Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math 1 Big Bang, Black Holes, No Math ASTR/PHYS 109 Dr. David Toback Lecture 13 & 14

Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math 2 Was due Today – L14 Reading: –BBBHNM Unit 3 Pre-Lecture Reading Questions: –Let us know if you were misgraded –Unit 3, Stage 1 End-of-Chapter Quizzes: –Chapter 8 Papers: –Paper 1, Stage 2 –Paper 2, Stage 1: Due before class on Wednesday (Text needs to be in turnitin on eCampus) Honors Paper: –Stage 1 due March 11th

Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math 3 Where we are… Topics 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  Done 5.Temperature and Thermal Equilibrium  This Time

Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math 4 Looking at the Lights in the Sky What we know about the universe comes from multiple places So far: Learned about the light coming from the stars The evidence that stars are made of atoms

Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math 5 Other Stuff Out There… We don’t just look at the stars… We can learn a lot from looking at light in other ways too… –Talk about this today…

Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math 6 The World in a Jar As we’ll see, in many ways when we look at the stuff in the sky (other than the stars) it looks like we’re sitting in a giant jar of stuff, like atoms What does it look like to sit inside a jar of atoms? Why should you care?

Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math 7 Start Simple: Atoms in a Jar Since we can see how atoms interact in a jar on Earth we can predict what would happen on Universe sizes Next: learn what it’s like to be inside a jar filled with atoms Gas (bunch of atoms) is well described by its Temperature and will eventually come into Thermal Equilibrium –Describe both these ideas next

Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math 8 Overview of Today’s Material 1.Temperature: Photons and Atoms 2.Thermal Equilibrium 3.Moving in a Gas 4.Different types of Equilibrium 5.What we can, and can’t, learn from a system in Thermal Equilibrium

Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math 9 Temperature What do we mean when we use the word temperature?

Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math 10 Temperature How do we typically “think” about Temperature? When we’re outside and we “feel” cold, the thermometer reads a small number When we’re outside and we “feel” hot, the thermometer reads a large number What is the thermometer measuring?

Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math 11 “Feeling” Cold What is hitting you when you are outside? 1.Photons 2.Atoms Can think of temperature as the energy of the particles hitting you

Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math 12 Temperature of Atoms Same number, and type, of atoms in both Low Energy: Cold Gas High Energy: Hot Gas

Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math 13 Temperature of Atoms and Photons Even if a room is completely dark we can still feel warm because atoms hit our skin –High energy atoms  high temperature –Low energy atoms  low temperature Our skin is a lousy thermometer  Feels “cooler” in the shade because we absorb fewer photons

Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math 14 Overview of Today’s Material 1.Temperature: Photons and Atoms 2.Thermal Equilibrium 3.Moving in a Gas 4.Different types of Equilibrium 5.What we can, and can’t, learn from a system in Thermal Equilibrium

Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math 15 Thermal Equilibrium Lets say I’m hanging out in a room and part of the room is hot and part of the room is cold Eventually the air mixes and the room has the same temperature everywhere Same as putting ice in a cooler full of water  Eventually it will get cold

Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math 16 What’s really happening? Look at the atomic level You have high energy atoms and low energy atoms What happens to high energy atoms when they collide with low energy atoms?

Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math 17 Atomic Perspective High energy atom’s perspective: I collide with a low energy atom and “transfer” some of my energy Low energy atom’s perspective: I collide with a high energy atom and “take” some of its energy

Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math 18 What happens in a room with lots of atoms after lots of collisions? The higher energy atoms will slowly become lower energy atoms The lower energy atoms will become higher energy atoms Eventually we get lots of medium energy atoms

Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math 19 Thermal Equilibrium Eventually all the atoms will (roughly) have the same energy –Said better: The same temperature We call this Thermal Equilibrium

Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math 20 A Bigger Example With More Than Two Balls Think of a perfect pool table (no friction to slow down the balls) with a cue ball and a rack of balls at the other end; all are stationary –We then shoot the cue ball at the rack (we break) Right after we shoot, but before the cue hits the rack, we’re are NOT in equilibrium –One ball is VERY energetic and the others have no kinetic energy

Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math 21 After the Cue Ball Hits the Rack After the cue ball strikes the rack, the cue ball has smaller energy and all the other balls have some energy –As the balls bounce off each other they will, eventually, all have roughly the same energy Actually more complicated, but it turns out we can predict the distribution of energies –Call this Thermal Equilibrium

Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math 22 Pool Table Example Cue ball after it hits the rack  All balls have roughly the same energy Call This THERMAL EQUILIBRIUM

Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math 23 Silly Pool Table Example NOT THERMAL EQUILIBRIUM

Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math 24 Next consider some things that don’t typically happen to jars in the real world

Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math 25 Overview of Today’s Material 1.Temperature: Photons and Atoms 2.Thermal Equilibrium 3.Moving in a Gas 4.Different types of Equilibrium 5.What we can, and can’t, learn from a system in Thermal Equilibrium

Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math 26 Moving in a Gas What if the jar is moving? What if the jar is stationary, and I (as the observer) am moving inside it? –These are equivalent by relativity

Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math 27 An Observer Inside a Gas in Thermal Equilibrium What does it look like “in here”? 1.Equal number from all directions 2.Same “temperature” in all directions

Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math 28 What if I, or the Jar, is Moving? What does it look like “in here”? 1.Equal number from all directions 2.DIFFERENT “temperature” in different directions Blue Shifted Red Shifted

Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math Fish “Temperature” The fish have the same “temperature” in both cases –Just “looks” different Can tell I’m in a bunch of fish that are at Thermal Equilibrium 29

Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math 30 Bottom Line I can tell that I am located in a gas in thermal equilibrium if: 1.The temperature is the same in all directions OR 2.The temperature looks as if either me or the gas is moving in a single direction A gas in Thermal Equilibrium is well described by its Temperature

Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math 31 Overview of Today’s Material 1.Temperature: Photons and Atoms 2.Thermal Equilibrium 3.Moving in a Gas 4.Different types of Equilibrium 5.What we can, and can’t, learn from a system in Thermal Equilibrium

Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math 32 Other Types of Thermal Equilibrium? There are other types of Thermal Equilibrium Different types of gas can mix and come into thermal equilibrium Atoms (or particles) can interact and come into thermal equilibrium

Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math 33 Example 1: Two Gases Mixing Let’s say I have two different gases with different temperatures on opposite sides of a jar –High Mass atoms and Low Mass Atoms Before: Not in thermal equilibrium, doesn’t LOOK like equilibrium –Different temperatures on each side –If I weren’t at the center, it would look different than if I were at the center During: The atoms “mix” and come to thermal equilibrium After: We’re in thermal equilibrium  equal temperatures everywhere

Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math 34 Two Gases Mixing Low Mass Atoms High Mass Atoms

Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math 35 Other Examples Different types of atoms can “mix” and come into thermal equilibrium with each other Hydrogen and oxygen can mix and turn into water in thermal equilibrium

Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math 36 Electrons and Photons An electron and an anti- electron can collide and turn into two photons Two photons can collide and turn into an electron and an anti-electron –If they have enough energy

Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math 37 Photons and “Electrons” 2 Photons can turn into 2 “Electrons” 2 “Electrons” can turn into 2 Photons

Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math 38 Electron and Photons If we have lots of electrons they will interact and create more photons If there are lots of high energy photons they will interact and create more electrons Eventually both the number of electrons and photons, as well as the energy, comes into Thermal Equilibrium

Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math 39 Positron Electron Photon Electrons, positrons, and photons in equilibrium between production and annihilation Visualize: Electrons and Photons

Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math 40 Always end up the same way If I start with ONLY high energy electrons and positrons, eventually I’ll end up with electrons, positrons and photons in thermal equilibrium If I start with ONLY high energy photons, eventually I’ll end up with electrons, positrons and photons in thermal equilibrium

Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math 41 Lots of Types of Thermal Equilibrium Given enough time (and things not changing) all places in the room will come to have the same temperature i.e., be in thermal equilibrium Depending on what the particles are (electrons, photons, atoms etc.) they can turn into different types of particle bring the number of objects AND energy into Thermal Equilibrium also If we know how it all starts, we can always figure out how it will end

Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math 42 Overview of Today’s Material 1.Temperature: Photons and Atoms 2.Thermal Equilibrium 3.Moving in a Gas 4.Different types of Equilibrium 5.What we can, and can’t, learn from a system in Thermal Equilibrium

Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math 43 What Thermal Equilibrium Can, and Can’t, Tell Us Lots of different ways of starting out will come to the same thermal equilibrium So what? Since this is true we can’t learn a lot about what happened BEFORE it went into equilibrium –Single cue ball hit a rack of balls? –Two balls hit the rack at the same time? Can’t tell the difference looking at much later times…

Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math 44 Different Initial Conditions Much later in time (after we’re in thermal equilibrium) can’t tell if the system started in Funny Way Usual Way

Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math 45 A Universe in Thermal Equilibrium We will see evidence that the Universe appears to have the same temperature everywhere –Was in Thermal Equilibrium at some point in its history Tells us a lot about the Universe and how it evolved (and will evolve) Can’t tell us about what happened BEFORE it came into Thermal Equilibrium –For example: Was there actually a Big Bang? Something else?

Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math 46 The Plan… Finished: 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 Next time: Starting Unit 3 Using the “Physics We Need” to teach us about the EVIDENCE for the Big Bang

Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math 47 Prep for Next Time – L13 Reading: –BBBHNM Unit 3 Pre-Lecture Reading Questions: –Unit 3, Stage 1 due Monday before class End-of-Chapter Quizzes: –If we finished Chapter 9 then end-of-chapter quiz 9 (else just up to Chapter 8) Papers: –Paper 1, Stage 2: Due Monday before class –Paper 2, Stage 1: Due before class on Wednesday (Text needs to be in turnitin on eCampus) Honors Paper: –Stage 1 due March 11th

Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math 48 Prep for Next Time – L14 Reading: –BBBHNM Unit 3 Pre-Lecture Reading Questions: –Unit 3, Stage 2 due Wednesday before class End-of-Chapter Quizzes: –If we finished Chapter 9 then end-of-chapter quiz 9 (else just up to Chapter 8) Papers: –Paper 1 Revision, Stage 1 Due Wed after Spring Break, but Stage 2 will be Mon March 30 –Paper 2, Stage 1: Due before class on Wednesday (Text needs to be in turnitin on eCampus) Honors Paper: –Stage 1 due March 11th

Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math Full set of Readings So Far Required: –BBBHNM: Chaps Recommended: –TFTM: Chaps. 1-3 –BHOT: Chaps. 1-7, 9 and 11 ( ) –SHU: Chaps. 1-3, 4(77-86), 5(95-104), 6, 7 (up-to-page 153) –TOE: Chaps. 1 & 2 49

Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math 50

Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math 51 Clicker Question Two mystery galaxies (on the right) only have a single spectral line in the visible spectrum as shown below. If the above galaxy is stationary, which way is the below galaxy moving? a)Towards us b)Away from us c)It is also stationary d)Not enough information

Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math 52 Clicker Question A star is observed with the following light pattern. Which way is it moving? a)Towards us, slow speed b)Away from us, slow speed c)Towards us, high speed d)Away from us, high speed e)Stationary

Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math 53 Clicker Question Which best describes the two galaxies below? a)Both are moving towards us, but the left one is moving faster than the one on the right b)Both are moving towards us, but the right one is moving faster than the one on the left c)Both are moving away from us, but the left one is moving faster than the one on the right d)Both are moving away from us, but the right one is moving faster than the one on the left

Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math Clicker Question True or False: Two stars at the same temperature in the Milky Way are in thermal equilibrium a)Yes b)No 54

Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math Clicker Question True or False: Once a bunch of atoms are in thermal equilibrium, the energy of an individual atom doesn’t change a)True b)False 55

Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math Clicker Question True or False: If I have a bunch of electron, positrons and photons in thermal equilibrium, we will never have another positron annihilate with an electron and raise the number of photons a)True b)False 56

Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math Clicker Question Why can electrons, positrons, and photons be in thermal equilibrium with each other, even if they are creating and annihilating one another? a)They can be the same temperature b)They are in thermal contact c)Can only become in thermal equilibrium when interactions cease d)A and B 57

Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math Clicker Question On a cold winter morning, which is a lower temperature, a metal sign pole or a wooden bench? a)The metal pole b)The wooden bench c)They are the same temperature d)They are at absolute zero 58

Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math 59 Was due today – L7 Reading: –BBBHNM: All reading through Chapter 11 Reading Questions: –All reading questions through 11 eLearning Quizzes: –All quizzes through Chapter 8 Papers: –Calibrations and grading you didn’t pass Paper 1, were due before class –Text submission of Paper 2 was due in CPR and turnitin.com before class

Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math 60 Was Due Today– L14 Reading: –BBBHNM: All reading through Chapter 9 Pre-Lecture Reading Questions: –Through Chapter 9 End of Chapter Quizzes: –Chapter 8 Papers: –Paper 0: Grades were posted in eCampus. Let you know if you were misgraded –Paper 0 Revision (if necessary – See eCampus score, not CPR Score): Open now, Text due Monday before class. All Calibrations/Reviews following Monday –Paper 1: Changed due date, Calibrations/Reviews due this coming Tuesday at 11:55PM –Paper 2: Changed due date, Text due Wednesday before class

Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math 61 Was Due Today– L15 Reading: –BBBHNM: All reading through Chapter 10 Pre-Lecture Reading Questions: –Through Chapter 10 End of Chapter Quizzes: –Chapter 8 Papers: –Paper 0: Grades were posted in eCampus. Let us you know if you think you were misgraded. Currently done with all regrade requests –Paper 0 Revision (if you didn’t pass the first time – See eCampus score, not CPR Score): Text was before class. All Calibrations/Reviews next Monday –Paper 1: Calibrations/Reviews due Tomorrow (Tuesday) at 11:55PM –Paper 2: Text due Wednesday before class

Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math Paper 2 Organization Stuff I have extended the due date until Tuesday at 5:45PM Want feedback before turning it in? –Post it in eLearning in.doc (or.pdf) for comments by the TA by 5PM Thursday –Make sure you polish it If you have lots of grammar and spelling mistakes we’ll just make you resubmit it –Will be due in CPR and turnitin.com at the same time Calibrations will be due right after Spring Break 62

Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math 63 Prep for Today (Is due now) – L12 Reading: –BBBHNM 9 Reading questions: –Chapter 9 or the recommended reading End-of-Chapter Quizzes: –Chapter 7 & 8 Papers: –Calibrations for Paper 1, if needed –Text of Paper 2 due next week

Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math 64 Prep for Today (Is due now) – L13 Reading: –BBBHNM 10 Reading questions: –Chapter 10 or the recommended reading End-of-Chapter Quizzes: –Chapter 8 Paper 2: –Text due Tuesday at 5:45PM –Calibrations/Reviews due Monday March 19

Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math Paper 2: The Assignment Abbreviated Description: What is the evidence that Stars are made of Atoms? Explain it to someone who isn’t taking the class (no jargon) Format: –Introduction paragraph –~1 paragraph per piece of evidence –Conclusion paragraph that ties it together – gAssignments/samplepaper.shtmlhttp://faculty.physics.tamu.edu/toback/109/Writin gAssignments/samplepaper.shtml 65

Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math 66 Prep for Next Time – L12 Reading: –BBBHNM 10 –Lots of fun recommended Reading also on next slide Reading questions: –Chapter 10 or the recommended reading End-of-Chapter Quizzes: –If we finished Chapter 9, end-of-chapter quiz due before next class (else just 8) Papers: –If you did a Paper 1 Revision, Calibration due Monday –Paper 2 due Tuesday on CPR and turnitin.com

Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math 67 Prep For Next Time – L7 Note: May change depending on how far we get in lecture Reading: –BBBHNM: All reading through Chapter 12 Reading Questions: –All reading questions through 12 eLearning Quizzes: –If we finished Chapter 9 then end-of-chapter quiz 9 (else just through Chapter 8) Papers: –Paper 2 text feedback (if desired) due Monday March 11th for guaranteed feedback. –Due Tuesday March 19 th in CPR and turnitin.

Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math 68 Prep For Next Time – L14 Note: May change depending on how far we get in lecture Reading: –BBBHNM: All reading through Chapter 10 Pre-Lecture Reading Questions: –Through Chapter 10 End of Chapter Quizzes: –If we finished Chapter 9 then end-of-chapter quiz 9 (else just up to Chapter 8) Papers: –Paper 0: Grades were posted in eCampus. Let us know if you were misgraded. –Paper 0 Revision (if necessary – See eCampus score, not CPR Score): Open now, Text due Monday before class. All Calibrations/Reviews following Monday –Paper 1: Changed due date, Calibrations/Reviews due this coming Tuesday at 11:55PM –Paper 2: Changed due date, Text due Wednesday before class

Physics We Need Topic 5: Temperature and Equilibrium Big Bang, Black Holes, No Math 69 Prep For Next Time – L15 Note: May change depending on how far we get in lecture Reading: –BBBHNM: All reading through Chapter 10 (already assigned) Pre-Lecture Reading Questions: –Through Chapter 10 (already assigned) End of Chapter Quizzes: –Chapter 9 Papers: –Paper 0: Grades were posted in eCampus. Let us you know if you think you were misgraded. Currently done with all regrade requests –Paper 0 Revision (if you didn’t pass the first time – See eCampus score, not CPR Score): Text was before class. All Calibrations/Reviews next Monday –Paper 1: Calibrations/Reviews due Tomorrow (Tuesday) at 11:55PM –Paper 2: Text due Wednesday before class