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  1. Announcements • Lecture PowerPoint's are posted on class website as PDF files and as PowerPoint slides • Next time: if we don’t finish The Five Ages of the Universe today, we will finish it next time so start reading the Foundations of Modern Cosmology textbook. • Exam 1 is scheduled for two weeks from today. Will cover Five Ages of the Universe plus first few chapters of Foundations of Modern Cosmology.

  2. The degenerates all start off as stars White dwarf’s, neutron stars and stellar mass black holes all start as stars. There are larger black holes, galactic black holes, that didn’t start as stars, though.

  3. Brown Dwarf Stars are failed stars These are not degenerate. These, planets and any surviving asteroids or comets are the sole reservoirs of ordinary matter left during the degenerate era.

  4. There are currently many more stars than brown dwarfs

  5. Brown Dwarfs are comparable in size to Jupiter The interiors of brown dwarf’s become highly compressed so they don’t get much larger than Jupiter even with 40 or 50 times the mass. They can become degenerate at their core

  6. White Dwarfs are the size of planets with the mass of stars

  7. Some White Dwarfs “grow” by accreting mass from companions During the Degenerate Era this doesn’t happen any more but it is not uncommon during the Stelliferous Era

  8. In degenerate matter only the highest energy levels are available Degenerate Matter Energy Level Diagram Single atom Energy Level Diagram

  9. Degenerate objects get smaller when mass is added This applies to white dwarf’s and neutron stars but not black holes. Black holes are beyond degenerate

  10. During the Degenerate Era most of the energy may come from dark matter annihilation

  11. Neutron Stars aren’t entirely neutrons

  12. Eventually the protons decay There are other possible decay mechanisms. The current best estimate for the half-life of the proton is ~1034years. Once all the protons decay away, there is no ordinary matter, degenerate or non-degenerate, left in the universe

  13. At the end of the Degenerate Era only black holes are left

  14. The Black Hole Era To understand black holes, we need to explore Einstein’s General Theory of Relativity

  15. The Equivalence Principle

  16. Consequence of Equivalence Principle: Light is affected by gravity

  17. Space-time gets warped near any massive object

  18. Near a black hole the warping of space-time is extreme

  19. Visual distortions caused by a black hole

  20. In Ya Face!

  21. Time runs differently near a black hole

  22. Tidal forces stretch and squeeze anything falling into a black hole The process is called Spaghettification. Watch spaghettification video

  23. Schwarzschild Black Hole

  24. Kerr Black Hole

  25. Most black holes now are accreting mass and have jets Because the star that formed the black hole was rotating and the mass falling in spirals inward, the black hole is rotating: it is a Kerr black hole

  26. The Binary Pulsar When they finally collide, they will form a black hole. Watch Binary Pulsar and Neutron Star Merger videos On thumb drive

  27. Black holes won’t last forever

  28. Hawking Radiation

  29. At the end of the Black Hole Era only electrons, positrons, extremely long wavelength photons and a few exotic elementary particles remain. The Dark Era is truly dark

  30. The Dark Era e+ e- e+ e-

  31. Phase Transitions Ice pockets forming in a salt water pool

  32. Quantum Mechanical Tunneling

  33. The Universe could tunnel to a new vacuum energy state

  34. The probability of tunneling depends on the wave properties of the universe

  35. The Heat Death of the Universe

  36. An Alternate End: The Big Crunch

  37. The more likely ending: The Big Rip