Visions of the Universe
Visions of the Universe ISP 205
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Ms. Adrian Buckridge
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This 17 page Class Notes was uploaded by Ms. Mckenzie Labadie on Saturday September 19, 2015. The Class Notes belongs to ISP 205 at Michigan State University taught by Jack Baldwin in Fall. Since its upload, it has received 24 views. For similar materials see /class/207720/isp-205-michigan-state-university in Integrative Studies Physical at Michigan State University.
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Date Created: 09/19/15
ISP 205 nal exam Review from first 3 exams Numbers to be familiar with Age of universe 137 billion years Age of sun 45 billion years Age of solar system 45 billion years Content of solar systemuniverse hydrogen 75 helium 25 normal matter 15 dark matter 85 Fraction of mass of solar system in Sun 998 in Jupiter 01 8 planets in solar system Major Ideas 0 Kepler s laws 0 1 Each planet moves around orbit in ellipse with the Sun at one focus 0 2 The straight line joining the planet and the Sun sweeps out equal areas of space in equal amounts of time o 3 PA2aA3 period of orbit squared is equal to semimajor axis of orbit cubed o Newton s Laws 0 In the absence of a net overall force acting upon it an object will remain in motion with a constant velocity 0 Force Mass X Acceleration 0 For any force there is an equal and opposite reaction force 0 Law of gravity gravitational force Gmlm 0 Conservation of energy 0 Energy remains constant Kinetic and Potential energies may change around from one form to another but total energy remains the same 0 Light has a dual waveparticle nature 0 a wave I light can happen at any wavelength smaller wavelength blue colors longer wavelength red colors Frequency how many peaks pass per unit of time Low frequency long wavelength I High frequency short wavelength 0 As a particle I Light is a stream of particles moving through space carrying energy I Called photons I Energy is inversely proportional to the wavelength I Energy is directly proportional to the frequency 0 EmissionAbsorption lines 0 Absorption lines atoms remove light at certain wavelengths photons vanish 0 Emission lines atoms emit light at certain wavelengths photons are created 0 Tell us what type of gas it is Emission lines are seen when temperature brightness increases when electrons jump to lower energy level Deexcitation since they need to produce photons giving off added energy increasing temp 0 Absorption lines are when temperature brightness decreases when electrons jump to next higher energy level Excitation since they require energy from a passing photon that energy is absorbed and vanishes which decreases temp 0 Doppler Effect 0 The change in frequency of a wave for an observer moving relative to the source of the 0 wave Redshift If the distance between observer and causer gets longer the frequency becomes lower and the wavelength is longer this causes a shift towards the red end of the spectrum 0 Blueshift source of wave and observer get closer so the wavelength becomes shorter and the frequency gets higher this causes a shift in color towards the blue end of the spectrum 0 The Solar System 0 General structure of and motions within the Solar System 0 Rotating disk 0 Orbits in same direction with the exception of Venus and Uranus 0 Why did terrestrial planets turn out differently than giant planets 0 High vs low density 0 Rocks vs mostly gas 0 Composition heavy elements vs primarily HHe Difference due to distance from Sun 0 How do general characteristics of atmospheres and surfaces ofVenus and Mars differ from Earth Why do they differ 0 Venus I same sizedensity as Earth also differentiated like Earth I However has a very thick C02 atmosphere due to the runaway greenhouse effect I Very hot surface temperature 12 the diameter of Earth I C02 atmosphere but very thin I Loss of atmosphere due to low escape velocity and solar wind stripping off the gas I Couldn t retain heat 0 Radioactive age dating 7 what is the general principle 0 Radioactive decay measures how much of an element remains in an object depends on its half life the time it take for half of the element to decay 0 Age dating by crater counting o More craters older 0 Less craters younger o What are asteroids What are comets o Asteroids are small rocky bodies in orbit around the sun They are left over from formation of solar system Most in asteroid belt 0 Comets are mostly ice in eccentric orbits They have tails Most come from Oort comet cloud Stars o What powers the Sun and other main sequence stars 0 Nuclear reactions I 4 x lH 94He neutrinos energy 0 Why do stars always try to collapse 0 What keeps stars from collapsing What are the three possible end states of stars 0 White dwarfil4 solar masses 10000 km size of earth 0 Neutron Staril4ltmasslt3 solar masses 20 km size of city 0 Black hole73 solar masses or more 0 What initial characteristic of a star determines its future life 0 0 Which stars have the shortest lives The longest lives 0 Massive stars have very short lifetimes 0 Old stars last a very long time o How is gravity described by General Relativity o Gravity curvature in space I Photons planets etc follow shortest paths through curved space I Analogy 2D bug on surface that curves into an extra 3rddimension o What is a black hole 0 Gravity so strong that escape velocity exceeds speed of light So light falls back 0 Schwarzschild radius or event horizon radius around mass concentration within which light can no longer escape to outside Review from last part of course The Milky Way 0 Gas large fraction of stars in thin disk 0 1000 light years thick 0 Spiral structure 0 Spherical halo I 150 globular clusters I Spherical distribution of stars 0 Nuclear bulge o Orbits for the disk circular orbits approximately in plane of disk Bulge and Halo elongated orbits going off in all directions 0 Our galaxy is Hubble type is Sb or possibly SBb 0 Sb galaxies are spiral galaxies 0 E0 galaxies are elliptical galaxies that are very round 0 E6 galaxies are elliptical galaxies that are very elongated cigar shaped The Galaxy 0 Originally all gas 0 Now 10011 stars similar to our sun 0 Stars are born evolve the die 0 Material processed through stars 0 Source of all chemical elements I Except hydrogen helium and lithium made in big bang o How does this lead to the gradual buildup of the chemical elements heavier than Helium 0 Stars convert H He then He C and on up through Iron in their cores then recycle a fraction of this enriched gas back into interstellar gas supply Supemovae make the elements heavier than iron and also recycle them back into the interstellar gas Then new stars form from the enriched gas The process repeats over and over 0 Where does star formation occur within our own galaxy and other similar spirals 0 Mostly in spiral arms interstellar gas is there The Cosmic Distance Ladder 0 Parallax o 300 pc 1000 light years 0 Calibrate main sequence tting 0 Calibrate luminosities of pulsating variables 9map out rest of Milky Way and out to M31 0 Measure luminosities of brightest stars brightest globular clusters brightest H II regions can now measure distances to more distant galaxies 0 Why is it called a ladder 0 You must work your way out rung by rung starting with the parallax method I H ow does the parallax method work Pulsating variablesused to get position of center of our galaxy distance to M31 etc I What are pulsating variables anal how are they used77stars that appear brighter or dimmer over time periodluminosity relation Apparent brightness ux and luminosity can be used to nd distance 0 Hubble s Law 0 V H ad 0 How do we measure v to plug it into Hubble s law I V is measure from Doppler red shift 0 How is H0 related to the age of the Universe 39 1 H0 is approximately the age of the Universe 0 Which distance method works out to the largest distances How is that method calibrated 0 Works best at large distances It is calibrated by methods involving the most luminous standard candles calibrated via Cosmic Distance Ladder Dark Matter 0 Dark matter does not interact with light through the electromagnetic force so we cannot see it emitting or absorbing radiation That made it hard to notice We know Dark Matter exists because it interacts gravitationally with normal matter and because of its gravitational effect on the path of light 0 3 candidates for explaining Dark Matter 0 Massive Compact Halo Objects made of dense blobs of normal matter were ruled out because there was no detection of gravitational lensing that would be expected when the blobs pass in front of background stars Hot dark matter means very lowmass particles moving at nearly the speed of light Cold dark matter means much more massive particles moving at slower speeds WIMPS weakly interacting massive particles9 left over from earlier phase of universe I We now know that is it predominately cold dark matter because of simulations showing a bottomup structure formation 0 Structure of galaxy galaxy clusters lie on surfaces of gigantic empty bubbles O O The Expanding Universe 0 The figures are for an analogy of a bug living on a rubbersheet universe which is a 2D surface curved into a 3rd spatial dimension We live in 3D universe curved into a 4th spatial dimension although we cannot sense that 4th dimension or leave our 3D universe 0 But what is meant by space time The figures show 3 possible solutions for the Universe as a 2D surface analogy for the case when the mass and energy content of the universe are smeared out uniformly throughout all space Space is expanding at every point in space so Observers would see galaxies expanding away from them 0 How did Hubble measure the distance used in his plot 0 Hubble used standard candles calibrated with Cosmic Distance Ladder to measure distances and Doppler shifts to measure velocities H0 is the slope of the straight line through the points 0 The Universe 0 What does the Scale Factor Rt measure 0 Rt is how stretched out space has become as a function of time t A personrbyrperson e p05 e outside the main doors u o S OzirxLIGnm00mgt FRONT OF CLASSROOM projection screen etc siman leave empty Aardvark ailey Eiaizhassarov Eiurrel Flaggman Hamly Hannaford Kamps Kazem Lesnick Lewandowski Mcmillen MC twald Spenchian Walbrun Waldecki Zzzz shunruwr leave empty REAR 0F CLASSROOM main entry doors 2 o S OZEFXh Io nmuomgt ISP 205 Final Exam Seating Chart SIT IN CORRECT ROW but either side of central aisle is OK Anthony Hall room 1281 Friday May 6 Take ONLY the exam with YOUR name printed on front cover Bring Photo ID Study Guide for ISP205 Final The final will be 23 over the material since midterm 3 to the same level of detail as the midterms The other 13 will be over the material covered on the midterms mostly aimed at major concepts but you should know some obvious key factoids about planets such as their order out from the Sun their relative sizes the surface and atmospheric conditions on Mars and Venus see the following page This study guide includes several ofthe most important slides from the lectures since Midterm 3 Some questions are asked on each slide in blue italics You should know the answers If you don t I have given some short and cryptic answers on the final page of this Study Guide to help you get started towards figuring out more complete answers IMPORTANT Just knowing what is in this study guide is NOT enough to get you a high grade in this course You are responsible for knowing about all ofthe topics l have talked about in class You should review your own lecture notes and also the following material that is available on the course web site www pa msueducoursesisp205sec 1 the PowerPoint slides from the lectures the study guides for the three midterms the review questions and answers Use the textbookto help explain the things that you don t understand as you review all of the above Remember that specific references to the textbook are given in square brackets on the PowerPoint slides Also remember that there is a reading schedule that is part of the Course Syllabus which can be viewed from the Angel Lessons tab PROF BALDWIN S OFFICE HOURS including during finals week Mo1245200 Tu 300400 in room 3270 BPS FINAL EXAM 1012 PM FRIDAYMay 6 in Anthony Hall room 1281 Sit in your assigned row COURSE GRADES available on Angel by Wed May 11 I ll send everybody an email when they are ready Review over first 3 parts of course Specific numbers to know I try to stay away from having you memorize lots of numbers But I hope that you will have learned the following specific numbers The age of the universe ie how many years ago it started to expand The age of the Solar System The percentages of hydrogen helium and everything else that make up the normal matter content of the solar system and of the universe The percentages of normal matter dark matter and dark energy that make up the total content of the universe The fraction of the mass of the solar system that is in the Sun and in Jupiter The number of planets in the Solar System There are some other quantities for which you should have some general idea of the size to an order of magnitude but do NOT need to know an exact number For example the number of stars in our galaxy the number of galaxies in a typical galaxy cluster or to have a sense of the relative sizes of and distances between the Sun Earth Jupiter and the nearest star as in for example a model Solar system I presented in class using a basketball to represent the Sun Except for the above I will avoid asking you about details discussed during the first three parts of the course But I will ask you about some ofthe biggerpicture ideas listed in the righthand column Major Ideas You should knowunderstand Background Physics Kepler s laws Newton s laws including gravity Types of energy Conservation of Energy Angular momentum Nature of light wave vs particle Wavelength vs frequency vs photon energy Emission and Absorption lines and under what circumstances they are formed Basic ideas about thermal emission The Doppler effect The Solar System General structure of and motions within the Solar System How were the planets formed Why did terrestrial planets turn out differently than giant planets How do general characteristics of atmospheres and surfaces of Venus and Mars differ from Earth Why do they differ Radioactive age dating what is the general principle Age dating by crater counting What are asteroids What are comets Stars What powers the Sun and other main sequence stars Why do stars always try to collapse What keeps stars from collapsing What are the three possible end states of stars What initial characteristic of a star determines its future life Which stars have the shortest lives The longest lives Why How is gravity described by General Relativity What is a black hole The Milky Way Slide 1 Gas large fraction of stars in thin disk 1000 LY thick Spiral stiucrure globular V39 clusters Spheiical halo 39 150 globular clusters 39 Spheiical distribution of stars i Nuclear bulge spiral arms The Sun 100 rligmyears 3 23000 gmyears Globular cluster globular cluslevs 47 Tucanae in the galaxy39s halol WvWD39igmVears What are the orbii s like for siars and gas in the three dii ferenf cornponenfs Whatis fhe Hubble type of our Galaxy What are SB galaxies What are E0 and E6 galaxies 739 I The Galaxy 39 39 Originally all gas Now 10 stars similar to our sun Stars are born evolve then die 0 Material processed through stars A Galactic ecology gas stars 39 This is source of all chemical elements except Hydrogen H Helium He Lithium Li made in big bangquot Slide 2 How does this lead to the gradual buildup of the chemical elements heavier than Helium Where does star formation occur Within our own Galaxy and other similar spirals The Cosmic Why is it mm ZIPUM 39 Distance Ladder fa eda Mu ladder 3 Parallax c 300 pc 1000 LY What 39 Calibrate main sequence constitutes the mllg39 first rung 39 Calibrate luminosmes of M Pulsf fgi abl What method and out to M31 first calibrate Measure luminosities of tze pOS t On ff Brightest stars 10000 Le t 6 center 0 100000 LY Brightest globular clusters 100000 LD our GaaXy39 Brightest H 11 regions 100000 La 30d thequot the Em distance to 39 9 can now measure distances to more distant galaxies Milky Way Also Hubbe s law v Hod How do we measure v to plug it into Hubbe s law How is HO related to the age of the universe Which distance determination method works out to the largest distances How is that method calibrated DARK MATTER We expected falling Keplerian curve out beyond outermost luminous matter ORBITAL VELOCITV 9 Ovialal WEN ltgt 7 ohm rm 5a A ovarian rurvn luv planuHiIIe mm 39 Faster orbital motions found in outer parts of galaxies What 9 large amounts of additional Wis H dark matterquot in outer parts ac ua y seen of spiral galaxies 011139 Galaxy observed expected Gill rillO7r 433 mom 0 DISTANCE FROM CENTER Measured l l l v39 Ir L a Famusikptl 7 V V Expected j 39 NEE 257 l2 Tiny fluctuations in Cosmic Microwave Background Structures form due to gravitational attraction of dark matter Simulations 9 cold dark matter massive particles moving slowly 9 BottomUp structure formation Learning the Gravitational Lens in Galaxy Cluster Abell 221 8 numerous u 39 Foreground cluster distorts images of Fig 15 10 background galaxies Use to determine total mass of foreground cluster Shows that 85 of mass is Dark Matter Properties of Dark Matter Supercomputer simulations of growth of Cosmic Web Today39s giant bubbles of m matter Why was it so hard to discover Dark Matter ll iat does it mean when we call it dark What does it NOT do that other matter does do How do we know that the Dark Matter is there 2 basic methods What were the three general candidates for explaining Dark Matter one was ruled out by a gravitational lensing test What is meant by hot and col in terms of Dark Matter How do we now know that it is predominantly Cold Dark Matter And what does this plot show What are the measured structures like on different size scales How did Hubble measure the distances used in his plot How are the velocitbs measured What is the Hubble constant HO 1 Velocity gt Distance gt The Expanding Universe K Q C I 9 What do these 20 surfaces have to do with the 3D universe If we were ridin on different raisins in the loaf of bread would we What is expanding in the expanding universe Thereis 7 The Universe Sl39de 5 I F39Q 1516 Curve 4 3 Distance 9 Lookback time a i 7 billion yrs I E E A 5 a g 8 I B 9 s pernova data 8 5 AlEJrve 1 I 39 g 8 0 2 a K Ca 0 f a p L R 9 2 39 What is 8 3 112 this sketch U i i i I I l Showing 14130 49839s 44 about the Pas behavior of Age Of Iimein biliions light as it iookbaok times fol bllllon yTS based on apparen travels through an expanding What does the Scale Factor Rt measure universe What two quantities compete With each other in curves 12 The shape of curve 4 indicates the presence of What additional quantity 7 The History of the Universe 7 7 e shown on this gure I Q EYEE t Iri ahun Quark Soup First Galaxies Modern 1 1 OJ 3 OJ 2 C I q 0 OJ 51 I b Ir 1 1032 Sec 1 520171119 300000 Years 1 Billion Years 13 7 Billion Yars Time Planck Formation I Galaxy NOW me Of H He Ll Formatlon What underlying phenomenon In at39on DeCOUPImQ 0f is driving all ofthe events CMB shown on the gure Hquot Cw ii High density Low density Freezmg out the forces Them fo EVCIytthg 551931 Note that Dark 10 43 5 Energy does not Grand Uni ed appear on this Theory plot It is 10 35 5 something INFLA different again What doesthe Do scientists 10123 term quotInflationquot know what it is refer to What in ated By a little or by a lot I with See Fig 173 rg g i l El 5 gtlt 1039 s i now What are the 4 fundamental forces of today Did they always exist If not what caused the situation to change 3K 9 What causes curve 4 to swing upwards on the right half of the plot I What is the Cosmic ExpandingFurever i L 39 f 1 Microwave Background closed r t39 Wh is it so im ortant Cosmic Background gt 39 y p Fluctuations A a 39 1 db 39E 8 73 56 E E m 3 Q We infer these are there but we don 39t know what How do we know that they are Dark Energy eXSt57 73 Dark Energy using E mcz 23 Dark Matter How do we know that 4 Normal Matter Dark Matter exists
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