Table Of Contentomputin
J
Froese Fischer
I
OUG1AS
AYNER
AKTREE
His Life in
Science and
Computing
This page is intentionally left blank
OUG1AS
AYNER
AKTREE
His Life in
Science and
Computin;
Froese Fischer
Vanderbilt University, USA
\HJP World Scientific
NEW JERSEY • LONDON • SINGAPORE • SHANGHAI • HONGKONG • TAIPEI • BANGALORE
Published by
World Scientific Publishing Co. Pte. Ltd.
5 Toh Tuck Link, Singapore 596224
USA office: Suite 202, 1060 Main Street, River Edge, NJ 07661
UK office: 57 Shelton Street, Covent Garden, London WC2H 9HE
British Library Cataloguing-in-Publication Data
A catalogue record for this book is available from the British Library.
DOUGLAS RAYNER HARTREE: HIS LIFE IN SCIENCE AND COMPUTING
Copyright © 2003 by World Scientific Publishing Co. Pte. Ltd.
All rights reserved. This book, or parts thereof, may not be reproduced in any form or by any means,
electronic or mechanical, including photocopying, recording or any information storage and retrieval
system now known or to be invented, without written permission from the Publisher.
For photocopying of material in this volume, please pay a copying fee through the Copyright
Clearance Center, Inc., 222 Rosewood Drive, Danvers, MA 01923, USA. In this case permission to
photocopy is not required from the publisher.
ISBN 981-238-577-0
Printed in Singapore by World Scientific Printers (S) Pte Ltd
Preface
Anyone familiar with quantum mechanics will have heard of Douglas R
Hartree and his self-consistent field method. Though Fock pre-empted
Hartree's work on equations with exchange, Hartree later extended the
equations to include configuration interaction. In doing so, he played an
important role in laying the foundation not only of modern day atomic
physics but also of quantum chemistry. Not nearly as well known are his
contributions in other areas. In fact, it has been said that Hartree only
had this one idea, churning out atom after atom. This was hardly the
case. Early in his career he became interested in radio wave propagation
and derived the equation for the index of refraction that in atmospheric
physics today is called the "Appleton-Hartree equation." During World
War II, he applied the self-consistent field idea to the study of the cavity
magnetron then part of radar development. Computationally, this was a far
more challenging problem than atoms because the geometry of cavities and
slots precluded the assumption of radial symmetry, requiring the solution
of two-dimensional partial differential equations. From these computations,
he made a number of discoveries, one being the "Hartree condition" for the
operation of a magnetron. There were others.
The common denominator of Hartree's research was differential equa
tions, either ordinary or partial. He combined his wide range of interests
with a talent for problem solving. Given a problem, he would express the
phenomena investigated in the form of one or more differential equations,
devise a scheme for solving the equations in their simplest possible form,
and perform the calculations. In the 1930's this led him to the differential
analyzer and its application to a variety of problems, the most important
being in control theory and fluid dynamics. Hartree knew the accuracy of
the differential analyzer was insufficient for most atomic structure work,
VI Douglas Rayner Hartree
but he believed there were many industrial applications where great accu
racy was not needed and the differential analyzer would be a very welcome
tool. In this he was correct. During the war, he dealt with problems that
were partial differential equations, and in later years, Hartree was greatly
interested in equations arising in hydrodynamics. Because he believed in
solving a problem with any tool available - slide-rule, desk calculator, or
differential analyzer - he acquired great computational skills and knowledge
of what was later called numerical analysis.
Hartree did not hide his "love of arithmetic." This was not universally
greeted with admiration or acclaim. Slater, in his autobiography, classified
scientists as the "hand-waving magical type" or the "matter-of-fact type."
He placed Hartree in the latter category, saying that the hand-waving-
magical type considered him a "mere computer," yet he made a greater
contribution than most of them.
So why would someone under those circumstances take such an uncon
ventional stand and pursue "arithmetic?" I believe the answer lies in the
unusual family background, and the Bedales school Hartree attended prior
to University. Both nurtured the development of his unique talents and
at Bedales he learned to consider his role in society. For this reason, the
present biography starts with the Hartree family.
Because the extent of Hartree's contributions is not well known, the rest
of the book attempts to chronicle his science as well as his life. Many of his
publications are not readily accessible today, so a summary is appropriate.
Hartree did not consider himself important and did not keep correspon
dence, neither with scientists nor with family members. Fortunately, some
archive collections have kept Hartree's letters - Edward V Appleton, Niels
Bohr, Vannevar Bush, Robert B Lindsay, Fritz London, Rudolf Peierls,
John C Slater, Ivar Waller - but particularly before World War II, letters
were written by hand without carbon copies so the "conversations" in many
letters are somewhat one-sided. As a document of his activities, it has been
necessary to rely on Hartree's own publications supplemented by letters, as
available, and documents from the Public Record Office, London, relating
to war time activities.
Hartree spent the 1920's in Cambridge, first as an undergraduate, then
as a graduate student and research Fellow at the Cavendish laboratory.
During this time, Ernest Rutherford was Professor of Physics and Ralph H
Fowler, a lecturer in Mathematics, supervised those more theoretically in
clined. Rutherford attracted many physics students from around the world
to the Cavendish. The students of these two men were the "community"
Preface VII
with which Hartree identified. The science world at that time was much
smaller than today so the same "cast of characters" will appear in different
chapters of this book, ranging from World War I, quantum theory, World
War II, and the emerging computer era.
In placing Hartree's early work in context, it has been necessary to
outline some of the developments in quantum theory, but I do not con
sider this to be a history of quantum mechanics. John Slater, who was
more intimately involved in some of the theoretical ideas, has written an
autobiography, Solid State and Molecular Theory: A scientific biography,
which, in spite of its title, presents an account of historical developments,
and could be an excellent companion for readers desiring a more detailed
account still at a simple level.
In discussing Hartree's science, I made the decision that, when neces
sary, differential equations would be included, but often they only show
the nature of the problem in a concise way. The detailed meaning is of
lesser importance. His papers are not cited here, but a complete list of his
publications is included at the end of the book.
Finally, let me say that, as Hartree's student, I unfortunately did not get
to know him well. I never attended any lectures that he presented. Shortly
after my arrival at Cambridge, Hartree was getting ready for his year at
Princeton. When he got back, he understandably was exceedingly busy and
soon thereafter, I was getting ready to return to Canada. The subsequent
year we corresponded and Hartree arranged for my dissertation defense at
the University of Toronto. Six months later he died unexpectedly. Thus
not much of this book is from personal recollections.
This biography could have been a lot different had it been started
sooner. I did contact Bertha Swirles Jeffreys and Jack Howlett in 1999,
shortly before they died, getting some valuable information. I had one let
ter from David Myers who had been Dean of Engineering at the University
of British Columbia during my time there, but we were just establishing
contact when he too passed away. I was not aware how intimately he had
been associated with Hartree and his work on the differential analyzer until
starting this biography.
However, I was fortunate in other respects. I got to meet Hartree's
first PhD student, Arthur Porter, who alerted me to the importance of
their work on control theory. In the last few years, a great deal of in
formation has become available on the Internet that was a great asset.
The "Nobel e-Museum" has a wonderful selection of biographies and lec
tures (http://www.nobel.se). Anyone not familiar with computing de-
vni Douglas Rayner Hartree
vices can visit the museum of HP calculators (http://www.hpmuseum.org)
and get more information about slide-rules, calculating machines, and cal
culators than they might wish to know. And there are many others.
In some instances, the web sites were a source of information, such as
http://www.alanturing.net which has on-line copies of the minutes of NPL
meetings in which Hartree participated, but in others, such as the one for
calculators, they illustrated the fact that readers can readily find addi
tional information of a general nature. Unfortunately, web sites come and
go, therefore they have not always been included here as references.
The Internet also made it possible for me to contact the Hartree family.
I was desperately searching for pictures of Hartree that are few in num
ber. I knew Hartree had collaborated with Robert Bruce Lindsay at Brown
University. While searching the Brown University site, I came across the
address of his son-in-law who provided me with the address of Hartree's
daughter, Margaret Hartree Booth. As soon as we made contact, the
Hartree family (Margaret, Oliver, and Richard) graciously shared with me
the family pictures included in this book.
Several factors motivated me in undertaking this project. I noticed that
the Emile Segre Visual Archives had 36 (it now has 53) pictures of Dirac
and only one of Hartree, and that is a group photo with Einstein. This
indicated to me that pictures of Hartree were badly needed for an accurate
historical "picture gallery" of the scientists of his time. Then in searching
the McGraw-Hill online encyclopedia, I found Hartree's name associated
not only with atomic physics, quantum chemistry, band-theory of solids,
the nuclear molecule, and nucleon-nucleus scattering, all of which I was
aware of to various degrees, but there also was the Hartree equation in
electronics! This was totally new to me. I later found it to be related to
the operation of a magnetron. At the same time, there was no mention of his
work with the differential analyzer though the biography of Vannevar Bush
mentioned that a large differential analyzer had been completed in 1935
at Manchester University and was now an exhibit in the Science Museum,
London, without mentioning that the person to do so was Hartree! All this
suggested to me that a biography was needed to describe the many facets
of his work.
In this biography, I have attempted to gather available information
about Hartree and his work as well as give a sense of the times in which he
lived.
Charlotte Froese Fischer
Acknowledgments
This biography has relied on many valuable sources of information.
The Hartree family - Margaret, Oliver, and Richard - provided me with
the pictures included in this biography, unless indicated otherwise. Christ's
College, Cambridge, was most helpful in getting me started, sending me
Margaret Hartree Booth's memoirs, and obtaining letters from Hartree to
Edward V Appleton from the Special Collections, Edinburgh University Li
brary. Dr Michel Godefroid of the Free University of Brussels, shared with
me his collection of articles on the Meccano differential analyzer. Dr Jon
Agar, of the Centre for the History of Science, Technology and Medicine,
University of Manchester, provided me with some difficult to find Hartree
publications and an exceptional picture of Hartree demonstrating his differ
ential analyzer. Dr James Peters, Manchester University Archivist, clarified
Hartree's involvement in the development of the Faculty of Music.
The Niels Bohr Library, Center for History of Physics, American Insti
tute of Physics, College Park, MD through their oral history interviews,
provided notes of a conversation with Elaine Hartree, transcripts of inter
views with Sir Nevill Mott and John C Slater as well as the Robert Bruce
Lindsay autobiography. Through the Archives for the History of Quan
tum Physics program, I received letters from Hartree to Samuel Goudsmit,
Robert B Lindsay, and Niels Bohr. The Niels Bohr Archive in Copenhagen
provided letters to Niels Bohr, Oskar Klein, and Leon Rosenfeld. The
Center for History of Science, of the Royal Swedish Academy of Science,
Stockholm, kindly furnished copies of correspondence between Hartree and
Ivar Waller. Letters between Hartree and Fritz London are part of the Fritz
W London Papers in the Duke University Archives whereas the correspon
dence with John C Slater is part of a collection found in the library of the
American Philosophical Society, Philadelphia. I am grateful to all these
ix
