Time travel in Newton's universe was inconceivable, but in Einstein's universe it has become a possibility. J. Richard Gott III, a Princeton astrophysicist who is a leading researcher in the field, gives readers a guided tour of the potential of traveling through time. Although scientists such as Stephen Hawking and Kip Thorne have previously considered the topic, the delightfully refreshing but scrupulously careful Gott goes light-years beyond them in his exploration of this exciting idea.Gott begins by describing how the finest science fiction about time travel has inspired some of today's top scientific ideas on the subject. He goes on to explain how travel to the future is not only possible but has actually happened (astronauts have aged a bit less than we whose feet have stayed solidly on earth), and he examines whether travel to the past might also be possible, given certain physical conditions. He then offers up his most stunning material: the study of time travel can be used to discover whether the universe could have created itself. Finally, asserting that no book on time travel would be complete without a report from the future, Gott predicts the span of human existence, based on a scientific technique he has developed. His conclusion is humbling but wondrous: just in the short time we have lived so far, consider how much we have already learned about the universe.TIME TRAVEL IN EINSTEIN'S UNIVERSE is a book to read not only for its extraordinary subject matter and scientific brilliance but for its joyful writing.

J. Richard Gott III is a professor of astrophysical sciences at Princeton University.

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.

Excerpted from Time Travel in Einstein's Universe by J. Richard Gott. Copyright © 2001 by J. Richard Gott III. Excerpted by permission. All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.