Physics 55 Syllabus, Fall 2005

Welcome:

Welcome to Physics 55 , Duke University's one-semester introduction to astronomy. You are fortunate to be living during the greatest period of astronomical exploration and discovery in the history of the human race, with many discoveries being reported weekly on the front pages of national newspapers and magazines. These discoveries are constantly challenging our perception of who we are as humans, what we know about the world, and what will be the fate of society and of the universe.

During this semester, you will be exposed to many of the extraordinary facts that have been discovered about the universe and about our relation to the universe. You will learn some science so that you can understand how these facts were discovered by invention, observation, and deduction. You will see that scientists have conceived many remarkable ideas to explain the observed facts. Using telescopes and observational data, you will have a chance to appreciate first hand the richness of our universe and some of the mysteries that remain.

Time and Place

Classes will meet Monday and Friday afternoons from 1:15 pm to 2:30 pm in Physics 113. The lectures will begin promptly at 1:15 pm so please come on time.

I plan to hold a weekly recitation of 1-2 hours in length, probably on Wednesdays, to help students with homework assignments, with any questions that they might have about the lectures, or just to chat about astronomy. I will poll the class during the first week of school to identify a good time for the recitation, will then send email to the class about where and when the recitations will be held.

There will be occasional supplementary classes, to watch an astronomy-related movie, to hear a talk by a visiting astronomer, to have a tour of a local science facility related to astronomy (e.g., TUNL), and to play with some demos that didn't fit into a lecture. These supplementary classes are completely voluntary and for your own enrichment and enjoyment. These will be announced on the course web page and by e-mail.

Prerequisites:

1. A curiosity and open mind to learn about the universe.
2. Some skepticism and a willingness to ask questions: how do we know what we know about astronomy?
3. A knowledge of high-school mathematics at the Algebra-I level:
   • The ability to manipulate numbers written in scientific notation, e.g., you should know how to multiply 1.2 ×10⁶ times the number -3.4 ×10^-2 to get the value -4.1 ×10⁴ to two significant digits.
   • The ability to appreciate and to make simple x-y plots.
   • The ability to manipulate and to understand simple algebraic expressions, for example you should be able to solve for the quantity d in the equation F= G M₁ M₂ / d² to get the expression d=(G M₁ M₂ / F)^1/2.
   The course will not use much mathematics. Appendix C of the textbook ("A Few Mathematical Skills") reviews most of what you need to know so please read this appendix if your skills are rusty. The course will also give you numerous opportunities to review and to practice your mathematical skills throughout the semester.

   Note: Students with a more advanced background in math and physics will be able to do more advanced problems in the homework assignments in place of problems that assume only the prerequisite math background.

Requirements:

1. The text The Cosmic Perspective, Third Edition by Jeffrey Bennett et al. This can be purchased in the Bryan Center textbook store, one level down.
2. An inexpensive calculator that can handle scientific notation, i.e., numbers of the form 1.23×10^-4 (which might appear as 1.23E-4 on some calculators). Such calculators can be purchased for about $10 at many stores. (A graphing calculator like a Texas Intsruments TI-83 is fine but overkill for this course, you will mainly need to compute products, ratios, and powers of numbers.)
3. A PRS transmitter. You purchase your own transmitter from the Duke Computer Store (not from the Book Store). Your astronomy text comes with a $20 rebate coupon for a transmitter.
4. A computer with color display screen, CD-ROM, and a connection to the Internet. You will be installing and using a digital planetarium program called SkyGazer that comes free with your textbook. You will also be running tutorials from the Mastering Astronomy associated with the text.
5. A Duke computer account for browsing the Internet and for e-mail. Your browser should be configured to display PDF (Portable Document Format) and QuickTime files. The OIT web page has links that explain how to do this, the TA (Teaching Assistant) and I can also help.

Expectations:

• Each week, you will need to reserve an average of about 8 hours for reading and for homework.
  1. You should plan on about 2-3 hours of reading for each lecture for a total of about 4-6 hours of reading per week. Astronomy, like many sciences, is a technical subject that involves new and challenging concepts. Most students will require several passes through the text to understand what is being said. Later material builds on earlier material so that you need to keep up with the weekly reading so that you do not fall behind.

     Please appreciate that the three hours of lectures each week will only be able to address the key ideas associated with each topic. It will be your job to learn and master the details by reading the text and doing the homework .

  2. You should plan on spending 2-3 hours on the weekly homework assignment. The amount of time will vary from week to week and will depend on the types of problems and projects.

• I expect you to be courteous and ethical throughout the semester, in class, during exams, and when completing homework assignments.
  1. Be courteous to me and to your classmates:
     1. You should show up to class on time.
     2. You should be attentive (stay awake!).
     3. You should avoid disruptions to the class: do not leave class early and do not make a lot of noise as the class comes to an end; do not read the Chronicle during class; turn off your cell phone before class begins; do not use radios, music players, internet browsers, or read email during class.
     4. Please be respectful to your fellow students.
     5. If you will be late or have to leave early, please tell me beforehand.
     Students who do not practice common courtesy should expect their final grade to be reduced substantially.

  2. Be ethical: do not cheat on quizzes, midterms, exams, or homework assignments. Duke University has an Undergraduate Academic Honor Code that you should read and think about carefully several times before and during the semester. The penalties for cheating can be severe, including expulsion for a semester, for an academic year, or entirely from Duke.

     If you feel under pressure to cheat, please first take a constructive step by trying to talk with any of the many people on Duke campus who will be glad to meet with you and try to find ways for you to avoid yielding to this pressure. These people include myself, the Teaching Assistant for the course, the Director of Undergraduate Studies in Physics, faculty from your other courses, fellow students, and various counselors on campus.

Grading

Your final grade for the course will be based on the following components which I discuss in turn:

Activity	Percent of Total Grade
In-class PRS questions	5%
Observation sessions	15%
Midterm exam	15%
Quizzes	20%
Homework assignments	20%
Final exam	25%
Extra credit	Up to 10% of the course grade

1. In-class questions and projects: To help keep the class actively involved, most lectures will have interactive PRS-based questions or in-class projects to carry out in small groups. This grade will be determined by what fraction of the PRS questions over the semester that you answer (but not whether your answer was right or wrong), and by the projects sheets that your class group hands in. All members of your group will get the same grade.

2. Observation sessions: Discussing astronomy without observation of the sky would be like explaining art to a blind person or music to a deaf person. All students are required to participate in at least two 2-hour evening observation sessions and write up a 1-2 page summary of what they did and learned at each session (full details will be provided later in the semester, see the Observation webpage). You can get extra credit by attending extra observation sessions and investigating some astronomical object of your own choosing.

3. Quizzes:
   About once every four lectures, there will be an in-class closed-book 15-minute quiz consisting of some multiple-choice questions and a few questions that require a calculation or some explanation. These quizzes should help you to keep up with the material by testing your basic knowledge and conceptual understanding. These quizzes are not cumulative, they will test you on the material covered since the previous quiz.

   The quizzes will begin promptly at the beginning of class, do not be late!

4. Homework assignments:
   • There will be a homework assignment, roughly once per week, and typically due one week after being handed out.

   • Because of the difficulty of grading all the problems for all the students, only some homework problems will be graded for each assignment. You will not know in advance which problems are the ones to be graded so you should do your best on each problem.

     Although some problems will not be graded, you will still benefit substantially by doing them:

     • You will learn the material more thoroughly.
     • Some of the quiz and exam problems will be drawn from the homework problems.

   • Late homeworks are not accepted! If you think you will not be able to hand in your homework by its due date, please get in touch with me or with the TA as soon as possible (at least two days before the due date) and explain what the situation is.

   • You are allowed to collaborate with your classmates on an assignment. (This is realistic, scientists collaborate all the time in research!) However, you must write up your homework on your own, in your own words, and with your own understanding. You must also acknowledge explicitly at the beginning of your homework anyone who gave you substantial help, e.g., classmates or the TA or myself. (Again, scientists usually acknowledge in their published articles colleagues that helped in completing some particular research.) Failure to write your homeworks in your own words and failure to acknowledge help when given may lead to severe academic penalties so please play by the rules.

   • Your homework assignments should be of collegiate quality. For questions that require a written answer, please be clear and demonstrate insight. Writing clearly means using a word processor or using readable handwriting (no tiny or crowded script). You should use proper grammar, correct spelling, and good sentence and paragraph structure. For questions that require a mathematical answer, show your work clearly. Use plenty of space between symbols and use blank lines to separate successive lines of equations. You will get partial or no credit if the TA or myself can not easily read your answer.

     Demonstrating insight means using complete sentences that explain what you are doing and why. Cryptic brief answers like "yes", "no", or "24"" will not be given credit. Your written answers must show that you understand how you got your answer and that you appreciate the significance of your answer. A simple criterion for a well-written complete answer is that you will be able to understand the answer yourself several weeks after you have written your answer, even without remembering what the original question was. Writing clearly especially pays off when it comes time for you to review your assignments in preparation for the midterm and final exams. Learning to write clearly is also one of the most valuable skills you can learn at Duke, one that will pay off many times over as you seek jobs after graduation.

   • While writing your homework assignments, please pay attention to details. All symbols should be given names the first time you introduce them. For example, you should say "the distance d" or "the angle a" instead of just using the symbols d and a. Physical units should be given for any answer that is a physical quantity. For example, you should say "the distance was d=0.02 km", "the angle was a=32 degrees", or "the temperature T had the value 6000 K". Graphs should be carefully drawn and have their axes clearly labeled by symbol and units. Each graph should have a title explaining what is being plotted.

     Numbers obtained from a calculator should be rounded to one significant digit unless otherwise requested. Thus if you obtain an answer 7.8237564E-03 for some problem, you should write this down in your assignment as 8×10^-3 (i.e., hold onto the first rounded nonzero digit when your number is written in scientific notation.) One significant digit is fine for most problems in astronomy, especially for an introductory course.

5. Midterm and Final Exams: The exams will be closed-book and scaled (grades adjusted according to how the class did overall). Questions will be a mix of multiple choice questions and questions requiring written solutions, many of them based on PRS questions, examples worked in class, quizz problems, and homework assignments. All relevant equations and data will be provided with the exams so you will not need to memorize such information. Instead, your goal during the exam will be to show that you can think conceptually and scientifically.

   The midterm exam will be cumulative and cover all material up to the week before the midterm. The final exam is cumulative and will cover material learned over the entire semester.

6. Extra credit: I would like to encourage you to explore astronomy beyond the class during this semester. You can earn extra credit, up to 10% of the total course grade, in several ways:
   1. Keep a biweekly journal (or, even better, a blog that can be shared with the class). Examples of blogs from the 2004 astronomy class can be found at this site, information about how to get started at this site.
   2. Attend a local astronomy club, local astronomy event, or tour a local research facility like TUNL, TCO , or the Morehead Planetarium and write a summary of your experience.
   3. Try your hand at some simple astronomical experiment such as following sunspots over a week with our sunspot telescope, measuring the height of a crater on the Moon, following a Galilean moon to confirm Kepler's law, or studying sunlight spectroscopically.
   4. Do one of the CLEA astronomy projects, which are software-based astronomy labs using real data.
   5. Participate in a Duke outreach program to a local elementary or middle school and talk about some aspect of astronomy.
   6. Prepare a lecture for a Physics 55 class on some topic that is not covered in the syllabus. (You do not have to give the lecture, just prepare a good one, but I would encourage you to give the lecture at least to me and some fellow students.)
   7. Interview a local scientist doing research related to astronomy (e.g., one of Duke's string theorists, neutrino researchers, nuclear physics scientists, or gravitational lensing theorists, or one of the professors in UNC's Dept of astronomy) and summarize his or her research interests and goals at a level appropriate for Physics 55 students.
   8. Write an essay, a poem, a short story, or a play related to some theme of astronomy. An essay or play could be on some astronomical event or discovery that has influenced your life or our culture (or the opposite, how many people are indifferent to astronomical discoveries); on some political issue such as how the US should allocate scarce monetary resources between fundamental astronomical research and societal needs like education, health, and defense; you could write a short story involving science fiction, some historical astronomical event seen through the eyes of a contemporary, a future first-contact scenario, or the interaction of an astronomer with a non-scientist, and so on.
   9. Do a book report on some book related to astronomy. Examples could be some current non-technical science book, a science fiction novel, one or more children's books, a book on history of science, or a historical novel. A brief list of possible books can be found here.
   If you are interested in such a project, please first make an appointment to meet with me, to work out the details of what you will do and how you will be graded. Any course project must be completed at least one week before the end of the semester so that I will have time to grade it, but it would be best to start earlier than that.

References

The following textbook is required for the course:
Cosmic Perspective with Skygazer CD-ROM (3rd edition) by Jeffrey Bennett, Megan Donahue, Nicholas Schneider, and Mark Voit (Addison-Wesley, 2005).
This book has a web page associated with it, Mastering Astronomy , that you should bookmark with your web browser since you will be using this site substantially during the course.

Lecture notes in the form of PowerPoint files will be available at the following link:

http://www.phy.duke.edu/~hsg/55/lectures/

The following three books will be on reserve in the Vesic Library for Engineering, Mathematics, and Physics in the Teer Engineering building.
1. Universe, 7th Edition by Roger A. Freedman and William J. Kaufmann III (W.H. Freeman & Company, 2004). This a widely used introductory textbook that is slightly more technical and detailed than the Bennett et al book, and that can help students to review for quizzes and exams. The book is also a good source of extra worked-out examples.
2. The Physical Universe: An Introduction to Astronomy by Frank Shu (University Science Books, 1982). An older but still good astronomy text with interwoven calculus- and non-calculus-based tracks. A good reference for students who would like to use their knowledge of calculus and calculus-based physics in an astronomy course.
3. Nightwatch: A Practical Guide to Viewing the Universe, 3e by Terence Dickinson (Firefly Books Ltd, 1998). This is one of the better introductory guides for becoming familiar with the night sky.

A huge amount of information related to this course is available through the Internet. You may like to consult the notes and exercises associated with other introductory astronomy courses (a list of webpages for other astronomy courses is available at this link, and also explore various astronomy-related links at this link.

Office Hours

I do not have official office hours. You can make an appointment to meet with me by email ( hsg@phy.duke.edu), phone (660-2548), or by talking with me in person. I will do my best to meet with you as soon as possible after your request and, in many cases, will be able to meet the same day or the next day.

I am often logged into the Duke computer network during evenings and weekends. If you have a question short enough to answer via e-mail, please e-mail me a message and I will try to respond quickly. Please feel free to ask me about any aspects of the course: topics discussed in lecture or in the text, the current homework assignment, a recent quiz, or some interesting article that you recently saw that might be fun to share with the class.

If you are in the Physics building, please drop by my office (Physics 047), introduce yourself and chat. I would greatly enjoy the chance to meet with you outside of class. My office is a bit hard to find: you have to go to the far back of the building and down one floor.

The observation assistant Nigel Barrella will have office hours on Mondays from 12 noon to 1pm. He will be glad to discuss questions that arise related to observation sessions and writeups of the observation sessions, and also help you with homework problems.

Course Schedule

The following is the approximate weekly schedule for reading, quizzes, and exams. Further details about what to read each week will be available in the course announcements. The supplementary observational meetings will be posted on the course web page and e-mailed to the class. Please make sure to read the course announcements a few times each week and especially before each class.

A 14-week semester consisting of about 40 lecture hours is not enough time to cover the entire book, at least in depth and with quality. As a compromise, this course will emphasize the chapters on observation, gravity and light, stars, Einstein's theories of special and general relativity, and cosmology since I personally find these to involve some of the most interesting scientific ideas, issues, and unsolved questions. We will touch upon chapters related to the solar system mainly during our evening observation times.