Big Bang Black Holes No Math ASTRPHYS 109
Big Bang, Black Holes, No Math ASTR/PHYS 109 Dr. David Toback Lecture 28 Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 1
Rest of the Semester-L 28 Date Lecture number Due Before class/11: 55 PM What we do in Class Assigned after class Mon Nov 22 nd 25 EOC 14 (A-D) Chapter 16 EOC 14 (E-G) Wed Nov 24 th (Reading Day, No Class) Mon Nov 29 th 26 EOC 14 (E-G) (if not done already) Finish Chapter 16 + Most of Chapter 17 EOC 15 & 16, Paper 4 Text & Reviews, Unit 6 Reading Wed Dec 1 st 27 EOC 15 & 16, Unit 6 Reading Finish 17 EOC 17, Unit 6 PLRQ Quiz Mon Dec 6 th (Redefined day, No class) EOC 17, Unit 6 Quiz - - Wed Dec 8 th 28 (Last day of class) Paper 4 Text & Reviews Chapters 1820 Chapter EOC 18, 19, AMS II and EOC 20 Mon Dec 13 th No Final EOC 18, 19, AMS II and EOC 20, Paper 4 Feedback and any Revisions must be completed by today - - Notes: • Mis-graded on any Assignment? Let us know • Will start calculating grades on Mon Dec 13 th Honors Section: • Stage 4, Final Draft due Mon Nov 29 th • Stage 5, First Draft due Mon Dec 6 th Early Times & Fate Big Bang, Black • Stage 5, Final Draft due Wed Dec 8 th Holes, No Math of the Universe Topic 1: Possibilities 2
Reminder About Grades • From Syllabus Since almost everyone is in the penalty, the Advisory Grade is currently the lowest of the four averages so you know how to make sure you get the grade you want You make keep doing revisions until grades are posted Big 3 Bang, Black Holes, No Math
Course Evaluations Course evaluations will be done online: • You should have gotten an email about this already The Fall 2021 evaluation period: • Began Nov 20 th and end Dec 9 th • https: //tamu. aefis. net/index. cfm/page/Aefis. Survey. home? surveycontrolleritemid=199 Please do them… won’t take long Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 4
Unit 6 Going back in time and going forward in time Before the first millionth of a second and the Fate of the Universe Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 5
Outline of Unit 6 1. Possible Fates of the Today Universe, Dark Matter and Dark Energy 2. Particle Physics, Dark Matter and the Very Early Universe 3. Inflation Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 6
Caveats While the data is VERY powerful, some of the interpretations of the data are not fully “proven” or understood Still need data to tell us about theory, and theory to tell us about the data New data and theoretical advances have recently changed our understanding of the Universe Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 7
The Fate of our Universe Will the Universe continue expanding forever? • That depends, mostly, on a few things: 1. How fast is it expanding now 2. How much STUFF there is in the Universe 3. How big it is now 4. Are the laws of physics really understood? Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 8
Why the first three are so important • Gravity is trying to pull space-time back together again – Attractive force – Expansion of the Universe should be slowing down or decelerating • Either it’s strong enough to pull the universe back together again, or it isn’t Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 9
What about that last issue? • Dark Energy fits into this story, but it is an effect that only impacts on the largest scales • Takes 10 billion years and HUGE distance scales to have ANY effect • Start by discussing all-but-Dark Energy first (gravity), then come back to it – Kinda like when we did the expanding universe Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 10
Gravity: Two Possibilities There are only a few possibilities Use an analogy… Shooting a bullet into the air at the surface of the Earth Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 11
Possibility 1: Small Speed Universe ends in a Big Crunch • If the bullet is shot up with a small speed, gravity will eventually stop it and it will fall back to the Earth • Can think of the gun shooting the bullet as an explosion (our big bang) • If the “Bang” is too small, all the stuff in the Universe will eventually all fall back together as the space-time collapses on itself…like an extra-supermassive black hole Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 12
Continue the analogy… It’s a balance between the speed of the bullet and the density of the object the bullet is trying to leave Does the bullet have a speed below the escape velocity? Early Times & Fate of the Universe Big Bang, Black 13 Holes, No Math Topic 1: Possibilities
A bullet has a speed smaller than the escape velocity Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 14
The Sun Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 15
Possibility 2: Big Speed Universe expands forever If the bullet has a speed greater than the escape velocity, gravity will not be strong enough to pull it back è Will keep on going away from the Earth forever è Like launching a rocket into outer space but using a slingshot, not thrusters-that-keep-firing Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 16
Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 17
The Moon has a “small” escape Velocity Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 18
To infinity and beyond • As the bullet gets further and further from the moon the gravitational attraction gets smaller and smaller… It still slows the bullet down, but less and less… • Eventually, the gravitational attraction is so small (since they are so far away from each other) that the bullet effectively moves off into space at the same speed forever Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 19
Back to the Universe with Our Examples • Since there is a lot of mass in the Universe, if it were expanding slowly enough the force of gravity would cause it to eventually stop expanding and then start contracting again • Even with a large speed today gravity might force it to stop expanding and then contract Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 20
Possibility 1: A Universe Ending in a Big Crunch • Remember this is only an analogy There is no center or edge of the Universe Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 21
Possibility 2: A Universe That Expands Forever Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 22
How do we tell which is right? • Looking at distant galaxies shows that the Universe is expanding • Since there is lots of mass in the Universe, the expansion should be slowing down – Like a ball thrown up into the air, it should slow down – Question: Is it slowing down so much that we’ll end in a big crunch, or will it just continue to expand forever? Let’s gather some data! Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 23
How do we measure the deceleration? • Look at Supernovae since they are REALLY bright for about a month so we can see them from far away • We believe we understand these explosions really well Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 24
Measuring the “Deceleration” of the Universe • Can use the brightness of Supernova to tell how far they are away • Can use spectral lines to tell how fast they are moving Early Times & Fate of the Universe Big Bang, Black Holes, No Math Topic 1: Possibilities 25
What Does the Data Say? • The most distant things in the Universe are further away than we think they should be • The Universe doesn’t appear to be slowing down, it’s speeding up! • Accelerating! • It’s like there was an explosion and then something CONTINUES to force the stuff further apart • Throw a ball into the air and the ball speeds up!? ? ! Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 26
The Accelerating Universe Big Bang, Black Holes, No Math 27
What the ? ? ? • Is there some Force that is pushing things apart faster? • Gravity, as we know it, only attracts… Give the “whatever -it-is” a name: Dark Energy Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 28
Why do we call it Dark Energy? • Can’t see it àCall it Dark • Doesn’t seem to interact like mass Not mass or matter, but is forcing the Universe apart so it has energy (E=mc 2). Not Dark Matter • From the acceleration can measure how much energy must be “doing the forcing” ~72% of the mass/energy of the Universe Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 29
Dark Energy and Dark Matter related? • Not clear dark matter and dark energy have anything to do with each other – Just because we use the word DARK for both doesn’t mean we know how they are related • Probably IS something fundamental that is similar, but we don’t know enough about either to say anything useful yet Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 30
It all adds up! • Add up all the mass/energy in the Universe – Atoms account for ~5% – Dark Matter is about 5 times more mass in a galaxy than atoms ~23% – Dark Energy is about ~72% Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 31
The Evolution and Fate of the Universe Dark Energy overcomes the deceleration of Gravity about 6 billion years ago, Universe starts accelerating Deceleration due to Gravity for the first 6 billion years Dark Energy Makes the Universe Accelerate (keep expanding Faster and faster) Big Bang, Black Holes, No Math We don’t know the nature of Dark Energy Lots of possible Fates… but it looks like we’ll expand forever… and it could get REALLY cold! Big Bang, Black Early Times & Fate of The Universe Topic 5: Dar 32 Holes, No Math Energy
Lots of Questions How will we figure out the fate of the Universe? Need to know the Nature of Dark Energy What is Dark Energy? We don’t know yet… Just starting to have ideas. . Big Bang, Black Holes, No Math This result was so important that it was Early Times & Fate of the awarded the Universe Nobel Prize for 2012 33 Topic 1: Possibilities
Lecture on Chapter 18 now complete Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 34
Rest of the Semester-L 27 Date Lecture number Due Before class/11: 55 PM What we do in Class Assigned after class Mon Nov 22 nd 25 EOC 14 (A-D) Chapter 16 EOC 14 (E-G) Wed Nov 24 th (Reading Day, No Class) Mon Nov 29 th 26 EOC 14 (E-G) (if not done already) Finish Chapter 16 + Most of Chapter 17 EOC 15 & 16, Paper 4 Text & Reviews, Unit 6 Reading Unit 6 PLRQ Quiz Wed Dec 1 st 27 EOC 15 & 16, Unit 6 Reading, Unit 6 Quiz Finish 17, Chapter 18 + Chapter 19 EOC 17 & 18 Mon Dec 6 th (Redefined day, No class) EOC 17 & 18 - - Wed Dec 8 th 28 (Last day of class) Paper 4 Text & Reviews Chapter 19 + Chapter 20 Chapter EOC 19, AMS II and EOC 20 Mon Dec 13 th No Final EOC 19, AMS II and EOC 20, Paper 4 Feedback and any Revisions must be completed by today - - Notes: • Mis-graded on any Assignment? Let us know • Will start calculating grades on Mon Dec 13 th Honors Section: • Stage 4, Final Draft due Mon Nov 29 th • Stage 5, First Draft due Mon Dec 6 th • Stage 5, Final Draft due Wed Dec 8 th Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 35
End of Semester Notes • – • • End of Chapter quizzes • While the EOC quizzes are due before then, I’m planning to do my final download on Tuesday May 4 th at 11: 55 PM • This includes AMS 2 – End of semester measure of some of the things you learned – Not part of your grade, but you will need to do it before you can attempt the rest of the end of chapter quizzes If you don’t pass the EOC quizzes for all 20 Chapters the EOC quizzes (50%), you cannot get a passing grade for the course • If you need an extension, let me know ahead of time – Please do the Course Evaluations We will accept Revisions for all papers, but you need to do them with enough time for you to get a grade before the 4 th There is no statue of limitation on mis-graded items. If you think you were mis-graded on ANYTHING, we will work to make sure you get the grade you deserve Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 36
Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 37
2 paragraph in-class quiz • Paragraph 1: What are the most important properties of a stellar black hole? • Paragraph 2: How do stellar black holes form? Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 38
1 Paragraph in-class Quiz • What is the evidence for stellar black holes? Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 39
Clicker Question Can you "fill up" a black hole? a) Yes b) No Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 40
Clicker Question Can a Black Hole orbit another star? a)Yes b)No Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 41
Clicker Question Could the Earth orbit a black hole? a)Yes b)No Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 42
Clicker Question What would happen if two black holes collided? a) They would make a supermassive black hole b)They would just make a black hole that is has about the same mass as the two original black holes combined c) Black holes can’t collide Big Bang, Black Holes, No Math 43
Clicker Question If there really is dark energy, what is the ultimate fate of our universe? a) Big crunch b) Expand forever, but slowing down c) Expand forever, but speeding up. Black Early Times & Fate of the Universe Big Bang, 44 Holes, No Math Topic 1: Possibilities
Clicker Question What does dark energy do to the photons in the universe? a) Makes them more energetic by adding energy to the universe b) Stretches them by stretching space time making them more energetic c) Stretches them by stretching space time making them less energetic Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 45
Clicker Question Dark energy is forcing the universe to accelerate. What is accelerating? A) The galaxies moving through space B) The expansion of space-time C) Only the dark matter Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 46
Clicker Question What is happening to the density of the universe over time? a) Increases b) Decreases c) Stays the same Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 47
Clicker Question What does dark energy do to the temperature in the universe? a) Raises it by adding energy to the universe b) Lowers it by stretching spacetime c) Dark Energy doesn’t affect temperature Early Times & Fate of the Universe Big Bang, Black 48 Holes, No Math Topic 1: Possibilities
Clicker Question What will happen to galaxies 100 billion years in the future? a) They'll stay the way they are now because dark matter will keep them together b) They'll slowly get ripped apart because dark energy will expand the universe so quickly it will overcome the attraction of gravity Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 49
Let's say I have two galaxies in space and they are exactly stationary relative to each other. Over a billion years, what will happen? A) They will attract each other by gravity so that they are moving towards each other B) They will each expand as space-time expands, and the distance between them will grow as space-time expands C) The galaxies will stay the same size, and the distance between them will grow as space-time expands. D) It depends on the overall distance between 50 Bang, Black Big them. Holes, No Math
If space-time is expanding, why isn't our galaxy expanding? A) It is B) Because the gravitational attraction of masses pulls the galaxy back together again C) Both are true, but A is a more important effect than B D) Both are true, but B is more true that A. 51 Bang, Black Big Holes, No Math
Clicker Question If space-time is expanding, why aren't atoms expanding? a) They are b) Because the electric charge attraction and quantum mechanics keep the atoms the same size in space c) Both are true, but A is a more important effect than B d) Both are true, but B is more true that A. Black Early Times & Fate of the Universe Big Bang, 52 Holes, No Math Topic 1: Possibilities
If the acceleration of the universe continues, will we ever notice this with our own eyes? A) No, only very sensitive experiments can measure the expansion of the universe B) Yes, it is just a matter of time before the nearest stars are so far away from us that we can't see them anymore. 53 Bang, Black Big Holes, No Math
End of Semester • • • Monday May 1 st: – Last day of class – Unit 6, Stage 1 Due – Paper 3 Revision (if desired), Stage 2 is due – Chapter 17 EOC quizzes due There is no final Wednesday, May 3 rd – Unit 6, Stage 2 due – Paper 4, Stage 1 due Monday, May 8 th – Remaining EOC quizzes due. • Let me know if you need an extension Tuesday, May 9 th – Paper 4, Stage 2 due at 11: 55 PM Revisions for Unit 6 and Paper 4 will be by request only. Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 54
Was due Today – L 27 Last day of Class • Reading: – (Unit 6) • Pre-Lecture Reading Questions (PLRQ) – Unit 6, Stage 1: Was due today before class – Unit 6, Stage 2: Due before usual class time Wednesday, May 3 rd • End-of-Chapter Quizzes: – Chapter 17 • Papers: – Paper 3 Revision (if desired), Stage 2: Was due today before class • Turn in to both CPR and turnitin on e. Campus even if the text is the same (that way we know that it’s the same) – Paper 4, Stage 1: Due before the usual class time on Wednesday, May 3 rd – Paper 4, Stage 2: Due Tuesday May 9 th by 11: 55 PM • Honors Paper: – Due tonight at 11: 55 PM in turnitin. Let me know if you need an extension • General: – CPR: Mis-graded on any Assignment? Let us know – Extra credit for students who do PLRQ Unit 6 and/or Paper 4 stuff in Peerceptiv Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 55
Possibility 3: In between • It will approach zero speed as it gets farther from the Earth • It’s true that it can orbit the Earth it has just the right speed, but that’s not what we are talking about here… Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 56
Look at it the Other Way Since we can observe the speed of the expansion of the Universe we ask the question the other way “Is the density of the universe big enough to make the Universe contract again? Collapse back on itself? A Big Crunch? ” Timesa & Fate of the Universe Big Bang, Black it. Early Does have “critical” density? 57 Topic 1: Possibilities Holes, No Math
Summary: 3 Possibilities 1. Over the critical density: Collapse (an anti-big bang, or a Big Crunch, Gnab Gib) 2. Under the critical mass: Expanding forever, but slows down and eventually hits a constant speed 3. Exactly critical mass: Eventually stops expanding just barely enough… Speeds get smaller and smaller, although never quite reaches. Early zero Times & Fate of the Universe Big Bang, Black Holes, No Math Topic 1: Possibilities 58
Look at all three together Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 59
Critical Density Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 60
Well? • Which universe do we live in? • Need to know the present rate of expansion and the density of the universe Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 61
Measure Both • Can measure the speed of expansion fairly accurately – What Hubble originally measured • What do we know about the density of the Universe? – Add up the mass of all the stars we can see – Add in all the stuff between the stars (hydrogen and helium gas) èThis density is about 5% of the critical density Early Times & Fateup of the Universe Big Black • Bang, Dark Matter makes about 23% 62 Holes, No Math Topic 1: Possibilities
Below the Critical Density? • The naïve scientist would conclude that we “must” be in a Universe that would expand forever • Is this right? • How could we check this? • Any evidence we’re missing something? Early Times & Fate of the Universe Big Bang, Black 63 Holes, No Math Topic 1: Possibilities
Other Ways? Are there other ways to predict the Fate of the Universe? Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 64
The Data Measure the Density of the Universe from the Cosmic Background Radiation Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 65
The Cosmic Background Radiation Look at the size of the spots Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 66
Look at the Spots We know what the size of the spots should be back during recombination, but we can ask how much the light was lensed as it moved through space Big Crunch Big Bang, Black Holes, No Math Critical Density Expands Forever Early Times & Fate of the Universe Topic 1: Possibilities 67
Computer Simulations Big Crunch Big Bang, Black Holes, No Math Critical Density Early Times & Fate of the Universe Topic 1: Possibilities Expands Forever 68
Which Universe Do We Live In? Big Crunch Critical Expand Forever? Looks like a Universe The with the Data Critical Density 69 Early Times & Fate of the Universe Big Bang, Black Holes, No Math Topic 1: Possibilities
Summarizing the Data 1. Speed of far-away galaxies moving away from us gives us the speed of expansion fairly accurately 2. The measured density of the “known matter and dark matter” is about 28% of the critical density 3. The background radiation says the density is consistent with being 100% of the critical density Something is inconsistent… Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 70
It all adds up! • Add up all the mass/energy in the Universe – Atoms account for ~5% – Dark Matter is about 5 times more mass in a galaxy than atoms ~23% – Dark Energy is about ~72% Cosmic Background Radiation says the Universe has 100% of Big Bang, Black Holes, No Math the critical density Big 71 Bang, Black Early Times & Fate of The Universe Topic 5: Dark Holes, No Math Energy
Was due today– L 26 • Reading: – Already due • Pre-Lecture Reading Questions: – Already due – Can do make ups in CPR. Instructions at http: //people. physics. tamu. edu/toback/109/Question_Guideline_109_CPR. pdf – Will need to submit 4 questions, and do the entire CPR assignment to get credit • End-of-Chapter Quizzes: – All end-of-chapter quizzes are due by 11: 55 PM of Monday December 2 nd. This includes AMS-2 • Papers: – Paper 3: Working on recent re-grade requests – Paper 3 Revision: Text due tomorrow before 4: 10 PM. Rest of assignment. Monday before 4: 10 PM – Paper 4: Text due tomorrow before 4: 10 PM. Rest of assignment. Monday before 4: 10 PM Early Times & Fate of the Universe Big Bang, Black 72 Topic 1: Possibilities Holes, No Math
Prep for Next time – L 26 • Reading: – Already due • Pre-Lecture Reading Questions: – Already due. If you want to do a make up, you need to email me • End-of-Chapter Quizzes: – All end-of-chapter quizzes are due by 11: 55 PM of Monday December 2 nd. This includes AMS-2 • Papers: – Paper 3: Working on recent re-grade requests – Paper 3 Revision: Text due Monday before class – Paper 4: Text due Monday before class Big 73 Bang, Black Holes, No Math
Course Evaluations Course evaluations will be done online: • You should have gotten an email about this already The Fall 2013 evaluation period will: • Begin on Wednesday November 27 th at 8 AM • Ends on Friday December 13 th at 5 PM – Please do them… won’t take long Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 74
Adding it up • Atoms and the other known particles make up about 5% of the Critical Density – Most in atoms – Other stuff in photons, neutrinos etc. • Dark Matter makes up about Early Times & Fate of the Universe Big Bang, Black 23% Holes, No Math Topic 1: Possibilities 75
Look at the Spots Look at the average separation of the spots • Essentially: – Large amount of mass (large density) Large distance between spots Big Crunch – Medium amount of Mass (medium density) Medium distance between spots Critical Density – Small amount of Mass (small density) Small distance between spots Universe expands forever • Model the different possibilities with a computer Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 76
Which Universe Do We Live In? Crunch Critical Forever? Looks like a Universe The with the Data Critical Density 77 Early Times & Fate of the Universe Big Bang, Black Holes, No Math Topic 1: Possibilities
End of the Semester – L 12 • Only 3 more days of class – Today, Nov 20 th, and Nov 27 th • Need to finish all the end of Chapter quizzes as well as AMS 2 – That’s the end of semester evaluation – Need to finish this before you can finish all the end of chapter quizzes • Will not do the 5 th paper, but will allow a paper 4 revision Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 78
End of the Semester – L 13 • All Reading Questions are now due • Chapter 17 End of Chapter questions now due • All chapters due by Tues Dec 4 th at midnight • Only 2 more days of class – Today, and Nov 27 th • Need to finish all the end of Chapter quizzes as well as AMS 2 – That’s the end of semester evaluation – Need to finish this before you can finish all the end of chapter quizzes – If they are not complete, you will get an Incomplete for the course • Will not do the 5 th paper, but will allow a paper 4 revision with a short time scale – Text due Monday Dec 3 rd Early – Rest due by Dec Times 7 th & Fate of the Universe Big Bang, Black 79 Topic 1: Possibilities Holes, No Math
Prep For Next Time – L 12 • Reading: –BBBHNM: All reading through Chapter 20 • Reading Questions: – All reading questions through 20 • e. Learning Quizzes: – Chapter 18 • Papers: – Text of Paper 4 assignment due Wednesday at 11: 55 PM – Calibrations, Reviews and Self-assessment due before class on Monday Big 80 Bang, Black Holes, No Math
Prep For Next Time – L 12 • Note: May change depending on how far we get in lecture • Reading: – BBBHNM: All reading through Chapter 20 • Reading Questions: – All reading questions through 20 • e. Learning Quizzes: – If we finished Chapter 18 then end-of-chapter quiz 18 (else just through Chapter 17) • Papers: – Text of Paper 4 assignment due Wednesday at 11: 55 PM – Calibrations, Reviews and Self-assessment due before class on Monday Big 81 Bang, Black Holes, No Math
Prep For Next Time – L 12 • Reading: –BBBHNM: All reading through Chapter 20 • Reading Questions: – All reading questions through 20 • e. Learning Quizzes: – Quizzes through Chapter 17 • Papers: – Text of Paper 4 assignment due before class on Tuesday Big 82 Bang, Black Holes, No Math
Prep For Next Time – L 13 • Note: May change depending on how far we get in lecture • Reading: – BBBHNM: All reading through Chapter 20 • Reading Questions: – All reading questions through 20 • e. Learning Quizzes: – If we finished Chapter 18 then end-of-chapter quiz 18 (else just through Chapter 17) • Papers: – Rest of Paper 4 assignment due before class on Tuesday Big 83 Bang, Black Holes, No Math
Prep for Next Time – P 24 • Reading – Reading the rest of BBBHNM • Reading questions – Chapter 18, 19 and 22 (can do in installments) • End-of-Chapter Quizzes – If we finished Chapter 18 then end-of-chapter quiz 18 (else just 17) • Papers – Paper 2 Revision or Paper 3: Misgraded? Let us know. – Paper 3 Revision: Due Monday before class. Want feedback? Due Thursday for quick response – Paper 4: Due Wednesday before class. One week Big Bang, Blackwe finish Chapter 17 84 after Holes, No Math
Prep for Next Time – P 25 • Reading – Reading the rest of BBBHNM • Reading questions – Chapter 18, 19 and 22 (can do in installments) • End-of-Chapter Quizzes – If we finished this lecture, do Chapter 18, 19 and 22 (else just 17) • Papers – Paper 1, 2 or 3: Misgraded? Let us know – Paper 3 revision: Was due today, Reviews due next Monday – Paper 4: Due Wednesday (same format as last two papers) Big Bang, Black Holes, No Math 85
Prep for Next Time – P 26 • Reading – Reading the rest of BBBHNM • Reading questions – Chapter 18, 19, 20 and 22 (can do in installments) • End-of-Chapter Quizzes – If we finished this lecture, do Chapter 18, 19 and 22 (else just 17) • Papers – Paper 1, 2 or 3: Misgraded? Let us know – Paper 3 revision: Was due Monday, Reviews due next Monday – Paper 4: Was due today (same format as last two papers), Reviews due next Wednesday Big Bang, Black Holes, No Math 86
Full set of Readings So Far • Required: – BBBHNM: Chaps. 1 -19 • Recommended: – TFTM: Chaps. 1 -5 – BHOT: Chaps. 1 -7, 8 (68 -76), 9 and 11 (117 -137), 12 – SHU: Chaps. 1 -3, 4(77 -86), 5(95114), 6 -8 (up-to-page 164) – TOE: Chaps. 1 -3 – Seeds (Cosmology in the 21 st Century) Big Bang, Black Holes, No Math
The Cosmological Constant • Back in the 1920’s, when there was no evidence that the Universe was expanding, Einstein tried to explain why it wasn’t collapsing • He put in a special “forcetype thing” in General Relativity so that it wouldn’t predict that the Universe was decelerating • Call this “trick” the Cosmological Constant Big Bang, Black Holes, No Math Big 88 Bang, Black Early Times & Fate of The Universe Topic 5: Dark Holes, No Math Energy
The Cosmological Constant? The story goes that when Einstein saw Hubble’s data that the Universe is expanding he called this trick his “greatest blunder” • Was Einstein right after all (albeit for the wrong reasons)? • Is this “force” accelerating the way the Universe is expanding? Big Bang, Black Holes, No Math Big 89 Bang, Black Early Times & Fate of The Universe Topic 5: Dark Holes, No Math Energy
Prep for Today (Is now due) – L 24 • Reading: – BBBHNM 18 & 19 • Reading questions: – Chapter 18 & 19 • End-of-Chapter Quizzes: – Chapter 17 • Paper Stuff – Paper 1, 2 or 3: Misgraded? Let us know – Paper 3 revision: Due Monday – Paper 4: Due Monday (same format as last two papers) Big 90 Bang, Black Holes, No Math
Prep for Today (Is now due) – L 25 • Reading: – Rest of BBBHNM • Reading questions: – Chapter 18, 19 and 22 • End-of-Chapter Quizzes: – Chapter 17 • Paper Stuff – Paper 1, 2 or 3: Misgraded? Let us know – Paper 3 revision: Was due today, Reviews due next Monday – Paper 4: Due Wednesday (same format as last two papers) Big 91 Bang, Black Holes, No Math
Prep for Today (Is now due) – L 26 • Reading: – Rest of BBBHNM • Reading questions: – Chapter 18, 19, 20 and 22 • End-of-Chapter Quizzes: – Chapter 17 • Paper Stuff – Paper 1, 2 or 3: Misgraded? Let us know – Paper 3 revision: Was due Monday, Reviews due next Monday – Paper 4: Was due today (same format as last two papers), Reviews due next Big 92 Bang, Black Wednesday Holes, No Math
End of the Semester – L 26 • Only 2 more days of class – Today and next Monday • Will try to cover all but Chapter 21 • Need to finish all the end of Chapter quizzes as well as AMS 2 – That’s the end of semester evaluation – Won’t do Chapter 21 in e. Learning • Will not do the last paper, but will allow a paper 4 revision Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 93
Some Recent Results • Short and Sweet lecture on some interesting data from the last ten years • This new data has completely changed our view of the evolution and fate of the Universe • Still working on this stuff… Take it with a grain of salt… Big 94 Bang, Black Holes, No Math Big Bang, Black Holes, No Math Early Times & Fate of The
Overview of Section 6 The things that determine the Fate of the Universe are the dominant effects in the VERY early Universe Thus, to understand either requires learning about both Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 95
Prep for Next Time – P 24 • Reading – BBBHNM 19 & 20 • Reading questions – Chapter 19 & 20 • End-of-Chapter Quizzes – If we finished Chapter 18 then end-of-chapter quiz 18 (else just 17) • Papers – Paper 1, 2 or 3: Misgraded? Let us know – Paper 3 revision: Due Monday – Paper 4: Due Monday (same format as last two papers) Big Bang, Black Holes, No Math 96
Today’s Lecture: Outline The Fate of the Universe is determined by what type of Universe we live in • Different Models of the Fate of the Universe • The impact of each and how we could tell • What the data says Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 97
What Type of Universe do we live in? Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 98
Course Evaluations This semester course evaluations will be done online "Department of Physics On-Line Course Evaluation System“ http: //evaluation. tamu. edu/ Please, take a few minutes to fill these out. I really appreciate it! 99 Bang, Black Big Holes, No Math
Schedule from here on out • Mon Nov 22: Ch 19 & 20(? ) • Wed Nov 24: No class, Thanksgiving (paper 4 due) • Mon Nov 29: Ch 20 & 21 (? ) • Wed Dec 1: Ch 21 & 22 – last day of class – paper 5 due – Honors paper due Big Bang, Black Holes, No Math 100
Course Evaluations This semester two separate course evaluations will be done online (until Midnight, Tues May 4 th) 1. "Department of Physics On-Line Course Evaluation System“ http: //evaluation. tamu. edu/ 2. SLATE Award Evaluations http: //pica. tamu. edu Please, take a few minutes to fill Big Bang, Black Holes, these No Math out. I really appreciate it! 101
For Next Time What are we missing? • Chap 19: Evidence for Dark Matter After that • Chap 20: Particle Physics • Chap 21: Inflation • Chap 22: Dark Energy Full reading through Unit 6: • BBBHNM: Chaps. 1 -22 • TFTM: Chaps. 1 -5 • BHOT: Chaps. 1 -7, 8 (68 -76), 9 and 11 (117 -137), 12 • SHU: Chaps. 1 -3, 4(77 -86), 5(95 -114), 6 -8 (up-to-page 164) • TOE: Chaps. 1 -3 • Seeds (Cosmology in the 21 st Century) Lecture prep: Turn in on e. Learning Two questions from Chapter 19 you want to know the answer to Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 102
The Reading for Unit 6 Full reading for Unit 6: • BBBHNM: Chaps. 18 -22 • SHU: 8 (159 -164) • BHOT: 11 (122 -137), 12 • Seeds (Cosmology in the 21 st Century, Web Handout) Full reading through Unit 6: • BBBHNM: Chaps. 1 -22 • TFTM: Chaps. 1 -5 • BHOT: Chaps. 1 -7, 8 (68 -76), 9 and 11 (117 -137), 12 • SHU: Chaps. 1 -3, 4(77 -86), 5(95 -114), 6 -8 (up-topage 164) • TOE: Chaps. 1 -3 • Seeds (Cosmology in the 21 st Century) Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 103
Papers • Paper 1 is done • Paper 2 grades are on e. Learning – All grades fixed, revision papers posted • Paper 3: – We have fixed papers for calibration problems – Still mis-graded? Let us know! – Do CPR if you submitted a revisions • Paper 4: – Due next Monday before class • Paper 5 (last paper, no final) – Assigned after we start Chap 20 Big 104 Bang, Black Holes, No Math
Writing Assignments Short Assignments 1 & 2 Re-do’s are still possible. Want to revise again? Talk to me e. Learning: Unit 5 now due Need to be working on Unit 6 Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 105
Papers AFTER Paper 2 Two options 1. Two short papers like the first one • One on Black Holes (due Thursday before class) • One on Dark Matter (due last day of class) 2. Research Paper If you want this option Stage 1 must be approved ASAP • Was due last week • Final paper due the last day of Early Times & Fate of theth. Universe Big Bang, Black 106 class, Tuesday Dec 8 Topic 1: Possibilities Holes, No Math
Today’s Lecture: Evidence • Using the Density to predict the Fate of the Universe • Measuring the Curvature of Space-Time • Summarizing the data so far… Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 107
Density of the Universe and General Relativity teaches us that the Density of the Universe determines the Curvature of Space-Time Big Bang, Black Holes, No Math Remember, we’re not talking about local curvature, but the curvature of the entire universe Early Times & Fate of the Universe Topic 1: Possibilities 108
Density of the Universe and General Relativity What type is our Universe? • Local depression? • Essentially Flat? • Something else? Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 109
Size scale of the Universe Look at the Same Picture Again Big Bang, Black Holes, No Math Universe will expand forever Universe will collapse again Early Times & Fate of the Universe Topic 1: Possibilities The curvature of the Universe may tell us the fate 110
Other Ways? Can we measure the curvature of the Universe? Is the evidence consistent with a curved (open) universe? Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 111
Surface of a sphere 2 -dimensional analogy of the Universe For a creature living on the sphere, having no sense of the third dimension, there’s no center (on the sphere!): All points are equal Alternative: Any point on the surface can be defined as the center of a coordinate system Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 112
Shape and Geometry of the Universe Flat surface (zero curvature) Closed surface (positive curvature) Open surface (negative curvature) Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 113
Shape and Geometry of the Universe How can a 2 -D creature investigate the geometry of the sphere? Measure curvature of its space! 180 270? Question: How many degrees in a triangle? Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 114
The Expanding Universe The fate of our expanding Universe depends, mostly, on two things: 1. How fast is it expanding now 2. The density of the Universe Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 115
Size scale of the Universe Draw This Out Big Bang, Black Holes, No Math Density less than the critical density universe will expand forever Density more than the critical density Universe will collapse again Early Times & Fate of the Universe Topic 1: Possibilities 116
Measuring the Density • What do we know about the density? – Add up the mass of all the stars we can see – Add in all the stuff between the stars èThe observed density is about 4% of the critical density Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 117
For Next Time • Evidence we are in a critical Universe • After that: – Other stuff out there? Reading for next time: BBBHNM: Chapter 15 (assuming I finish it) So far: • BBBHNM: Chaps. 1 -15 • TFTM: Chaps. 1 -5 • Prelude • BHOT: Chaps. 1 -7, 8 (68 -76), 9 and 11 (117 -122) • SHU: Chaps. 1 -3, 4(77 -86), 5(95 -114), 6 -8 (up-topage 164) • TOE: Chaps. 1 & 2 • Seeds Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 118
Big Bang, Black Holes, No Math ASTR/PHYS 289 Dr. David Toback Lectures 19 & 20 Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 119
Unit 6 Going back in time and going forward in time Before the first millionth of a second and the Fate of the Universe Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 120
Overview of Unit 5 The things that determine the Fate of the Universe are the dominant effects in the VERY early Universe Thus, to understand either requires learning about both Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 121
Outline of Section 5 1. Possible Fates of the Universe Today 2. Flatness 3. The Case for Dark Matter 4. Particle Physics and Dark Matter • The Standard Model and Supersymmetry Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 122
The Question of the Day What type of Universe do we live in? Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 123
Size scale of the Universe Draw This Out Big Bang, Black Holes, No Math Density less than the critical density universe will expand forever Density more than the critical density Universe will collapse again Early Times & Fate of the Universe Topic 1: Possibilities 124
Other Names Also have other names for these 1. Closed Universe (collapses) 2. Open Universe (stays open forever) 3. Critical Universe (has the critical density to just barely stay open) Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 125
Possibility 1: Closed The Universe expands, but eventually collapses back onto itself Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 126
Possibility 2: Open Gravity can’t overcome the speed The Universe Expands forever Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 127
Possibility 3: Critical The option right in-between the other two Call this the Critical Density The Universe expands and slowly asymptotes to zero speed Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 128
A Simulation http: //bigbang. physics. tamu. edu/Figures/Stolen. Animations/cannonball_mass_vs_orbit. swf Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 129
In class Quiz What is happening in this region? Big Bang, Black Holes, No Math { Early Times & Fate of the Universe Topic 1: Possibilities 130
For Next Time • Evidence we are in a critical Universe • After that: –Other stuff out there? –Inflation… Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 131
Size scale of the Universe Draw This Out Big Bang, Black Holes, No Math r < rc universe will expand forever r > rc Universe will collapse back Early Times & Fate of the Universe Topic 1: Possibilities 132
Outline of Section 5 1. Possible Fates of the Universe 2. Flatness 3. The Case for Dark Matter 4. Particle Physics and Dark Matter • The Standard Model and Supersymmetry 5. Inflation 6. Dark Energy and the Accelerating Universe Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 133
TFTM 2 still continued… • Figure 4 on open vs. closed universes… • Later parts of this chapter are pretty out of date unfortunately (need to really know what the answers are) Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 134
SHU 12 • Some random notes on (p 236) on why we can’t just look further and further out into the universe to see what happened. • “Theory tells us that at extremely hot temperatures everything has to be opaque; we will not be able to distinguish shape and structure. It is rather as if everything is hidden within an intense hot fog Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 135
• So, even if we can find ways to build more and more powerful telescopes, capable of seeing even deeper into space than the quasars, we already know that we will not be able to see right back into the time of the big bang…. • As we journey back in time, we will hit this fog of intense heat some 300, 000 years before we hit the big bang. ) Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 136
• Note: No THING can travel faster than the speed of light • However: Space can expand faster than the speed of light… This is a consequence of General Relativity Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 137
• Some text Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 138
BHOT 7 cont… • However, there is lots of “dark matter” that we cannot see direction but which we know must be there because of its influence of its gravitation attraction on the orbits of stars in the galaxies. • More on this later… Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 139
TOE 2 • “A static universe should start contracting under the influence of gravity • But suppose that, instead of being static, the universe was expanding • If it was expanding fairly slowly, the force of gravity would cause it to eventually stop expanding and then start contracting Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 140
BHOT 7 cont… • “A static universe is unstable, for there is no comparable repulsive force to balance the gravitational pull that all the stars and galaxies exert on each other • Therefore even if at sometime the universe had been static, it wouldn’t have remained static because the mutual gravitational attraction of all the stars and galaxies would soon have started it contracting • In fact, even if the universe was expanding fairly slowly, the force of gravity would cause it to eventually stop expanding, and it would start to contract Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 141
TFTM 2 cont… • Friedman models? Infinite universe or closed universe that will eventually collapse? Critical point in between the two? Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 142
Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 143
Deceleration of The Universe • Expansion of the universe should be slowed down by mutual gravitational attraction of the galaxies • Fate of the universe depends on the matter density in the universe • Define “critical density”, rc, which is just enough to slow the cosmic expansion to a halt at infinity Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 144
Note: Universe is not infinite in space, but there is no boundary: Gravity is so strong that space is bent around onto itself (kind of like the surface of the earth) Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 145
Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 146
• Learned a lot lately • TOE 2, BHOT 7 dark matter, dark energy, WMAP and flatness… Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 147
Evidence of Flatness Look at the full sky Temperature Map in a single map Stretch out a sphere onto a flat Incredibly Uniform! page Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 148
Perfectly Flat? • Subtract off the same amount everywhere • What are we left with? The overall temperature is 2. 728 degrees Kelvin The variation is very small Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 149
Hotter and Colder? Colder here? Big Bang, Black Holes, No Math Hotter here? Early Times & Fate of the Universe Topic 1: Possibilities 150
What if we’re moving? Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 151
Better Explanation Doppler effect of Moving away from this direction 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 rotating around the Milky Way at Moving in this direction 250 km/sec Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 152
Subtract Further Since we understand the Doppler effect we can subtract if off to see what’s left Remember: Overall temperature is 2. 728 degrees Kelvin Now looking at VERY small variations Extra light from the Milky way, Subtract this off also… Early Times & Fate of the Universe Big Bang, Black Holes, No Math Topic 1: Possibilities 153
Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 154
Evidence of Flatness? Measure the temperature of the photons in the Universe today to be incredibly uniform Gives us confidence that our story of the Big Bang and the Evolution of the Universe is correct Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 155
Analysis of the Cosmic Background Fluctuations Analyze frequency of occurrence of fluctuations on a particular angular scale Universe has a flat geometry Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 156
• First time 1 -20 • Second time: 1 - Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 157
• The reading for this is SHU 6 and BHOT 11 Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 158
Reminder • Universe is not infinite in space, but there is no boundary • Gravity is so strong that space is bent around onto itself – Kind of like the surface of the earth Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 159
The Cosmic Background Radiation The Famous COBE satellite map of the allsky structure of the Cosmic Background Radiation Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 160
The Cosmic Background Radiation The famous new results from the recent WMAP satellite experiment Clear variation Consistent with the General Relativity models of galaxy formation and Quantum Fluctuations Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 161
Subtract Further Since we understand the Doppler effect we can subtract if off See what’s left… Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 162
Shape and Geometry of the Universe Closed surface (positive curvature) Big Bang, Black Holes, No Math Flat surface (zero curvature) Open surface (negative curvature) Early Times & Fate of the Universe Topic 1: Possibilities 163
• Talk about the different types of Universes and the curvature • How would we tell? Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 164
• Should we talk about Curvature? • Evidence that the Universe is flat and that this implies we’re missing some of the matter/density? Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 165
• Learned a lot lately • TOE 2, BHOT 7 dark matter, dark energy, WMAP and flatness… Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 166
TFTM 2 still continued… • Figure 4 on open vs. closed universes… • Later parts of this chapter are pretty out of date unfortunately (need to really know what the answers are) Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 167
SHU 12 • Some random notes on (p 236) on why we can’t just look further and further out into the universe to see what happened. • “Theory tells us that at extremely hot temperatures everything has to be opaque; we will not be able to distinguish shape and structure. It is rather as if everything is hidden within an intense hot fog Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 168
• So, even if we can find ways to build more and more powerful telescopes, capable of seeing even deeper into space than the quasars, we already know that we will not be able to see right back into the time of the big bang…. • As we journey back in time, we will hit this fog of intense heat some 300, 000 years before we hit the big bang. ) Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 169
Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 170
• Some text Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 171
TOE 2 • “A static universe should start contracting under the influence of gravity • But suppose that, instead of being static, the universe was expanding • If it was expanding fairly slowly, the force of gravity would cause it to eventually stop expanding and then start contracting Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 172
BHOT 7 cont… • “A static universe is unstable, for there is no comparable repulsive force to balance the gravitational pull that all the stars and galaxies exert on each other • Therefore even if at sometime the universe had been static, it wouldn’t have remained static because the mutual gravitational attraction of all the stars and galaxies would soon have started it contracting • In fact, even if the universe was expanding fairly slowly, the force of gravity would cause it to eventually stop expanding, and it would start to contract Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 173
TFTM 2 cont… • Friedman models? Infinite universe or closed universe that will eventually collapse? Critical point in between the two? Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 174
Deceleration of The Universe • Expansion of the universe should be slowed down by mutual gravitational attraction of the galaxies • Fate of the universe depends on the matter density in the universe • Define “critical density”, rc, which is just enough to slow the cosmic expansion to a halt at infinity Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 175
Deceleration of the Universe • Expansion of the universe should be slowed down by mutual gravitational attraction of the galaxies. • Fate of the universe depends on the matter density in the universe. • Define “critical density”, rc, which is just enough to slow the cosmic expansion to a halt at infinity. Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 176
Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 177
st 21 Century Cosmology The solution: Inflation! • Inflation: period of sudden expansion during the very early evolution of the universe Big Bang, Black Holes, No Math • Triggered by the sudden energy release from the decoupling of the strong and electroweak forces Early Times & Fate of the Universe 178 Topic 1: Possibilities
Cosmology and General Relativity According to theory of general relativity, gravity is caused by the curvature of space-time. The effects of gravity on the largest cosmological scales should be related to the curvature of space-time! The curvature of space-time, in turn, is determined by the distribution of mass and energy in the universe. Space-time tells matter how to move; matter tells space-time how to curve. Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 179
Big Bang, Black Holes, No Math Early Times & Fate of the Universe Topic 1: Possibilities 180
- Slides: 180