Physics 303a - Statistical Physics

In Brief: Treatment of many particle systems using classical and quantum statistics to derive the laws of thermodynamics and the properties of macroscopic systems. The course includes applications to solids, liquids, and gasses, both classical and quantum. Monte carlo computer methods are used to discuss phase transitions in a final project.

A bit more: The subject of statistical mechanics is part of the core of physics. It is concerned with predicting the bulk properties of macroscopic matter, especially those affected by thermal energy, from microscopic principles. It provides a fundamental explanation of the laws of thermodynamics including the second law. It accounts for the behavior of photons and phonons, explains what happens to ideal gasses in the quantum limit, and accounts for the transformations of matter between different phases. Statistical physics explains what happens as the absolute zero of temperature is approached, explains the transport of heat and momentum, and provides insight into novel phenomena at the frontiers of physics, including the amazing Bose-Einstein condensation, the behavior of nuclear matter in stars, and other exciting developments involving many particle systems.

The central conceptual ideas in statistical physics include the laws of thermodynamics, especially the second law and the concept of entropy; the canonical probability distribution, which specifies how likely it is that a system at constant temperature will be found in a particular one of its many possible states; the partition function, from which all the thermodynamic properties of a system can be obtained; and the chemical potential, which allows one to understand diffusive equilibrium in a system whose particles can move around.

Students who haven’t experienced the subject often misunderstand what statistical physics is about, thinking from the name that it’s about computing odds for atoms to do different things. However, given the huge number of particles (atoms, photons, electrons, etc.) in a typical macroscopic system, it really provides perfectly definite predictions or explanations of most important properties.

In recent years, statistical physics has undergone an amazing expansion, so that it is now often used outside its traditional domain (thermal properties of matter), e.g. in biological physics, including efforts to understand genetic sequences, and in "financial physics", to understand stock market fluctuations(!). If you pay attention, you might make a lot of money (or you might not).

Background: The background required for this course is modest. From quantum physics, you need to understand the existence of energy eigenstates and the oncept of the de Broglie wavelength. From classical mechanics, you don’t need much more than introductory physics. The ideas of thermodynamics will be taught from scratch in the course. The mathematical level of the course is comparable to sophomore physics, i.e. multivariable calculus, but vector calculations are not usually needed.

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