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How many universes are there, anyway

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We look at the history of the multiverse, the big bang theory, the problem of fine-tuning, how it is solved by the anthropic principle, how the combination of eternal inflation & string theory might create many universes, and a bit of discussion as to the odds of the multiverse being true.

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How many universes are there, anyway

  1. 1. http://timeandquantummechanics.comMultiverse - Balticon, May 23rd, 2015John Ashmead Anyway? Just how many universes are there,
  2. 2. http://timeandquantummechanics.comMultiverse - Balticon, May 23rd, 2015 • Rainbow gravity • Gravity leaking into nearby dimensions • Miniature black holes
  3. 3. http://timeandquantummechanics.comMultiverse - Balticon, May 23rd, 2015 • The multiverse today • The problem of fine-tuning • A scientific hypothesis? • What are the odds?
  4. 4. http://timeandquantummechanics.comMultiverse - Balticon, May 23rd, 2015 The Multiverse Today • A brief history of the multiverse • The edge of the known • From the Big Bang to now
  5. 5. http://timeandquantummechanics.comMultiverse - Balticon, May 23rd, 2015 A brief history of the Multiverse • Eratothenes’s Earth • Kepler’s Moon • Galileo’s Jupiter • Wright’s Galaxies • Bessel’s Star
  6. 6. http://timeandquantummechanics.comMultiverse - Balticon, May 23rd, 2015 • Chief Librarian at Alexandria at 245 BC • Sieve of primes • Beta/Pentathelete • Camel-Days • Right order of magnitude Eratothenes’ Earth
  7. 7. http://timeandquantummechanics.comMultiverse - Balticon, May 23rd, 2015 Kepler’s Somnium (1608+) • Autobiographical • Revised thru his life • Copernican theory • The view from the moon
  8. 8. http://timeandquantummechanics.comMultiverse - Balticon, May 23rd, 2015 • Careful reasoning • Notebooks • Time series • A lot to love here Galileo & The Moons of Jupiter(1610)
  9. 9. http://timeandquantummechanics.comMultiverse - Balticon, May 23rd, 2015 Wright’s Galaxies (1750) • Milky way as galaxy • Nebulae as galaxies • An indifferent universe
  10. 10. http://timeandquantummechanics.comMultiverse - Balticon, May 23rd, 2015 Bessel’s Star (1838)
  11. 11. http://timeandquantummechanics.comMultiverse - Balticon, May 23rd, 2015 Cosmic Distance Ladder • Parallax (Blue) • Standard Candles (Light Orange) • Supernovae (Red) • The red shift (Dull green)
  12. 12. http://timeandquantummechanics.comMultiverse - Balticon, May 23rd, 2015
  13. 13. http://timeandquantummechanics.comMultiverse - Balticon, May 23rd, 2015 • 30 billion years away • But only 13.7 billion years since start? • Space has been expanding!
  14. 14. http://timeandquantummechanics.comMultiverse - Balticon, May 23rd, 2015 Finite but no edge! • Finite but no edge • It’s getting bigger every minute • Now is a good time for observers
  15. 15. http://timeandquantummechanics.comMultiverse - Balticon, May 23rd, 2015 Big Bang Theory (De Luce) • Only theory with a TV show • Robert Grossteste, 1175 - 1253. • The Big Bang theory is not about the Big Bang
  16. 16. http://timeandquantummechanics.comMultiverse - Balticon, May 23rd, 2015 • Why is the universe so flat? • With matching temperature • & curvature?
  17. 17. http://timeandquantummechanics.comMultiverse - Balticon, May 23rd, 2015 Too Hot to Shine • Only ionized particles • The unfortunate photon no sooner escapes from one particle • Than it is absorbed by another!
  18. 18. http://timeandquantummechanics.comMultiverse - Balticon, May 23rd, 2015 Tri-Alpha Process • Helium stable • Beryllium (next) is NOT • But there is a resonance with Carbon • Tunnel thru!
  19. 19. http://timeandquantummechanics.comMultiverse - Balticon, May 23rd, 2015 The problem of fine- tuning • Just six numbers • Quantum fluctuations • String theory
  20. 20. http://timeandquantummechanics.comMultiverse - Balticon, May 23rd, 2015
  21. 21. http://timeandquantummechanics.comMultiverse - Balticon, May 23rd, 2015 Anthropic testsCurious when you think about it that the universe is perfectly adapted for velociraptors What if there are lots of universes & we just got lucky? I see dinner!
  22. 22. http://timeandquantummechanics.comMultiverse - Balticon, May 23rd, 2015 Vulcan Science Directorate Thinks not A parallel universe. The science directorate has examined all these theories. They've found no evidence of alternate realities.
  23. 23. http://timeandquantummechanics.comMultiverse - Balticon, May 23rd, 2015 Quantum Fluctuations • Quantum fluctuations • Fractals • Led to universe • And galaxies
  24. 24. http://timeandquantummechanics.comMultiverse - Balticon, May 23rd, 2015 Eternal Inflation • Parts of the mega universe suddenly cool out • Creating a bubble universe • That inflates with specific values of the fundamental physical constants
  25. 25. http://timeandquantummechanics.comMultiverse - Balticon, May 23rd, 2015 Live, Die, Repeat • Origin of species • “Generate & test” • Galaxies, stars, planets, & us • Universes & their observers • And theories of the multiverse, e.g. String Theory
  26. 26. http://timeandquantummechanics.comMultiverse - Balticon, May 23rd, 2015 String theory • Most popular today • Gets rid of some infinities • Lets us combine particle physics & gravity • 10 dimensions for superstrings
  27. 27. http://timeandquantummechanics.comMultiverse - Balticon, May 23rd, 2015 Compactification
  28. 28. http://timeandquantummechanics.comMultiverse - Balticon, May 23rd, 2015 Calabi-Yau Manifolds • The “extra” dimensions are curled up into complex structures • Many possible ways to do this
  29. 29. http://timeandquantummechanics.comMultiverse - Balticon, May 23rd, 2015 String-scape • 10^500 possibilities • Most are uninteresting • A few “Happy Valleys”
  30. 30. http://timeandquantummechanics.comMultiverse - Balticon, May 23rd, 2015 Fringe Science? • Hot scientists? • Equations? • Intense but puzzled expressions? • Fate of the universe at stake?
  31. 31. http://timeandquantummechanics.comMultiverse - Balticon, May 23rd, 2015 How to think about WeirdThings • Testability • Fruitfulness • Scope • Simplicity • Conservatism
  32. 32. http://timeandquantummechanics.comMultiverse - Balticon, May 23rd, 2015 Testability
  33. 33. http://timeandquantummechanics.comMultiverse - Balticon, May 23rd, 2015 Cosmological Microwave Background
  34. 34. http://timeandquantummechanics.comMultiverse - Balticon, May 23rd, 2015 Bubble universes
  35. 35. http://timeandquantummechanics.comMultiverse - Balticon, May 23rd, 2015 Bubbles in the CMB? • Nearby parallel universe • Leaves smudge on the CMB • Sister universes?
  36. 36. http://timeandquantummechanics.comMultiverse - Balticon, May 23rd, 2015 Gravitational waves • Distant universes • Remnants of collisions • From before the Big Bang
  37. 37. http://timeandquantummechanics.comMultiverse - Balticon, May 23rd, 2015 Fruitfulness • Gives you something to look for at small scales • And at large • Can rock the mind loose from hard- wired assumptions
  38. 38. http://timeandquantummechanics.comMultiverse - Balticon, May 23rd, 2015 Scope • Largest possible scope • See as far as possible • And then drive imagination a bit further than that
  39. 39. http://timeandquantummechanics.comMultiverse - Balticon, May 23rd, 2015 Simplicity • # of hypotheses • not number of parts, but the kinds of parts • is a Calabi-Yau manifold simple or complex?
  40. 40. http://timeandquantummechanics.comMultiverse - Balticon, May 23rd, 2015 Wheeler’s Radical Conservatism • The combination of Eternal Inflation & String theory gives the multiverse as a straight forward prediction • Gellmann’s totalitarian principle + the 30 odd constants also imply multiverse • And Many Worlds Interpretation implies that the multiverse a natural implication of quantum mechanics
  41. 41. http://timeandquantummechanics.comMultiverse - Balticon, May 23rd, 2015
  42. 42. http://timeandquantummechanics.comMultiverse - Balticon, May 23rd, 2015 The universe whisperer
  43. 43. http://timeandquantummechanics.comMultiverse - Balticon, May 23rd, 2015 • Shift your assumptions to match those of your target world • Absurd • And profound Syllogismobile
  44. 44. http://timeandquantummechanics.comMultiverse - Balticon, May 23rd, 2015 one universe or many?
  45. 45. http://timeandquantummechanics.comMultiverse - Balticon, May 23rd, 2015 Thanks! • Balticon & Miriam Kelly • Ferne Welch • Brenda Welch & Jamie Laird • Other quasi-willing ears
  46. 46. http://timeandquantummechanics.comMultiverse - Balticon, May 23rd, 2015 • Stenger - God & the Multiverse - 2014 • Greene - Hidden Reality - 2011 • Barrow - The Book of Universes - 2011 • Clegg - Before the Big Bang - 2009 • Susskind - The Cosmic Landscape - 2006

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