Physics 12c
Statistical Mechanics
Spring 2013

Go to home page for Ph12b

Course description: An introductory course in statistical mechanics.

Class meetings: Tuesday and Thursday 10:30-11:55 am in 269 Lauritsen, starting April 2, 2013.

Feedback: If you want to send a comment about the course, click here.


John Preskill,, office hours Mon. 2-3 pm in 206 Annenberg.


Recitation leaders:

Michael Beverland, mbeverla(at)caltech(dot)edu, section Wed. 3-4 pm in 243 Annenberg, office hours Wed. 4-5 pm in 243 Annenberg.

Kung-Yi Su, ksu(at)caltech(dot)edu, section Wed. 7-8 pm in 107 Downs, office hours Wed. 8-9 pm in 107 Downs.


Enrico Herrmann, eherrmann(at)caltech(dot)edu, 421 Lauritsen

Min-Feng Tu, mtu(at)caltech(dot)edu, 54 Bridge


Textbook: Thermal Physics (2nd edition) by Charles Kittel and Herbert Kroemer

We will cover most of the first 10 chapters of Kittel and Kroemer, plus part of Chapter 14 and some supplementary material.

Grading: Grades will be based on weekly problem sets (30%), a midterm (30%), and a final exam (40%).

Homework: Problem sets will be posted on this page on Thursday, and will be due in the Physics 12c IN-box outside 264 Lauritsen at 5:00 pm the following Thursday. Graded homework will be returned to the Physics 12b OUT-box in 264 Lauritsen by the following Monday morning. Solution sets will be posted on this page.

Unexcused late homework will be accepted for half credit up until one week after the due date; there is no credit if your assignment is more than one week late.
-- If your homework will be late for a good reason, you may request an extension before the assignment is due by sending email to that week’s grader.
-- One extension, for up to one week, is allowed without question (your silver bullet). Please put a note at the top of your problem set indicating that you are using your silver bullet.

Honor Code: Discussion with others is encouraged, but the work you hand in must be your own. In particular, do not use homework solutions from previous years or exams and exam solutions from previous years.

Lectures (tentative schedule):

  1. Apr 2. Counting states (lecture notes)
  2. Apr 4. Entropy and temperature (lecture notes)
  3. Apr 9. Boltzmann distribution and free energy (lecture notes)
  4. Apr 11. Ideal gas, mixing (lecture notes)
  5. Apr 16. Planck distribution (lecture notes, plus supplement)
  6. Apr 18. Debye theory, Johnson-Nyquist noise (lecture notes, plus supplement)
  7. Apr 23. Chemical potential, Gibbs distribution (lecture notes, plus supplement)
  8. Apr 25. Indistinguishable particles, thermodynamics of ideal gas (lecture notes)
  9. April 30. Fermi gases (lecture notes)
  10. May 2. Bose-Einstein condensation (lecture notes)
  11. May 7. BEC continued (lecture notes, BEC homepage, Physics World March 1997)
  12. May 9. Heat engines, laws of thermodynamics (lecture notes)
  13. May 14. Gibbs free energy (lecture notes)
  14. May 16. Equations of state (lecture notes)
  15. May 21. 1st and 2nd order phase transitions (lecture notes)
  16. May 23. Ferromagnetism (lecture notes)
  17. May 28. Landau theory of phase transitions and scaling
  18. May 30. Kinetic theory  (lecture notes)
  19. Jun 4. Diffusion and viscosity (lecture notes)
  20. Jun 6. Maxwell’s demon (lecture notes)


Typed Lecture Notes: Courtesy of Sam Elder (2010), available here.


Lecture Videos: Recorded in 2011, available here. These are mkv files, which you may download and play on your own computer. The lectures this year will be somewhat different than in 2011, but the videos may be useful if you miss a lecture.


Ombudsfolks:: Chiraag Nataraj (Fleming), Jeff Picard (Blacker), Nico Salzetta (Page), Ann Wang (Ruddock), Carla Watson (Dabney). We’d like to have an ombudsperson from each house. Contact John Preskill to volunteer.

Homework assignments: 
(Enrico grades Problem Sets 1-4, Min-Feng grades Problem Sets 5-8.)
Problem Set 1, due Apr 11. Probability and fluctuations. Solutions
Problem Set 2, due Apr 18. Boltzmann distribution. Solutions
Problem Set 3, due Apr 25. Black body radiation. Solutions
Problem Set 4, due May 2. Chemical potential. Solutions
Problem Set 5, due May 16. Quantum gases and heat engines. Solutions
Problem Set 6, due May 23. Phase coexistence. Solutions
Problem Set 7, due May 30. Critical phenomena and scaling. Solutions
Problem Set 8, due Jun 6. Kinetic theory and diffusion. Solutions

Midterm exam, due May 9. Solutions
Fifty-six exams were received. The median was 96 and the mean was 92. Fourteen students scored 100.

Final exam, due June 14. Solutions
I deliberately made the final harder than the midterm, though it turned out to be harder than I intended. Fifty-five exams were received. The median was 70 and the mean was 66. Eight students scored in the 90s, and the highest score was 99.

The distribution of letter grades for the course was:
6 A+, 8 A, 18 A-, 10 B+, 5 B, 7 B-, 1 C+ (55 total)

I hope you enjoyed Ph 12c and learned a lot. If you have not already done so, please review the course by responding to the TQFR survey. Your feedback is very helpful, especially if you have suggestions for improving the course. In particular, I would like to know: whether you liked the book, whether the online notes and videos were useful, whether the lectures were too much like the book, whether the homework helped you to learn, whether the recitations were effective, whether the exams were reasonable and the grading was fair... Or whatever else you think is relevant.

Thanks, and have a great summer.