1. Big Bang, Black Holes, No Math ASTR/PHYS 109 Dr
Big Bang, Black Holes, No Math ASTR/PHYS 109 Dr. David Toback Lecture 21 & 22

2. Was due Today – L21 Reading: Unit 5 Pre-Lecture Reading Questions:
Unit 4 Revision (if desired): Stage 2
Unit 5: Stage 2
End-of-Chapter Quizzes:
Chapter 14
Papers:
Paper 3: Stage 2
Honors Papers:
(Stage 2)
Final paper due on the last day of class

3. Was due Today – L22 Reading: (Unit 5) Pre-Lecture Reading Questions:
None
End-of-Chapter Quizzes:
(Chapter 14)
Papers:
Honors Papers:
(Stage 2)
Final paper due on the last day of class

4. Quick Review: Various Times
Walking through 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?
} Chap 13
} Chap 14
} Chaps 15-17
} Unit 6

5. Unit 5 Overview
It turns out that the way Galaxies and Stars form have similarities… start there
The way stars die depends on the star itself… sometimes they die to form a Black Hole
Black Holes are some of the weirdest things in the Universe…
In many ways the formation of Black Holes is like the Big Bang in Reverse

6. Unit 5: Big Objects and Black Holes
Galaxies
Star Birth and Death
Black Hole Formation
Properties of Black Holes
Today

7. Galaxy Formation: Overview
Big picture: What Galaxies “look like”
A gravity dominated Universe allows galaxies to form
Stars in Galaxies
When do galaxies form?

8. What do galaxies look like?
All have common properties
Stars (produce the light we see)
Gas (atoms not in stars)
Dark Matter (most of the mass)

9. Visualizing a Galaxy The light comes from the stars
Most of the mass is Dark Matter
In some ways, Dark Matter surrounds the stars in a galaxy like the water in a fishbowl surrounds a fish in the middle of the bowl.
Not exactly the same… denser in the middle because of the pull of gravity

10. Two example “Types” of Galaxies
Elliptical Galaxy:
One giant bulge, stars are like bees buzzing around the center, biggest galaxies are ellipticals
Spiral Galaxy: like the Milky Way
Bulge in the middle
Disk on the sides

11. From the Early Universe to Galaxies
After about ~3 minutes things are cool enough for nuclei to form
After ~300,000 years things are cool enough for electrons and nuclei combine to form atoms
Let’s move to a half a billion years after the bang

12. Where are we now in the history?
Half a billion years after the bang

13. A Gravity Dominated Universe
The gravitational attraction between massive things ONLY makes them move towards each other through space
Dark Matter and atoms are neutral and massive
Both are most attracted to the closest place with lots of mass

14. 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”
Huge numbers of these clumps, each helps form galaxies!

15. Galaxy Creation Over Time

16. Galaxy Formation Analogy: People Jumping on a Trampoline
If two people touch, then will stick together
If they fall they create a big dent in the trampoline (like a dent in space-time)
Once you get that first dent on the trampoline everyone starts falling into it

17. More Analogies
Water being poured into a bowl and flowing to the bottom
Water swirling in a bowl
Water in a bathtub with the drain open (and ignoring what happens to the water that goes down the drain)

18. Water Flowing Think about water moving towards a drain in the bathtub
All falls in quickly  can get bubbling at the drain
Falls in slowly  Get swirling
Different types of galaxies can form

19. Stars in Galaxies
Atoms fall towards the center of the galaxy or orbit around it
Stars form where there are lots of atoms
Once the atoms form stars there is a large amount of distance between stars
About 4 light years between us and our nearest neighbor star
A good exception is binary stars where two stars formed together
Stars can orbit around the center of the galaxy

20. Slow Atoms Outside the Galaxy
Where does the disk of the Milky Way come from?
Lots of atoms moving around, far outside the center of the galaxy

21. Spinning into Shape
Gravity attracts mass to the densest place
Center of the Galaxy
As the mass is pulled in, it starts moving slightly around the center
Why does this happen?

22. Can also think about water falling into a toilet after it’s flushed
Analogy: Ice Skater
Matter far away
from the center
Spins slowly
You’ve seen on TV
Try this at home in a chair that rotates
Get yourself spinning with your arms and legs stretched out, then pull them in
Pull the Matter in
 Spins faster
Can also think about water falling into a toilet after it’s flushed
For those of you who have taken PHYS 218, this is Conservation of Angular Momentum

23. Dark Matter Vs. Atoms
Dark Matter and Atoms behave differently in galaxies
When atoms get near each other they can bump into each other like people moving in a movie theater
Dark Matter is more like two ships passing in the night

24. Why is there a disk on the outside?
Focus on the atoms in the outer part of the galaxy… Not very dense out there, so stars don’t form quickly
As atoms fall toward the center they are like the water from the outer part of a toilet bowl
They start bumping into other atoms, change the direction they are moving
Once enough atoms are going in different directions a swirl CAN start; atoms moving WITH the swirl can keep moving nicely and can go orbit like a planet around the sun
Like in a toilet, an effective swirl can continue
Atoms that try to go into other directions bang into the swirl and lose energy (fall in, or go off into space)
Eventually, most of the atoms have either fallen in or become part of the swirl
Eventually, the cloud gets drawn in close enough that the atoms get close enough that they form stars
Stars just stay in the disk orbit
Call this the disk

25. Visualize the process
Start right after things start to contract…

26. Time progresses
As the galaxy contracts, things can start moving very quickly

27. More time Passes Things start to “flatten out”
Said differently, the flay part can continue, but the non-flat-part bets bumped out of orbit

28. More time…

29. Even more time…

30. Even more time..

31. Stable Galaxies
The stuff in this stable state forms Stars: Call this a Galaxy
Can give us disk-like rotating galaxies
Can also form other types like elliptical galaxies
Galaxies often collide and get even more complicated

32. Fun video
Move from the simple view of a galaxy forming to a more complete computer model from NASA
How a disk galaxies gets created

33. Andromeda tied to the rocks
Another fun video
Andromeda tied to the rocks
Simulation of a future collision between Andromeda and the Milky Way, where the two would create a combined galaxy

34. Move from what galaxies look like to WHEN galaxies form in the history of the Universe

35. When?
Oldest observed galaxies appear about 500 million years after the bang
Do we understand why this is? Use computer simulations to see when, after the Big Bang, galaxies form
It turns out that if the Universe had exactly the same temperature everywhere it would take more than a hundred billion years to get even one galaxy
What????

36. Reason things might clump earlier?
Clearly galaxies DID form before that, so SOMETHING must have caused them to start earlier
Example of possible answer: If the temperature weren’t perfectly uniform then we could get clumping earlier
Go back to our trampoline analogy

37. Kids on a Trampoline
The galaxies form shortly after we get that first big dent in space time
If we start with all the kids equally spaced, then it will take longer to get that first collision
If two of the kids happen to start slightly nearer each other, then those two are more likely to get a collision sooner and create the first dent sooner

38. Quantum Mechanics
It turns out that when the Universe is really small, the effects of Quantum Mechanics can have a big effect on the smoothness of the Universe
Can cause small variations in the temperature at different places in space
Scientists gave this a cool name: Quantum fluctuations

39. So What?
Different Temperature  Variation in the amount of matter in different places
A region with slightly more matter is more likely to be the place where matter clumps
Thus, Quantum Fluctuations in the Early Universe could cause Galaxy formation to occur earlier in time

40. How would we look for this?
How do we look at the temperature in the Universe?
Study the Cosmic Background Radiation temperature distribution
Any variations in different directions?

41. Look for Variation in the Cosmic Background Radiation
Look at the full sky in a single map
Stretch out a sphere onto a flat page
Temperature Map (i.e, different colors correspond to different temperatures)
Incredibly Uniform, but are there small variations?

42. Exactly the same everywhere?
Subtract off the same amount everywhere
What are we left with?
The overall temperature is degrees Kelvin
The variation is very small
DT = mK

43. Hotter and Colder?
Colder here? Hotter here?
DT = mK

44. What if we’re moving?

45. Better Explanation
Doppler effect of our speed relative to the rest frame of the photon background
Earth is going around the sun at ~30 km/sec and the solar system is moving around the Milky Way at ~250 km/sec
Moving away from this direction
Moving toward this direction

46. The Cosmic Background Radiation
Subtract off all the known effects and look for “Variations”
Lots of small fluctuations (Spots) Everywhere
Combining Quantum Mechanics and General Relativity predict where the galaxies form AND how long it takes

47. For Next Time – L21 Reading: (Unit 5) Pre-Lecture Reading Questions:
Unit 5 Revision (if desired): Stage 1 due Monday
End-of-Chapter Quizzes:
Chapter 15 (if we finished Chapter 15, else just 14)
Papers:
Paper 3 Revision (if desired): Will be opened after any regrade requests
Honors Papers:
(Stage 2)
Final paper due on the last day of class

48. For Next Time – L22 Reading: (Unit 5) Pre-Lecture Reading Questions:
Unit 5 Revision (if desired): Stage 1 due Monday
End-of-Chapter Quizzes:
Chapter 15 (if we finished Chapter 15, else just 14)
Papers:
Paper 3 Revision (if desired): Stage 1 due Wednesday
Honors Papers:
(Stage 2)
Final paper due on the last day of class

49. Full set of Readings So Far
Required:
BBBHNM: Chaps. 1-16
Recommended:
TFTM: Chaps. 1-5
BHOT: Chaps. 1-7, 8 (68-85), 9 and 11 ( )
SHU: Chaps. 1-3, 4(77-93), 5(95-114), 6, 7 (up-to-page 159)
TOE: Chaps. 1-3

50. End of Lecture

51. Dark Matter in Galaxies
Finished looking at the things that produce light we can see in a Galaxy
Move to the parts which have most of the mass
Since Dark Matter doesn’t interact much, expect it to engulf the Galaxy

52. The Planets and the Sun
General Relativity does a good job of predicting the planets path around the sun assuming virtually all the mass of the Solar system is located at the Sun
Only small influence due to the small masses of the other planets

53. Dark Matter in Galaxies
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
Important properties of Dark Matter:
Massive
Neutral
Doesn’t interact much
Not sure when it shows up in the Universe, but we think it was before protons could form

54. Prep For Next Time – L22
Note: May change depending on how far we get in lecture
Reading:
BBBHNM: All reading through Chapter 17
Pre-Lecture Reading Questions:
All reading questions through 17
End-of-Chapter Quizzes:
If we finished Chapter 15 then end-of-chapter quiz 15 (else just through Chapter 14)

55. Papers - 22
Papers:
Paper 0: Grades posted. Check to see that you got the correct grade.
Paper 1 Revision: No known problems
Paper 2:
Bad Rubric fixed (everyone given credit for low-quality calibration)
Finished re-grades
Paper 2 Revision: Opened a new version. Need to resubmit ONLY if you want. Was due before class. Let me know if you need it re-opened
Paper 3: Text was due today before class

56. Prep for Next time – L23 Reading: Chapter 18
Pre-Lecture Reading Questions:
End-of-Chapter Quizzes:
Chapter 15 (Already Done)
Papers:
Paper 2 Revision: Was due before class today. Let us know if you were mis-graded
Paper 3: Calibrations, reviews and Self-assessment due Wednesday before class

57. Prep For Next Time – L10
Note: May change depending on how far we get in lecture
Reading:
BBBHNM: All reading through Chapter 18
Reading Questions:
All reading questions through 18
eLearning Quizzes:
If we finished Chapter 15 then end-of-chapter quiz 15 (else just through Chapter 14)
Papers:
Paper 3 revisions (if desired) due before class on Tuesday

58. Prep for Today (Is now due) – L20
Reading:
BBBHNM 15
Reading questions:
Chapter 15
End-of-Chapter Quizzes:
Chapter 14
Paper Stuff
Paper 2 Revision: Text was due already. Calibrations and Review are due Monday
Paper 3: Text was due already. Calibrations and Review due Monday

59. Prep for Today (Is now due) – L21
Reading:
BBBHNM 16
Reading questions:
Chapter 16
End-of-Chapter Quizzes:
Chapter 14
Paper Stuff
Paper 2 Revision: Calibrations and Review were due before class
Paper 3: Calibrations and Review were due before class

60. Prep for Next Time – P20 Reading BBBHNM 16 Reading questions
Chapter 16
End-of-Chapter Quizzes
If we finished Chapter 15 then end-of-chapter quiz 15 (else just 14)
Paper Stuff
Paper 2 Revision: Text was due already. Calibrations and Review are due Monday
Paper 3: Text was due already. Calibrations and Review due Monday

61. Prep for Next Time – P21 Reading BBBHNM 16 Reading questions
Chapter 16
End-of-Chapter Quizzes
If we finished Chapter 15 then end-of-chapter quiz 15 (else just 14)
Paper Stuff
Paper 2 Revision: Calibrations and Review were due before class
Paper 3: Calibrations and Review were due before class

62. Billions of Years go by…
As the regions get smaller, they spin faster and faster
Eventually, when it comes into a type of equilibrium, gravity can’t pull it in any further and the atoms stop speeding up
Kinda like the planets going around the sun

63. The Transition From a “Charged” Universe to a “Neutral” Universe
Some Time Passes

64. 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

65. Subtract Further
Since we understand the Doppler effect we can subtract if off to see what’s left
Remember: Overall temperature is degrees Kelvin
Now looking at VERY VERY small variations
DT = 18mK
Extra light from the Milky way,
Subtract this off also…

66. How it all ends up…
An example galaxy like our own
This explains why some galaxies
Look mostly flat
Have a halo
Bulge at the center…

67. For Next Time Topics Galaxy Formation  Done Stars  Next
Black Holes  After that
Reading for Next time:
BBBHNM: Chap 16
Full reading for Unit 5:
BBBHNM: Chaps. 1-17
TFTM: Chaps. 1-5
BHOT: Chaps. 1-7, 8 (68-85), 9 and 11 ( )
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 16 you want to know the answer to

68. Papers 1 and 2 Paper 1 and 2 grades are posted on eLearning
Can’t get to the Paper 2 grading anymore
If you would like the opportunity to re-submit Paper 2 I’ll open it for you.

69. Papers 3 and 4 Paper 3: Due Wed. March 24th before class
Calibrations and grading due on Friday at noon
Now open
Paper 4:
Will be assigned after we start Chapter 17 69

70. Other Stuff Elearning: Unit 3 now due Unit 4 now due
Unit 5 in progress
Make sure you pick up the latest version of the online textbook!!!
Been updating it all semester 70

71. Look for variation in the Cosmic Background Radiation
Full sky in a
single map
Stretch out a sphere onto a flat page
Temperature Map
Incredibly Uniform, but are there Small Variations?

72. The Reading So Far and For Unit 5
Reading for Unit 5:
BBBHNM: Chaps
SHU: 4(87-93)
TOE: 3
BHOT: 8(76-85)
Full reading through Unit 5:
BBBHNM: Chaps. 1-17
TFTM: Chaps. 1-5
BHOT: Chaps. 1-7, 8 (68-85), 9 and 11 ( )
SHU: Chaps. 1-3, 4(77-93), 5(95-114), 6, 7 (up-to-page 159)
TOE: Chaps. 1-3

73. Papers 1 and 2 Done with grades for both Graded unfairly? Let us know!
Want to do better? We can help!
Want to revise Paper 2?
CPR now open, due Friday at noon
You are required to do the calibrations for the new papers
You are required to do the reviews for your peers
Overall grade will reflect both original paper and the revision

74. Re-do’s are still possible. Want to revise again? Talk to me.
Writing Assignments
Short Assignments 1 & 2
Re-do’s are still possible. Want to revise again? Talk to me.
eLearning:
Unit 4 now
Need to be working on Unit 5 74

75. Evolution of the Early Universe
Photons
Atoms
Electrons
Protons
Photons
Some Time Passes

76. The Story of Galaxy Formation
After the Big Bang we just had lots of stuff floating around in space
Can think of it as a giant tank of gas

77. Papers AFTER Paper 2 Two options Two short papers like the first one
One on Black Holes (due mid Nov)
One on Dark Matter (due last day of class)
Research Paper
If you want this option you must get Stage 0 approved ASAP
Was due last week
Stage 1 due Thurs Nov 5th
Final paper due the last day of class, Tuesday Dec 8th 77

78. So What?
Ok... New idea of galaxy formation. Lots of kids jumping on a trampoline, not just straight up and down, but in random directions. Each time they hit the ground they create a little dent in the trampoline. Sooner or later two of the kids, because they will get near each other (perhaps because the dents make them more likely to get near each other) will hit each other and fall to the trampoline itself and create a big dent. The other kids jumping near that dent are now more likely to be bounced towards the center (because of the indentation) and collide with the other kids making an even bigger dent. Eventually, all the kids that are nearby the dent will be located in the same place.
If we start with all the kids equally spaced, then it will take longer to get that first big collision. If two of the kids start nearer each other, then we're more likely to get a collision sooner and get all the kids at the big dent sooner.

79. Tigers in a Jungle
Let’s say we have a jungle with a number of hungry tigers looking for food
If a tiger finds food they will get bigger and be more effective at hunting
If they don’t find food, they won’t grow and will starve, maybe get eaten by another tiger
Since there is only so much food, it’s just a matter of time before we are left with a few well-fed tigers

80. Not all Tigers are Located Equally
Tigers nearer the food:
Will get to eat slightly sooner
Will be more energetic sooner, can go hunting sooner and be a more effective hunter sooner
 more likely to bigger quicker and thrive
Tigers farther from the food:
Will be longer until they eat and become effective hunters
Less food available if they get there later
 more likely to die

81. Tigers in the Universe
If all the Tigers are equally spaced then it will take longer, on average, before all the food is gone and we’re left with a few well-fed tigers
If there are “fluctuations” then some of the Tigers will start closer and have an advantage over other tigers  it will take less time to have a Universe with a few well-fed tigers

82. Where is the party?
How long it takes to get a good size Friday night party can depend critically on how many cute people there are at the beginning of a party
Scenario 1) If a bunch of cute people happen to be at same place early in the night  won’t take long before LOTS of people will be attracted to that party
Scenario 2) If all the cute people are evenly scattered all over then people who get to a party might leave to see if there are more cute people somewhere else  Will take longer before everyone settles on a party and stays there
Bottom line: Takes much less time to get a set of good sized parties if the number of cute people isn’t exactly uniform

83. The Cosmic Background Radiation
The famous results from the WMAP satellite experiment

84. Look at the Spots Look at the average separation of the spots
Probes the geometry of space-time
Not a simple relationship between the separation of the spots and the geometry of space time
Essentially:
Lots of Mass (large density) Lots of clumping of matter  Closed Universe
Medium amount of Mass (medium density)  Some clumping  Flat Universe
Small amount of Mass (small density)  Small clumping  Open Universe
Model the different possibilities with a computer

85. Ok… The Ripples are WHERE the galaxies form, but HOW do they form?

86. Formation of the first stars
Wait a Billion Years
After less than ~1 billion years, galaxies and the first stars form
Formation of the first stars

87. Example of Galaxy Formation
Today’s Lecture
Overview of the story
The Cosmic Background Radiation data and why we believe in our models of Galaxy formation
Example of Galaxy Formation

88. Schedule from Here on Out
Mon Nov 10th: 22nd lecture (today): Galaxy Formation
1 page Research topic proposal due, must be approved
Rest of the semester reading due
Wed Nov 12th: 23rd lecture: Stars
Early version of Short Paper 2 due if you want comments back early
Mon Nov 17th: 24th lecture: Black Holes
Wed Nov 19th: 25th lecture: Inflation
Mon Nov 24th: 26th lecture: Dark Energy
Wed Nov 26th: No class
Research paper and 2nd short paper due at midnight
Day before Thanksgiving. Class cancelled
Dec 1st: No classes redefined day
Dec 3rd: Reading period, no classes
Dec 8th: Finals week, no final

89. Looking for Ripples
To an excellent degree of precision the temperature of the photons in the Universe today is incredibly uniform
Gives us confidence that our story of the Big Bang and the Evolution of the Universe is correct

90. Hotter and Colder?
Colder here? Hotter here?

91. Subtract off the same amount everywhere
Perfectly Flat?
Subtract off the same amount everywhere
The overall temperature is degrees Kelvin
The variation is very small

92. Doppler Effect
Take into account our relative speed to the rest frame of the photon background
Earth is going around the sun at 30 km/sec and the solar system is rotating around the Milky Way at 250 km/sec
Moving away from this direction
Moving in this direction

93. Subtract Further
Since we understand the Doppler effect we can subtract if off to see what’s left
Remember: Overall temperature is degrees Kelvin
Now looking at VERY VERY small variations
Extra light from the Milky way
Subtract this off also…

94. Large Scale Structure
Distribution of bright galaxies in the Virgo region indicates the Virgo cluster and presence of more distant, larger scale structure

95. Large Scale Structure (2)
A large survey of distant galaxies shows the largest structures in the universe:
Filaments and walls of galaxy superclusters, and
voids, basically empty space.

96. What if we’re moving?

97. The Cosmic Background Radiation
The Famous COBE satellite map of the all-sky structure of the Cosmic Background Radiation

98. Add pictures from Seeds on whether we believe the structure formed first and then galaxies formed
Or if the galaxies formed and then combined to create structure

99. The Growth of Clusters of Galaxies
Structures in the Universe could have developed in two fundamentally different ways:
a) Small structures (galaxies) could have developed first, then clustering into larger and larger structures
b) The largest structures (superclusters, voids) could have developed first, then breaking up into smaller and smaller units.
The latter scenario seems to be favored by observational evidence.

100. 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

101. BHOT 7 cont..,
New CMB results: tiny ripples in the CMB can be used as an indicator of the large-scale geometry of the universe and they appear to indicate that the universe is flat after all
Since there doesn’t seem to be enough matter and dark matter to account for this, physicists have postulated the existence of another as yet undetected substance to explain it
Dark Energy
More on tall this stuff later… Supernovae results…

102. TFTM 3 cont… WMAP Pictures on variation in the temperature?
Some cool numbers: Earth is going around the sun at 30 km/sec and the solar system is rotating around the Milky Way at 250 km/sec.
Fix this number: 1 billion photons per nuclear particle in the average contents of the universe

103. The three WMAP pictures…
Flat
Dipole
Variation

104. Slide 29 Maps based on 53 GHz (5
Slide 29 Maps based on 53 GHz (5.7 mm wavelength) observations made with the DMR over the entire 4-year mission (top) on a scale from K, showing the near-uniformity of the CMB brightness, (middle) on a scale intended to enhance the contrast due to the dipole described in the slide 19 caption, and (bottom) following subtraction of the dipole component. Emission from the Milky Way Galaxy is evident in the bottom image.

106. This is some text…

108. Eventually, when the region got small enough it would be spinning fast enough to balance the attraction of gravity to balance the attraction of gravity and in this way, we believe, disk-like rotating galaxies were born
Others would form other times of galaxies like elliptical galaxies

113. SHU 5 cont…
Pictures of the ripples
Page 107
COBE launched in 1989 (Nobel prize for this in 2006),
Picture on Page 112