From Propagation to Structure: The Experimental Technique of Bombardment as a Contributing Factor to the Emerging Quantum Physics

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I observe that quantum physics emerged at the turn of the last century when physics had shifted its concern from propagation phenomena to questions of structure. This transition materialized with the development of a new experimental technique, the bombardment method. The transition is well exemplified by the move from the experimental studies of Heinrich Hertz to those of Ernest Rutherford, and from those of Heinrich Hertz and Philipp Lenard to those of James Franck and Gustav Hertz. I trace the history of Rutherford's experimental bombardment method as it emerged from nineteenth-century propagation studies. I then demonstrate the use of the bombardment method in another experimental context, namely, in the celebrated experiment of Franck and Hertz. I locate the root of this experiment in Lenard's experimental studies and analyze Franck and Hertz's flawed interpretation of it. I conclude by underlining the crucial role that Bohr's quantum theory of the atom played in helping to establish these bombardment experiments as milestones of modern physics.

Original languageEnglish
Pages (from-to)150-173
Number of pages24
JournalPhysics in Perspective
Issue number2
StatePublished - Jun 2003

Bibliographical note

Funding Information:
* This article is based on a talk I gave on December 16, 2000, at a Symposium on ‘‘The Foundations of Quantum Physics before 1935’’ in Berlin, Germany. I acknowledge with gratitude the financial support of the Alexander von Humboldt Foundation that facilitated my participation in the Symposium.

Published in a Hungarian translation [“A bombázás kísérleti technikája és a kvantumfizika keletkezése”] in a book containing case studies on “turning points” in science


  • Bombardment
  • Elastic and inelastic collisions
  • Ernest Rutherford
  • Excitation
  • Experimentation
  • Franck-Hertz experiment
  • Gustav Hertz
  • Heinrich Hertz
  • Ionization
  • James Franck
  • Niels Bohr
  • Philipp Lenard
  • Propagation
  • Rutherford atom
  • Structure

ASJC Scopus subject areas

  • History
  • General Physics and Astronomy


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