Welcome to PHYS 406!

Statistical and Thermal PhysicsInstructor: Xiaoming Mao

Outline of the first class

• Overview: why thermal physics and stat mech are interesting?

• Important questions we will answer in the course

• The Syllabus

Overview

• What we have already learn?– Mechanics: statics and dynamics of single-/few-body problems– E&M: interactions between charged objects– Quantum Mechanics: single-particle wave-functions in fields

• To summarize– Single or few particle problems– Fundamental laws are reversible in time

• Objects in our daily life and many more systems in physics study: particles

• How to bridge the gap?

Can we just solve the same problem for many particles?

• It is not possible• There are better ways to do it– Macroscopic (phenomenological) approach:

Thermodynamics• Developed without knowledge of microscopic world• Essential for the industrial revolutions

– Microscopic approach: Statistical Mechanics• Explains the origin of irreversibility

Two important questions

• “What is the origin of irreversibility in nature?”• “Which quantum phenomena are genuinely many-

body physics?”

Irreversibility

Friction Inelastic collision

Electric flow through resistor

R

Free expansion of gas

Mixing of two fluids Spontaneous chemical reactions

An amusing example

• The Dog-Flea model (Ehrenfests)

reversible

irreversible

Relations between irreversible processes

Reversible

Irreversible

“No heat engine can have efficiency ”

Equivalent

Kelvin statement of the second law of thermodynamics.

Two important questions

• “What is the origin of irreversibility in nature?”• “Which quantum phenomena are genuinely many-

body physics?”

Quantum many-body phenomena I

Black-body Radiation: one of the founding experiments that led to the discovery of quantum mechanics

Quantum many-body phenomena II

Bose-Einstein Condensation (BEC)

Superfluidity

Superconductivity

Quantum many-body phenomena III

Insulators Conductors

Quantum many-body phenomena IV

White dwarf star

Syllabus I (will be posted on CTools)

• Lecture notes will be posted on CTools after each class (including today’s slides, and a detailed Syllabus)

• We will roughly follow the course-pack, but not everything will be covered

• Additional optional textbooksEquilibrium thermodynamics, Author: C.J. Adkins

Thermal physics, Author: Charles Kittel; Herbert Kroemer

An introduction to thermal physics, Author: Daniel V. Schroeder

Statistical and thermal physics: with computer applications, Author: Harvey Gould and Jan Tobochnik

States of matter., Author: David L. Goodstein

Fundamentals of statistical and thermal physics, Author: F. Reif

Syllabus II

• Course work:– Weekly problem sets (20%): posted online on Wed mornings and

due the succeeding Wed in class– Final Exam (30%): 1:30-3:30pm, Monday, Dec 17– Midterm Exams (20% each): week of Oct 8-12 & week of Nov 12-

16, afternoon. Let me know your schedule conflictions before Sep 7.

– Class participation (10%):• Class discussions• Discussions on Piazza

Syllabus III

• Office hour:Mondays 10-12am2251 Randall

• Email: maox@umich.edu• Website for lecture notes, homeworks and

announcements: CTools• Website for discussion on physics: Piazza (there is a link to

Piazza on our CTools page)• Personal webpage:

http://www-personal.umich.edu/~maox/index.html