Sample text for Time travel in Einstein's universe : the physical possibilities of travel through time / J. Richard Gott, III.


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Preface
The neighborhood children think I have a time machine in my garage.
Even my colleagues sometimes behave as if I have one. Astrophysicist
Tod Lauer once sent me a formal letter inviting me to Kitt Peak
National Observatory to give a talk on time travel. He sent this
invitation six months after I had already given the talk. The
invitation explained that since I was an expert in time travel, I
should presumably have no trouble in returning to the past to make
the appearance. On another occasion, at a cosmology conference in
California, I happened to wear a turquoise sports jacket -- which I
imagined might fit in nicely with the California ambiance. Bob
Kirshner, then chair of Harvard"s astronomy department, came up to me
and said, "Richard, this is the "Coat of the Future"; you must have
gotten this in the future and brought it back, because this color
hasn"t been invented yet!" Since then, I"ve always worn this coat
when giving talks on time travel.
Time travel is certainly one of the most fun topics in physics, but
it has a serious side as well. I have received calls from people who
want to know about recent developments in time travel because they
wish to return to the past to rescue a loved one who died under
tragic circumstances. I treat such calls with great seriousness. I
have written this book partly to answer such questions. One reason
that time travel is so fascinating is that we have such a great
desire to do it.
Physicists like me who are investigating time travel are not
currently at the point of taking out patents on a time machine. But
we are investigating whether building one is possible in principle,
under the laws of physics. It"s a high-stakes game played by some of
the brightest people in the world: Einstein showed that time travel
to the future is possible and started the discussion. Kurt Gödel, Kip
Thorne, and Stephen Hawking have each been interested in the question
of whether time travel to the past is possible. The answer to that
question would both give new insights into how the universe works and
possibly some clues as to how it began.
This book is a personal story, not a history of science. Imagine me
as your guide, taking you to the summit of Mount Everest. The climb
is sometimes challenging, sometimes easy, but I promise that we will
ascend by the easiest possible route. It"s a path of ideas I know
well, having marked some of the trail myself. Along the way, we will
intersect the work of many of my colleagues. I have mentioned many of
them to give you a fair idea of the other trailblazers of this
terrain. Some contributions are emphasized and others briefly noted,
in or out of historical sequence, as they play into telling my story.
To those whose work I"ve not mentioned -- though it may be equally
important but following a different route up the mountain -- I
apologize in advance.
We start our journey at base camp: the dream of time travel itself
and the pathbreaking science fiction of H. G. Wells.

Copyright © 2001 by J. Richard Gott III


Library of Congress subject headings for this publication:
Space and time.
Time travel.