In Search of the Big Bang: The Life and Death of the Universe

362 Pages·2014·2.65 MB·English

by  John Gribbin

IN SEARCH OF THE BIG BANG
The Life and Death of the Universe

by
JOHN GRIBBIN

Published by ReAnimus Press

Other books by John Gribbin: Cosmic Coincidences
Ice Age
In Search of the Double Helix
Q is for Quantum

© 2014, 1998, 1986 by John and Mary Gribbin. All rights reserved.
The moral right of the author has been asserted.

http://ReAnimus.com/authors/johngribbin

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~~~

I am always surprised when a young man tells me he wants to work at
cosmology. I think of cosmology as something that happens to one, not
something one can choose.

—Sir William McCrea, FRS

~~~
Table of Contents
Acknowledgements
Preface to the Second Edition
Chapter 1
Chapter 2
Chapter 3
Chapter 4
Chapter 5
Chapter 6
Chapter 7
Chapter 8
Chapter 9
Chapter 10
Chapter 11
Appendix
Cosmology Up To Date
Notes
Bibliography
ABOUT THE AUTHOR
Acknowledgements
The roots of this book go back a long way, to the birth of my fascination with
science in the early 1950s. I cannot quite recall which author first introduced me
to the mystery and wonder of the Universe, but I know that it must have been
either Isaac Asimov or George Gamow, since I began reading the books of both
of them so long ago that I literally cannot remember ever being without them.
And it was not just science, but specifically the mystery of the origin of the
Universe, that fascinated me from the outset. Thanks to Gamow and his fictitious
‘Mr Tompkins’ I cut my intellectual teeth on the Big Bang model of the origin of
the Universe and, although later on I learned of the Steady State hypothesis, it
has always been the idea of the Big Bang, the idea that there was a definite
moment of creation when the Universe came into being, that held my
fascination. It never occurred to me that I might make a career out of studying
such deep mysteries, or writing about them. Indeed, I scarcely appreciated that
being an astronomer, let alone a cosmologist, was a viable job for anyone, let
alone myself, until 1966. Then, just before taking my final undergraduate
examinations at Sussex University, I discovered that Bill (now Sir William)
McCrea was about to establish a research centre in astronomy on the campus.
That discovery changed my life. First, it led to a swift change of direction
from a planned period of postgraduate research in particle physics to a year
working for an MSc in astronomy in McCrea’s group. Then I moved on to
Cambridge, becoming a very junior founder member of another new astronomy
group, Fred (now Sir Fred) Hoyle’s Institute of Theoretical Astronomy, as it then
was. For reasons which I have never quite fathomed myself, I somehow became
sidetracked into working on problems involving very dense stars (white dwarfs,
neutron stars, pulsars and X-ray sources) for my thesis, and never did do any real
research in cosmology. But while in Cambridge I met Hoyle himself, Jayant
Narlikar, Martin Rees, Geoffrey and Margaret Burbidge, Stephen Hawking,
William Fowler and many other eminent astronomers who were deeply
immersed in problems of literally cosmic significance. I learned from them what
research at this level was really like, and I learned, too, that I could never hope
to achieve anything of comparable significance myself. So I became a writer,
reporting on new developments not just in cosmology and astronomy but across
the sciences, keeping in touch with new developments even though I was not
involved in making those new developments.
When cosmology made a great leap forward in the 1980s, it came about
through a marriage with particle physics, the line of work I had abandoned so
lightly in 1966. After initially struggling to cope with new developments that
seemed to be appearing faster than I could write about them, I had an
opportunity to catch up by attending as an observer a joint meeting organized by
the European Southern Observatory and CERN, the European Centre for
Nuclear Research, in Geneva in November 1983. There, participants from both
sides of the fence discussed the links between particle physics and cosmology. It
was that meeting, and the fact that I convinced myself that I could understand
most of what was going on there, that convinced me that I could tackle writing
this book. Following the meeting, I was able to straighten out my ideas and
improve my understanding of the new idea of inflation, the key to understanding
the modern version of Big Bang cosmology, in correspondence with Dimitri
Nanopoulos of CERN and with two of the founders of the inflationary
hypothesis, Alan Guth of MIT and Andrei Linde in Moscow.
It looks as if science has achieved, in outline at least, a complete
understanding of how the Universe as we know it came into being, and how it
grew from a tiny seed, via the Big Bang, into the vastness we see about us.
Martin Rees, of Cambridge University, has put the importance of the new work
clearly in perspective. At that meeting in Geneva, in November 1983, he
commented that, when asked if the Big Bang was a good model of the Universe
we live in, he used to say that ‘it is the best theory we’ve got’. That was indeed a
very cautious endorsement. But now, he said in Geneva, if asked the same
question he would reply that ‘the Big Bang model is more likely to be proved
right than it is to be proved wrong’. Coming from Rees, one of the most cautious
of modern cosmologists, who makes no claim lightly, this is a much stronger
endorsement of the Big Bang, and amply sufficient justification for me to
proceed in writing this book!
The fact that I can understand the physics underlying these new ideas is a
tribute to the skills of teachers going back to my schooldays, and to the
universities of Sussex and Cambridge; to be alive at a time when such mysteries
are resolved, and to be able to understand how they have been resolved, is the
greatest stroke of fortune I can imagine. Maybe new mysteries will emerge to
disturb the present picture, and the completeness of our understanding of the
moment of creation will prove to be an illusion. But the picture today is
satisfyingly complete, and I hope I can share with you, through this book, the
wonder of its completeness, and of the search which led to a successful theory of
the creation, less than sixty years after the discovery that the Universe is
expanding and that, therefore, there must indeed have been a moment of
creation.
If I succeed at all in holding your attention, that is largely because the story is
so fascinating that only the most inept of storytellers could fail to make it
interesting. It is also thanks to Asimov and Gamow, who first told an earlier
version of the tale to me; to Bill McCrea who, by appearing on the campus at
Sussex University, showed me that cosmologists were real people and that I
might work alongside them; to Fred Hoyle, who established an Institute where
briefly it was possible for me to mingle with cosmologists of the first rank; and
to CERN, for inviting me to attend the first ESO-CERN symposium. Once the
book was underway, I received direct help from Alan Guth and Andrei Linde,
from Dimitri Nanopoulos, and from Martin Rees in Cambridge and Jayant
Narlikar at the Tata Institute in Bombay. Bill McCrea found time in a busy life
to read parts of the book in draft and to correct some of my historical
misconceptions, while Martin Rees tactfully pointed out the places where my
understanding of the new ideas in cosmology was still inadequate.
Many other people, listed below in no particular order, helped by providing
copies of their papers and/or giving up time to discuss their ideas with me.
Thanks to: John Huchra, Tom Kibble, Roger Tayler, Carlos Frenck, Vera Rubin,
Frank Tipler, John Barrow, Michael Rowan-Robinson, Stephen Hawking, Jim
Peebles, David Wilkinson, Marcus Chown, John Ellis, Tjeerd van Albada,
Adrian Melott, Paul Davies and John Bahcall.
No doubt some errors remain. These are entirely my responsibility. If you spot
one, let me know and I will do my best to correct it in future editions of the
book. But I hope that they are few enough, and minor enough, not to mar your
enjoyment of the story of the search for the ultimate cosmic truth, the origin and
fate of the Universe itself.
Preface to the Second Edition
The first edition of this book appeared in 1986; it was my personal response to
the wave of interest in Big Bang cosmology created by the idea of cosmological
inflation. Among other things, inflation requires that the Universe contains
essentially enough matter to be ‘closed’, so that, having been born in a superhot,
superdense state (the Big Bang itself) and after expanding for many billions of
years it may one day recollapse into a mirror image of the Big Bang, the Big
Crunch. This in turn implies that there must be something like a hundred times
more matter in the Universe than we can see, dark stuff that surrounds the bright
stars and galaxies.
During the late 1980s and early 1990s, inflation theory was put on an
increasingly secure footing, and the search for this dark matter intensified. When
the COBE satellite found ripples in the background radiation which fills the
Universe and is interpreted as the afterglow of the Big Bang itself, the pattern of
those ripples (now confirmed and extended by ground-based observations)
exactly matched the pattern expected from the combination of the standard Big
Bang model with inflation, provided that the Universe contains enough matter to
be closed. This new edition of In Search of the Big Bang brings the story up to
date, and incorporates material from my book The Omega Point (now out of
print) and new material to tell the whole story of the life of the Universe, from
Big Bang to Big Crunch. Something had to go to make room for the new
material, and I have left out most of the technical discussion of particle physics,
which was tangential to the main story, and which you can find in my other
books.
Although the latest cosmological ideas are not yet as complete as the basic
theory of the Big Bang, which still forms the bulk of the book, the fact that they
cannot explain everything does not mean that the Big Bang theory is terminally
flawed. Every time that some specific detail of the developing understanding of
inflation and dark matter has to be revised in the light of new observations of the
Universe, somebody is sure to write an obituary for the Big Bang; but such
obituaries are, like the legendary example of the premature obituary of Mark
Twain, exaggerated. The Big Bang theory is very much alive and well, as I hope
this book makes clear. Indeed, it now goes further than before. In 1986, I could
only tell you how the Universe began; now, I can give you a fair idea of how it
will end, as well. I hope you enjoy the story.
—John Gribbin, 1998
Chapter 1
The Arrow of Time
The most important feature of our world is that night follows day. The dark
night sky shows us that the Universe at large is a cold and empty place, in which
are scattered a few bright, hot objects, the stars. The brightness of day shows that
we live in an unusual part of the Universe, close to one of those stars, our Sun, a
source of energy which streams across space to the Earth and beyond. The
simple observation that night follows day reveals some of the most fundamental
aspects of the nature of the Universe, and of the relationship between life and the
Universe.
If the Universe had existed for an eternity, and had always contained the same
number of stars and galaxies as it does today, distributed in more or less the
same way throughout space, it could not possibly present the appearance that we
observe. Stars pouring out their energy, in the form of light, for eternity, would
have filled up the space between themselves with light, and the whole sky would
blaze with the brightness of the Sun. The fact that the sky is dark at night is
evidence that the Universe we live in is changing, and has not always been as it
is today. Stars and galaxies have not existed for an eternity, but have come into
existence relatively recently; there has not been time for them to fill the gaps in
between with light. Astrophysicists, who study the way in which the stars
produce their energy by nuclear reactions deep in their hearts, can also calculate
how much light a typical star can pour out into space during its lifetime. The
supply of nuclear fuel is limited, and the amount of energy a star can produce,
essentially by the conversion of hydrogen into helium, is also limited. Even
when all the stars in all the galaxies in the known Universe have run through
their life cycles and become no more than cooling embers, space, and the night
sky, will still be dark. There is not enough energy available to make enough light
to brighten the night sky. The oddity, the strangeness of the observation that
night follows day, is not that the sky is dark, but that it should contain any bright
stars at all. How did the Universe come to contain these short-lived (by
cosmological standards) beacons in the dark?
That puzzle is brought home with full force by the light of the Sun in the
daytime. This represents an imbalance in the Universe, a situation in which there
is a local deviation from equilibrium. It is a fundamental feature of the world
that things tend towards equilibrium. If an ice cube is placed in a cup of hot
coffee, the liquid gets cooler and the ice melts as it warms up. Eventually, we are
left with a cup of lukewarm liquid, all at the same temperature, in equilibrium.
The Sun, born in a state which stores a large amount of energy in a small volume
of material, is busily doing much the same thing, giving up its store of energy to
warm the Universe (by a minute amount) and, eventually, cooling into a cinder
in equilibrium with the cold of space. But ‘eventually’, for a star like the Sun,
involves a time span of several thousand million (several billion) years; during
that time, life is able to exist on our planet (and presumably on countless other
planets circling countless other stars) by feeding off the flow of energy out into
the void.
Because night follows day, we know that there are pockets of non-equilibrium
conditions in the Universe. Life depends on the existence of those pockets. We
know that the Universe is changing, because it cannot always have existed in the
state we observe today and still have a dark sky. The Universe as we know it
was born, and will die. And so we know, from this simple observation, that there
is a direction of time, an arrow pointing the way from the cosmological past into
the cosmological future.