The Birth of Quantum Theory
Mini-symposium

Monday 11 December 2000, "De Sitter" Lecture Hall,
Oort building, Niels Bohrweg 2, Leiden

Co-Sponsored by
Instituut-Lorentz -- LION -- Studium Generale
University of Leiden

In December 1900, now one hundred years ago, the German physicist Max Planck introduced his constant h, specifying the relation between the radiation energy E and frequency f -- E=hf. His discovery implied that radiation energy can only change in steps of hf, called quanta. Planck broke in a spectacular way with the classical theory, in which energy can change in a continuous way. Planck thus laid the foundations for the Quantum Theory. We celebrate this Planck centennial with a mini-symposium, that also discusses the role of Lorentz and Ehrenfest.

Programme

14h00-14h15

Nico van Kampen (UU)

Introduction

14h15-15h00

Michael Nauenberg (UC Santa Cruz)

Max Planck and the experiments which gave rise to the quantum hypothesis

15h00-15h30

Break

--

15h30-16h15

Anne Kox (UvA)

H.A. Lorentz's contributions to early quantum theory

16h15-17h00

Frans van Lunteren (UU)

Paul Ehrenfest's struggle with the quantum hypothesis

17h00-17h15

Martin J. Klein (Yale)

Closing comments



Abstracts

Michael Nauenberg (Santa Cruz)

Max Planck and the experiments which gave rise to the quantum hypothesis

In December of 1900 Max Planck explained the spectrum of black body radiation with "an act of desperation", the quantum hypothesis, which ushered in a new era in physics. This lecture will present a historical perspective including the crucial but often neglected advances in measurements of long wave infrared radiation which culminated in this event.

Anne Kox (UvA)

H.A. Lorentz's contributions to early quantum theory

As one of the leaders of theoretical physics at the beginning of the twentieth century, Lorentz played an important role in clarifying the meaning of the quantum hypothesis. This talk analyzes Lorentz's contributions, which were made in published papers as well as in correspondence with colleagues such as Max Planck and Wilhelm Wien.

Frans van Lunteren (UU)

Paul Ehrenfest's struggle with the quantum hypothesis

Quantum theory was born in confusion. Before the Solvay-meeting of 1911 very few physicists were aware of the threat that Planck's work posed to established views in physics. Even fewer made a serious attempt to clarify the nature of the break with the past. Among them a young Austrian physicist, soon to become a professor in Leiden, stands out. After some initial successes, Ehrenfest's quest for clarity turned into an uphill battle ending in a tragic defeat.

Summary of the meeting by Michael Nauenberg