Big Bang Black Holes No Math ASTRPHYS 109
Big Bang, Black Holes, No Math ASTR/PHYS 109 Dr. David Toback Lectures 6, 7 & 8 Big Bang, Black Holes, No Math Introduction Topic 4: Scientific Methods 1
Prep For Today (is now due) – L 7 • • • Reading: – BBBHNM Unit 2 (Chapters 5 -9): Not yet assigned – Recommended Reading: • See P 3 of http: //people. physics. tamu. edu/toback/109/Syllabus. pdf e. Campus Stuff – Warm-up Quiz Part 4 (Peerceptiv): Not yet assigned Pre-Lecture Reading Questions: – Unit 2 Text Submission: Not yet assigned • Submit in e. Campus quiz • Submit ONLY 4 questions, need all 4 to be excellent to pass • Pass/Revise assignment. If you don’t pass we will set up dates for Revisions after you get Feedback – Unit 2 Quiz: Not yet assigned End-of-Chapter Quizzes: – EOC 3: Was due before class Honors Section: – “Stage 0 Reading Selection Check”: Was due Monday before class if you don’t already have Stage 0 approved – In a. Black heavy reading stage Introduction Bang, Big Holes, No Math Topic 4: Scientific Methods 2
Prep For Today (is now due) – L 8 • • • Reading: – BBBHNM Unit 2 (Chapters 5 -9): Was due before class – Recommended Reading: • See P 3 of http: //people. physics. tamu. edu/toback/109/Syllabus. pdf e. Campus Stuff – Warm-up Quiz Part 4 (Peerceptiv): Not yet assigned Pre-Lecture Reading Questions: – Unit 2 Text Submission: Not yet assigned. Will assign today to be due before next class • Updated instructions. Please see them before you submit • Submit in e. Campus quiz • Submit ONLY 4 questions, need all 4 to be excellent to pass • Pass/Revise assignment. If you don’t pass we will set up dates for Revisions after you get Feedback – Unit 2 Quiz: Not yet assigned. • Will open up for you in e. Campus AFTER the written submission is graded and only if you get a Pass. Also requires Unit 1 and EOC 3. • Final due date not yet assigned, Will probably assign next time End-of-Chapter Quizzes – (EOC 3) Honors Section: – “Final draft of Stage 0”: Due Monday before class if not already completed – In a heavy reading stage, need to hear from you at least once every 7 days Big Bang, Black Holes, No Math Introduction Topic 4: Scientific Methods 3
Next Topic: Scientific Methods Unit 1: 1. Introduction Done 2. Going Big Done 3. Going Small Done 4. Evidence and the Scientific Method Today we move on to the Questions and How we go about answering them Big Bang, Black Holes, No Math Introduction Topic 4: Scientific Methods 4
Plan for the Next Few Weeks } 1. More on the Questions and How we go about answering them Today 2. Some of the history to teach us about the method 3. Need to learn some Unit 2 (Chapters 5 -9) physics } Big Bang, Black Holes, No Math Introduction Topic 4: Scientific Methods 5
Next few Weeks Continued… The tools in our toolbox… Learning some Physics 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… Big Bang, Black Holes, No Math Introduction Topic 4: Scientific Methods 6
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 Big Bang, Black Holes, No Math Introduction Topic 4: Scientific Methods 7
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 and disciplined – 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 Big Bang, Black Holes, No Math Introduction Topic 4: Scientific Methods 8
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 Big Bang, Black Holes, No Math Introduction Topic 4: Scientific Methods 9
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 https: //www. youtube. com/watch? v=XTTDWhky 9 HY Video of stars moving, including the Milky Way (from Chile) https: //www. youtube. com/watch? v=JEHm-XUHw. Nw Introduction Big Bang, Black Topic 4: Scientific Methods Holes, No Math 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 planets move backward through the stars for awhile Hypothesis: They orbit the Earth in mostly circular paths, but there are “mini-orbits” way out there which we call “epicycles”. It’s these the mini-orbit part that “explains” the back and forth part Big Bang, Black Holes, No Math Introduction Topic 4: Scientific Methods 11
Looking at Mars in the Stars http: //bigbang. physics. tamu. edu/Figures/Stolen. Animations/Mars. Retrograde_top. mp 4 Big Bang, Black Holes, No Math Introduction Topic 4: Scientific Methods 12
How Ptolemy envisioned it http: //bigbang. physics. tamu. edu/Figures/Stolen. Animations/ptolemy. model. swf • 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 Big Bang, Black Holes, No Math Introduction Topic 4: Scientific Methods 13
Cracks in the `early cosmology’ In 1514, Copernicus hypothesized that the Planets and the Earth orbit the Sun (he wasn’t really the first one to suggest this…) Much simpler in some ways no epicycles More complicated in others Says Earth is rotating Big Bang, Black Holes, No Math Introduction Topic 4: Scientific Methods 14
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) http: //bigbang. physics. tamu. edu/Figures/Stolen. Animations/mars_retrograde_motion. swf How would this explain the epicycles that people saw? Big Bang, Black Holes, No Math Introduction Topic 4: Scientific Methods 15
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 the Earth rotates? • Why doesn’t the rotating Earth move under our feet when we jump? Introduction Big Bang, Black Holes, No Math Topic 4: Scientific Methods 16
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 Introduction Big telescopes Bang, Black Holes, No Math Topic 4: Scientific Methods 17
Early Data Provides Evidence Discover moons orbiting Jupiter! Solid evidence that not EVERYTHING orbits the Earth! Big Bang, Black Holes, No Math Introduction Topic 4: Scientific Methods 18
Another Piece of Evidence • Can understand the phases of the Moon because of the locations of all three • Not eclipses Big Bang, Black Holes, No Math Introduction Topic 4: Scientific Methods 19
Venus Consider the two different predictions for how Venus moves in space Big Bang, Black Holes, No Math Introduction Topic 4: Scientific Methods 20
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 Big Bang, Black Holes, No Math Introduction Topic 4: Scientific Methods 21
More data • With more accurate data Kepler realizes an even better description of the data is that all planets orbit the Sun in ellipses, 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, Introduction Big Bang, Black 22 and they are more “perfect”) Topic 4: Scientific Methods Holes, No Math
Need to Separate the Issues • The fights up to 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 Big Bang, Black Holes, No Math Introduction Topic 4: Scientific Methods 23
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 spinning Earth Introduction Big a Bang, Black Holes, No Math Isaac Newton 1687 Topic 4: Scientific Methods 24
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 Big Bang, Black Holes, No Math Introduction Topic 4: Scientific Methods 25
Lecture on Chapter 4 now complete Big Bang, Black Holes, No Math Introduction Topic 4: Scientific Methods 26
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 Big Bang, Black Holes, No Math Introduction Topic 4: Scientific Methods 27
Prep For Next Time – L 6 • • • Reading: – BBBHNM Unit 2 (Chapters 5 -9): – Recommended Reading: • See P 3 of http: //people. physics. tamu. edu/toback/109/Syllabus. pdf e. Campus Stuff – Warm-up Quiz Part 4 (Peerceptiv): Will assign next time Pre-Lecture Reading Questions: – Unit 2 Text Submission: Due before next class • Submit in e. Campus quiz • Submit ONLY 4 questions, need all 4 to be excellent to pass • Pass/Revise assignment. If you don’t pass we will set up dates for Revisions after you get Feedback – Unit 2 Quiz: Will assign next time End-of-Chapter Quizzes: – If we finished Chapter 4 then End-of-Chapter Quiz 4 (else just Chapters 1 -3) Honors Section: – “Stage 0 Reading Selection Check”: Was due before class if you don’t already have Stage 0 approved – In a heavy reading stage Big Bang, Black Holes, No Math Introduction Topic 4: Scientific Methods 28
Prep For Next Time – L 6 • • • Reading: – BBBHNM Unit 2 (Chapters 5 -9): Will likely assign Wednesday, not yet assigned – Recommended Reading: • See P 3 of http: //people. physics. tamu. edu/toback/109/Syllabus. pdf e. Campus Stuff – Warm-up Quiz Part 4 (Peerceptiv): Will likely assign Wednesday, not yet assigned Pre-Lecture Reading Questions: – Unit 2 Text Submission: Will likely assign Wednesday, not yet assigned • Submit in e. Campus quiz • Submit ONLY 4 questions, need all 4 to be excellent to pass • Pass/Revise assignment. If you don’t pass we will set up dates for Revisions after you get Feedback – Unit 2 Quiz: Will likely assign Wednesday, not yet assigned End-of-Chapter Quizzes: – EOC 3: Due before next class Honors Section: – “Stage 0 Reading Selection Check”: Was due before class if you don’t already have Stage 0 approved – In a heavy reading stage Big Bang, Black Holes, No Math Introduction Topic 4: Scientific Methods 29
Prep For Next Time – L 7 • • • Reading: – BBBHNM Unit 2 (Chapters 5 -9): Due before next class – Recommended Reading: • See P 3 of http: //people. physics. tamu. edu/toback/109/Syllabus. pdf e. Campus Stuff – Warm-up Quiz Part 4 (Peerceptiv): Not yet assigned Pre-Lecture Reading Questions: – Unit 2 Text Submission: Due before next class • Submit in e. Campus quiz • Submit ONLY 4 questions, need all 4 to be excellent to pass • Pass/Revise assignment. If you don’t pass we will set up dates for Revisions after you get Feedback – Unit 2 Quiz: Not yet assigned End-of-Chapter Quizzes: – If we finished Chapter 4 then End-of-Chapter Quiz 4 (else just Chapter 3) Honors Section: – “Stage 0 Reading Selection Check”: Was due Monday before class if you don’t already have Stage 0 approved – In a Black heavy reading stage Introduction Bang, 30 Big Holes, No Math Topic 4: Scientific Methods
Prep For Next Time – L 7 • • • Reading: – BBBHNM Unit 2 (Chapters 5 -9): Due before next class – Recommended Reading: • See P 3 of http: //people. physics. tamu. edu/toback/109/Syllabus. pdf e. Campus Stuff – Warm-up Quiz Part 4 (Peerceptiv): Not yet assigned Pre-Lecture Reading Questions: – Unit 2 Text Submission: Will probably assign next time • Submit in e. Campus quiz • Submit ONLY 4 questions, need all 4 to be excellent to pass • Pass/Revise assignment. If you don’t pass we will set up dates for Revisions after you get Feedback – Unit 2 Quiz: Not yet assigned End-of-Chapter Quizzes: – (Chapter 3) Honors Section: – “Stage 0 Reading Selection Check”: Was due Monday before class if you don’t already have Stage 0 approved – In a Black heavy reading stage Introduction Bang, 31 Big Holes, No Math Topic 4: Scientific Methods
Prep For Next Time – L 8 • • • Reading: – BBBHNM Unit 2 (Chapters 5 -9): Was due before class – Recommended Reading: • See P 3 of http: //people. physics. tamu. edu/toback/109/Syllabus. pdf e. Campus Stuff – Warm-up Quiz Part 4 (Peerceptiv): Not yet assigned Pre-Lecture Reading Questions: – Unit 2 Text Submission: Due before next class • Updated instructions. Please see them before you submit • Submit in e. Campus quiz • Submit ONLY 4 questions, need all 4 to be excellent to pass • Pass/Revise assignment. If you don’t pass we will set up dates for Revisions after you get Feedback – Unit 2 Quiz: Not yet assigned • Will open up for you in e. Campus AFTER the written submission is graded and only if you get a Pass. Also requires Unit 1 and EOC 3. • Final due date not yet assigned, Will probably assign next time End-of-Chapter Quizzes – If we finished Chapter 4 then End-of-Chapter Quiz 4 (else just Chapter 3) Honors Section: – “Final draft of Stage 0”: Due Monday before class if not already completed Bang, Blackreading stage, need to. Introduction 32 – In a heavy hear from you at least once every 7 days Big Holes, No Math Topic 4: Scientific Methods
Prep For Next Time – L 8 • • • Reading: – BBBHNM Unit 2 (Chapters 5 -9): Was due before class – Recommended Reading: • See P 3 of http: //people. physics. tamu. edu/toback/109/Syllabus. pdf e. Campus Stuff – Warm-up Quiz Part 4 (Peerceptiv): Not yet assigned Pre-Lecture Reading Questions: – Unit 2 Text Submission: Due before next class • Updated instructions. Please see them before you submit • Submit in e. Campus quiz • Submit ONLY 4 questions, need all 4 to be excellent to pass • Pass/Revise assignment. If you don’t pass we will set up dates for Revisions after you get Feedback – Unit 2 Quiz: Not yet assigned • Will open up for you in e. Campus AFTER the written submission is graded and only if you get a Pass. Also requires Unit 1 and EOC 3. • Final due date not yet assigned, Will probably assign next time End-of-Chapter Quizzes – End-of-Chapter Quiz 4 Honors Section: – “Final draft of Stage 0”: Due Monday before class if not already completed Bang, Blackreading stage, need to. Introduction 33 – In a heavy hear from you at least once every 7 days Big Holes, No Math Topic 4: Scientific Methods
Big Bang, Black Holes, No Math Introduction Topic 4: Scientific Methods 34
Clicker Quiz A muon is observed to decay into an electron and two different neutrinos. Is a muon considered a fundamental particle? a) No, because it has the electrons and neutrinos inside it so it can't be fundamental b) Yes, because it isn't composed of electrons and neutrinos, it just decays into them c) No, because fundamental particles can't decay Big Bang, Black Holes, No Math Introduction Topic 4: Scientific Methods 35
Clicker Quiz Q: What does it mean for an electron to be "stable? " a) It is balanced with exactly one proton b) Its orbit ring exists in one plane (no wobble) c) It has reached minimum size (10 -19 m) d) Undisturbed, it can go on living forever and ever e) They don't appear to be made of anything smaller Big Bang, Black Holes, No Math Introduction Topic 4: Scientific Methods 36
PLRQ Unit 1 Grades • Criteria for Pass/Revise grades for CPR Unit 1 are described in the FAQ (http: //people. physics. tamu. edu/toback/109 FAQ. shtml#CPRGrades) • Send an email to 109 help@physics. tamu. edu if you think you were misgraded or we gave you the wrong grade • Will post the grades in e. Campus after we are done with re-grade requests • You should go to e. Campus to make sure you got the grade you think you did. Many people are surprised. • What do you do if your e. Campus grade says “Revise”? – http: //people. physics. tamu. edu/toback/109 FAQ. shtml#Requirements Big Bang, Black Holes, No Math Introduction Topic 4: Scientific Methods 37
Prep For Next Time – L 5 • Reading: – Required: BBBHNM Unit 2 (Chapters 5 -9) – Recommended Reading: • See P 3 of http: //people. physics. tamu. edu/toback/109/Syllabus. pdf • Pre-Lecture Reading Questions: – Unit 1: • Pass/Revise: You must get a 10/10 • If you were misgraded, need help or an extension let me know – Unit 2: Due before class Monday • Make sure you get a Receipt from Turn. It. In • End-of-Chapter Quizzes – If we finished Chapter 4 then End-of-Chapter Quiz 4 (else just Chapter 3) • Papers – Paper 0 (training): • Nothing to write! • Reviews due before class Monday • Back-Evaluations before class Wednesday Big Bang, Black Holes, No Math Introduction Topic 4: Scientific Methods 38
For People in the Honors Section Stage 0 (not in CPR): th Due Monday Sept 26 For details see http: //people. physics. tamu. edu/ toback/109/Honors/ Big Bang, Black Holes, No Math Introduction Topic 4: Scientific Methods 39
TAMU Star Party Great opportunity to meet astronomers and their students, ask questions, see the Milky Way and planets, have fun! Big Bang, Black Holes, No Math Introduction Topic 4: Scientific Methods 40
Paper 0 Stuff • Want feedback before turning it in? – Post it in e. Campus in. doc (or. pdf) for comments by the TA by 5 PM Friday – Make sure you polish it • If you have lots of grammar and spelling mistakes we’ll just make you resubmit it Introduction Big Bang, Black 41 Holes, No Math Topic 4: Scientific Methods
First CPR Assignment: PLRQ for Unit 1 in Calibrated Peer Review (CPR) Will announce due dates soon Big Bang, Black Holes, No Math Introduction Topic 4: Scientific Methods 42
Prep For Next Time – L 6 • Reading: – BBBHNM Unit 2 • Pre-Lecture Reading Questions – e. Campus quizzes (all 6) – Unit 1 Revision (if needed): Stage 1 before Class • Let us know if you were misgraded – Unit 2: Stage 2 due before class • End-of-Chapter Quizzes – If we finished Chapter 4 then End-of. Chapter Quiz 4 (else just Chapter 3) Big Bang, Black Holes, No Math Introduction Topic 4: Scientific Methods 43
Pre-Lecture Reading Questions in CPR • The full PLRQ Assignments will be done online using the Calibrated Peer Review (CPR) system – Will be doing a full Unit at a time – Each assignment has 2 stages (more on in the next slide) – The quizzes in e. Campus are about practicing before you start on the CPR system Big Bang, Black Holes, No Math Introduction Topic 4: Scientific Methods 44
Learning to Write and Critique • Each CPR Assignment has two parts (Call them Stage 1 and Stage 2) 1. You do your own writing and submit 2. You review and evaluate other papers (and your own) • Why? – Learn how to determine the difference between excellence and mediocrity (according to the class standard), and give feedback (evaluate) papers to make them better – Learn to better evaluate your own work to make it excellent BEFORE you turn it in • Want you to get good at writing and being able to tell you Black have written excellently before we get to the 45 Introduction Big if Bang, main. Nopaper for this Methods class Topic 4: Scientific Holes, Math assignments
The “I hate CPR Club” • Most students HATE CPR until they get good at it • Many reasons: – Takes practice to get good at the system – Learning how to both be a good writer and be a good evaluator is really difficult (and incredibly important) skill – Takes practice – We require you follow the instructions – You need to learn the standards we will be using in the class, not your own, personal standards • My advice: Don’t fight the system, blame it for being “unfair”, or wish it were “better. ” Just do what it takes to get good at it • Don’t hesitate to ask for help (instructions in the FAQ) • If you are grumbling and neither I nor the TA have heard from you to talk to you about it, then you get what you deserve – Don’t pretend this is a way to get free grading by the Introduction Big Bang, Black 46 instructor… You’ll be wrong and it will just piss you off Topic 4: Scientific Methods Holes, No Math
Stage I and Stage II in CPR Stage I: (Typically due before the first class of the Unit) – Write 4 questions and turn them into CPR (online) Stage II: (Typically due before the following lecture) • Three-Parts 1. Calibrations (learning to use the Rubrics) – Read an example submission and use the grading rubric to answer Yes/No questions and count the fraction of Yeses to assign a score. Evaluate three example submissions (get only one free try to pass the grading rubric) – You have practiced these in e. Campus for the first assignment 2. Reviews (Evaluate three other submitted submissions) – Ignore that it says you have only 5 minutes for this. I have set it so you can start the reviews right after you finish your calibrations 3. Self-Assessment (Evaluate your own submission) Note: You get a separate score for each of the 4 parts (Text, Calibrations, Reviews and Self-Assessment) Big Bang, Black Holes, No Math Introduction Topic 4: Scientific Methods 47
Help Available for Stage I • Now that you have practiced with the Boot Camp, you can revise your questions before submission to CPR • If you want, you can submit a draft for feedback from the TA – Submit on e. Campus in “Rough Drafts (Optional)” • We also recommend going to the Writing Center – This is especially true for when we get to the papers • Most common problems: – Not reading the instructions Big Bang, Black Holes, No Math Introduction Topic 4: Scientific Methods 48
Help Available for Stage II • Stage II help: – Each calibration is graded 0 or 100%. – You only get 2 tries for each of the 3 calibrations – Many students have trouble with the calibrations because they do them RIGHT before they are due, and do them too quickly (and then fail them) • Our advice: – Do them early and ask for help if you fail one the first time – Practice in e. Campus quizzes to help you get good at them Big Bang, Black Holes, No Math Introduction Topic 4: Scientific Methods 49
Unit 1 and Later Units PLRQ Unit 1 in CPR is different than the others since we want to make sure you get good at CPR • It is Pass/Revise • You must pass ALL four parts separately, just a 70% overall score is NOT good enough. You will need: – >70% on the overall score – >35/50 on the text portion of your paper – >14/20 on the calibration portion – >14/20 on the reviews – >7/10 on the self-assessment • I’ll post the grades in e. Campus • If you don’t pass the first time, you will have to do a Revision Assignment (all the parts) until you pass • Later units are just your combined score for all parts – You can do a revision if you want to get a better grade – We will average the two scores Big Bang, Black Holes, No Math Introduction Topic 4: Scientific Methods 50
PLRQ Concerns • Many people don’t seem to realize that there were two different PLRQ assignments – In e. Campus: Quizzes 1 -4 – In CPR: Submit questions (Stage 1) and do all the Review parts (Stage 2) in CPR • Let us know if you think you were misgraded • How to tell if you need to do a Revision – Only the grade in e. Campus matters – Why didn’t I pass? What do you need to do if your e. Campus grade says “Revise”? – See http: //people. physics. tamu. edu/toback/109/ Introduction Big Bang, Black 51 109 FAQ. shtml#CPRGrades Topic 4: Scientific Methods Holes, No Math
Prep For Today (is now due) – L 5 • Reading: – None • Pre-Lecture Reading Questions –Unit 1: Grades posted. • End-of-Chapter Quizzes –Chapters 2 and 3 Big Bang, Black Holes, No Math Introduction Topic 4: Scientific Methods 52
Prep For Next Time – L 5 • Reading: – Required: BBBHNM Unit 2 (Chapters 5 -9) – Recommended Reading: • See P 3 of http: //people. physics. tamu. edu/toback/109/Syllabus. pdf • Pre-Lecture Reading Questions – Unit 1 Revision (if Needed): Stage 1 in CPR due before class • Let me know if you think you were misgraded • Must do entire assignment if your grade in e. Campus says “Revise” – Unit 2: Stage 1 due before class • No more e. Campus stuff for PLRQ • End-of-Chapter Quizzes – If we finished Chapter 4 then End-of-Chapter Quiz 4 Big Bang, Black Holes, No Math Introduction Topic 4: Scientific Methods 53
Some words; “It’s a theory…” • Theory: “A set of rules that relate quantities in a model to observations we make” • Hypothesis: “A tentative assumption that is useful in that it predicts the outcome of an experiment; can be tested” Big Bang, Black Holes, No Math Introduction Topic 4: Scientific Methods 54
Science • For us to “believe” in a theory, or said better, to think it might correspond to truth, we agree that it has to be tested in such a way it can be tested over and over again such that the results must always confirm theory • Does the world function in a “predictable” manner? • What happens when you test a hypothesis? Big Bang, Black Holes, No Math Introduction Topic 4: Scientific Methods 55
What Makes a Good Theory? Two requirements: 1. It must accurately describe a large class of observations, clues, or other pieces of evidence. – For example g, the acceleration due to gravity. Same everywhere on the Earth? 2. It must make DEFINTE PREDICTIONS about the results of FUTURE (not yet done) observations or experiments • Creates testable hypotheses • An astronaut hits a golf ball on the moon. Can we predict its path? Big Bang, Black Holes, No Math Introduction Topic 4: Scientific Methods 56
Yet more on Scientific Method • It also must be falsifiable • If we do an experiment and the results disagree with the predictions of theory, then theory is wrong or has to be modified – It has been said that “even the most beautiful theory can be slain by a single ugly fact” • If theory makes predictions for a new experiment and the data agrees then it gives us really good reason to believe there really are underlying principles in the world we live in Big Bang, Black Holes, No Math Introduction Topic 4: Scientific Methods 57
What science does not promise Science does not promise eternal truths Only promises the systematic elimination of false hypotheses and the establishment of what is currently the most likely explanation of an aspect of reality… Big Bang, Black Holes, No Math Introduction Topic 4: Scientific Methods 58
Everyday Conversation • Explanations that stand the test of time and LOTS of experiments are what we call Theories – Gravity, Quantum Mechanics etc. • When someone says “Well… It’s a theory” we know what they mean. They mean “it’s a hypothesis” – We don’t yell at them for the same reason we don’t get upset when someone says the “Sun is setting” 59 Introduction Big Bang, Black Holes, No Math Topic 4: Scientific Methods
Better experiments… At some point our experiments get so good that we can “observe” things that our eyes can’t see directly – The very small – The very faint and/or far away What happens if theories that explain what we can see with our eyes don’t explain what we see in a microscope? Big Bang, Black Holes, No Math Introduction Topic 4: Scientific Methods 60
Weirdness… Have to try new weirder theories • What if we come up with a theory that accurately “predicts” the results of both the experiments we can do with our eyes AND the really sensitive ones we can do with really special microscopes? • What if that theory is counter to our intuition? Big Bang, Black Holes, No Math Introduction Topic 4: Scientific Methods 61
More weirdness • What if our weird theory then makes further weird predictions? • What if it predicts that if we do a simple experiment we will get crazy results? • What if we DO the experiment and GET the crazy results? At what point do start believing there is some “truth” to theory? Do we change our mind if we don’t LIKE the implications of theory? (The Earth isn’t the center of the universe) Big Bang, Black Holes, No Math Introduction Topic 4: Scientific Methods 62
Fact is Stranger than Fiction • Typically we have confidence in theories that do a good job of predicting the results of experiments have some basis in reality • In the 1920’s scientists starting coming up with such theories: General Relativity and Quantum Mechanics are good examples… Stood up to 90 years of experiments – Will talk in the next unit about what’s weird about them, and what weird things they predict and explain Big Bang, Black Holes, No Math Introduction Topic 4: Scientific Methods 63
Another Piece of Evidence • Can understand the phases of the Moon because of the locations of all three • Not eclipses Big Bang, Black Holes, No Math Introduction Topic 4: Scientific Methods 64
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 rotates around the Earth Big Bang, Black Holes, No Math Introduction Topic 4: Scientific Methods 65
Class trip to Cyclotron Clicker question • Any interest in a class trip to the Cyclotron? If so, which day would you be most interested • A = Wednesday • B = Friday • C = Other day please!!! • D = Not likely to make it Big Bang, Black Holes, No Math Introduction Topic 4: Scientific Methods 66
Prep For Next Time – L 5 • Reading: –BBBHNM: Chap 5 • Reading Questions: – Two questions from Chapter 5 or the recommended reading • End-of-Chapter Quizzes – If we finished Chapter 4 then end-of-chapter quiz 4 (else just 3) Introduction Big Bang, Black 67 Holes, No Math Topic 4: Scientific Methods
Prep For Next Time – L 4 • Note: May change depending on how far we get in lecture (some may have already been due) • Reading: – BBBHNM: All reading up to Chapter 6 • Pre-Lecture Reading Questions: – Two reading questions from Chapter 6 • End-of-Chapter Quizzes – If we finished Chapter 4 then end-of-chapter quiz 4 (else just 3) • Paper 0 – Paper 0 has been posted on CPR – If we finished Chapter 4, then Paper 0 is due one week from today Big Bang, Black Holes, No Math Introduction Topic 4: Scientific Methods 68
Full set of Readings So Far • Required: – BBBHNM: Chap 1 -5 • Recommended: – BHOT: Chap. 1 -3 – SHU: Chap. 1 -3 (p 55 -69) – TOE: Chap. 1 Big Bang, Black Holes, No Math Introduction Topic 4: Scientific Methods 69
Prep for Today (Is now due) – L 5 • Reading: – BBBHNM: Chap 4 • Reading questions – Two questions from Chapter 4 • End-of-Chapter Quizzes: – Chapter 3 Big Bang, Black Holes, No Math Introduction Topic 4: Scientific Methods 70
Phase I, Phase II and Phase III Phase I: (Paper due 1 week after we finish Chapter 4) • Turn in a polished draft to e. Campus • TA’s will provide feedback, but not if there are multiple spelling/grammar mistakes • Pass/Fail grade Phase II: (Due one week after Phase I) • A revised version will be done 1 week later on CPR • When you submit to CPR (after revision), you will need to also submit a copy of your to the turnitin. com line on e. Campus Phase III: (Due one week after Phase II) • Calibrations and Reviewing due one week after you submit Introduction Big Bang, Black Holes, No Math Topic 4: Scientific Methods 71
Paper 0 Stuff – L 9 faculty. physics. tamu. edu/toback/109/Writing. Assignments/ • Phase I: Due last Wednesday – You will get feedback soon, work on revisions now – Email if you need an extension • Phase II: – Due in CPR/Turnitin. com Wednesday • Phase III: – Will talk more about CPR and reviewing Wednesday – Following Wednesday Introduction Big Bang, Black 72 Holes, No Math Topic 4: Scientific Methods
History and Just-So Stories State of our understanding 2500 years ago: “The earth is, obviously, flat…” So, how DID they figure out the earth is round? – Ships on the horizon: Top of the mast first – Aristotle (340 BC): The earth’s shadow on the moon Big Bang, Black Holes, No Math Introduction Topic 4: Scientific Methods 73
Worse… Actually, it’s even worse • What we “believe” can deceive us from understanding how things actually work • Unfortunately, our history is littered with “Just-so stories…” that have set back our understanding Big Bang, Black Holes, No Math Introduction Topic 4: Scientific Methods 74
What we “believe” can mislead us • We “see” the sun/moon go around the Earth, must be so! • The Church demanded that this model be accepted for Religious reasons… – Man should be at the center of the universe – Circular orbits – Perfection! • This model was accepted for nearly 1500 years Big Bang, Black Holes, No Math Introduction Topic 4: Scientific Methods 75
The Church and Science • It’s easy to pick on the church with hindsight • Then again, much of the great progress in our understanding of the physical world comes because science (and lots of other things) were its beneficiary • In today’s lingo “The Church” was the one of the few funding agencies for hundreds of years… – What if you weren’t independently wealthy and wanted to do science? (Want to learn to read? ? ? ) And be able to eat? Either become a priest or a monk… Maybe work for a King? Big Bang, Black Holes, No Math Introduction Topic 4: Scientific Methods 76
Interesting aside Continued: The backlash… • These findings contradicted the Church! • Now scientists have a problem: Galileo was a leading scientist in Italy (close to Rome!) and he was Loud! • The Church spurned this as heretical and set back science (nearly ex-communicated, sentenced to life of house arrest) Big Bang, Black Holes, No Math Introduction Topic 4: Scientific Methods 77
Reading Quizzes • We are not looking for questions where we could get the answer on Google (which you could do) • Wrong questions: – How big is the largest planet we’ve found? – When was the telescope invented? Big Bang, Black Holes, No Math Introduction Topic 4: Scientific Methods 78
Epicycles… Big Bang, Black Holes, No Math Introduction Topic 4: Scientific Methods 79
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Copernicus Continued • This is a test… Big Bang, Black Holes, No Math Introduction Topic 4: Scientific Methods 81
Ptolemy • Eight “bodies” rotating the earth in circular orbits (2 nd century BC). • People accepted this theory even though it had problems (moon should be twice as big. . ) – Church liked it… it stuck and was largely unquestioned – It didn’t offend anyone Big Bang, Black Holes, No Math Introduction Topic 4: Scientific Methods 82
Kepler Big Bang, Black Holes, No Math Introduction Topic 4: Scientific Methods 83
Ptolomy Big Bang, Black Holes, No Math Introduction Topic 4: Scientific Methods 84
Brahe Big Bang, Black Holes, No Math Introduction Topic 4: Scientific Methods 85
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SHU: Chapter 1 • Eratosthenes (Greek mathematician) • Different length shadows at the same TIME of day. • Pictures? Pages 22 and 23 Big Bang, Black Holes, No Math Introduction Topic 4: Scientific Methods 87
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Greek view of the universe Big Bang, Black Holes, No Math Introduction Topic 4: Scientific Methods 92
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