Early Times & Fate of the Universe Topic 1: Possibilities

Early Times & Fate of the Universe Topic 1: Possibilities
Big Bang, Black Holes, No Math ASTR/PHYS 109 Dr. David Toback Lecture 39 Early Times & Fate of the Universe Topic 1: Possibilities

Was due Today – L39 General: Mis-graded on any Assignment? Let us know Reading: (Unit 6) Pre-Lecture Reading Questions (PLRQ) End-of-Chapter Quizzes: Chapter 17 Papers Paper 4: Note shorter time for Reviews Text Feedback (if desired): Friday Apr 27th Text: Wed May 2nd (Reading Day - no class) Reviews: Friday May 4th (Finals Day - no class) Back-evaluations: Mon May 7th (Finals Day - no class) Early Times & Fate of the Universe Topic 1: Possibilities

Rest of the Semester-L39 Week 14: Fri, Apr 27: In class: Finish Chapter 18. Assign EOC 18 Paper 4 text for feedback (if desired) due Week 15: (Last week of class and Finals) Mon, Apr 30: Due: EOC 18 In class: Chapter 19. Assign EOC 19 Tues, May 1st: (Redefined Friday, Last day of class) Due: EOC 19, PLRQ Unit 6 Revision (if desired) In class: Chapter 20. Assign AMS-II and EOC 20 Wed May 2nd: No class Due: Text of Paper 4 Fri May 4th: No Class Due: AMS-2 and EOC 20 due, Paper 4 Reviews Week 16: (Finals) Mon, May 7th: No Class Due: Paper 4 back-evaluations Early Times & Fate of the Universe Topic 1: Possibilities

Course Evaluations Course evaluations will be done online: I believe you should have gotten an about this already The Spring 2018 evaluation period: Already Begun ( Ends Thurs May 10th, 5PM Please do them… won’t take long Early Times & Fate of the Universe Topic 1: Possibilities

Before the first millionth of a second and the Fate of the Universe
Unit 6 Going back in time and going forward in time Before the first millionth of a second and the Fate of the Universe Early Times & Fate of the Universe Topic 1: Possibilities

Outline of Unit 6 Possible Fates of the Universe, Dark Matter and Dark Energy Particle Physics, Dark Matter and the Very Early Universe Inflation Today Early Times & Fate of the Universe Topic 1: Possibilities

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 the theory, and theory to tell us about the data New data and theoretical advances have recently changed our understanding of the Universe Early Times & Fate of the Universe Topic 1: Possibilities

The Fate of our Universe
Will the Universe continue expanding forever? That depends, mostly, on a few things: How fast is it expanding now How much STUFF there is in the Universe How big it is now Are the laws of physics really understood? Early Times & Fate of the Universe Topic 1: Possibilities

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 Early Times & Fate of the Universe Topic 1: Possibilities

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 Early Times & Fate of the Universe Topic 1: Possibilities

Gravity: Two Possibilities
There are only a few possibilities Use an analogy… Shooting a bullet into the air at the surface of the Earth Early Times & Fate of the Universe Topic 1: Possibilities

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-super supermassive black hole Early Times & Fate of the Universe Topic 1: Possibilities

Does the bullet have a speed below the escape velocity?
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 Topic 1: Possibilities

A bullet has a speed smaller than the escape velocity
Early Times & Fate of the Universe Topic 1: Possibilities

The Sun Early Times & Fate of the Universe Topic 1: Possibilities

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 Will keep on going away from the Earth forever Like launching a rocket into outer space but using a slingshot, not thrusters-that-keep-firing Early Times & Fate of the Universe Topic 1: Possibilities

The Moon has a “small” escape Velocity

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 Early Times & Fate of the Universe Topic 1: Possibilities

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 Early Times & Fate of the Universe Topic 1: Possibilities

Possibility 1: A Universe Ending in a Big Crunch
Remember this is only an analogy  There is no center or edge of the Universe Early Times & Fate of the Universe Topic 1: Possibilities

Possibility 2: A Universe That Expands Forever

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: How much is it slowing down? Do an experiment! Early Times & Fate of the Universe Topic 1: Possibilities

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 Early Times & Fate of the Universe Topic 1: Possibilities

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 Topic 1: Possibilities

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!??! Early Times & Fate of the Universe Topic 1: Possibilities

The Accelerating Universe
Big Bang, Black Holes, No Math

What the ??? Is there some Force that that is pushing things apart faster? Gravity, as we know it, only attracts… Give the “whatever-it-is” a name: Dark Energy Early Times & Fate of the Universe Topic 1: Possibilities

Why do we call it Dark Energy?
Can’t see it Call it Dark Doesn’t seem to interact like mass  Not mass or matter, but is forcing the Universe apart so it has energy (E=mc2). Not Dark Matter From the acceleration can measure how much energy must be “doing the forcing” ~72% of the mass/energy of the Universe Early Times & Fate of the Universe Topic 1: Possibilities

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 Early Times & Fate of the Universe Topic 1: Possibilities

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% Early Times & Fate of the Universe Topic 1: Possibilities

The Evolution and Fate of the Universe
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! 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 Early Times & Fate of The Universe Topic 5: Dar 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.. Early Times & Fate of the Universe Topic 1: Possibilities This result was so important that it was awarded the Nobel Prize for 2012

Lecture on Chapter 18 now complete

For Next Time – L38 General: Mis-graded on any Assignment? Let us know Reading: (Unit 6) Pre-Lecture Reading Questions (PLRQ) PLRQ Unit 6 Revision (if desired): Tuesday before class End-of-Chapter Quizzes: Chapter 18 if we finished Chapter 18 (else just Chapter 17) Papers Paper 4: Note shorter time for Reviews Text Feedback (if desired): Friday Apr 27th Text: Wed May 2nd (Reading Day - no class) Reviews: Friday May 4th (Finals Day - no class) Back-evaluations: Mon May 7th (Finals Day - no class) Early Times & Fate of the Universe Topic 1: Possibilities

For Next Time – L38 General: Mis-graded on any Assignment? Let us know Reading: (Unit 6) Pre-Lecture Reading Questions (PLRQ) PLRQ Unit 6 Revision (if desired): Tuesday before class End-of-Chapter Quizzes: Chapter 17 Papers Paper 4: Note shorter time for Reviews Text Feedback (if desired): Friday Apr 27th Text: Wed May 2nd (Reading Day - no class) Reviews: Friday May 4th (Finals Day - no class) Back-evaluations: Mon May 7th (Finals Day - no class) Early Times & Fate of the Universe Topic 1: Possibilities

For Next Time – L39 General: Mis-graded on any Assignment? Let us know Reading: (Unit 6) Pre-Lecture Reading Questions (PLRQ) PLRQ Unit 6 Revision (if desired): Tuesday before class End-of-Chapter Quizzes: Chapter 18 if we finished Chapter 18 (else just Chapter 17) Papers Paper 4: Note shorter time for Reviews Text Feedback (if desired): Friday Apr 27th Text: Wed May 2nd (Reading Day - no class) Reviews: Friday May 4th (Finals Day - no class) Back-evaluations: Mon May 7th (Finals Day - no class) Early Times & Fate of the Universe Topic 1: Possibilities

For Next Time – L39 General: Mis-graded on any Assignment? Let us know Reading: (Unit 6) Pre-Lecture Reading Questions (PLRQ) PLRQ Unit 6 Revision (if desired): Tuesday before class End-of-Chapter Quizzes: Chapter 18 Papers Paper 4: Note shorter time for Reviews Text Feedback (if desired): Friday Apr 27th Text: Wed May 2nd (Reading Day - no class) Reviews: Friday May 4th (Finals Day - no class) Back-evaluations: Mon May 7th (Finals Day - no class) Early Times & Fate of the Universe Topic 1: Possibilities

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 Monday May 7th at 11:55PM This includes AMS 2 End of semester measure of some of the things you learned Will need to do it before you can finish all the end of chapter quizzes If they are not complete, you will get an Incomplete for the course If you need an extension, let me know ahead of time Will start calculating grades after May 7th (after Paper 4 back-evaluations are due) Please do the Course Evaluations There is no statue of limitation on misgraded items. If you think you were misgraded on ANYTHING, we will work to make sure you get the grade you deserve Early Times & Fate of the Universe Topic 1: Possibilities

End of Lecture Early Times & Fate of the Universe Topic 1: Possibilities

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? Early Times & Fate of the Universe Topic 1: Possibilities

1 Paragraph in-class Quiz
What is the evidence for stellar black holes? Early Times & Fate of the Universe Topic 1: Possibilities

Clicker Question Can you "fill up" a black hole? Yes No Early Times & Fate of the Universe Topic 1: Possibilities

Clicker Question Can a Black Hole orbit another star? Yes No Early Times & Fate of the Universe Topic 1: Possibilities

Clicker Question Could the Earth orbit a black hole? Yes No Early Times & Fate of the Universe Topic 1: Possibilities

Clicker Question What would happen if two black holes collided?
They would make a supermassive black hole They would just make a black hole that is has about the same mass as the two original black holes combined Black holes can’t collide

Clicker Question If there really is dark energy, what is the ultimate fate of our universe? Big crunch Expand forever, but slowing down Expand forever, but speeding up Early Times & Fate of the Universe Topic 1: Possibilities

Clicker Question What does dark energy do to the photons in the universe? Makes them more energetic by adding energy to the universe Stretches them by stretching space-space time making them more energetic Stretches them by stretching space-space time making them less energetic Early Times & Fate of the Universe Topic 1: Possibilities

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 Early Times & Fate of the Universe Topic 1: Possibilities

Clicker Question What is happening to the density of the universe over time? Increases Decreases Stays the same Early Times & Fate of the Universe Topic 1: Possibilities

Clicker Question What does dark energy do to the temperature in the universe? Raises it by adding energy to the universe Lowers it by stretching space-time Dark Energy doesn’t affect temperature Early Times & Fate of the Universe Topic 1: Possibilities

Clicker Question What will happen to galaxies 100 billion years in the future? They'll stay the way they are now because dark matter will keep them together They'll slowly get ripped apart because dark energy will expand the universe so quickly it will overcome the attraction of gravity Early Times & Fate of the Universe Topic 1: Possibilities

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.

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 them.

Clicker Question If space-time is expanding, why aren't atoms expanding? They are Because the electric charge attraction and quantum mechanics keep the atoms the same size in space Both are true, but A is a more important effect than B Both are true, but B is more true that A. Early Times & Fate of the Universe 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.

End of Semester Monday May 1st: 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 3rd Unit 6, Stage 2 due Paper 4, Stage 1 due Monday, May 8th Remaining EOC quizzes due. Let me know if you need an extension Tuesday, May 9th Paper 4, Stage 2 due at 11:55PM Revisions for Unit 6 and Paper 4 will be by request only. Early Times & Fate of the Universe Topic 1: Possibilities

Was due Today – L27 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 3rd 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 eCampus 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 3rd Paper 4, Stage 2: Due Tuesday May 9th by 11:55PM Honors Paper: Due tonight at 11:55PM 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 Early Times & Fate of the Universe Topic 1: Possibilities

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… Early Times & Fate of the Universe Topic 1: Possibilities

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?” Does it have a “critical” density? Early Times & Fate of the Universe Topic 1: Possibilities

Summary: 3 Possibilities
Over the critical density: Collapse (an anti-big bang, or a Big Crunch, Gnab Gib) Under the critical mass: Expanding forever, but slows down and eventually hits a constant speed Exactly critical mass: Eventually stops expanding just barely enough… Speeds get smaller and smaller, although never quite reaches zero Early Times & Fate of the Universe Topic 1: Possibilities

Look at all three together

Critical Density Early Times & Fate of the Universe Topic 1: Possibilities

Well? Which universe do we live in? Need to know the present rate of expansion and the density of the universe Early Times & Fate of the Universe Topic 1: Possibilities

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) This density is about 5% of the critical density Dark Matter makes up about 23% Early Times & Fate of the Universe 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 Topic 1: Possibilities

Are there other ways to predict the Fate of the Universe?

The Data Measure the Density of the Universe from the Cosmic Background Radiation Early Times & Fate of the Universe Topic 1: Possibilities

The Cosmic Background Radiation
Look at the size of the spots Early Times & Fate of the Universe Topic 1: Possibilities

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 Critical Density Expands Forever Early Times & Fate of the Universe Topic 1: Possibilities

Computer Simulations Big Crunch Critical Density Expands Forever Early Times & Fate of the Universe Topic 1: Possibilities

Which Universe Do We Live In?
Big Crunch Critical Expand Forever? Looks like a Universe with the Critical Density The Data Early Times & Fate of the Universe Topic 1: Possibilities

Summarizing the Data Speed of far-away galaxies moving away from us gives us the speed of expansion fairly accurately The measured density of the “known matter and dark matter” is about is about 28% of the critical density The background radiation says the density is consistent with being 100% of the critical density Something is inconsistent… Early Times & Fate of the Universe Topic 1: Possibilities

Big Bang, Black Holes, No Math
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 the critical density Big Bang, Black Holes, No Math Early Times & Fate of The Universe Topic 5: Dark Energy

Was due today– L26 Reading: Already due Pre-Lecture Reading Questions: Can do make ups in CPR. Instructions at 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 11:55PM of Monday December 2nd. This includes AMS-2 Papers: Paper 3: Working on recent re-grade requests Paper 3 Revision: Text due tomorrow before 4:10PM. Rest of assignment. Monday before 4:10PM Paper 4: Text due tomorrow before 4:10PM. Rest of assignment. Monday before 4:10PM Early Times & Fate of the Universe Topic 1: Possibilities

Prep for Next time – L26 Reading: Already due
Pre-Lecture Reading Questions: Already due. If you want to do a make up, you need to me End-of-Chapter Quizzes: All end-of-chapter quizzes are due by 11:55PM of Monday December 2nd. 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

Course Evaluations Course evaluations will be done online: You should have gotten an about this already The Fall 2013 evaluation period will: Begin on Wednesday November 27th at 8AM Ends on Friday December 13th at 5PM Please do them… won’t take long Early Times & Fate of the Universe Topic 1: Possibilities

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 23% Early Times & Fate of the Universe Topic 1: Possibilities

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 Early Times & Fate of the Universe Topic 1: Possibilities

Which Universe Do We Live In?
Crunch Critical Forever? Looks like a Universe with the Critical Density The Data Early Times & Fate of the Universe Topic 1: Possibilities

End of the Semester – L12 Only 3 more days of class Today, Nov 20th, and Nov 27th 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 5th paper, but will allow a paper 4 revision Early Times & Fate of the Universe Topic 1: Possibilities

End of the Semester – L13 All Reading Questions are now due Chapter 17 End of Chapter questions now due All chapters due by Tues Dec 4th at midnight Only 2 more days of class Today, and Nov 27th 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 5th paper, but will allow a paper 4 revision with a short time scale Text due Monday Dec 3rd Rest due by Dec 7th Early Times & Fate of the Universe Topic 1: Possibilities

Prep For Next Time – L12 Reading:
BBBHNM: All reading through Chapter 20 Reading Questions: All reading questions through 20 eLearning Quizzes: Chapter 18 Papers: Text of Paper 4 assignment due Wednesday at 11:55PM Calibrations, Reviews and Self-assessment due before class on Monday

Prep For Next Time – L12 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 eLearning 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 11:55PM Calibrations, Reviews and Self-assessment due before class on Monday

Prep For Next Time – L12 Reading:
BBBHNM: All reading through Chapter 20 Reading Questions: All reading questions through 20 eLearning Quizzes: Quizzes through Chapter 17 Papers: Text of Paper 4 assignment due before class on Tuesday

Prep For Next Time – L13 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 eLearning 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

Prep for Next Time – P24 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 after we finish Chapter 17

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)

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

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 ( ), 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 21st Century)

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 “force-type 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 Early Times & Fate of The Universe Topic 5: Dark 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 Early Times & Fate of The Universe Topic 5: Dark Energy

Prep for Today (Is now due) – L24
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)

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)

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 Wednesday

End of the Semester – L26 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 eLearning Will not do the last paper, but will allow a paper 4 revision Early Times & Fate of the Universe Topic 1: Possibilities

Big Bang, Black Holes, No Math
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 Bang, Black Holes, No Math Early Times & Fate of The Universe Topic 5: Dark Energy

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 Early Times & Fate of the Universe Topic 1: Possibilities

Prep for Next Time – P24 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)

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 Early Times & Fate of the Universe Topic 1: Possibilities

What Type of Universe do we live in?

Course Evaluations This semester course evaluations will be done online "Department of Physics On-Line Course Evaluation System“ Please, take a few minutes to fill these out. I really appreciate it!

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 103

Course Evaluations This semester two separate course evaluations will be done online (until Midnight, Tues May 4th) "Department of Physics On-Line Course Evaluation System“ SLATE Award Evaluations Please, take a few minutes to fill these out. I really appreciate it!

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 ( ), 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 21st Century) Lecture prep: Turn in on eLearning Two questions from Chapter 19 you want to know the answer to Early Times & Fate of the Universe Topic 1: Possibilities

The Reading for Unit 6 Full reading for Unit 6: BBBHNM: Chaps SHU: 8 ( ) BHOT: 11 ( ), 12 Seeds (Cosmology in the 21st 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 ( ), 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 21st Century) Early Times & Fate of the Universe Topic 1: Possibilities

Papers Paper 1 is done Paper 2 grades are on eLearning
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

Writing Assignments Short Assignments 1 & 2 Re-do’s are still possible. Want to revise again? Talk to me eLearning: Unit 5 now due Need to be working on Unit 6 Early Times & Fate of the Universe Topic 1: Possibilities 108

Papers AFTER Paper 2 Two options Two short papers like the first one One on Black Holes (due Thursday before class) One on Dark Matter (due last day of class) Research Paper If you want this option Stage 1 must be approved ASAP Was due last week Final paper due the last day of class, Tuesday Dec 8th Early Times & Fate of the Universe Topic 1: Possibilities 109

Today’s Lecture: Evidence
Using the Density to predict the Fate of the Universe Measuring the Curvature of Space-Time to predict the Fate of the Universe Measuring the Curvature of Space-Time Summarizing the data so far… Early Times & Fate of the Universe Topic 1: Possibilities

Density of the Universe and General Relativity
General Relativity teaches us that the Density of the Universe determines the Curvature of Space-Time Remember, we’re not talking about local curvature, but the curvature of the entire universe Early Times & Fate of the Universe Topic 1: Possibilities

Density of the Universe and General Relativity
What type is our Universe? Local depression? Essentially Flat? Something else? Early Times & Fate of the Universe Topic 1: Possibilities

Look at the Same Picture Again
Universe will expand forever Size scale of the Universe The curvature of the Universe may tell us the fate Universe will collapse again Early Times & Fate of the Universe Topic 1: Possibilities

Is the evidence consistent with a curved (open) universe?
Other Ways? Can we measure the curvature of the Universe? Is the evidence consistent with a curved (open) universe? Early Times & Fate of the Universe Topic 1: Possibilities

Surface of a sphere 2-dimensional analogy of the Universe
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 Early Times & Fate of the Universe Topic 1: Possibilities

Shape and Geometry of the Universe
Flat surface (zero curvature) Closed surface (positive curvature) Open surface (negative curvature) Early Times & Fate of the Universe Topic 1: Possibilities

How can a 2-D creature investigate the geometry of the sphere? Measure curvature of its space! Question: How many degrees in a triangle? 180 270? Early Times & Fate of the Universe Topic 1: Possibilities

The Expanding Universe
The fate of our expanding Universe depends, mostly, on two things: How fast is it expanding now The density of the Universe Early Times & Fate of the Universe Topic 1: Possibilities

Draw This Out Size scale of the Universe
Density less than the critical density  universe will expand forever Size scale of the Universe Density more than the critical density  Universe will collapse again Early Times & Fate of the Universe Topic 1: Possibilities

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 The observed density is about 4% of the critical density Early Times & Fate of the Universe Topic 1: Possibilities

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 ( ) SHU: Chaps. 1-3, 4(77-86), 5(95-114), 6-8 (up-to-page 164) TOE: Chaps. 1 & 2 Seeds Early Times & Fate of the Universe Topic 1: Possibilities

Big Bang, Black Holes, No Math ASTR/PHYS 289 Dr. David Toback Lectures 19 & 20 Early Times & Fate of the Universe Topic 1: Possibilities

Before the first millionth of a second and the Fate of the Universe
Unit 6 Going back in time and going forward in time Before the first millionth of a second and the Fate of the Universe Early Times & Fate of the Universe Topic 1: Possibilities

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 Early Times & Fate of the Universe Topic 1: Possibilities

Outline of Section 5 Possible Fates of the Universe Flatness The Case for Dark Matter Particle Physics and Dark Matter The Standard Model and Supersymmetry Today Early Times & Fate of the Universe Topic 1: Possibilities

What type of Universe do we live in?
The Question of the Day What type of Universe do we live in? Early Times & Fate of the Universe Topic 1: Possibilities

Draw This Out Size scale of the Universe
Density less than the critical density  universe will expand forever Size scale of the Universe Density more than the critical density  Universe will collapse again Early Times & Fate of the Universe Topic 1: Possibilities

Other Names Also have other names for these Closed Universe (collapses) Open Universe (stays open forever) Critical Universe (has the critical density to just barely stay open) Early Times & Fate of the Universe Topic 1: Possibilities

The Universe expands, but eventually collapses back onto itself
Possibility 1: Closed The Universe expands, but eventually collapses back onto itself Early Times & Fate of the Universe Topic 1: Possibilities

Gravity can’t overcome the speed The Universe Expands forever
Possibility 2: Open Gravity can’t overcome the speed The Universe Expands forever Early Times & Fate of the Universe Topic 1: Possibilities

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 Early Times & Fate of the Universe Topic 1: Possibilities

A Simulation Early Times & Fate of the Universe Topic 1: Possibilities

In class Quiz What is happening in this region? { Early Times & Fate of the Universe Topic 1: Possibilities

For Next Time Evidence we are in a critical Universe After that: Other stuff out there? Inflation… Early Times & Fate of the Universe Topic 1: Possibilities

Draw This Out r < rc  universe will expand forever
r < rc  universe will expand forever Size scale of the Universe r > rc  Universe will collapse back Early Times & Fate of the Universe Topic 1: Possibilities

Outline of Section 5 Possible Fates of the Universe Flatness The Case for Dark Matter Particle Physics and Dark Matter The Standard Model and Supersymmetry Inflation Dark Energy and the Accelerating Universe Early Times & Fate of the Universe Topic 1: Possibilities

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) Early Times & Fate of the Universe Topic 1: Possibilities

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 Early Times & Fate of the Universe Topic 1: Possibilities

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.) Early Times & Fate of the Universe Topic 1: Possibilities

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 Early Times & Fate of the Universe Topic 1: Possibilities

Some text Early Times & Fate of the Universe Topic 1: Possibilities

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… Early Times & Fate of the Universe Topic 1: Possibilities

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 Early Times & Fate of the Universe Topic 1: Possibilities

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 Early Times & Fate of the Universe Topic 1: Possibilities

TFTM 2 cont… Friedman models? Infinite universe or closed universe that will eventually collapse? Critical point in between the two? Early Times & Fate of the Universe Topic 1: Possibilities

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 Early Times & Fate of the Universe Topic 1: Possibilities

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) Early Times & Fate of the Universe Topic 1: Possibilities

Learned a lot lately TOE 2, BHOT 7 dark matter, dark energy, WMAP and flatness… Early Times & Fate of the Universe Topic 1: Possibilities

Evidence of Flatness Look at the full sky in a single map
Stretch out a sphere onto a flat page Temperature Map Incredibly Uniform! Early Times & Fate of the Universe Topic 1: Possibilities

Subtract off the same amount everywhere What are we left with?
Perfectly Flat? Subtract off the same amount everywhere What are we left with? The overall temperature is degrees Kelvin The variation is very small Early Times & Fate of the Universe Topic 1: Possibilities

Hotter and Colder? Colder here? Hotter here? Early Times & Fate of the Universe Topic 1: Possibilities

What if we’re moving? Early Times & Fate of the Universe Topic 1: Possibilities

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 rotating around the Milky Way at 250 km/sec Moving away from this direction Moving in this direction Early Times & Fate of the Universe Topic 1: Possibilities

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… Early Times & Fate of the Universe Topic 1: Possibilities

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 Early Times & Fate of the Universe Topic 1: Possibilities

Analysis of the Cosmic Background Fluctuations
Analyze frequency of occurrence of fluctuations on a particular angular scale Universe has a flat geometry Early Times & Fate of the Universe Topic 1: Possibilities

First time 1-20 Second time: 1- Early Times & Fate of the Universe Topic 1: Possibilities

The reading for this is SHU 6 and BHOT 11 Early Times & Fate of the Universe Topic 1: Possibilities

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 Early Times & Fate of the Universe Topic 1: Possibilities

The Famous COBE satellite map of the all-sky structure of the Cosmic Background Radiation Early Times & Fate of the Universe Topic 1: Possibilities

The famous new results from the recent WMAP satellite experiment Clear variation Consistent with the General Relativity models of galaxy formation and Quantum Fluctuations Early Times & Fate of the Universe Topic 1: Possibilities

Subtract Further Since we understand the Doppler effect we can subtract if off See what’s left… Early Times & Fate of the Universe Topic 1: Possibilities

Closed surface (positive curvature) Flat surface (zero curvature) Open surface (negative curvature) Early Times & Fate of the Universe Topic 1: Possibilities

Talk about the different types of Universes and the curvature How would we tell? Early Times & Fate of the Universe Topic 1: Possibilities

Should we talk about Curvature? Evidence that the Universe is flat and that this implies we’re missing some of the matter/density? Early Times & Fate of the Universe Topic 1: Possibilities