Table Of ContentG E N E S I S
O F T H E
B I G B A N G
This is a story of the theory of the Big
Bang model of the birth of the Universe.
All of it is here, pre-Big Bang cosmology,
development of the Big Bang theory, obser
vational confirmations, alternatives to the
model and the future of the Universe accord
ing to laws of the Big Bang theory. But more
than just a concise, readable exploration of
theory, “Genesis of the Big Bang” is a first
hand account of the work and struggle that
went into proposing and developing these
models by two of the scientists who were
first to suggest possible proof of a Big Bang:
residual background radiation. Alpher lets
us into the world of the working physicist
and shows us the frustrations, the exhilara
tion, and the realities of taking part in one
of the most significant, fundamental cosmo
logical transitions.
“Genesis of the Big Bang” is a fascinating
account of what it is like to be at the forefront
of theoretical physics and the emotion that
can ride along with it, as well as a clear and
refreshing look at our current knowledge of
the way the universe works.
Genesis of the Big Bang
GENESIS
OF THE
BIG BANG
Ralph A. Alpher
Robert Herman
OXFORD
UNIVERSITY PRESS
2001
OXFORD
UNIVERSITY PRESS
Oxford New York
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Copyright © 2001 by Oxford University Press, Inc.
Published by Oxford University Press, Inc.
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All rights reserved. No part of this publication may be reproduced,
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Library of Congress Cataloging-in-Publication Data
Alpher, Ralph.
Genesis of the big bang / by Ralph A. Alpher and Robert Herman,
p. cm.
Includes bibliographical references and index.
ISBN 0-19-511182-6
1. Big bang theory. I. Herman, Robert, 1914- II. Title.
QB991.B54 A47 2000
523.1'8-dc21 00-023888
135798642
Printed in the United States of America
on acid-free paper
Preface
^)ne of the reasons for writing a preface is to explain why the authors
have felt moved to write a book in the first place. A second reason in this
case is not only to arouse curiosity and interest in cosmology and its
scholarship but also to stimulate potential readers to read this book, since
there are others dealing with many of the same topics we cover.
Our book has had a long gestation period. We have had in mind writing
about the development of the Big Bang model of the universe ever since a
landmark event took place in 1965. It was in that year that Arno A. Penzias
and Robert W. Wilson, then at the Bell Telephone Laboratories, published
their discovery of a residual cosmic microwave background, the now-
famous three-degree radiation, which pervades the universe. Almost over
night the scientific community as well as the lay public found reason to
believe that a dynamic, evolving universe beginning with a singular event,
the so-called Big Bang, was a credible model. This discovery was only the
most recent significant step, because it had become clear many years ear
lier that the idea of an expanding universe was not only consistent with
but virtually required by Einstein's general theory of relativity. Moreover,
the observation of that expansion by the astronomers Vesto M. Slipher,
Edwin Hubble, and Milton Humason had come to be widely accepted.
Finally, it had also become evident that it was necessary to invoke an
extremely hot, dense early stage in the expanding universe in order to
understand the cosmic abundances of the lightest elements—namely,
deuterium, helium, and lithium—relative to hydrogen.
In our view, the discussion of these concepts by Steven Weinberg in
his book The First Three Minutes, first published in 1977 (the revised
edition of 1988 is still in print), made a significant contribution to the
widespread acceptance of the Big Bang model by many scientists, despite
its targeting a general audience. Since 1977, other books have dealt with
the model in more or less detail and with more recent observational and
theoretical developments. Some of these books purport to convey the
human side of the conception and development of the model as well. So,
again, why another book?
We have been intimately connected with the conception and develop
ment of the Big Bang model since 1947. Following the late George Gamow's
ideas in 1942 and more particularly in 1946 that the early universe was
an appropriate site for the synthesis of the elements, we became deeply
involved in the question of cosmic nucleosynthesis and particularly the
synthesis of the light elements. In the course of this work, we developed
a general relativistic model of the expanding universe with physics folded
in, which led in a progressive, logical sequence to our prediction of the
existence of a present cosmic background radiation some seventeen years
before the observation of such radiation was reported by Penzias and
Wilson. In addition, we carried out with James W. Follin, Jr. a detailed
study of the physics of what was then considered to be the very early
universe, starting a few seconds after the Big Bang, which still provides
a methodology for studies of light-element nucleosynthesis.
Because of our involvement, we can bring a personal perspective to the
subject. Our goal is to present a picture of what is now believed to be the
state of knowledge about the evolution of the expanding universe and
to delineate from our own unique vantage point the story of the devel
opment of the Big Bang model as we have seen and lived it. Our princi
pal contributions have been our work on the synthesis of the chemical
elements in the early stages of the Big Bang and our prediction of
the existence and magnitude of a thermal cosmic background radiation
with intensity peaking in the microwave region of the electromagnetic
spectrum.
Because we were closely associated with the late George Gamow from
the end of World War II until his death in 1968, we intersperse some
reflections and anecdotal material about this remarkable physicist, his
legacy in science, and the influence of his personality and image on the
way our joint and individual contributions in cosmology have been per
ceived by the scientific community. Gamow was a prolific writer of books
vi Preface
