expansion 1929-Hubble demonstrated his famous result: The farther away an object is from us, the faster it moves away from us. Courtesy of the Archives, California Institute of Technology

13. Image Credit: NASA, NOAO, ESA, the Hubble Helix Nebula Team, M. Meixner (STScI), and T.A. Rector (NRAO) Modern Cosmology Theory of universe’s origins developed Expansion and GR equations imply a beginning, called “singularity” Came to be called “Big Bang Theory” Explosion of space, matter, energy Use known laws of physics to reconstruct history of Universe, predict new phenomena.

14. Image Credit: Credit: NASA, ESA, S. Beckwith (STScI) and the HUDF Team Hubble Ultra Deep Field Source: The Birth of the Universe: The Kingfisher Young People’s Book of Space

15. Image Credit: NASA, ESA, and Martino Romaniello (European Southern Observatory, Germany) Cosmic Microwave Background About 300,000 yrs ATB, “era of recombination” Photons can pass through universe unimpeded Before this time, universe was a plasma

16. Image Credit: NASA, ESA, and The Hubble Heritage Team (STScI/AURA) Observational Consequences Universe itself (space) emits radiation, because it’s hot After “Era of Recombination” universe is transparent to photons Blackbody Radiation predicted- “Cosmic Microwave Background” (CMB) in 1960’s.

17. Pleiades Star Cluster. Image Credit: Robert Gendler. Major Discovery AT&T Bell Laboratory, Penzias & Wilson inadvertently discover “background noise” in the microwave region. Awarded Nobel Prize in 1978

18. Image Credit: NASA, ESA, HEIC, and The Hubble Heritage Team (STScI/AURA) Cat’s Eye Nebula Cosmic Microwave Background COBE (Cosmic Background Explorer) found that CMB is uniform (isotropic) to 1 part in 10,000 Source: Ned Wright’s Cosmology Tutorial http://www.astro.ucla.edu/~wright/cosmolog.htm

19. Image Credit: NASA,ESA, M. Robberto (Space Telescope Science Institute/ESA) and the Hubble Space Telescope Orion Treasury Project Team Problem-Galaxy Formation If all matter is spread out uniformly, how could matter clump together and form galaxies and star clusters?

20. Image Credit: NASA, NOAO, ESA, the Hubble Helix Nebula Team, M. Meixner (STScI), and T.A. Rector (NRAO) Source: Ned Wright’s Cosmology Tutorial http://www.astro.ucla.edu/~wright/cosmolog.htm Anisotropy Discovered CMB is nonuniform to 1 part in 100,000. Slightly denser region of space implies slightly hotter region of space

21. Image Credit: NASA, ESA, and Martino Romaniello (European Southern Observatory, Germany) Major Discovery Slightly hotter (more dense) regions are the “seeds” of galaxy formation Further evidence for dark matter? John Mather and George Smoot – Awarded 2006 Nobel Prize in Physics for this work

22. Image Credit: Credit: NASA, ESA, S. Beckwith (STScI) and the HUDF Team Hubble Ultra Deep Field Brief Recap Source: The Birth of the Universe: The Kingfisher Young People’s Book of Space

23. Image Credit: NASA, ESA, and Martino Romaniello (European Southern Observatory, Germany) Olber’s Paradox If the universe was infinite & static, then along any line of sight, you will eventually hit a star. Then the night sky should be as bright as an average star!