Michio Kaku - Hyperspace: A Scientific Odyssey through Parallel Universes, Time Warps, and the Tenth Dimension

HYPERSPACE

A Scientific Odyssey
Through
Parallel Universes,
Time Warps, and
The Tenth Dimension

Michio Kaku

Illustrations by Robert OKeefe

Oxford University Press

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Library of Congress Cataloging-in-Publication Data
Kaku, Michio.
Hyperspace : a scientific odyssey through parallel universes,
time warps, and the tenth dimension /
Michio Kaku.
p. cm.
Includes bibliographical references and index.
ISBN 0-19-508514-0
1. Kaluza-Klein theories. 2. Superstring theories.
3. Hyperspace. I. Title.
QC793.3.F5K35 1994 530.142dc20 93-7910

Cosmic Gall. From Telephone Poles and Other Poems by John Updike.
Copyright 1960 by John Updike.
Reprinted by permission of Alfred A. Knopf, Inc.
Originally appeared in The New Yorker.

Excerpt from Fire and Ice. From The Poetry of Robert Frost,
edited by Edward Connery Lathem.
Copyright 1951 by Robert Frost.
Copyright 1923, 1969 by Henry Holt and Company, Inc.
Reprinted by permission of Henry Holt and
Company, Inc.

2 4 6 8 9 7 5 3 1

Printed in the United States of America
on acid-free paper

This book is dedicated
to my parents

Scientific revolutions, almost by definition, defy common sense.

If all our common-sense notions about the universe were correct, then science would have solved the secrets of the universe thousands of years ago. The purpose of science is to peel back the layer of the appearance of objects to reveal their underlying nature. In fact, if appearance and essence were the same thing, there would be no need for science.

Perhaps the most deeply entrenched common-sense notion about our world is that it is three dimensional. It goes without saying that length, width, and breadth suffice to describe all objects in our visible universe. Experiments with babies and animals have shown that we are born with an innate sense that our world is three dimensional. If we include time as another dimension, then four dimensions are sufficient to record all events in the universe. No matter where our instruments have probed, from deep within the atom to the farthest reaches of the galactic cluster, we have only found evidence of these four dimensions. To claim otherwise publicly, that other dimensions might exist or that our universe may coexist with others, is to invite certain scorn. Yet this deeply ingrained prejudice about our world, first speculated on by ancient Greek philosophers 2 millennia ago, is about to succumb to the progress of science.

This book is about a scientific revolution created by the theory of hyperspace,its most advanced formulation is called superstring theory, which even predicts the precise number of dimensions: ten. The usual three dimensions of space (length, width, and breadth) and one of time are now extended by six more spatial dimensions.

We caution that the theory of hyperspace has not yet been experimentally confirmed and would, in fact, be exceedingly difficult to prove in the laboratory. However, the theory has already swept across the major physics research laboratories of the world and has irrevocably altered the scientific landscape of modern physics, generating a staggering number of research papers in the scientific literature (over 5,000 by one count). However, almost nothing has been written for the lay audience to explain the fascinating properties of higher-dimensional space. Therefore, the general public is only dimly aware, if at all, of this revolution. In fact, the glib references to other dimensions and parallel universes in the popular culture are often misleading. This is regrettable because the theorys importance lies in its power to unify all known physical phenomena in an astonishingly simple framework. This book makes available, for the first time, a scientifically authoritative but accessible account of the current fascinating research on hyperspace.

To explain why the hyperspace theory has generated so much excitement within the world of theoretical physics, I have developed four fundamental themes that run through this book like a thread. These four themes divide the book into four parts.

In , I develop the early history of hyperspace, emphasizing the theme that the laws of nature become simpler and more elegant when expressed in higher dimensions.

To understand how adding higher dimensions can simplify physical problems, consider the following example: To the ancient Egyptians, the weather was a complete mystery. What caused the seasons? Why did it get warmer as they traveled south? Why did the winds generally blow in one direction? The weather was impossible to explain from the limited vantage point of the ancient Egyptians, to whom the earth appeared flat, like a two-dimensional plane. But now imagine sending the Egyptians in a rocket into outer space, where they can see the earth as simple and whole in its orbit around the sun. Suddenly, the answers to these questions become obvious.

From outer space, it is clear that the earths axis is tilted about 23 degrees from the vertical (the vertical being the perpendicular to the plane of the earths orbit around the sun). Because of this tilt, the northern hemisphere receives much less sunlight during one part of its orbit than during another part. Hence we have winter and summer. And since the equator receives more sunlight then the northern or southern polar regions, it becomes warmer as we approach the equator. Similarly, since the earth spins counterclockwise to someone sitting on the north pole, the cold, polar air swerves as it moves south toward the equator. The motion of hot and cold masses of air, set in motion by the earths spin, thus helps to explain why the winds generally blow in one direction, depending on where you are on the earth.

In summary, the rather obscure laws of the weather are easy to understand once we view the earth from space. Thus the solution to the problem is to go up into space, into the third dimension. Facts that were impossible to understand in a flat world suddenly become obvious when viewing a three-dimensional earth.

Similarly, the laws of gravity and light seem totally dissimilar. They obey different physical assumptions and different mathematics. Attempts to splice these two forces have always failed. However, if we add one more dimension, a fifth dimension, to the previous four dimensions of space and time, then the equations governing light and gravity appear to merge together like two pieces of a jigsaw puzzle. Light, in fact, can be explained as vibrations in the fifth dimension. In this way, we see that the laws of light and gravity become simpler in five dimensions.

Consequently, many physicists are now convinced that a conventional four-dimensional theory is too small to describe adequately the forces that describe our universe. In a four-dimensional theory, physicists have to squeeze together the forces of nature in a clumsy, unnatural fashion. Furthermore, this hybrid theory is incorrect. When expressed in dimensions beyond four, however, we have enough room to explain the fundamental forces in an elegant, self-contained fashion.