1. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math 1 Big Bang, Black Holes, No Math ASTR/PHYS 109 Dr. David Toback Lectures 20

2. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math 2 Was due Today – L20 Reading: –(Unit 4) Pre-Lecture Reading Questions: –Unit 4 Revision (if Desired): Stage 1, due Wednesday End-of-Chapter Quizzes: –Chapter 13 Papers: –Paper 2 Revision (if desired): Stage 2 due Wednesday –Paper 3: Stage 1, due today Honors Papers: –(Stage 2) –Final paper due on the last day of class

3. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math 3 A Big Bang Occurs… Then What? Universe goes through a phase of being hot and small with lots of high energy particles in thermal equilibrium Then the Universe gets bigger and cooler As it gets bigger, it “evolves”

4. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math 4 The History of the Universe Universe expands as time passes Universe cools down as time passes 1 second 10 billion years 10 billion degrees 1 degree

5. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math 5 Various Times Explain what happens during each of a number of different periods in time –The VERY early universe –The first three Minutes –The next 300,000 years –The next billion years –~13 billion years later (now) –The ultimate fate of the universe? The first four will take a couple of lectures } Chap 14 } Chaps 15-17 } Unit 6 } Chap 13

6. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math 6 Where are we now in the history? 3 Minutes

7. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math 7 After the First Three Minutes At about the 3 minute mark the temperature of the Universe is about 1 billion degrees Electrons and positrons have mostly annihilated each other –No particles energetic enough to produce new ones ~1 electron for every proton

8. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math 8 What else? The temperature drops so that the photons, on average, can’t even break up deuterium –Easier to start building up the heavier nuclei

9. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math 9 Proton + Proton  Deuterium + Electron + Neutrino Forming Heavy Nuclei in the Early Universe Proton  Deuterium Nuclear Reaction Electron Neutrino

10. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math 10 Nuclei and Low Energy Photons Deuterium Low Energy Photon At the 3 minute mark, low energy photons only “bump” nuclei

11. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math 11 Proton + Deuterium  3 He + Photon Can Now Build Heavier Nuclei Deuterium Proton  3 He Nuclear Reaction Photon

12. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math 12 3 He + 3 He  4 He + 2 Protons Creating Stable Helium 3 He 4 He Nuclear Reaction Proton Replenishes the hydrogen in the Universe

13. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math 13 Why so few atoms Heavier than Helium? Nuclear Physics Can build up Hydrogen and Helium one at a time So What? Since 5 He and 5 Li decay quickly they don’t have enough time to find another proton to become 6 Li and be stable  Almost no elements heavier than helium are produced in the early Universe  Next possibility, 5 He or 5 Li, isn’t stable

14. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math 14 The Helium Story Able to predict the fraction of the atoms in the Universe that are Helium –75% of atomic mass in hydrogen –25% of observed mass in helium Same as saying about 91% of the atoms are hydrogen Helium is the same in every direction because it was created everywhere –Entire Universe had the same temperature everywhere –If it was created mostly in stellar cooking we’d see it coming from the directions where there are more stars I.e., the direction of galaxies More on this in Chapter 16

15. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math 15 Time marches on… Universe continues to expand and cool Number of protons goes up and number of neutrons goes down –Why? Neutrons can decay into protons

16. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math 16 Neutron  Proton + Electron + Neutrino Neutron Decay Neutron Proton Decay Electron Neutrino

17. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math 17 The End of an Era For the next couple hundred thousand years things don’t change much Nuclear processes eventually stop making new heavy nuclei since the Universe gets so big But it’s still MUCH too hot for atoms to form

18. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math 18 The beginning of a new Era From 200,000-700,000 years the universe expands and cools All the protons, neutrons and electron combine to form atoms –Translation: Universe cools until the photons in the universe can’t knock all the electrons out of the atoms any more

19. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math 19 Atoms in a Lower Temperature Universe Proton Electron  Hydrogen Atom ElectroMagnetic Reaction At these lower temperatures photons can’t easily break up atoms Photon

20. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math 20 Where are we now in the history? 200,000-700,000 years

21. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math 21 Some Time Passes The Transition From a Hot Universe to a Cool Universe

22. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math 22 The Universe at ~700,000 Years Old At a temperature of about 3000K, photons, on average, can’t knock apart atoms We can now have stable atoms and all the electrons become part of atoms The atoms are now free to form into stars and galaxies

23. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math 23 Give this special time in history a name Call this time “Recombination” Crappy Word! Atoms are combining for the first time, not recombining!

24. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math 24 Atoms in the Universe Early Universe A couple hundred Thousand Years Later These days

25. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math 25 Before and After the Creation of Atoms Lots of electrons and protons in the Universe  Photons scatter from charged particles Protons and electrons combine to form atoms  Universe becomes transparent for photons

26. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math 26 Transparent Universe The Universe now LOOKS different! The light (photons) have no free electrons to interact with Since all the electrons are in atoms, because of Quantum Mechanics, they largely ignore the photons Photons just travel in a straight line  Like traveling through glass

27. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math 27 Atoms in the Universe Early Universe Photons bust apart atoms A couple hundred Thousand Years Later Photons can only excite atoms These days Universe is transparent to photons Hydrogen High energy photon

28. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math 28 A Cartoon… Before Recombination: Photons interact with charged particles Scatter and change directions + + + + + + + + After Recombination: Atoms ignore the photons Photons travel in straight lines forever

29. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math Cosmic Background Radiation The photons we see in the cosmic background radiation are essentially the photons AFTER they interacted with their last charged particle Well… they’ve been traveling for awhile so they’ve changed a little 29

30. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math 30 Photons in the Universe After recombination, photons can travel freely through space Their wavelength is only stretched (red shifted) by cosmic expansion  Observe most photons as as the cosmic background radiation!  Also can observe photons emitted from Galaxies a billion years ago (just reaching us now) as being red-shifted

31. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math 31 Looking Back at the Early Universe The more distant the objects we observe, the further back into the past of the universe we are looking

32. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math 32 The next few billion years After less than ~0.5 billion years, the first stars form  Stars produce heavy elements (“Stellar Cooking”)

33. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math 33 A Neutral Universe After the electrons and protons combine to form atoms the Universe is almost completely neutral i.e., neutrally charged Why is this so important? All the particles in the Universe stop attracting each other due to their electric charge –Not completely true, just true outside the atoms –Basically can ignore electric charge from here on out

34. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math 34 Some Time Passes The Transition From a “Charged” Universe to a “Neutral” Universe

35. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math Aside on Dark Matter Dark matter is a BIG part of this story because there is 5 times more mass in the Universe in dark matter than in atoms –Will come back to this in Chapter 15 However, the story doesn’t change much with Dark Matter since we think it is just another neutral particle 35

36. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math 36 A Gravity Dominated Universe The only thing left is gravity! The gravitational attraction between massive things ONLY makes them move towards each other Any single atom would be most attracted to the closest place with lots of mass

37. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math 37 Wait a Half Billion Years As the years go by, mass clumps together By a half a billion years after the bang, most of the mass is in one of a large number of “clumps” Billions of these clumps, each becomes a galaxy!

38. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math 38 Fast Forward… Fast forward 13 billion years –Temperature of space is now ~3 degrees –Cosmic Background Radiation We get people… More on Stellar and Galaxy Formation next

39. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math 39 Looking Forward Finished Unit 4 –Evolution of the Universe Starting Unit 5 –Big Objects and Black Holes

40. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math 40 For Next Time – L20 Reading: –Unit 5 Pre-Lecture Reading Questions: –Unit 4 Revision (if Desired): Stage 1 –Unit 5: Stage 1 End-of-Chapter Quizzes: –Chapter 14 (if we finished Chapter 14, else just 13) Papers: –Paper 2 Revision (if desired): Stage 2 due Wednesday –Paper 3: Stage 2 due Monday before class Honors Papers: –(Stage 2) –Final paper due on the last day of class

41. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math Full set of Readings So Far Required: –BBBHNM: Chaps. 1-15 Recommended: –TFTM: Chaps. 1-5 –BHOT: Chaps. 1-7, 8 (68-85), 9 and 11 (117-122) –SHU: Chaps. 1-3, 4(77-93), 5(95-114), 6, 7 (up-to-page 159) –TOE: Chaps. 1-3 41

42. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math 42

43. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math Clicker Question Why can we only see so far back into space? a)Because before recombination the light in the universe was scattering off most of the particles b)Because there are too many things in the way which block our ability to see 43

44. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math Clicker Question Which of the following requires the highest energy photon? a)Breaking apart a Proton b)Breaking apart a helium nuclei c)Breaking an electron out of a hydrogen atom 44

45. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math Clicker Question Order the following in the order of highest required energy to lowest required energy A.Breaking apart a Proton B.Breaking apart a helium nuclei C.Breaking an electron out of a hydrogen atom a)A>B>C b)A>C>B c)B>A>C d)B>C>A e)C>A>B f)C>B>A 45

46. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math Clicker Question What was the last thing a typical photon in the universe (part of the Cosmic Background Radiation) did before we detected it? a)Broke apart a Proton b)Broke apart a helium nuclei c)Broke the electron out of a hydrogen atom 46

47. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math Clicker Question Why do the photons in the universe appear to be in thermal equilibrium? a)Because they all have exactly the same energy b)They are in thermal equilibrium c)The universe was in thermal equilibrium, and the photons are just one of the particles in the Universe 47

48. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math Clicker Question Why is hydrogen the most abundant element in the universe? a)It is the lightest element b)Any heavy elements that might have been present would have been broken apart by high energy photons in the early universe c)Both of these contribute 48

49. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math Clicker Question Q: Which of the following statements is MOST correct? a)The photons in the cosmic background radiation are there because the Universe has been expanding for ~13 billion years b)The photons in the cosmic background radiation are there because the universe was in thermal equilibrium c)The photons in the cosmic background radiation are there because photons can exist forever 49

50. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math Papers 50 Papers: –Paper 0 Revision: Still working on re-grades. Will post in eCampus by Wednesday –Paper 1 Revision: Let us know if you were misgraded –Paper 2: Bad Rubric fixed (everyone given credit for low-quality calibration) Working on re-grades –Paper 2 Revision: Changed due date to Wednesday before class –Paper 3: Text due Wed before class

51. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math 51 Prep for Today (Is now due) – L19 Reading: –BBBHNM 14 Reading questions: –Chapter 14 End-of-Chapter Quizzes: –Chapter 13 Paper Stuff –Paper 2 Revision: Text was due before class. Calibrations and Review due Monday –Paper 3: Text was due before class. Calibrations and Review due Monday

52. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math 52 For Next Time – L19 Reading: –Unit 5 Pre-Lecture Reading Questions: –Unit 4 Revision (if Desired): Stage 1 Due Monday before class –Unit 5: Stage 1 due Monday before class End-of-Chapter Quizzes: –Chapter 14 (if we finished Chapter 14, else just 13) Papers: –Don’t forget that ALL papers must be submitted to turnitin.com –Paper 2 Revision (if desired): Stage 2 due Monday before class –Paper 3: Stage 2 due Wednesday before class Honors Papers: –Stage 1 Revision

53. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math 53 Prep For Next Time – L21 Note: May change depending on how far we get in lecture Reading: –BBBHNM: All reading through Chapter 16 Pre-Lecture Reading Questions: –All reading questions through 16 End-of-Chapter Quizzes: –If we finished Chapter 14 then end- of-chapter quiz 14 (else just through Chapter 13)

54. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math Prep for Next Time – P19 54 Reading –BBBHNM 15 –Recommended: SHU: 4(87-93) TOE: 3 BHOT: 8(76-85) Reading questions –Chapter 15 End-of-Chapter Quizzes –If we finished Chapter 14 then end-of-chapter quiz 14 (else just 13) Papers –Paper 2 Revision: Text was due before class. Calibrations and Review due Monday –Paper 3: Text was due before class. Calibrations and Review due Monday

55. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math 55 Prep For Next Time – L9 Note: May change depending on how far we get in lecture Reading: –BBBHNM: All reading through Chapter 17 Reading Questions: –All reading questions through 17 eLearning Quizzes: –If we finished Chapter 14 then end-of-chapter quiz 14 (else just through Chapter 13) Papers: –Paper 3 text due in CPR and turnitin.com on Wednesday –Paper 3 calibrations, reviews and self-assessment before next class –Paper 2 revision: Text due Monday before class (if desired)

56. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math Papers 56 Papers: –Paper 0 Revision: Still working on re-grades. Will post in eCampus by Wednesday –Paper 1 Revision: Let us know if you were misgraded –Paper 2: Bad Rubric fixed (everyone given credit for low-quality calibration) Working on re-grades –Paper 2 Revision: Changed due date to Wednesday before class –Paper 3: Text due Wed before class

57. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math 57 Part II In class Quiz for Next Time: What is happening in each region? {

58. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math 58 Why not much Heavier than Helium? Nuclear Physics Can build up Hydrogen and Helium one at a time So What? Since 5 He and 5 Li decay quickly they don’t have enough time to find another proton to become 6 Li and be stable  Almost no elements heavier than helium are produced  Next possibility, 5 He or 5 Li, isn’t stable

59. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math 59 Aside on Helium Why is Helium important to the story? Explains two things: 1.Why the atoms in the Universe are mostly Hydrogen and Helium, and not much else 2.Why the Helium, like the photons is evenly distributed around the universe

60. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math 60 The Reading So Far and For Unit 5 Reading for Unit 5: BBBHNM: Chaps. 15-17 SHU: 4(87-93) TOE: 3 BHOT: 8(76-85) Full reading so far for Unit 5: BBBHNM: Chaps. 1-17 TFTM: Chaps. 1-5 BHOT: Chaps. 1-7, 8 (68-85), 9 and 11 (117-122) SHU: Chaps. 1-3, 4(77-93), 5(95-114), 6, 7 (up- to-page 159) TOE: Chaps. 1-3 Lecture prep: Turn in on eLearning Two questions from Chapter 15 you want to know the answer to

61. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math 61 Some Time Passes The Transition From a Hot Universe to a Cool Universe Electrons Protons Photons Atoms Electrons Protons Photons

62. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math 62 Writing Assignments 1.Short Assignment 1 Want to revise again? Talk to me. Still not getting it? Need to get you to the writing center! 2.Short Assignment 2 is posted Due Today eLearning: Unit 3 now due Need to be working on Unit 4

63. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math 63 Papers AFTER Paper 2 Two options 1.Research Paper If you want to do the research paper option you must turn in Stage 0 at the end of class today. Must be approved Stage 1 due Thurs Nov 5 th Final paper due the last day of class, Tuesday Dec 8 th 2.Two short papers like the first one One on Black Holes (due mid Nov) One on Dark Matter (due last day of class)

64. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math 64 Before 700,000 years: Summary Photons are incessantly scattered by free electrons; photons are in equilibrium with matter Radiation dominated era Photons-electron soup  have the same temperature (energy)

65. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math 65 After 700,000 Years: “Recombination” Protons and electrons combine to form atoms  universe becomes transparent for photons Transition to matter dominated era Crappy Word! Atoms are combining for the first time, not recombining!

66. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math 66 A cartoon of an atom and a photon Mostly this is happening now since the photons are low energy

67. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math 67 The Cosmic Background Radiation After recombination, photons can travel freely through space Their wavelength is only stretched (red shifted) by cosmic expansion This is what we can observe today as the cosmic background radiation!

68. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math 68 Wait a Billion Years After less than ~ 1 billion years, the first stars form  Produce Heavy Elements in Stellar Cooking Formation of the first stars

69. Evolution of the Universe Topic 2: After The First Three Minutes Big Bang, Black Holes, No Math 69 The First Three Minutes http://bigbang.physics.tamu.edu/Figures/StolenAnimations/first3minutes.swf