Astronomy 350: Introduction to Cosmology University of Illinois Fall 2012


Professor Teaching Assistant
Brian Fields
Astronomy Building Room 216
Office Hours: Wednesday 1:00-2:00pm, or by appointment
Chun Yin (Ricky) Chue
Astronomy Building Room 132
Office Hours: Thursday 9:30-10:30 am

course webpage:

Cosmology is science on the grandest of scales. It is one of the hottest areas of research today, weaving together a wide range of disciplines, including observational astronomy, astrophysics, relativity, and the physics of elementary particles and quantum gravity.

At this moment, cosmology is enjoying a golden age in which observation and theory come together to finally settle longstanding questions, but in doing so stumbling upon unexpected and profound new mysteries. We now have an increasingly precise understanding of the scale, shape, motion, and ingredients of the present-day universe. But in detail, we find that most of the matter in the universe must take an exotic form unlike anything found in laboratory experiments to date. This startling result points up a fundamental incompleteness in our understanding of elementary particles and their interactions. We are even more staggeringly ignorant as to the nature of the dominant constituent of the universe today, the "dark energy."

Yet despite these enormous open questions, we can already say a surprisingly great deal about the history of the universe. We have particularly precise and quantitative understanding of the formation of the most abundant elements in the cosmos and the much later quenching of the cosmic fireball. We are developing a detailed understanding of how tiny variations in cosmic matter across space grow with time to form the structured cosmos of the present day.

In this course, we will survey these topics, and their interrelations. The emphasis will be on cosmology as a centerpiece of modern science. We will develop and then applying physical principles to understand observations--using the laws of nature measured here and now to reveal what happened "there and then." We will also turn the problem around, and view the universe as a laboratory for fundamental physics--using the observed properties of the cosmos to reveal the nature of matter, space, and time on both the grandest cosmic scales and the tiniest subatomic scales. The goal is for ASTR350 alumni to understand the fundamentals of cosmology, and to have knowledge of open questions, and of observational and theoretical tools.

Course Requirements

Requirement Percentage of Grade Points
2 Hour Exams 2 x 10% each 20% 200
Final Exam 15% 150
Homework (best 10 of 11) 10 x 5% each 50% 500
Discussion Questions (best 10 of 11) 10 x 1% each 10% 100
Participation 5% 50
Total 100% 1000

Each of the 11 homework assignments, are worth 50 points and thus 5% of the final grade; the lowest homework score will be dropped. Similarly, each of the 11 discussion questions are worth 10 points and thus 1% of the final grade, and the lowest discussion question score will be dropped.

Course Prerequisites

The formal course prerequisites are to have one introductory astronomy course, i.e.: ASTR 100, or ASTR 121, or ASTR 122, or ASTR 210, or consent of instructor. In particular, a background in physics or calculus is not a course requirement. Consequently, it will be possible to do all of the required coursework with only the introductory background in the prerequisites. So if you are not a science major, and/or you do not have a physics or math background, this course is meant for you. But some students with a more technical background do take this course, and enjoy it and benefit from it.

Because of the diversity of student backgrounds, the level of the lectures and class discussion cannot at every instant be tuned to the background of every student. Inevitably, there will be some moments (I hope only a few) when either the discussion is not aimed at your level. My intention is to reward your occasional patience with a degree of "customization." That is, the required materials in lecture and in the homework will all be accessible to everyone regardless of background. But I intend to make some homework assignments, as well as the entire term paper, to have optional elements which are aimed at nonscience majors as well as optional elements aimed at those more familiar with physics. Thus to some degree you can choose how technical you wish the course to be.

Note for "Technophiles" = students with a more technical background: Cosmology is presented in a more quantitative and physics-based manner in one undergraduate course offered every year, Astronomy 406: Galaxies and the Universe. This course also offered this semester. Also, the graduate course Astronomy 507: Cosmology will be offered next year, and may be offered in an undergraduate version.

Note for Astronomy Majors and Minors: a careful reading of the major requirements will reveal that this course can count as an advanced elective. Similarly, for the minor, this course will count as an advanced Astronomy course. But you will not receive credit for this course if you have already taken ASTR 406: Galaxies and the Universe.

Course Text

Recommended: Todd Duncan and Craig Tyler, Your Cosmic Context: An Introduction to Modern Cosmology.
This book gives a modern and up-to-date overview of cosmology. It has about the right level, i.e., it is not too math-heavy, and it has excellent figures which are extremely useful.

I do not make it a practice to follow the textbook in structuring the course or the lectures. Rather, I will present material in the manner that I find most pedagogical and, I hope, entertaining; the textbook will serve to offer an excellent alternative discussion for those times when you find my own to be unclear and/or incomplete.


The following table shows the approximate grading scale in this course.

Grade Approximate Range
A 93-100%
B 83-93%
C 73-83%
D 63-73%
F <63%

Final course grades will follow these guidelines. The ranges are approximate in that I may have to adjust them if, for example, I give an exam that is a little too hard. In any case, I will not increase the minimum cutoffs for each letter grade. In other words, you should expect that grade or higher. Plusses and minuses will be used.


There will be two in-class hour exams, and a comprehensive final exam. Exam dates and information posted here.


There will be 11 homework assignments given throughout the course. These are meant to sharpen your thinking on the material covered in lecture, to develop your intuition and quantitative skills, and to help prepare you for the exams. Homework is due at the beginning of class on almost every Friday. You should turn in a copy of your work in class (or a printout if you do it on a computer). You are also encouraged to upload your assignment (or a scan of it) on Compass2g; this will serve as your proof that you have done the assignment on time, should there be any questions about possible lost homework.

Homework assignments posted here, while solutions will appear on Compass2g.

You are responsible for all of the material covered on all 11 homework assignments. Thus, it is to your advantage to do all 11 of the assignments, and hand them in on time.

Discussion Questions

This course will include the use of a discussion board to facilitate out-of-class interaction, discussion and submission of the final class projects. Access to the discussion is via the course Compass2g site;see me if for whatever reason you do not receive your userid and password on the first day of class.

On most Wednesdays, I will post a discussion question on the Discussion Board area of the course Compass site. Answers are due by midnight the next Wednesday. Each student will be responsible for posting at least one substantive, on-topic response to this question or to another student's response to it. The content and correctness of these responses will not be evaluated, but they must be substantive (at least one complete sentence, and not simply, for example, "I agree with Pat") and relevant to the posted discussion topic in order to receive credit. Profanity, personal attacks, and other inappropriate posts will be deleted by the instructor and will result in zero.

Class Participation

You are expected to attend lectures. I will cover material in class that will not always be in the text, and the lecture material will be included on the exam. Class time is the most valuable for you if you come prepared, and are ready to actively engage the material. To encourage your engagement, the lectures will often be punctuated by opportunities for your feedback, in the form of asking questions, voting on the possible outcomes of observations or demonstrations, or brainstorming answers to open-ended questions. To reward your participation in these activities, you will often be asked to respond via the iClicker. Either the old iClicker or the new iClicker2 will work.

Make sure to register your iClicker here by Sept 5.

These participation surveys are not "quizzes" in the usual sense, in that you are not required to get all answers right. Rather, you will always get substantial credit simply by offering a scientifically reasonable response even if it is wrong (and in some cases the questions have no single correct answer, in which case all responses receive full credit). The point of this is that the survey is always an opportunity to gain points as long as you are actively engaged, even if you are still a little confused. Indeed, the most difficult and potentially confusing subjects are precisely those that most require you participation!

For each iClicker poll, 1.5 participation points will be available: the full 1.5 points will be awarded to correct response(s), while 1 point will be given for any other scientifically reasonable responses. Your total participation points will accumulate until they reach a maximum of 50 total participation points; if you faithfully attend class and answer correctly most of the time, you can reach this maximum a few weeks before the end of the semester. There are thus ample opportunities to attain this maximum score, even if several classes are missed due to situations such as late class registration, family emergencies, job interviews, and malfunctioning iClickers; therefore no additional participation opportunities will be available beyond those in each class.

The iClicker scores will reflect what is recorded by the instructor's receiver. Recorded iClicker scores will be posted on Compass every few days. Students are responsible for checking throughout the course and verifying that their clicker responses are properly received.

Classroom Etiquette and Use of Electronic Devices

For the benefit of your fellow students and your instructor, you are expected to follow these basic rules of decorum.

Electronic devices such as laptops, tablets, mobile phones, and the like, are tools that can enhance the classroom but also can be disruptive if misused. I will allow the use of such devices in class for the purpose of taking notes only. But you are expected to pay attention in class, and these devices and be very distracting; you are expected to use them only for note-taking.

Students must respect the classroom environment. Unless specifically directed by the instructor, students shall refrain from sending email and instant messages, or from engaging in other activities (reading non-course materials, engaging in private conversations and so on) that disrespect the classroom environment and learning conditions for others.

Disruptive behavior and/or misuse of electronic devices can affect your participation grade for that day. If the behavior continues, there will be additional reduction in the overall course participation grade.

Late Course Registration

Students considering late registration, particularly after Sept. 7, are welcome but strongly encouraged to speak with the instructor prior to joining the course.

Out of fairness, the same grading standards will be used for all students in the course, and all students will be responsible for all assignments and all lecture material. Those students who register late are welcome, but join the course with the understanding that they are responsible for the material covered before they joined the course. The policy of dropping the lowest two assignments allows late registering students to avoid penalty on any assignments missed before joining the course, as long as the remaining assingnments are completed.

Academic Integrity and Collaborative Work

Academic honesty is essential to this course and the University. Any instance of academic dishonesty (including but not limited to cheating, plagiarism, falsification of data, and alteration of grade) will be documented in the student's academic file. In addition, the particular exam, homework, or report will be given a zero.

Guidelines for collaborative work: Discussing course material with your classmates is in general not only allowed but in fact a good idea. However, each student is expected to do his or her own work. On homework, you may discuss the questions and issues behind them, but you are responsible for your own answers. Finally, on exams your work and your answers must of course be entirely your own.

Brian D. Fields
Last modified: Sun Aug 26 16:20:58 CDT 2012