I didn’t write a foreword to the
original edition of A
Brief History of Time. That was done by Carl Sagan. Instead, I
wrote a short piece titled "Acknowledgments" in which I was advised
to thank everyone. Some of the foundations that had given me support
weren’t too pleased to have been mentioned, however, because it led
to a great increase in applications.
I don’t think anyone, my publishers, my agent, or myself, expected
the book to do anything like as well as it did. It was in the London
best-seller list for 237 weeks, longer than any other book (apparently,
the Bible and Shakespeare aren’t counted). It has been translated
into something like forty languages and has sold about one copy for
every 750 men, women, and children in the world. As Nathan Myhrvold
of Microsoft (a former post-doc of mine) remarked: I have sold more
books on physics than Madonna has on sex.
The success of A Brief History
indicates that there is widespread interest in the big questions
like: Where did we come from? And why is the universe the way it is?
I have taken the
opportunity to update the book and include new theoretical and
observational results obtained since the book was first published (on
April Fools’ Day, 1988). I have included a new chapter on wormholes
and time travel. Einstein’s General Theory of Relativity seems to
offer the possibility that we could create and maintain wormholes,
little tubes that connect different regions of space-time. If so, we
might be able to use them for rapid travel around the galaxy or
travel back in time. Of course, we have not seen anyone from the
future (or have we?) but I discuss a possible explanation for this.
I also describe
the progress that has been made recently in finding "dualities" or
correspondences between apparently different theories of physics.
These correspondences are a strong indication that there is a
complete unified theory of physics, but they also suggest that it
may not be possible to express this theory in a single fundamental
formulation. Instead, we may have to use different reflections of
the underlying theory in different situations. It might be like our
being unable to represent the surface of the earth on a single map
and having to use different maps in different regions. This would be
a revolution in our view of the unification of the laws of science
but it would not change the most important point: that the universe
is governed by a set of rational laws that we can discover and
On the observational side, by far
the most important development has been the measurement of
fluctuations in the cosmic microwave background radiation by COBE (the
Cosmic Background Explorer satellite) and other collaborations.
These fluctuations are the finger-prints of creation, tiny initial
irregularities in the otherwise smooth and uniform early universe
that later grew into galaxies, stars, and all the structures we see
around us. Their form agrees with the predictions of the proposal
that the universe has no boundaries or edges in the imaginary time
direction; but further observations will be necessary to distinguish
this proposal from other possible explanations for the fluctuations
in the background. However, within a few years we should know
whether we can believe that we live in a universe that is completely
self-contained and without beginning or end.