Colloquium

Upcoming Colloquium

Resurrecting the Past: The Undying Relevance of 19th Century Physics for Stellar Corpses
Dr. Thomas Klaehn, CSU Long Beach

April 7, 2025
11:00am in HSCI-105

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Before Newton published his Principia in 1687, laying the foundations of classical mechanics, Francis Bacon in 1620 pondered the nature of heat, stating: "Heat itself, its essence and quiddity is motion and nothing else." Boyle's law, which relates the change in pressure to a change in volume, was published in 1662. The industrial revolution of the late 18th century sparked a keen interest in understanding and quantifying thermodynamic processes, crucial for the efficiency of steam engines. The following 19th century saw the formulation of relationships between particle statistics and thermodynamics, leading to the development of statistical mechanics. Concepts such as entropy and thermodynamic potentials emerged during this time.

The 20th century brought a significant shift towards the newly formulated ideas of quantum mechanics and relativity, leading to rapid advancements and profound impacts on technology and society. The discovery of new particles throughout the century fostered the development of quantum field theory (QFT). Central to QFT are manifest symmetries of an underlying Lagrangian, which define the structure of theories like quantum chromodynamics and quantum electrodynamics.

Validating a quantum theory based on symmetry principles is a challenging process. It involves encoding these principles at the individual particle level, typically by modeling a Lagrangian or Hamiltonian, and then employing the full machinery of quantum (field) theory to relate these abstract entities to physical observables. In many-particle systems, this often requires approximations to be successful.

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