The accelerating Universe

289 Pages·2000·1.09 MB·English

by  Livio M.

B u s i n e s s C u l i n a r y A r c h i t e c t u r e
C o m p u t e r G e n e r a l I n t e r e s t
C h i l d r e n L i f e S c i e n c e s B i o g r a p h y
A c c o u n t i n g F i n a n c e M a t h e m a t i c s
H i s t o r y S e l f - I m p r o v e m e n t H e a l t h
E n g i n e e r i n g G r a p h i c D e s i g n
A p p l i e d S c i e n c e s P s y c h o l o g y
I n t e r i o r D e s i g n B i o l o g y C h e m i s t r y
e
WILEY
B O O K
WILEY
JOSSEY-BASS
PFEIFFER
J.K.LASSER
CAPSTONE
WILEY-LISS
WILEY-VCH
WILEY-INTERSCIENCE
T h e A c c e l e r a t i n g
U n i v e r s e
Infinite Expansion,
the Cosmological Constant,
and the Beauty of the Cosmos
Mario Livio
John Wiley & Sons, Inc.
New York • Chichester • Weinheim • Brisbane • Singapore • Toronto
To Sharon, Oren, and Maya, who I hope will find beauty
in their own lives
This book is printed on acid-free paper.
Copyright © 2000 by Mario Livio. All rights reserved
Published by John Wiley & Sons, Inc.
Published simultaneously in Canada
Illustrations by Jackie Aher
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Library of Congress Cataloging-in-Publication Data
Livio, Mario
The accelerating universe: infinite expansion, the cosmological
constant, and the beauty of the cosmos / Mario Livio.
p. cm.
Includes index.
ISBN 0-471-32969-X (alk. paper)
1. Cosmology. I. Title.
QB981.L57 1999
523.1—dc21 99-22278
Printed in the United States of America
10 9 8 7 6 5 4 3 2 1
Contents
Foreword v
Preface xiii
1
Prologue 1
2
Beauty and the Beast 14
3
Expansion 43
4
The Case of the Missing Matter 82
5
Flat Is Beautiful 105
6
When Inflation Is Good 139
7
Creation 171
iii
Contents
8
The Meaning of Life 196
9
A Universe Custom Made for Us? 237
10
A Cosmological Aesthetic Principle? 254
Index 266
iv
Foreword
When the history of ideas is written four hundred years
from now, the twentieth century will be known as the
dawn of the great scientific idea of the origin of a
changing universe that is still evolving. It recycles hydrogen and
helium through the stars in its galaxies and manufactures there-
from the heavier chemical elements that somehow can organize
themselves into complex structures that contemplate themselves.
Self-contemplation is but one of many miraculous things that the
natural chemical elements do over the age of the universe.
These ideas of origins and evolution have become part of
scientific literacy of our age. The major ideas of this twentieth-
century synthesis center around the understanding of the laws of
physics, the life history of the stars, and the consequences of that
history for mankind in an expanding universe.
This book is about how such grand ideas have come about us-
ing the cosmological discoveries made in astronomy and physics.
But it is also about much more. It concerns the philosophy of sci-
ence, of how one judges if a theory is fundamental and likely to last,
about truth, about the definition of beauty, and about the connec-
tion of science to art, literature, music, and the human endeavor.
Imagine two authors, one an art and literature fanatic, and the
other a theoretical physicist who is heavily involved in cosmology.
Imagine a decision to write a book jointly that would attempt to
bridge the two cultures. Could the two such authors make a syn-
thesis that would ring true, each to his or her own tradition, yet
also true to the other’s quite different creative style? Now imagine
v
Foreword
that the two authors are not two, but are the same person. What
you are about to read is that synthesis. Its author is that art fanatic
and theoretical physicist. What could such a book be like?
Near the middle third of the just-past century, a series of highly
influential, semipopular, yet scientifically astute books were pub-
lished that had a profound influence on the very young (and not so
young), many of whom prepared themselves for a scientific life be-
cause of them. Such books, especially by Sir James Jeans and Sir
Arthur Eddington, were important for astronomy. Perhaps the most
popular was The Mysterious Universe(1930) by Jeans, which Tallulah
Bankhead, the American actress of multiple reputations, said con-
tains “what every girl should know.” Other books of the same sort
were The Stars in Their Courses(1931), Through Space and Time(1933),
and the favorite of this writer, Physics and Philosophy (1943), all by
Jeans. Similar central books by Eddington were The Nature of the Phys-
ical World(1931), Science and the Unseen World(1929), The Expanding
Universe(1933), and again a favorite of mine, Space, Time, and Gravi-
tation (1920), which opened up general relativity and Riemannian
manifolds to the layman. More recently, the books by Fred Hoyle
such as The Nature of the Universe(1950), Frontiers of Astronomy(1955),
and Highlights of Astronomy(1975) had the same merit.
This book by Mario Livio is of that type. Not only is it a book on
the new astronomy and cosmology, but it also is a book on the “old”
philosophy—of art, and of culture. Livio’s deep purpose is to ex-
plore the meaning of beauty in science, using the developments in
twentieth-century cosmology as the subject with which to discuss a
concept of beauty in general and beauty in science in particular.
The author’s premise is that “beauty” is an essential ingredient in
all truly successful theories in science, and especially “true” theo-
ries of the nature of the universe. The aim of the book is to discuss
whether the laws of physics are actually determined by aesthetic
principles.
Livio believes they are, and makes a compelling case through-
out the book. He first defines what he means by beauty. He then
vi
Foreword
shows that so much of the modern standard model of cosmology
conforms to his stated definition. In the process he describes al-
most every aspect of both the old and the new cosmology. This is
the heart of the book, both for the young would-be scientist and
for the fascinated layman. In the process he shows what beauty
means in art, describing many paintings by many artists to illustrate
both the beauty and the philosophy of human artistic endeavor.
Said only this way, most hard-bench, experimental reduction-
ist scientists would likely be put off by such an attempt. We scien-
tists have generally been trained to regard art, literature, poetry,
and anything else to do with the “humanities” as subjective and
therefore not amenable to assessment by the scientific method. On
the other hand, science, and especially physics and astronomy, is
widely thought to refer to nature independently of subjective
thought, feeling, and categories made by the mind. Beauty often
is also placed outside that regime. This book is a revelation on how,
and at what price (if any), this notion of objectivity with no con-
cern for beauty is incompatible with modern science, especially in
cosmology.
In chapter 2, the author defines beauty as he will use it
throughout the book. Although he agrees with the often-quoted
definition by many that “beauty symbolizes a degree of perfection
with respect to some ideal,” yet this definition is too diffuse and
oversimplified to be of use. He also rejects the misquoted (out of
context) definition by Keats that “beauty is truth, truth beauty,”
and states that beauty defined by the poets is often a dangerous
thing, as Paris found by his association with Helen.
Livio does insist, as do many of the greatest scientists through-
out history, that the laws of physics are exquisitely beautiful. Before
defining beauty, he convinces us that in physics, the explanations
of what once were mysteries but which now are “understood” is of-
ten ineffably more beautiful than the questions, and that “beauty
in physics and cosmology is not an oxymoron.” To proceed in a way
that is precise enough so that in later chapters he can combine the
vii
Foreword
concept of beauty with the most esoteric and profound elements
of modern cosmology, Livio sets out his definition of beauty in this
early, introductory chapter.
Three requirements must be fulfilled if a theory is to be judged
beautiful:
1. It must describe a symmetry (or a series of symmetries); other-
wise its predictions will not be invariant to the two simplest trans-
formations as to place (i.e., space) or time (it makes no difference
if I do an experiment now or next week), or at a much deeper level
by circumstances in the equations (i.e., such as coordinate trans-
formations).
2. It must have simplicity in the sense of reductionism (i.e.,
many questions can be replaced by very few more basic questions
that can be solved as puzzles and not be left as mysteries).
3. A theory must obey a generalized Copernican principle, by
which is meant that we, or the circumstances, are nothing special,
in time, space, or category.
This last is probably the deepest requirement, and has the most
profound implication for the ultimate cosmological mystery, de-
scribed in the penultimate chapter as the Nancy Kerrigan ques-
tion, whose solution can be given in terms of “quintessence,” which
in fact provides an adherence to the postulated cosmological aes-
thetic principle. This, and the final chapter, provide the climax to
the full story of cosmology that has been set out in chapters 3
through 8.
These six chapters contain the description of much of cos-
mology of the twentieth century. The discovery of the expansion
in 1929 is in chapter 3, with its implications for the hot big bang
origin and the resulting prediction and subsequent discovery of
the relic radiation and the formation of the earliest elements out
of the gluon glue (once called the yelm), predictions made already
viii
Foreword
in 1945 by George Gamow, Ralph Alpher, and Robert Herman.
Here, the more modern ideas that combine the high-energy par-
ticle physics of the 1980s with its Higgs fields and the grand unifi-
cation theories of the four forces are made easy by the many sur-
prising analogies from art, literature, and underground cultural
jokes combined with the straightforward style of the author. The
book itself has charm as well as beauty.
Chapter 4 combines the problem of the missing mass with the
question of the fate of the universe via the omega parameter. The
method of inferences from indirect data is illustrated with the ex-
amples of studies of the authenticity of Rembrandt paintings and
the deductions by Sherlock Holmes on the alcoholism and mari-
tal neglect of a client, and the discovery of the omega minus par-
ticle (no relation to the omega density parameter) independently
by Yuval Ne’eman after its prediction by Murray Gell-Mann. All this
is tied up with beauty in the simplicity of the deductions as they
ultimately relate to the fate of the expansion.
The richness of the narrative and the fun of the author is kept
throughout the book as it lays out even the most complicated of
the cosmological problems. The prime example is in chapters 5
and 6 where non-Euclidean geometry, curved space as the mani-
festation of gravity, and inflation via the behavior of the inflaton
fields following the Planck time are all explained better than in any
other semipopular book on this most profound of the cosmologi-
cal subjects. These ideas are at the heart of the question of origins
and the “cause” of the expansion, as well as the explanation of the
dominance of matter over antimatter.
Chapters 5, 6, and 7 are titled “Flat Is Beautiful,” “When Infla-
tion Is Good,” and “Creation.” These contain the essence of mod-
ern quantum cosmology as a theory of the origin, evolution, and
fate of the universe (or many universes in the variant called “eter-
nal inflation,” as invented by Alex Vilenkin and Andrei Linde).
Here the author is most persuasive and powerful in attempting to
ix