The theory of everything

148 Pages·2006·1.206 MB·English

by  Stephen W Hawking

STEPHEN W.
HAWKING
S P E C I A L A N N I V E R S A R Y E D I T I O N
THE THEORY OF
EVERYTHING
T H E O R I G I N A N D F A T E O F T H E U N I V E R S E
PPHHOOEENNIIXX
5F9A4512-DBD2-4640-B53D-F3CF22FFE0A2 BBOOOOKKSS
Copyright ©2005 Phoenix Books
First published under the title The Cambridge Lectures:
Life WorksCopyright © 1996 by Dove Audio, Inc.
All rights reserved. Written permission must be secured from the publisher
to use or reproduce any part of this book, except brief quotations in critical
reviews and articles.
ISBN: 1-59777-508-8
Library of Congress Cataloging-In-Publication Data Available
Book Design by Sonia Fiore
Printed in the United States of America
Phoenix Books
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Beverly Hills, CA 90212
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CONTENTS
Introduction
FIRST LECTURE
ideas about the universe . . . . . . . . . . . . . . . . . . . . . . .1
SECOND LECTURE
the expanding universe . . . . . . . . . . . . . . . . . . . . . . . .13
THIRD LECTURE
black holes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35
FOURTH LECTURE
black holes ain’t so black . . . . . . . . . . . . . . . . . . . . .57
FIFTH LECTURE
the origin and fate of the universe . . . . . . . . . . . . .77
SIXTH LECTURE
the direction of time . . . . . . . . . . . . . . . . . . . . . . . . .103
SEVENTH LECTURE
the theory of everything . . . . . . . . . . . . . . . . . . . . .119
5F9A4512-DBD2-4640-B53D-F3CF22FFE0A2 INDEX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .137
INTRODUCTION
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I N T R O D U C T I O N
In this series of lectures I shall try to give an outline of what we think is the
history of the universe from the big bang to black holes. In the first lecture
I shall briefly review past ideas about the universe and how we got to our
present picture. One might call this the history of the history of the universe.
In the second lecture I shall describe how both Newton’s and Einstein’s the-
ories of gravity led to the conclusion that the universe could not be static; it
had to be either expanding or contracting. This, in turn, implied that there
must have been a time between ten and twenty billion years ago when the
density of the universe was infinite. This is called the big bang. It would have
been the beginning of the universe.
In the third lecture I shall talk about black holes. These are formed when a
massive star or an even larger body collapses in on itself under its own
gravitational pull. According to Einstein’s general theory of relativity, anyone
foolish enough to fall into a black hole will be lost forever. They will not be
able to come out of the black hole again. Instead, history, as far as they are
concerned, will come to a sticky end at a singularity. However, general
relativity is a classical theory—that is, it doesn't take into account the
uncertainty principle of quantum mechanics.
5F9A4512-DBD2-4640-B53D-F3CF22FFE0A2 IV
I N T R O D U C T I O N
In the fourth lecture I shall describe how quantum mechanics allows energy to
leak out of black holes. Black holes aren’t as black as they are painted.
In the fifth lecture I shall apply quantum mechanical ideas to the big bang and
the origin of the universe. This leads to the idea that space–time may be finite
in extent but without boundary or edge. It would be like the surface of the
Earth but with two more dimensions.
In the sixth lecture I shall show how this new boundary proposal could explain
why the past is so different from the future, even though the laws of physics are
time symmetric.
Finally, in the seventh lecture I shall describe how we are trying to find a
unified theory that will include quantum mechanics, gravity, and all the other
interactions of physics. If we achieve this, we shall really understand the
universe and our position in it.
5F9A4512-DBD2-4640-B53D-F3CF22FFE0A2 V
FIRST
LECTURE
IDEAS ABOUT THE UNIVERSE
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