Physics 12c
Statistical Mechanics
Spring 2016

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 March 29, 2016.

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


John Preskill, preskill(at)caltech(dot)edu, 206 Annenberg.


Recitation leaders:

Kung-Yi Su, ksu(at)caltech(dot)edu, Wednesday 6:30pm-8:30pm in 11 Downs.

Brenden Roberts, broberts(at)caltech(dot)edu, Recitations Monday 6:30pm-7:30pm in 11 Downs. Office hours Wednesday 2:30pm-3:30pm in 240 Lauritsen.


Vijay Varma, vvarma(at)caltech(dot)edu, Assignments 1, 3, 5, 7.

Mykyta Hulko, mhulko(at)caltech(dot)edu, Assignments 2, 4, 6, 8.


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 (40%), a midterm (20%), 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 by the East Bridge mailboxes at 8:00 pm the following Thursday. Graded homework will be returned to the Physics 12c OUT-box in 264 Lauritsen by the following Wednesday 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. Please write legibly. You may use a symbolic manipulation tool such as Mathematica or MATLAB for doing computations on homework or exams, though this probably won’t be necessary.

Twitter: I’ll attempt to summarize each lecture in 140 characters or less. See the #Ph12c tweets.

Lectures (tentative schedule):

  1. Mar 29. Counting states (lecture notes)
  2. Mar 31. Entropy and temperature (lecture notes)
  3. Apr 5. Boltzmann distribution and free energy (lecture notes)
  4. Apr 7. Ideal gas, mixing (lecture notes)
  5. Apr 12. Planck distribution (lecture notes, plus supplement)
  6. Apr 14. Debye theory, Johnson-Nyquist noise (lecture notes, plus supplement)
  7. Apr 19. Chemical potential, Gibbs distribution (lecture notes, plus supplement)
  8. Apr 21. Indistinguishable particles, thermodynamics of ideal gas (lecture notes)
  9. April 26. Fermi gases (lecture notes)
  10. April 28. Bose-Einstein condensation (lecture notes)
  11. May 3. BEC continued (lecture notes, BEC homepage, Physics World March 1997)
  12. May 5. Heat engines, laws of thermodynamics (lecture notes)
  13. May 10. Gibbs free energy (lecture notes)
  14. May 12. Equations of state (lecture notes)
  15. May 17. 1st and 2nd order phase transitions (lecture notes)
  16. May 19. Ferromagnetism (lecture notes)
  17. May 24. Landau theory of phase transitions and scaling
  18. May 26. Kinetic theory  (lecture notes)
  19. May 31. Diffusion and viscosity (lecture notes)
  20. Jun 2. Maxwell’s demon (lecture notes)


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


Lecture Videos: Recorded in 2011, available at this YouTube Channel.

Also available here, as 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:: Julia Deacon, Arjun Goswami, Stephanie Kwan, Marc Muhleisen. Contact John Preskill to volunteer.

Homework assignments: 
Problem Set 1, due Apr 7. Probability and fluctuations. Solutions.
Problem Set 2, due Apr 14. Boltzmann distribution. Solutions
Problem Set 3, due Apr 21. Black body radiation. Solutions
Problem Set 4, due Apr 28. Chemical potential. Solutions
Problem Set 5, due May 12. Quantum gases and heat engines. Solutions
Problem Set 6, due May 19. Phase coexistence. Solutions
Problem Set 7, due May 26. Critical phenomena and scaling. Solutions
Problem Set 8, due Jun 2. Kinetic theory and diffusion. Solutions

Midterm Exam, Covers all material through Problem Set 4. Solutions
54 exams were received. The median was 83, the mean was 82, the standard deviation was 14. 12 students scored 95 or above, and 4 scored 100.

Final Exam, due June 10. Covers all material in the course. Solutions
52 exams were received. The median was 82 and the mean was 80. 11 students scored in the 90s, and the highest score was 97.

Final grades were determined using the formula Grade = 0.4(Homework) + 0.2(Midterm) + 0.4(Final).
The median final grade was 86 and the mean was 84.
The ranges for letter grades were:

A+       95-100
A         90-94
A-        85-89
B+       80-84
B         75-79
B-        55-74

The distribution of letter grades for the course was:
8 A+, 14 A, 7 A-, 9 B+, 9 B, 5 B- (52 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.

One other thing … A few of you mentioned in the TQFR comments that the Sam Elder notes contain serious typographical errors. It would be helpful if someone could point out the errors, either in an email to me, or by filling out the anonymous comment form on this page.

Thanks, and have a great summer.