In 1919, at Frankfurt, Otto Stern (1888-1969) implemented the molecular beam -- or molecular ray -- technique, which he characterized as follows: "the most distinctive characteristic property of the molecular ray method is its simplicity and directness. It enables us to make measurements on isolated neutral atoms or molecules with macroscopic tools. For this reason it is especially valuable for testing and demonstrating directly fundamental assumptions of the theory." Of special significance was the Stern-Gerlach experiment, carried out at Frankfurt in 1920-1922, which introduced the key concept of sorting quantum states via space quantization of angular momentum. Among its descendants are the prototypes for nuclear magnetic resonance, optical pumping, the laser, and atomic clocks, as well as incisive discoveries such as the Lamb shift and the anomalous increment in the magnetic moment of the electron, which launched quantum electrodynamics. In the 1960s, the molecular beam technique made inroads into chemistry as well, by fulfilling the pipe dream of disentangling from gaseous chaos elementary chemical reactions as single binary collisions of chemically well-defined reagents. Chemical reaction dynamics that ensued has remained one of the chief preoccupations of chemical/molecular physics to date. In the 1990s, a renaissance had begun in atomic physics, nurtured by the development of techniques to cool and trap atoms. Based on a combination of molecular beams with laser cooling, these techniques enabled the realization of quantum degeneracy in atomic gases, launched condensed-matter physics with tunable interactions, as well as transformed metronomy.
The Otto Stern symposium will survey both the historical aspects as well as the state of the art of what emerged from Otto Stern’s molecular beam laboratory at Frankfurt. The Physics Department at Frankfurt has been recently recognised by the European Physical Society (EPS) as an “EPS Historic Site,” which will be inaugurated during the symposium.
The symposium is funded by grants from the Wilhelm and Else Heraeus Foundation https://www.we-heraeus-stiftung.de/english/, the Deutsche Forschungsgemeinschaft https://www.dfg.de/, and Frontiers Media https://www.frontiersin.org/.
