The editors have benefited greatly from the assistance of many individuals and in-
stitutions. We extend our thanks to the members of the Executive Committee, and
wish to thank The Hebrew University of Jerusalem for granting us permission to
publish materials from its holdings.
The ongoing support of the Harold McGraw, Jr., endowment is deeply appreci-
ated. Generous assistance was provided by the provost’s office at the California
Institute of Technology and by the Virgle L. Hedgcoth and Susan Alexander Fund.
We thank Lisbeth Rausing, Peter Baldwin, and the Arcadia Fund for their inter-
est and generosity in supporting our work.
We gratefully acknowledge grant support from the National Science Foundation
and the National Endowment for the Humanities.
We owe profound thanks to Barbara Wolff for her dedicated and meticulous as-
sistance in proofreading numerous documents in this volume, as well as to Chaya
Becker and to Roni Grosz, director of the Albert Einstein Archives.
At Caltech, we are particularly indebted to the dedicated staff of the Millikan Li-
brary and the Institute Archives.Thanks to Mary Marshall and Walther de Gruyter
GmbH for facilitating access to the World Biographical Dictionary Online. We also
thank Urs Schoepflin, Matthias Schwerdt, and the staff of the Max Planck Institute
for the History of Science for their assistance in important literature searches, and
the staff of the Swiss Federal Institute of Technology Library, the University of Zu-
rich Archive, and Robert Schulmann for their continued assistance in examining
We thank Nurit Lifschitz and Brenda Shorkend, who have uncovered numerous
significant archival materials, and especially Seiya Abiko for his splendid research
into Japanese source materials.
Much historical information and detail were needed in the research and produc-
tion of this volume. The assistance of the following persons is gratefully acknowl-
edged: Maria Asp, Royal Swedish Academy of Sciences; Carlo Beenakker,
University of Leyden; Luis J. Boya, University of Zaragoza; Michael Eckert,
Sommerfeld Edition, Deutsches Museum, Munich; Stefanie Grunack, Geheimes
Staatsarchiv Preussischer Kulturbesitz, Berlin; Hanoch Gutfreund, Hebrew