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The University of Southampton

PHYS2024 Statistical Mechanics

Module Overview

Statistical mechanics links the microscopic properties of physical systems to their macroscopic properties. Thermodynamics, which describes macroscopic properties, can then be derived from statistical mechanics with a few well motivated postulates. It leads to a microscopic interpretation of thermodynamic concepts, such as thermal equilibrium, temperature and entropy. In the course the basic principles of statistical mechanics will be introduced with applications to the physics of matter.

Aims and Objectives

Learning Outcomes

Knowledge and Understanding

Having successfully completed this module, you will be able to demonstrate knowledge and understanding of:

  • Microcanonical ensemble (e.g. enumerate microstates for some simple physical systems)
  • Microscopic definition of entropy and temperature
  • Canonical ensemble, and applications to some simple physical systems immersed in a heat bath (temperature)
  • Probabilistic interpretation of entropy, heat and work
  • Chemical potential
  • How Bose-Einstein condensation leads to unique states of matter at low temperatures
Subject Specific Practical Skills

Having successfully completed this module you will be able to:

  • Employ quantum mechanics for a correct statistical description in terms of Fermi and Bose gases and their applications
  • Distinguish between Bose and Fermi gases and their ground states


- Revision of the basics laws of thermodynamics - Brief summary of combinatorics and probabilities - Discussion of basic concepts, notions and postulates of statistical mechanics e.g. microstates vs macrostates, notion of ensemble and postulate of equal a priori probability and ergodicity - Microcanonical ensemble (isolated system). From where a microscopic definition of entropy and temperature emerges. - Canonical ensemble (system in a heat reservoir). Uncover the free energy F as the natural thermodynamic potential. - Discuss the equivalence of microcanonical and canonical ensemble in the thermodynamic limit. - Applications: paramagnetism, heat capacity of solids (phonons); - Grand canonical ensemble (systems with a variable numbers of particles); Discussion of the chemical potential; - Discussion of indistinguishable particles in quantum mechanics and introduce the two types of particles: bosons and fermions - Applications: Fermi gases; zero point pressure, zero point energy, discuss the free fermion electron model - Bose gases: Black body radiation, Bose-Einstein condensation

Learning and Teaching

Teaching and learning methods

Lectures and problem classes.

Follow-up work18
Wider reading or practice46
Completion of assessment task10
Preparation for scheduled sessions18
Total study time150

Resources & Reading list

S Blundell and K Blundell Р(2006). Concepts in Thermal Physics. 

R,Baierlein. Thermal Physics. 


Assessment Strategy

Weekly course work will be set and assessed in the normal way, but only the best ‘n-2’ attempts will contribute to the final coursework mark. Here n is the number of course work items issued during that Semester. As an example, if you are set 10 sets of course work across a Semester, the best 8 of those will be counted. In an instance where a student may miss submitting one or two sets of course work, those sets will not be counted. Students will, however, still be required to submit Self Certification forms on time for all excused absences, as you may ultimately end up missing 3+ sets of course work through illness, for example. The submitted Self Certification forms may be considered as evidence for potential Special Considerations requests. In the event that a third (or higher) set of course work is missed, students will be required to go through the Special Considerations procedures in order to request mitigation for that set. Please note that documentary evidence will normally be required before these can be considered."


MethodPercentage contribution
Continuous Assessment 20%
Final Assessment  80%


MethodPercentage contribution
Set Task 100%


MethodPercentage contribution
Set Task 100%

Repeat Information

Repeat type: Internal & External

Linked modules

Pre-requisite: PHYS1013

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