# Astronomy 129: Cosmology

## Archive of Announcements

### Week 12

We'll go back to the era of inflation this week - almost back to the Planck time. And we'll see how a brief period of exponential growth of the scale factor could explain several remaining puzzles of the hot big bang cosmology.

Also, there are two more research talks in the department this week — by job candidates. They are on Monday and Thursday afternoons at 4:30. Please try to come if you can. Keep an eye out for email announcements about each one.

### Week 11

*posted 11/14*

We are moving back in time from the era of recombination to the first few minutes after the Big Bang. We'll focus on material in the textbook this week, and I'll set up a discussion forum for you to post questions about the reading and assignment.

Also, there are a couple of research talks in the department this week — by job candidates. They are about fundamental physics, including speculative stuff about string theory and axions, for example, that have relevance to cosmology. They are on Monday and Thursday afternoons at 4:30. Please try to come if you can. Keep an eye out for email announcements about each one.

### Week 10

*posted 11/7*

We are focusing more on the textbook again this week, but with some significant material in an on-line tutorial, and also some visualization tools to help us think about how the CMB anisotropies are described and how the cosmological parameters affect their statistical properties. Once again, the written, mathematical part of the assignment will not be super-intensive, but that means you have to hold yourselves to a high standard in trying to understand the material as you read it prior to coming to seminar, and then again in seminar when we discuss the material.

### Week 9

*posted 10/31*

Things are going to be a little different this week; more reading - and discussion - and fewer problems. See the assignment, and get started with the reading soon.

### Week 8

*posted 10/26*

We're back to our regular seminar material, with Ch. 7 on tap for this week. We'll also read (parts of) a research paper. We're moving into the more observational parts of the material.

### Week 7

*posted 10/20*

Our midterm will be in class on Wednesday. There is no other assignment — just to study and to prepare your sheet of notes and equations. Information about the exam is posted. Graded HW#6 are available to be picked up outside my office, with more to come soon.

### Week 6

*posted 10/3*

The assignment for week 6 is posted. We'll be studying multi-component universes.

### Week 5

*posted 9/28*

OK, I've now posted the complete assignment for week 5. Note that while there is another 1.5 pages of notes, sanity checks, and questions, there's nothing new for you to hand in, *except* for a plot that approximates Fig. 5.2 in the textbook.

Also, I will be out of town on Monday, but in my office most of the day on Tuesday. Get in touch with questions via email today or Monday, but feel free to drop by my office if you've got questions on Tuesday.

Note: There's an updated syllabus, with the midterm date now set for the week after break (in class). The midterm will probably be closed book, but you'll be allowed to bring a page of notes into the exam with you.

*posted 9/25*

We will look at "single component universes" — those dominated by matter, radiation, curvature, or cosmological constant — in week 5's assignment and seminar meeting.

Following up on week 3, Tristan gave me some information he thought you might want to take a look at: about expressing the Ricci scalar in terms of the metric; the equation that shows how the gravitational potential evolves when there is a small density fluctuation; and Tristan's derivation of equation 6.

### Week 4

*posted 9/18*

For week 4's seminar meeting, we're back to reading and discussing material from Ryden's textbook.

### Week 3

*posted 9/15*

Tristan has sent out a two part assignment, with reading and questions posted. It'll be a detour into GR this week, with Ch. 4 and the Friedmann equation next week.

### Week 2

*posted 9/11*

Next week will be unusual, as I will be out of town on Wednesday (through Sunday). We will have a seminar meeting on Wednesday, led by Tristan. It will be on General Relativity and will involve some reading but only a small number of problems. The following week we will read and discuss Ch. 4, so you can get started reading that, if you'd like (Tristan will try to draw some connections between the GR material and the material in Ch. 4, specifically the Friedmann equation).

*posted 9/8*

Brady will bring the snack for this Wednesday's seminar. The assignment is posted on the *Old Assignments page, and I will be in my office and happy to talk to you about this week's assignment and problems most all of Monday and Tuesday as well as the late morning on Wednesday.
*

### Week 1

*posted 8/29*

Our first seminar meeting is Wednesday, September 3. The assignment, which includes reading from the textbook and some questions to answer and problems to solve and hand in *prior* to the meeting, by Tuesday morning, is posted on the old assignments page.

Return to the main class page.

*This page is maintained by David Cohen
cohen -at- astro.swarthmore.edu
*

Last modified: December 6, 2014