PHYS 432/532 Cosmology (2017-2018)

Welcome to Cosmology! Cosmology is the study of the universe taken as a whole. In this class, we will explore the range of possible universes -- how they are born, how they evolve, distance and time-scale within them, and how they might end. We will also look at our universe in particular. What are the parameters that govern our universe? How do we measure them? How is our universe ``fine-tuned'' to allow for life as we know it?

This is a not terribly exciting webpage for our incredibly exciting cosmology course this winter. I'll post all sorts of things here, like links, images, homework assignments (should you be foolish enough to miss the classes in which I hand them out), and announcements.

[Course Information] [Announcements] [Material and Links]

Course Information

Syllabus - Ver. 1/3/18

Instructor:
Prof. Dave Goldberg (goldberg@drexel.edu)
Office: Disque Hall Room 810
Phone: x2715
Office Hours: M 11-12, Th 10-11 or by appointment in advance

Grader:
Mr. Dustin Hill (dustin.jay.hill@drexel.edu)
Office: Disque Hall Room 808

Lecture:
MWF, 10am-11am, Disque 919

Textbook:
Introduction to Cosmology, 2nd edition. By Barbara Ryden.
I will also supplement with handouts as needed.

Announcements

  • On Wednesday, February 14 (Valentine's Day) we will have our midterm exam during the regular class period. The exam will be comprehensive and will include everything discussed in class up to and including material from February 9 (but primarily the first 4 topics, and everything on the first 3 homeworks).

    I also strongly recommend you read Ryden Chapters 1-7. Some of the more important topics we've covered include:

    • The Cosmological Principle
    • The Friedmann Equation
    • Cosmological Models
    • Comoving, proper, angular, and luminosity distances
    • Observations in a curved universe
    • Cosmological tests
    • Measuring fundamental parameters (how? what they mean? what are the accepted values?)

      This list is not comprehensive. The exam will consist of 3-4 problems similar in style to those I've given you on the homework. Be aware that in past years, we've had 2x 1 1/2 hour lectures, but this year, our lectures are only an hour. As a result, the exam will be slightly shorter than in the past. As a help, please take a look at some old exams:

    • [2014 Midterm] -- [Solution Key]
    • [2016 Midterm] -- [Solution Key]
    Except for the equation sheet, below, the exam will be entirely closed book. You may bring a calculator, but are expected to use it only for basic arithmetic (addition, subtraction, multiplication, division) only.
  • [Midterm Solution Key]
  • Additional Lecture notes: [linear.pdf]
  • On >Wednesday, March 21 we will have our final exam from 3:30-5:30pm in Curtis 452 (Please make sure you know where that is ahead of time).

    Update - Because of the storm, we'll now be having our exam on Thursday, March 22 and 2pm in Disque 919.

    As with the midterm, the exam will be comprehensive and will include everything discussed in class.

    I also strongly recommend you review all of Ryden, with particular attention given to the sections outlined in the course syllabus (above). Some of the more important topics we've covered since the midterm include:

    • The timeline of the early universe
    • Big Bang Nucleosynthesis
    • Inflation (arguments for, how it works, etc.)
    • The growth of structure (linear perturbation theory)
    • The CMB (including especially how varying parameters changes the matter and CMB spectrum)
    • Nonlinear structure growth

      This list is not comprehensive. The exam will consist of 4-5 problems similar in style and difficulty to the midterm.As a help, please take a look at some old exams:

    • [2014 Final] -- [Solution Key]
    • [2016 Final] -- [Solution Key]
    Except for the equation sheet, below, the exam will be entirely closed book. Again, you may bring a calculator, but are expected to use it only for basic arithmetic (addition, subtraction, multiplication, division) only.
      [Equation Sheet] -- As always, if you are the first to find an error, let me know, and you'll get extra credit.
  • [Final Exam Solution Key]

Materials and Links

Homework Assignments

25%

Slides, Supplementary Links, Papers, and Data

  • Lecture Slides
  • Planck 2015 Cosmological Parameters [Paper] (Start with table 3)
  • Cosmological Perturbation Theory in Synchronous and Conformal Gauges [Paper] (in case you are interested in writing your own code).
  • A quick CMB and power spectrum code I wrote in python:
    [Code]
    To run (using a system with python2.x and above, matplotlib, and numpy):
    % python2.7
    >>> from structure import *
    >>> twoplots(0.3,0.04,0.7)
    Where the first argument is Omega_M, the 2nd in Omega_b, and the third i Omega_Lambda of the "changed" cosmology. It compares an approximation of the matter and CMB power spectrum to the concordance cosmology. All other calculations are in Hubble units. Some caveats:
    • You'll need to delve into the code to see the physics, and I'm afraid I did minimal documentation.
    • It only includes some of the physics, such as the Sachs-Wolfe Effect, pressure, and gravity. Outside the horizon, I simply grow everything linearly, as we discussed, and then "turn on" gravity as a mode enters the horizon.
    • Nothing is even close to normalized correctly.
    Here are a couple of snaps:

    omega_bar=0.1

    omega_m=0.5, omega_lam=0.5
Links