Big Bang Black Holes No Math ASTRPHYS 109

Big Bang, Black Holes, No Math ASTR/PHYS 109 Dr. David Toback Lectures 10 -13 Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 1

The Training Wheels are now off • I’m happy to help, but you are expected to know what to do for all assignments • If you have done the work diligently, you should be able to concentrate on just the science from here on out Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 2

Was Due for Today – L 11 • Reading: – (Unit 2) • Pre-Lecture Reading Questions: – (Unit 2 Question Writing Assignment) – (Unit 2 Quiz) • End-of-Chapter Quizzes – End-of-Chapter Quiz 6: Was due before class • Feynman Diagram Drawing Assignment – Will describe today – See http: //people. physics. tamu. edu/toback/109/Diagrams/Feynman. Diagram. Assignments. pdf • Papers – The text of Paper 1 will be due in Turn. It. In (in e. Campus) and Peerceptiv by 11: 55 PM on Mon Sept 28 th – You should do your Reviews right after submitting. Can do all 3 separately, but you should finish any that you start in a single sitting or Peerceptiv has problems – You will get Reviews (may take awhile to get the third), but you only have 72 hours after one arrives to finish or you will time out – You need to pass the Review and Feedback stage to get a grade – You can submit a revision at any time, but you have to do a new set of Reviews and Feedbacks for it to count • Honors Section: Physics Need – If Black your Stage 0 isn’t approved, I’d like We to hear from you Big Bang, 3 Need to hear. Topic from you least once every 7 days 3: at. Quantum Mechanics and Atoms Holes, –No Math

Was Due for Today – L 12 • Reading: – (Unit 2) • Pre-Lecture Reading Questions: – (Unit 2 Text Submission and Unit 2 Quiz) • End-of-Chapter Quizzes – (Chapter 6) • Feynman Diagram Drawing Assignment – Will assign today • Papers – The text of Paper 1 is due in Turn. It. In (in e. Campus) and Peerceptiv TONIGHT by 11: 55 PM (Mon Sept 28 th) – You are required to finish each Review within 72 hours after being assigned it. You are required to finish each Feedback within 72 hours – You need to pass the Review and Feedback stage to get a grade – You can submit a revision at any time, but you have to do a new set of Reviews and Feedbacks for it to count • Honors Section: – If your Stage 0 isn’t approved, I’d like to hear from you – Need to hear from you at. Physics least once every 7 days We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 4

Was Due for Today – L 13 • Reading: – (Unit 2) • Pre-Lecture Reading Questions: – (Unit 2 Text Submission and Unit 2 Quiz) • End-of-Chapter Quizzes – (Chapter 6) • Feynman Diagram Drawing Assignment – Feynman Diagram Assignment 1 (in e. Campus) will be assigned when we finish Chapter 7 – http: //people. physics. tamu. edu/toback/109/Diagrams/Feynman. Diagram. Assignments. p df – http: //people. physics. tamu. edu/toback/109/Diagrams/Drawing. Feynman. Diagrams. pdf • Papers – Paper 1 Text: Was due already – You are required to finish each Review within 72 hours after being assigned it. You are required to finish each Feedback within 72 hours – You need to pass the Review and Feedback stage to get a grade – You can submit a revision at any time, but you have to do a new set of Reviews and Feedbacks for it to count • Honors Section: – Stage 1 Draft is now due Physics We 7 Need – Need to hear from you at least once every days Big Bang, Black 5 Holes, No Math Topic 3: Quantum Mechanics and Atoms

Paper 1 • Abbreviated description: What is the evidence for Dark Matter? – More detail on Peerceptiv, you REALLY need to read ALL the instructions • Explain it to someone who isn’t taking the class (no jargon) • Follow the required Format: – Introduction paragraph • Lawyers opening arguments at a Trial – ~1 paragraph per piece of evidence/talking point • The case at a Trial – Conclusion paragraph that ties it together • Lawyers closing arguments at a Trial • Help: – Example of good paper Physics We Need Big http: //people. physics. tamu. edu/toback/109/Writing. Assignments/samplepaper. shtml Bang, Black 6 Holes, No Math Topic 3: Quantum Mechanics and Atoms

Taken from Peerceptiv for Paper 1 Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 7

Reminders about Papers Re-read pages 48 -52 of the Course Organization Document http: //people. physics. tamu. edu/toback/109/Course. Organization. pdf Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 8

So Far Topics 1. Light and Doppler Shifts Done 2. Gravity, General Relativity and Dark Matter Done 3. Atomic Physics and Quantum Mechanics Now 4. Nuclear Physics and Chemistry 5. Temperature and Thermal Equilibrium Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 9

Where We Are Going Next In Chapter 3 we learned a little about how the stuff of the Universe is put together • Big things are made from LOTS of small things • Small things: The Fundamental Building Blocks of Nature –What is the “stuff” in atoms? Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 10

The Largest Stuff • Most of the light we see from space comes from stars • What are stars made of? – Stars are lots of atoms interacting – The ways they interact creates light we can see – Can study the distant stars by looking at the light from them – Can study atoms here on Earth. Are they the Physics We Need Big Bang, Black Holes, same? No Math Topic 3: Quantum Mechanics and Atoms 11

How do Atoms work? • Electro. Magnetism (electric charge) – What holds electrons and protons together • Quantum Mechanics – The way atoms form and do the funny things they do (which allows us to exist) – Electrons in orbits – Atoms absorbing and emitting photons (light) Chapter 7 Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 12

Different Types of Atoms Chapter 8 • The Strong Force – Keeps protons and neutrons together in the atomic nucleus – Different types of nuclei different types of atoms – Different atoms Different light… • Nuclear Physics and Chemistry • Studying the Stars using their light – Spectral lines of the atoms – Atomic “fingerprints” – The light we see from the stars Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 13

Overview of the story • Big things are made from LOTS of small things • Small things: The Fundamental Building Blocks of Nature – What is the “stuff” in atoms • Electro. Magnetism (electric charge) – What holds electrons and protons together • Quantum Mechanics – Why atoms form the way they do – Electron in orbits – Atoms absorbing and emitting photons (light) This Lecture • The Strong Force – Keeps protons and neutrons together Next – Different types of nuclei different types of atoms Lecture – Different atoms Different light… • Nuclear Physics and Chemistry Different TYPES of Atoms • Studying the Stars using their light – Spectral lines of the atoms – Atomic “fingerprints” – The Black light we see from Physics the stars We Need Big Bang, 14 Holes, No Math Topic 3: Quantum Mechanics and Atoms

The Fundamental Building Blocks Our best understanding: The very BIG stuff is made up of LOTS of very small stuff Need to understand: 1. What are the fundamental building blocks of nature 2. How it’s all held together 3. How they “create” the light we see Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 15

Early Evidence for the Atomic Model (before we knew it was electrons orbiting a nucleus) Shoot atoms at a “target” Theory: Experiment (1910’s): 1? Bag stuffed with cotton 2? Bag stuffed with cotton and a few small rocks The experiment gives results like #2! The positive charge in an atom and most of its mass is concentrated in a tiny, very dense center: The Nucleus Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 16

The Building Blocks of Nature In the 19 -teens and 20’s experiments determined: • Atoms are made of a nucleus surrounded by electrons – Many types of nuclei – Only one kind of electron Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 17

Nuclear Physics Many years later (using many of the same methods): • Nucleus is composed of neutrons and protons • Number of protons and neutrons in the nucleus determines the atom type – Explains the periodic table 18 Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms

The Fundamental Building Blocks of Atoms • Electrons Talked about this • Neutrons in Chapter 3 More in Chapter 8 • Protons – Neutrons and Protons are really made of quarks • Discovered in the 1970’s • We’ll talk more about this in the next chapter Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 19

Putting Them Together Why do the fundamental building blocks stick together to form atoms? Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 20

Overview of the story • Big things are made from LOTS of small things • Small things: The Fundamental Building Blocks of Nature – What is the “stuff” in atoms • Electro. Magnetism (electric charge) – What holds electrons and protons together • Quantum Mechanics – Why atoms form the way they do – Electron in orbits – Atoms absorbing and emitting photons (light) • The Strong Force – Keeping protons and neutrons together – Different kinds of nuclei • Nuclear Physics and Chemistry different atoms • Spectral lines of the atoms – Atomic “fingerprints” – The light we see from the stars Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms This Lecture Next Lecture 21

Electro. Magnetism • You probably already know that protons and electrons have “electric” charges • Positive charge and negative charge attract each other • Call this Electro. Magnetism + - Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 22

Weirdness… You probably never thought about it this way but in many ways the way things with electric charge attract is very similar to gravity + - Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 23

Gravity vs. Electro. Magnetism Gravity • Every object in the universe attracts every other object in the universe • The bigger the mass, the bigger the attraction • The further the distance between the objects, the smaller the attraction Electro. Magnetism • Every charged object in the universe “attracts” every other charged object in the universe • The bigger the charge, the bigger the attraction • The further the distance between the objects, the smaller the attraction Physics 202 Physics 201 Physics We Need Big Bang, Black Physics 207 Physics 206 3: Quantum Mechanics and Atoms Holes, No Math Topic 24

What’s different? • Gravity: – All objects attract no matter what – (As far as we know…) • Electro. Magnetism: – Ignores neutral particles Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 25

Other Differences • Electro. Magnetism is MUCH stronger than gravity • If I have two electrons, the electric force between them is so powerful that it is 1042 times stronger than gravity –Can “ignore” gravity inside atoms Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 26

Aside • Electro. Magnetism is MUCH weaker than the Strong Force • For two quarks inside a proton the Strong Force is ~100 times stronger than the EM force – Can almost “ignore” Electromagnetism inside protons Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 27

Atomic Physics How do we make up atoms? 1. Start by describing a simple (partially wrong) atomic model – Positive Nucleus attracts the negatively charged electrons and keeps them in “orbit” 2. Then move to the weird world of Quantum Mechanics Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 28

A Hydrogen Atom The simplest atom: Hydrogen One electron and one proton (Partially wrong) Figure not to scale - | + | ~10 -15 m | ~10 -10 m Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms | 29

Is the world this simple? • This is a nice simple model • Why does the electron stay in “orbit”? • Simple (partially wrong) answer: There is a “Force” that keeps it in orbit just like Gravity keeps the Earth orbiting the Sun Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 30

Why the simple answer can’t be the whole story • Electromagnetism says electrons emit energy/slow down when they move in circles (are accelerated by the EM Force) – Kinda like friction • Observe this for electrons moving in big circles • Should be true for electrons in small circles (atoms) also Spiral down until they hit the nucleus and we’d have nothing: No atoms! – Calculations show it would take ~10 picoseconds (10 -11 s) – (This is one of the reasons people in the late 1800’s thought electrons orbiting protons was Physics We Need Big Bang, Black 31 WRONG!) Holes, No Math Topic 3: Quantum Mechanics and Atoms

Another Problem • Stars can be in orbit any distance from the center of the galaxy – Depends only on their speed • Electrons should, depending on their speed, be able to orbit almost anywhere near the nucleus (like a planet or a comet) • Don’t observe this… Electrons only observed to orbit at specific distances from a nucleus (energy levels) Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 32

Overview of the story • Big things are made from LOTS of small things • Small things: The Fundamental Building Blocks of Nature – What is the “stuff” in atoms • Electro. Magnetism (electric charge) – What holds electrons and protons together • Quantum Mechanics – Why atoms form the way they do – Electron in orbits – Atoms absorbing and emitting photons (light) • Different TYPES of Atoms – The Strong Force – Keeping protons and neutrons together (atomic nuclei) – Nuclear Physics and Chemistry – Different atoms Different light… • Studying the Stars using their light – Spectral lines of the atoms – Atomic “fingerprints” – The light we see from the stars Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms This Lecture Next Lecture 33

Quantum Mechanics • How do we explain these weird features that we observe about Atoms? • Quantum Mechanics! • LOTS we COULD say about QM, but since we could spend years on this we’ll focus only on the most important points you need Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 34

Quantum Mechanics • All particles are both particles AND waves –Saw this for photons –Turns out to be true for electrons also! Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 35

Energy of Electron Waves • Small-energy electrons have large wavelengths • Smallwavelength electrons have large energy Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 36

Quantized Numbers • This has big implications for electrons in atoms • The electron “wave” has to go all the way around an exact number of wavelengths – Whole (Integer) number of wavelengths – Otherwise it will “interfere with itself” or “cancel itself out” like a water wave or noisecancelling headphones http: //bigbang. physics. tamu. edu/Animations/Sign. Wave_atom. gif Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 37

Only Orbits with Specific Wavelengths Work • The electron “wave” has to go all the way around • Can have one peak/trough, two peaks/troughs, three peaks/troughs etc… – A quantized number – The Quantum in Quantum Mechanics Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 38

Only certain wavelengths work? • If only certain wavelengths work, only certain energies are allowed • This means electrons can ONLY be in one of the allowed energy states, and at certain distances from the nucleus – Keep atoms from collapsing! (Good!) – “Quantizes” the interactions with light i. e. only some energy photons interact with atoms Physics We Need Big Bang, Black 39 Holes, No Math Topic 3: Quantum Mechanics and Atoms

Only Orbits with Specific Wavelengths Work • Lower Energy and closer to the nucleus • Higher Energy and further away from the nucleus Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 40

Energy and Distance from The Nucleus Higher Energy and further away from the nucleus Lower Energy and closer to the nucleus Big Bang, Black Holes, No Math Only these levels Physics We Need are allowed! 41 Topic 3: Quantum Mechanics and Atoms

Next: How we “SEE” atoms Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 42

How Photons Interact with an Atom • To understand better how photons interact with the stuff in an atom, “how we’ll SEE atoms”, we need to say a bit more about Energy and about Quantum Mechanics • Lots of different ways they can interact… start with the simple interactions Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 43

Simple: Photon-Atom Collision • Before: Start with a high energy photon and a low energy atom • After: Lower energy photon, higher energy atom (like two billiard balls colliding) • Same TOTAL energy before and after collision – Conservation of Energy Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 44

Clicker Question After a collision with a stationary atom, the energy of a photon is a) Higher b) Lower c) Same Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 42

Clicker Question After a collision with a stationary atom, the speed of a photon is a) Higher b) Lower c) Same Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 46

Clicker Question After a collision with a stationary atom, the wavelength of a photon is a) Longer b) Shorter c) Same Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 47

Atom-Photon Perspective • Photon’s perspective: I collide with a low energy atom and “transfer” some of my energy • Atom’s perspective: A high energy photon collides with me and I “take” some of its energy Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 48

Next: Collisions, Quantum Mechanics and Electromagnetism Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 49

Quantum Mechanics and EM • In General Relativity we found that it is better to describe the “force” of gravity as the curvature of space-time • How do we “better” describe Electro. Magnetism, especially with Quantum Mechanics? – Electric fields • Answer: In Electro. Magnetism “Force” is essentially all about the “emission” and “absorption” of photons by charged particles like electrons and protons Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 50

Quantum Mechanics – Force Carriers • Think of the force between electrically charged things as being caused by the exchange of “virtual” photons • The force, or interaction, is “carried” by particles Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 51

Analogy with Two Electrons • First electron emits a “force-carrying” particle (a photon) • Causes a recoil of the first electron – You shoot a gun and lurch back • The other electron “catches” it and gets “banged” – Your friend gets hit with the bullet and falls backward • Net result: The two particles move differently, “as if” there were a force between them Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 52

Visualizing Our Analogy 1: Two electrons held in place, then let go 2: electron on the right “emits” a photon and “recoils” - - 3: Photon bangs into the left electron and bumps it Both now move apart: Same sign charges “repel” each other Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 53

A Proton and Electron 1: A proton and an electron hanging out 2: Proton on the right “emits” a photon and “recoils” - + 3: Photon bangs into the electron Doesn’t transfer Momentum Transfers information on how to move Opposite signs attract For those of you who know a little bit, this Physics We Need Big Bang, Black 54 is how “electric fields” work Holes, No Math Topic 3: Quantum Mechanics and Atoms

More Interactions • Can also get electrons and protons interacting with REAL photons – Photons we can see, as opposed to ones that are emitted then absorbed never to be seen outside the interaction • Real photons can be emitted or absorbed Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 55

Electron and Photon Interacting Electron can “absorb” a photon Electron becomes more energetic - Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 56

Electron Emitting a Photon Electron can “emit” a photon Electron becomes less energetic - Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 57

A Simple way of drawing things: Feynman Diagrams Electron can “absorb” a photon becomes more energetic Electron can “emit” a photon becomes less energetic e e g g We’ll have some assignments on learning how to do these soon Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 58

Feynman Diagram for an Atom Hydrogen Atom P P g e- e- • A diagram of how the particles “talk” to each other • These two are attracted Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 59

Photon interacting with an electron in an Atom If a photon with the right energy hits an atom and is absorbed, the electron can “jump” to an “excited state” Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 60

Excited Atom Emits a Photon If an atom is in an excited state, it’s just a matter of time before it emits a photon with exactly the energy between Physics We Need Bigthe Bang, Black two states Holes, No Math Topic 3: Quantum Mechanics and Atoms 61

Other ways of drawing the same thing • An electron can move into a more energetic orbit when it absorbs a real photon with exactly the right energy • The photon is absorbed, and the electron goes into an excited state • A high energy atom can “emit” a photon and go into a lower energy state Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 62

A Proton bumps into an atom and excites it Atom in a Higher Energy State Atom in Lowest Energy State Proton Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 63

An Excited Atom Emits a Photon Atom in Lowest State Atom in a high Energy State Photon with a specific energy Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 64

Absorbing and Emitting a Photon http: //bigbang. physics. tamu. edu/Figures/Stolen. Animations/bohr. swf Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 65

Lots of Different Energy States Physics We Need Big Bang, Black 66 http: //bigbang. physics. tamu. edu/Figures/Stolen. Animations/Bohr. Atom. avi Holes, No Math Topic 3: Quantum Mechanics and Atoms

Photons and Atoms Photons can interact with Atoms in three ways 1. Very low energy photon: Because the electron in the atoms can only have quantized states around the nucleus VERY low energy photons will be ignored, or bump the atom – Ignoring is a kind of interaction 2. If an atom encounters a photon with the “right energy” photon it can get “excited” and go into a higher energy state. The photon is absorbed and is gone forever 3. If a REALLY energetic photon comes along it can completely knock an electron out of orbit from a nucleus Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 67

Putting it All Together A cartoon of an atom and a photon Note: The electron being completely out of the atom is a perfectly good “energy state” Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 68

Atomic Transitions • Any photon that hits the atom with the right energy will be absorbed • Absorbs only special colors Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 69

How is this helpful? • Can look at light from a light bulb all colors observed • Look at light from a light bulb with Hydrogen gas in the way – Only special Atomic Fingerprinting colors will be Physics We Need Big Bang, Black 70 absorbed! Holes, No Math Topic 3: Quantum Mechanics and Atoms

Atomic Fingerprints • Each atom produces a large number of different wavelengths with VERY SPECIFIC values • Quantum Mechanics predicts ALL of them • If you see all the ones you expect and none you don’t, that gives you confidence Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 71

Feynman Diagram Assignments • Learning to write down the diagrams that dictate what occurs at various times during the evolution of the universe since the Big Bang until today • There are 4 short assignments for the course in e. Campus in the Quizzes Folder 1. Electromagnetic Force Interactions (Chapter 7) 2. Strong Force Interactions (Chapter 8) 3. Annihilation and Creation (Chapter 9) 4. Nuclear Decays (Chapter 12 and 14) http: //people. physics. tamu. edu/toback/109/Diagrams/Feynman. Diagram. Assignments. pdf and http: //people. physics. tamu. edu/toback/109/Diagrams/Drawing. Feynman. Diagrams. pdf Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 72

Lecture on Chapter 7 now complete Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 73

Outline for Unit 2: Physics We Need 1. Light and Doppler Shifts Done 2. Gravity, General Relativity and Dark Matter Done 3. Atomic Physics and Quantum Mechanics Done 4. Nuclear Physics and Chemistry Next 5. Temperature and Thermal Equilibrium Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 74

Prep For Next Time – L 10 • • • Reading: – (Unit 2) Pre-Lecture Reading Questions: – (Unit 2 Question Writing Assignment) – (Unit 2 Quiz) End-of-Chapter Quizzes – If we finished Chapter 7 then End-of-Chapter Quiz 7 a & 7 b (else, just through Chapter 6) Feynman Diagram Drawing Assignment – Will assign next time Papers – The text of Paper 1 will be due in Turn. It. In (in e. Campus) and Peerceptiv by 11: 55 PM on Mon Sept 28 th – Reviews and back-evaluations will be available as you fellow Aggies move through the system. Will be due 1 week after submission – You need to pass the Review and Back-evaluation stage to get a grade – You can submit a revision at any time, but you have to do a new set of Reviews and Back-evaluations for it to count Honors Section: – If your Stage 0 isn’t approved, I’d like to hear from you – Need to hear from you at least once every 7 days Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 75

Prep For Next Time – L 10 • • • Reading: – (Unit 2) Pre-Lecture Reading Questions: – (Unit 2 Question Writing Assignment) – (Unit 2 Quiz) End-of-Chapter Quizzes – Chapter 6 Feynman Diagram Drawing Assignment – Will assign next time Papers – The text of Paper 1 will be due in Turn. It. In (in e. Campus) and Peerceptiv by 11: 55 PM on Mon Sept 28 th – Reviews and back-evaluations will be available as you fellow Aggies move through the system. Will be due 1 week after submission – You need to pass the Review and Back-evaluation stage to get a grade – You can submit a revision at any time, but you have to do a new set of Reviews and Back-evaluations for it to count Honors Section: – If your Stage 0 isn’t approved, I’d like to hear from you – Need to hear from you at least once every 7 days Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 76

Prep For Next Time – L 11 • Reading: – (Unit 2) • Pre-Lecture Reading Questions: – (Unit 2 Text Submission and Unit 2 Quiz) • End-of-Chapter Quizzes – If we finished Chapter 7 then End-of-Chapter Quiz 7 a & 7 b (else, just through Chapter 6) • Feynman Diagram Drawing Assignment – If we finished Chapter 7, then Feynman Diagram Assignment 1 is due before class – http: //people. physics. tamu. edu/toback/109/Diagrams/Feynman. Diagram. Assignments. p df – http: //people. physics. tamu. edu/toback/109/Diagrams/Drawing. Feynman. Diagrams. pdf • Papers – The text of Paper 1 will be due in Turn. It. In (in e. Campus) and Peerceptiv by 11: 55 PM on Mon Sept 28 th – You are required to finish each Review within 72 hours after being assigned it. You are required to finish each Feedback within 72 hours – You need to pass the Review and Feedback stage to get a grade – You can submit a revision at any time, but you have to do a new set of Reviews and Feedbacks for it to count • Honors Section: – If Black your Stage 0 isn’t approved, I’d like We to hear from you Physics Need Big Bang, 77 – Need to hear. Topic from you at least once every 7 days 3: Quantum Mechanics and Atoms Holes, No Math

Prep For Next Time – L 11 • • • Reading: – (Unit 2) Pre-Lecture Reading Questions: – (Unit 2 Text Submission and Unit 2 Quiz) End-of-Chapter Quizzes – (Chapter 6) Feynman Diagram Drawing Assignment – Will assign next time Papers – The text of Paper 1 will be due in Turn. It. In (in e. Campus) and Peerceptiv by 11: 55 PM on Mon Sept 28 th – Reviews and back-evaluations will be available as you fellow Aggies move through the system. Will be due 1 week after submission – You need to pass the Review and Back-evaluation stage to get a grade – You can submit a revision at any time, but you have to do a new set of Reviews and Back-evaluations for it to count Honors Section: – If your Stage 0 isn’t approved, I’d like to hear from you – Need to hear from you at least once every 7 days Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 78

Prep For Next Time – L 12 • Reading: – (Unit 2) • Pre-Lecture Reading Questions: – (Unit 2 Text Submission and Unit 2 Quiz) • End-of-Chapter Quizzes – If we finished Chapter 7 then End-of-Chapter Quiz 7 a & 7 b (else, just through Chapter 6) • Feynman Diagram Drawing Assignment – If we finished Chapter 7, then Feynman Diagram 1 Assignment (in e. Campus) is due before class Wednesday – http: //people. physics. tamu. edu/toback/109/Diagrams/Feynman. Diagram. Assignments. p df – http: //people. physics. tamu. edu/toback/109/Diagrams/Drawing. Feynman. Diagrams. pdf • Papers – The text of Paper 1 is due in Turn. It. In (in e. Campus) and Peerceptiv TONIGHT by 11: 55 PM (Mon Sept 28 th) – You are required to finish each Review within 72 hours after being assigned it. You are required to finish each Feedback within 72 hours – You need to pass the Review and Feedback stage to get a grade – You can submit a revision at any time, but you have to do a new set of Reviews and Feedbacks for it to count Honors Section: Physics We Need Big • Bang, Black 79 – If your Stage 0 isn’t approved, I’d like to hear from you Holes, No Math Topic 3: Quantum Mechanics and Atoms

Prep For Next Time – L 12 • Reading: – (Unit 2) • Pre-Lecture Reading Questions: – (Unit 2 Text Submission and Unit 2 Quiz) • End-of-Chapter Quizzes – (Chapter 6) • Feynman Diagram Drawing Assignment – Feynman Diagram 1 Assignment (in e. Campus) will be assigned when we finish Chapter 7 – http: //people. physics. tamu. edu/toback/109/Diagrams/Feynman. Diagram. Assignments. p df – http: //people. physics. tamu. edu/toback/109/Diagrams/Drawing. Feynman. Diagrams. pdf • Papers – The text of Paper 1 is due in Turn. It. In (in e. Campus) and Peerceptiv TONIGHT by 11: 55 PM (Mon Sept 28 th) – Reviews and back-evaluations will be available as you fellow Aggies move through the system. Will be due 1 week after submission – You need to pass the Review and Back-evaluation stage to get a grade – You can submit a revision at any time, but you have to do a new set of Reviews and Back-evaluations for it to count • Honors Section: – If Black your Stage 0 isn’t approved, I’d like We to hear from you Physics Need Big Bang, 80 – Need to hear. Topic from you at least once every 7 days 3: Quantum Mechanics and Atoms Holes, No Math

Prep For Next Time – L 13 • Reading: – (Unit 2) • Pre-Lecture Reading Questions: – (Unit 2 Text Submission and Unit 2 Quiz) • End-of-Chapter Quizzes – If we finished Chapter 7 then End-of-Chapter Quiz 7 a & 7 b (else, just through Chapter 6) • Feynman Diagram Drawing Assignment – If we finished Chapter 7, then Feynman Diagram 1 Assignment (in e. Campus) is due before next class – http: //people. physics. tamu. edu/toback/109/Diagrams/Feynman. Diagram. Assignments. p df – http: //people. physics. tamu. edu/toback/109/Diagrams/Drawing. Feynman. Diagrams. pdf • Papers – Paper 1 Text: Was due already – You are required to finish each Review within 72 hours after being assigned it. You are required to finish each Feedback within 72 hours – You need to pass the Review and Feedback stage to get a grade – You can submit a revision at any time, but you have to do a new set of Reviews and Feedbacks for it to count • Honors Section: – Stage 1 Draft is now due Physics We Need Big Bang, Black 81 – Need to hear. Topic from you at least once every 7 days 3: Quantum Mechanics and Atoms Holes, No Math

Full set of Readings So Far • Required: – BBBHNM: Chap 1 -9 • Recommended: – BHOT: Chap. 1 -6, 9 and 11 (117 -122) – SHU: Chap. 1 -3, 6 and 7 (upto page 153) – TOE: Chap. 1 Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 82

Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 83

Clicker Quiz Which object creates the biggest part of the dent in space time for the Moon? a) Earth b) Sun c) They are equal d) It depends on which side of the Earth the Moon is on e) It depends on which side of the Sun the Earth is on Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 84

Clicker Quiz Let’s pretend that the Earth suddenly became twice as heavy (but stayed the same size), and the moon stayed at the same distance in its orbit and continued to orbit. Which of the following would be true about the moon’s speed? a) Same b) Faster c) Slower d)Bang, Not. Black enough information Physics We Need Big 85 Holes, No Math Topic 3: Quantum Mechanics and Atoms

Clicker Question As far as we know, Dark Matter exists: a) Everywhere in the universe b) Only near black holes c) Only in or around galaxies d) It doesn't exist e) We don't know anything about Physics We Need Big Bang, Black 86 where it exists Holes, No Math Topic 3: Quantum Mechanics and Atoms

Clicker Question What would happen if a "dark matter” bullet hit you from the front. Assume it has the same size and mass as a regular bullet, and moved at the typical speed as if it were shot from a high powered rifle? a) Your molecules would significantly spread out from an expansion of space-time b) A black hole would form inside you c) People behind you would see significant gravitational lensing d) Your body would barely notice e) You would die like you would if you got shot with any kind of bullet Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 87

Clicker Question Consider a near and far galaxy, where the light from the far galaxy is lensed by the near galaxy to create an Einstein ring. Let’s say a mythical Dark. Matter-Sucker came up to the near galaxy and sucked out ONLY the dark matter. What would happen to the size of the Einstein ring? a) Nothing b) It would get smaller c) It would get bigger d) It would disappear completely e) None of the above Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 88

Clicker Question Which of the following provide evidence for the existence of dark matter? Select all which apply: 1. The speeds of stars as they orbit the outer parts of a galaxy 2. Gravitational lensing 3. The total amount of light from outer space. Note: Here we are talking about the AMOUNT of light produced, not what happens to it as it travels through space 4. Colliding Stars 5. Most of space is dark 6. Observations of matter falling into Black holes a) b) c) d) e) 1 only 1 and 2 only 1, 2 and 3 1, 2 and 4 1, 2 and 5 Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 89

Star Party Tonight Howdy! The Texas A&M University Astronomy Group is hosting a star party on Wednesday, February 20 th from 7 -9 PM in front of Sbisa Dining Hall. The star parties are open to students and the public; no registration is necessary. For more information, check our Facebook page https: //www. facebook. com/TAMUStar. Party/, go to http: //instrumentation. tamu. edu/starparty or contact Dr. Jennifer Marshall at marshall@tamu. edu. Weather permitting -any cancellations will be posted on the website or Facebook. Sincerely, Doyeon Kim Star Parties Coordinator Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 90

Clicker Question A hydrogen atom is hit by a photon and the electron absorbs the photon and moves to an excited state. Later, a photon with the exact same energy is emitted from the atom, and the electron moves back to its original state. Is this the same photon as before? a) Yes, it was inside the electron b) Yes, it was bouncing around inside the atom c) No, the electron destroyed the original photon and created the new photon d) No, the nucleus destroyed the original photon and created the new photon Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 91

Clicker Question A man shoots a red photon straight up into the air next to a very tall building. The photon rises in the air. Which statements are true: a) The photon slows down as it rises, the same way a rock would b) The photon loses energy, the same way a rock would c) The photon gets blue-shifted Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 92

Clicker Question Instead of throwing a rock into the air, a man shoots a red photon straight up into the air next to a very tall building. The following question are about the photon when it reaches the top of the building. Which of the following statements are true Question 1: Speed a) The speed of the photon stays the same b) The speed of the photon slows down like a rock would Question 2: Energy a) The energy of the photon stays the same b) The energy of the photon gets lower (like the kinetic energy would for a rock) c) The energy of the photon gets larger (since it is getting closer to outer space) Question 3: Color a) The color of the photon stays the same b) The color of the photon is red-shifted (gets a longer wavelength) c) The color of the photon is blue-shifted (gets a shorter wavelength) Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 93

Clicker Question Why is dark matter "dark“? a) Because it is closely linked to dark energy b) Because it has no mass c) Because it is made of black holes d) Because it doesn’t interact Big Bang, Black light Physics We Need with 94 Holes, No Math Topic 3: Quantum Mechanics and Atoms

More Quantum Weirdness Electron can “absorb” a photon becomes more energetic g e e e Electron can “emit” a photon becomes less energetic g e Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 95

Summary: Atoms vs. Planets Quantum Mechanical effects only the very small (atoms) • Electron orbits around a nucleus: Quantized “radii” • Planets around the Sun: Not Quantized (too big) Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 96

• Aside: Actually true for the Earth also. However, it would take 1024 years (a Quadrillion years, or a yotta-year) to spiral down into the Sun. That’s a billion times the lifetime of the universe Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 97

Atomic Transitions • What happens if a photon doesn’t have the exact right energy to excite an atom it meets? • Passes the atom unabsorbed • Note… knocking the electron completely out of the atom is a perfectly good “excited state” Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms Wrong energy 98

Special Photon Energies Atoms only “absorb” or “emit” Special wavelength photons • Can only go from one state to another – Only specific colors absorbed – Only photons with specific energy can come out. Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 99

Analogy Think about Asteroids (or other space junk) banging into the Earth • Small piece of junk: Not much happens • Big asteroid: Wipes out the dinosaurs • REALLY BIG Asteroid: Knocks the Earth out of orbit and off into space (this would be bad) Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 100

Aside Smaller: • As far as we know all protons (and neutrons) are identical • Each particle has an anti-particle – More on this stuff later Bigger: • How atoms combine to form molecules and how molecules interact is really chemistry – Won’t spend too much time on this Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 101

Other Questions • What are stars made of? • What can we learn from looking at them? • How do we know? Need to know about the stuff out there and how it interacts to create the light we see on Earth Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 102

Big Picture: Looking at the Heavens What we know about the universe comes from multiple places • Already earned about the light coming from the heavens • Need to know more about WHAT PRODUCES the light we observe Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 103

Only Orbits with Specific Wavelengths Work • The electron “wave” has to go all the way around • Can “wave” once, twice, three times etc… – A quantized number Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 104

Only Orbits with Specific Wavelengths Work • Lower Energy and closer to the nucleus • Higher Energy and further away from the nucleus Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 105

Paper Stuff • Paper 1 now in progress – The calibration and review portions are due by Wed Feb 24 th, BEFORE class • Paper 2 will be due 1 week after we finish Chapter 8 – Tentatively, due March 8 th Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 106

What Do we Need to Know? When we look at the heavens, we want an answer to the question “what IS all that stuff made of? ” Going Further: What is all the stuff that the “stuff” is made of? What’s the evidence for all this? 107 Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms

In-Class Writing Assignment Write down, during the course of lecture, Two questions you want to know the answer to Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 108

In Class Quiz Answer the following question: Tell why the subject of “light” is SO IMPORTANT that we spent an entire on it Make sure to include what we learned that was so important (AND WHY!!) Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 109

Does this make sense? Most objects we know and love (the Earth, us etc. ) have LOTS of electrons and protons • If EM is so much stronger than Gravity why don’t we feel it? • Why doesn’t the Earth feel the electric charge of the electrons and protons in the Sun? Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 110

EM vs. Gravity • Answer: Equal numbers of protons and electrons – Each atom/molecule is exactly electrically neutral or they would attract more charge to make them so Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 111

– Bottom line: Accelerating charges emit photons, and accelerating masses emit gravity “waves. ” Can’t explain atoms in your body that “live for years” Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 112

What’s different? • Gravity: – All objects attract no matter what – (As far as we know…) • Electro. Magnetism: Like charges repel each other Opposite charges attract each other – Ignores neutral particles Physics We Need Big Bang, Black Holes, No Math Topic 3: Quantum Mechanics and Atoms 113