Big Bang, Black Holes, No Math

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1 ASTR/PHYS 109 Dr. David Toback Lecture 5 1

2 Prep For Today (is now due) L5 Reading: No new reading Unit 2 reading assigned at the end of class Pre-Lecture Reading Questions: Unit 1: Grades have been posted (let us know if you were misgraded) This assignment is Pass/Revise: You must get a 10/10. Revisions (if needed) will be due Thursday before class If you need an extension let me know End-of-Chapter Quizzes: Chapter 3: Was due before class Papers Paper 0 (Reviewer Training): Nothing to write! Will be assigned when we finish Chapter 4 You must do all the required parts of this assignment to pass it 2

3 How the course is organized Next few slides are on course organization, grades etc (Pages 46-55) And Paper Stuff 3

4 Papers Big Bang & Black Holes Course Organization Document 46

5 Paper Topics and Due Dates Papers will be announced before we start the chapter Assigned after we finish the chapter 4 Real Papers + 1 Practice Paper 0: Reviewer Training (no writing, just review) Assigned after Chapter 4, Typically week 3 Paper 1: Evidence for Dark Matter Assigned after Chapter 6, Typically week 5 Paper 2: Evidence Stars are made of Atoms Assigned after Chapter 8, Typically week 7 Paper 3: Evidence Universe started with a Big Bang Assigned after Chapter 12, Typically week 10 Paper 4: Evidence for Black Holes Assigned after Chapter 17, Typically week 14 Big Bang & Black Holes Course Organization Document 47

6 Style of the Paper Explain it to someone who isn t taking the class (no jargon) ~600 words (This is the equivalent of both sides of a sheet of paper, double spaced) No citations! Use your own words Only use information from the book Text should be professional. You are trusted guide not a buddy or comedian Big Bang & Black Holes Course Organization Document 48

7 Paper Format Must follow expected Format Like the case a trial lawyer will make Each paper is usually 5 paragraphs: paragraph that outlines the evidence Opening Statement 1 paragraph per piece of evidence (often, but not always, three) Testimony from the expert witnesses Conclusion paragraph that ties it together Closing arguments Big Bang & Black Holes Course Organization Document 49

8 Different than usual Each Paper Assignment has 3 Stages, all done in Peerceptiv 1. Text Submission: 50% Also submit to TurnItIn 2. Review (evaluate others text): 40% You are required to do 3 Extra credit if you do more 3. Back-evaluate your graders: 10% You are assigned points for each, and the entire assignment is graded on a curve Careful of late penalties Big Bang & Black Holes Course Organization Document 50

9 Due Dates and Help Papers are typically due on a Thursday, before class Can submit a draft for feedback on ecampus in Rough Drafts (Optional) in TurnItIn Due Friday before by 11:55PM If you submit late, we can try to give feedback but we can t guarantee it We also recommend going to the Writing Center Reviews are due the following Tuesday (before class) Back-Evaluations are due that Thursday before class Big Bang & Black Holes Course Organization Document 51

10 Biggest reasons people don t do well 1. Don t read all the hand-out instructions on Peerceptiv 2. Don t read all the instructions given in each assignment 3. Don t do all the Peerceptiv stages and/or Forget to submit to TurnItIn 4. Get help when you need it Go to the Writing Center Submit a draft to the TA Read the hints on the handouts Big Bang & Black Holes Course Organization Document 52

11 Peerceptiv for Papers In ecampus Big Bang & Black Holes Course Organization Document 53

12 Why are we using Peerceptiv? Skills: People in the real world need to keep working on documents, often with others, until they are excellent People in the real world need to know how to tell the difference between an excellent document and a mediocre one People in the real world need to know how to give feedback on documents that will help turn them from mediocre to excellent How does this impact you? You need to get good at this for after you graduate Learn to better evaluate/improve your own work to ensure it is excellent BEFORE you submit it for a grade Big Bang & Black Holes Course Organization Document 54

13 Paper 0 Reviewer Training in Peerceptiv Nothing to write!!! Will do a Reviewer Training assignment (Called Paper 0) to help you practice the reviewer portions of Paper assignments in Peerceptiv There is nothing to write Just do the Review and Back-Evaluation parts for some sample papers we give you Will be done after we start Chapter 4 Big Bang & Black Holes Course Organization Document 55

14 Next Topic: Scientific Methods Unit 1: 1. Done 2. Going Big Done 3. Going Small Done 4. Evidence and the Scientific Method Today Today we move on to the Questions and How we go about answering them 4

15 Plan for the Next Few Weeks 1. More on the Questions and How we go about answering them 2. Some of the history to teach us about the method 3. Need to learn some physics } Unit Today 2 (Chapters 5-9) 5

16 Next few Weeks Continued To learn Cosmology will need to learn a bit about: 1. Light and Doppler Shifts 2. Gravity, General Relativity and Dark Matter 3. Atomic Physics and Quantum Mechanics 4. Nuclear Physics and Chemistry 5. Temperature and Thermal Equilibrium Won t spend too long on these, just enough to get back to the big picture 6

17 Evidence and The Scientific Method Finished: What are some of the clues at the scene of the crime? Next: How can we use the clues to figure out what happened? And WHY? Scientific Method How do we know what we know? What is the evidence for some of the true things we heard growing up? E.g. Earth goes around the Sun 7

18 How do we know what we know? We have a lot of experience in the world around us Unfortunately, our experience is really lousy in guiding us to really understanding the bigger (and smaller) things in nature unless we re really careful We can misinterpret the clues It really does look like the Sun rises As you ve already seen, the world is incredibly complex and much of it is different from what we experience Good clues are hard to find, sometimes even harder to interpret 8

19 Single example to Show the Scientific Method in Action People have watched the sky and noticed that the stars (the dots of light in the sky) basically all move together over the course of the night and over years Five of them behave differently Start this story in the 2 nd century 9

20 Fun Videos of Just the Stars Start with things you can see with your own eyes! Video of stars moving with Polaris (north star) at the center Video of stars moving, including the Milky Way (from Chile) 10

Ptolemy s Universe (2 nd century) The Sun, Moon and Stars go around once a day, but a few (the planets) change their position relative to the other stars a little every night Every so often the

21 Ptolemy s Universe (2 nd century) The Sun, Moon and Stars go around once a day, but a few (the planets) change their position relative to the other stars a little every night Every so often the planets move backward through the stars for awhile Hypothesis: They orbit the Earth in mostly circular paths, but we need mini-orbits way out there (epicycles) to explain the back and forth part 11

Looking at Mars in the Stars http://bigbang.physics.

22 Looking at Mars in the Stars 12

23 How Ptolemy envisioned it The big circle is the main orbit, and the little circle is the epicycle This explains why the planets seem to go back and forth out there in space (retrograde motion) every so often 13

24 Cracks in the `early cosmology In 1514, Copernicus hypothesized that the Planets and the Earth orbit the Sun Much simpler in some ways no epicycles More complicated in others Says Earth is rotating 14

25 Copernicus s Hypothesis A more modern view of the motion of the Earth and Mars and the stars behind them (from the point of view of the center) How would this explain the epicycles that people saw? 15

26 If we lived in the 1500 s, should/would we have believed Copernicus? The Earth isn t at REST and rotates? Shouldn t we FEEL this? If the Earth is rotating, why don t we fall off like an ant on a bicycle wheel? Why don t we feel a wind as we rotate? Why doesn t the rotating Earth move under our feet when we jump? 16

27 Cracks in the `early cosmology Should his view have just been accepted? Perhaps his theory was just a different interpretation of the same data? Both models are consistent with observations Need more evidence! Need a better TOOL to test, experimentally, which is correct Early 1600 s: Kepler and Galileo started gathering data from telescopes 17

28 Data Provides Evidence Discover moons orbiting Jupiter! Solid evidence that not EVERYTHING orbits the Earth! 18

29 Another Piece of Evidence Can understand the phases of the Moon because of the locations of all three Not eclipses 19

30 Venus Consider the two different predictions of how Venus moves in space 20

31 The Phases of Venus Venus has a full set of phases, like the moon Sunlight shining off Venus and to our eyes No good way to explain this if Venus goes around the Earth 21

32 More data With more accurate data Kepler realizes an even better description of the data is that all planets orbit the Sun in an ellipse, not circles Sun-centered model now agrees with the high-quality observational data, Earth centered model does not No good REASON for ellipses though then again, no good reason they should be circles (except people LIKE circles, and they are more perfect ) 22

33 Need to separate the issues The fights at this point were about HOW the planets move There was no good explanation of WHY they move that way If someone could explain WHY they move that way, then maybe we can learn something close to the truth about the universe/nature 23

34 The next generation Newton Newton puts forward his theory of Gravity and describes it as a Force So what? The same force that pulls an apple to the ground from a tree ALSO pulls the planets towards the Sun and keeps them in orbit This explains why both the orbits are ellipses AND why we don t fall off a spinning Earth Isaac Newton

35 Scientific Method The history is fun, but we have a problem: How do we separate true stories from stories we d like to believe, but aren t actually true? Need EVIDENCE and a good Scientific THEORY Good hypothesis testing 25

36 Lecture on Chapter 4 now complete 26

37 Outline for Unit 2: Physics We Need Topics 1. Light and Doppler Shifts 2. Gravity, General Relativity and Dark Matter 3. Atomic Physics and Quantum Mechanics 4. Nuclear Physics and Chemistry 5. Temperature and Thermal Equilibrium 27

38 TAMU Star Party Great opportunity to meet astronomers and their students, ask questions, see the Milky Way and planets, have fun! 29

39 Prep For Next Time L5 Reading: Required: BBBHNM Unit 2 (Chapters 5-9), due before class Thursday Recommended Reading: See P3 of Pre-Lecture Reading Questions: Unit 1: Grades have been posted (let us know if you were misgraded) This assignment is Pass/Revise: You must get a 10/10. Revisions (if needed) will be due were Thursday before class If you need an extension let me know Unit 2: Due before class on Thursday End-of-Chapter Quizzes: If we finished Chapter 4 then End-of-Chapter Quiz 4 (else just Chapter 3) Papers Paper 0 (Reviewer Training): Nothing to write! If we finished Chapter 4, Reviewer part is due Thursday at 11:55PM You must do all the required parts of this assignment to pass 28

Big Bang, Black Holes, No Math

Big Bang, Black Holes, No Math ASTR/PHYS 109 Dr. David Toback Lecture 6 & 7 1 Prep For Today (is now due) L7 Reading: Required: BBBHNM Unit 2 (Chapters 5-9) Recommended Reading: See P3 of http://people.physics.tamu.edu/toback/109/syllabus.pdf