Union College Winter 2015 Astronomy Cosmology

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Percival Benson
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1 Union College Winter 2015 Astronomy Cosmology Time & Place: MWF 8:00 9:05; Science & Engineering, N303 Instructor: Jon Marr; Office: Sci.&Eng N327; Phone: x6443; Office Hours: MTWF 11-12:30 Resources: 1. Marr s Cosmology Notes 2. Introduction to Cosmology by Barbara Ryden 3. WebPage: contains following links Final Exam Questions: Important Equations Mathematica routine for numerically integrating d p for given z. Link to other cosmology web pages WMAP interactive fitting: Course Content: Where did everything we see come from? How did it all become what it is? These are two of the numerous questions that the subject of Cosmology pursues answers to, most (but not all) of which can now be answered satisfactorily. Cosmology is the study of the Universe as a whole its origin, its shape, its future, its evolution. We will discuss the most accepted models for the Universe with most of the emphasis on the models of the physics in the beginning moments. Since a correct model must involve general relativity, some time will also be spent developing a beginner s understanding of general relativity, discussing only in terms of what is needed for cosmology. Other topics we will discuss include: the astronomical evidence leading to the Big Bang Model, physics models of the very early Universe; dark matter as it applies to cosmology; the recent modifications to the Big Bang model (the two most important being the Inflation Model and the Acceleration of the Universe s Expansion, a.k.a. Dark Energy ); the composition of the universe; observations of the cosmic background radiation. Class Format: The class will function like a committee. I am the committee chair and you all are participants who will do research and give presentations. As such, you, the students, will give most of the lectures! In the schedule below, the lecturer for each day s class is given. The reason for structuring the class this way is two fold. First, your main job in this course is to learn how to talk about cosmology, and secondly, you will learn so much more by preparing lectures on the material. Each of you will give two 15 to 20-minute lectures in the first half of the term. By the end of the term, your knowledge, understanding, and ability to discuss cosmology will be quite strong. Prepare your lecture at least one day in advance. If you have any questions, please

2 come to my office and ask me about your confusion. At the start of each class, I will summarize the main points from the previous class, entertain and answer any questions you all may have, and then hand the floor over to the assigned student lectures. I also expect that you will read the material for all lectures, in advance not just for your own lecture. In the end, you will need to do well on the final exam, and so you need to learn all the material. By reading the material BEFORE the lecture, the lecture will make more sense and you will be able to ask questions about any points of confusion. We will, also, use any available class time to work on solving problems related to the day s discussion; if you have not done the reading, you will get much less out of the in-class work. I do expect this to take more work than usual. As such, the homeworks will be significantly reduced from that of a normal 200-level physics and astronomy class (see below). In respect for your fellow classmates, laptops and cellphones will not be permitted during the lectures; it can be distracting to lecture to a class in which some people s faces are glued to a computer screen, making expressions unrelated to the lecture, and similarly with faces looking down toward their laps, where both hands are clearly busy texting. Class Notes: On the course Nexus page, I have uploaded a pdf document of my typed notes from previous years of teaching this course. These notes are at a slightly lower level than the text by Ryden, assumes less prior physics knowledge, and will be the primary source for learning the material. Unfortunately, the notes are not complete...if my time permits (not likely this term) I ll update them during the term. Unfortunately, the order of material covered in my notes is not identical to that in the book by Ryden, which will become more useful later in the term. One extra advantage of the notes is that you can do a find on any word or phrase and jump right to the relevant section. Level of Class: I will treat this as an upper level physics class in cosmology so that physicists, as well as astronomers, can learn the material. After all, cosmology has been one of the motivating fields of thought behind physics for most of its history. Therefore, you should not need to know the background astronomy. However, you probably will find it helpful if you have taken some astronomy beforehand. Furthermore since I am trained as an astronomer, I may slip into astronomers' lingo at times--when I do please ask for clarification. Making this an upper level physics class, also means that it will be fairly rigorous, with knowledge through physics 121 (and some of physics 122) assumed. The official prerequisites for this course are Physics 121 and Math 115. However, it will be advantageous to have seen some of the material from Physics 122 (and Physics 220). Exams: There will be one mid-term exam and one final exam. They will be different from what you are used to. The link above will take you a list of Final Exam Questions. You can look at them

3 all right now. That s right, I am starting this course by giving you the final exam questions and you have the entire term to learn the answers to the questions. During Finals week, each of you will meet with me privately for 30-minutes, during which I will ask you just 10 questions from the list of 52. You can use absolutely any resource to learn the answers...as long as, when you come to the final exam you can discuss the answers with confidence without having any material in hand. Your ultimate goal for this class, in a sense, is to know all the answers for the final well enough to tell them to me off the top of your head in a pressure situation The mid-term exam will be based on a a subset of the final exam questions and will occur near the end of week 5. Homework: Because you will be busy preparing lecture, there will only be one homework assignment of problems every other week. The purpose of the assignments will be to get you to work on some involved problems that an undergraduate cosmologist should be able to do. In fact, the questions on the midterm and on the final exam will come directly from the homeworks...so if you get all the homework questions down, you ll ace the exams, and all the questions are already listed above (in the link for Final Exam Questions ). You are encouraged to work in groups on the homeworks. Students with Disabilities: If you have a specific disability that qualifies you for academic accommodations, please show your ID card from the Support Services Office as soon as possible and then we can meet to discuss any necessary special arrangements. Other policies: 1. Attendance: Attendance will not be taken. However, the discussions in this class will build on material covered in previous classes, so each time you miss a class, you ll find the next class harder to understand. You are better off never missing a class. My experience, both as a student and as an instructor, is that there is a strong relation between one s attendance in class and his/her resultant performance on the exams. Since you (or your parents) are paying a lot of money to attend this college, and you need to be relatively bright to get into this college, you probably do not want to completely waste your time and money by learning less than you could. 2. You must notify me in advance if you have any scheduling conflicts. 3. I will not offer or accept any work for extra credit. Approximate Weighting of Final Grades: Homework Problems 15% Student Lectures 15% Mid-Term Exam 30%

4 Final Exam 40%

5 Approximate Schedule: Monday Wednesday Friday 5-Jan Course Logistics and Policies Jon: Background Phys + Astro (Notes: 3-10, 23-26) 7-Jan Jon: Intensity of Radiation, Atomic- Scale Units, Escape Velocity Salina: Blackbody Radiation (Notes 10-16) 9-Jan Will: types of spectra, Doppler effect, Anthropic Princ, Copernican Rev. (Notes 16-21) Ben: Olber s Paradox, Hubble Law (Notes 22-24, 36-38) Paul P: Big Bang vs. Steady State (Notes: 39-42, Ryden 12-18) 12-Jan Paul D: Cosmo Assump ns (Notes 43-44, Ryden 9-12), Scale Factor (Notes 54-58, Ryden 13-15) Michael: Expanding U. eq ns, and possible futures. (Notes 58-60) 14-Jan Brendan: Cosmol. parameters, Steady State model (Notes: 60-62) Larenz: Measurements of distances (Notes 63-67) 16-Jan Sarka: H(z), Dark Energy, Pec. Vel. of Milky Way (Notes 67-71) Morgan: Lum. density, M/L ratios, Mass of Milky Way (Notes 71-75, Ryden ) 19-Jan Martin: Mass in disk galaxies (Notes 75-76; Ryden ), Mass in clusters, background density? (Notes 84-86; Ryden ) 21-Jan Ben: DM candidates, alternative theories (Notes 86-89, Ryden 143-5) The Cosmic Background Radiation 23-Jan Brendan: Dipole Anisotropy (Notes: , Ryden ) Larenz: CBR equations (Notes , ) Jon: In-Class problems Salina: Thermal, Isotropic, & Cosmological (Notes 94-7, Ryden ) 26-Jan General Relativity Jon: Review of Spec. Relativity Paul P: Principle of Equivalence (Notes: , Ryden 27-30) 28-Jan Paul D: Mass & Time in GR (Notes: ) Michael (15 min): Metrics (Notes: , Ryden 31-35) 30-Jan Morgan: Einstein s model (Notes: , Ryden 44-51) Michael (15 min): Robertson- Walker Metric, (Notes: , Ryden 35-37) Martin: Field Equations (Notes: , Ryden 52-56) 2-Feb 4-Feb Jon: Review 6-Feb Midterm Exam

6 9-Feb Martin: Field Equations (cont) Sarka: The Dust Universe (Notes: , Ryden 63-69, 72-76) Will: Radiation Univ. (Notes , Ryden 76-78) 16-Feb mag vs. z test, SNIa results, : D, vs. z test, source counts (Notes: , Ryden ) Flatness Problem, Alternative Cosmologies (Notes , Ryden 11.1) 23-Feb Primordial Nucleosynthesis principles, formation of 2 H, fusion reactions (Notes: , Ryden 171, 10.1, 10.3, 10.4) 2-Mar CBR fluctuations (Ryden pp ) 9-Mar Inflation (cont) 11-Feb Models including, the dominated Universe, + matter Universe (Notes: , Ryden 57-61, 80-84, 88-91) 18-Feb Early Universe Models particle horizons, R dependences, Interactions, Reaction time, particle equil.and annihilation (Notes , Ryden 175) 25-Feb Prediction of CBR, b, Baryon Assymetry (Ryden 10.5) 4-Mar VERY Early Universe Horizon Problem, Monopole Problem (Ryden 11.2, Ryden 11.3) 11-Mar Jon: WMAP/Planck Results, Relic neutrinos 13-Feb Tests of Geometry, Geodesics, What is Distance? D P, D L, r vs. z, D P in models (Notes: , Ryden 37-41, ) 20-Feb era of particle equilibrium, -ino decoupling, annihilations (Notes: , Ryden ) 27-Feb Epoch of Recombination, Decoupling, Recombination Physics + z of CBR (Ryden pp , 9.2) 6-Mar Inflation (Ryden ) 13-Mar Review

Stellar Astronomy 1401 Spring 2009

Stellar Astronomy 1401 Spring 2009 Instructor: Ron Wilhelm Office: Science Building Room 9 Contact information: Office Hours: 742-4707 or ron.wilhelm@ttu.edu MWF 10:00-11:00 PM T & Th 11:30-12:30 AM Or