The course “Modern Physics” deals with the revolutionary new developments that physics underwent during the early 20th century. It is an experimental physics course that largely focuses on a number of key experiments which made the limitations of classical physics clear, and which provided the basis for the new relativity theory of Einstein and quantum physics. The level is generally introductory, preparing the students for the full Quantum Mechanics course which is taught in the 4th semester.

More specifically, the course aims to:

• make the student aware of the fact that physics is a science that continuously develops,

• describe the historical context and development of physics in the early 20th century, with a series of observations being reported that could not be explained by the classical theories, and which thus led to the development of the special relativity theory and quantum mechanics,

• teach the student to apply the principles and laws of modern physics to solve problems, and to demonstrate how this approach has led to a number of technologies which we today take for granted but which would not be possible without the new understanding that we today refer to as “modern physics”.

- This year we use the book “Modern Physics for Scientists and Engineers” by Stephen Thornton und Andrew Rex (Cengage Learning) as core coursebook. It gives a very good and solid introduction to the topic, but we will complement it using the following two popular scientific books. They provide a very stimulating account of the historical development of modern physics.

- Introducing Quantum Theory (Totem books)

J. P. McEvoy and Oscar Zarate - Physics for Poets (Contemporary books)

Robert March

- Special relativity theory: Lorentz transformations; concept of simultaneity; spacetime; Doppler effect; relativistic momentum; mass and energy; conserved quantities vs. invariants. The Michelson-Morley experiment. Introduction to general relativity theory: the equivalence principle and its consequences.
- Statistical physics and thermodynamics primer, tailored for understanding the development of modern physics. Basic concepts: energy, heat, work, entropy, free energy. Statistic and thermodynamic formulations of the second law of thermodynamics. The energy equipartition theorem. The atomistic model and its proof through Brownian motion. Boltzmann statistics. The Maxwell velocity/speed distributions.
- Black-body radiation and Planck's suggestion to quantize energy in order to explain it.
- The photoelectric effect and the quantization of light into photons.
- X-rays and the Compton effect. The principle of scattering experiments to probe the structure of mater.
- The atomic nucleus and the discovery of radioactivity.
- Line spectra, the Balmer series and the Rutherford-Bohr atomic model. The Franck-Hertz experiment, characteristic x-ray spectra. Bohr's correspondence principle.
- More quantum numbers, electron spin and the Pauli exclusion principle, the Stern-Gerlach experiment and the explanation of the periodic system.
- Wave-particle dualism and the de Broglie matter waves. The Davison-Germer experiment. Primer on wave mechanics.
- Heisenberg’s matrix mechanics and the uncertainty relation.
- Schrödinger wave mechanics, as it was originally introduced and with Born’s probability interpretation.
- Dirac’s unification of quantum mechanics. Quantum probabilities, expectation values. The operator concept.
- Requirements on the wave function that solves Schrödinger's equation. Particle in a box, harmonic oscillator
- Tunneling, hydrogen atom wave functions, the orbital concept. Explaining the periodic system; the Aufbau principle and Hund's rules.

A list of learning objectives can be downloaded here and the current version of the syllabus is here.

The slides I show can be downloaded as pdf files (after each class) here (only for registered students). The exercise class will be given by Mr. Hugues Meyer.

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