Gravity's Arc

David Darling

Description

Advance Praise for Gravity's Arc


"A beautifully written exposition of the still mysterious force that holds our universe together--and the even more mysterious dark twin that may blow it apart."
--Joshua Gilder, coauthor of Heavenly Intrigue

"A lucid book as up-to-date as the effect of gravity on the bones of astronauts."
--Denis Brian, author of The Unexpected Einstein

How did they do it?

How did one of the greatest geniuses who ever lived retard the study of gravity for 2,000 years? How did a gluttonous tyrant with a gold nose revolutionize our view of the solar system? How could an eccentric professor shake the foundations of an entire belief system by dropping two objects from a tower? How did a falling apple turn the thoughts of a reclusive genius toward the moon? And how could a simple patent clerk change our entire view of the universe by imagining himself riding on a beam of light?

In Gravity's Arc, you'll discover how some of the most colorful, eccentric, and brilliant people in history first locked, then unlocked the door to understanding one of nature's most essential forces. You'll find out why Aristotle's misguided conclusions about gravity became an unassailable part of Christian dogma, how Galileo slowed down time to determine how fast objects fall, and why Isaac Newton erased every mention of one man's name from his magnum opus Principia. You'll also figure out what Einstein meant when he insisted that space is curved, whether there is really such a thing as antigravity, and why some scientists think that the best way to get to outer space is by taking an elevator.
Acknowledgments.

Prelude: The Weighting Game.

1 No Laughing Matter.

2 The Path of Dissent.

3 The Parabolic Man.

4 The Day the Sky Fell.

5 Escape from Earth.

6 One of Our Planets Is Missing.

7 When Gravity Became Geometry.

8 Alpha and Omega.

9 The Ripples of Space.

10 Disturbing News.

11 In the Dark.

12 All Together Now.

13 Engineers of the Continuum.

References.

Bibliography.

Index.

Sujets

• Mathematical
• Sciences et techniques
• (2653) Principia
• Galileo Galilei
• Computational
• Physics
• Christianity
• Principia
• Isaac Newton
• Galilée
• Science
• Albert Einstein
• Physique
• Physical attractiveness

Informations

• Publié par: Turner Publishing Company
• Date de parution: 27 juillet 2007
• Nombre de lectures: 0
• EAN13: 9780470238561
• Langue: English

Extrait

Gravity s Arc
Also by David Darling
Deep Time
Equations of Eternity
Soul Search
Zen Physics
The Extraterrestrial Encyclopedia
Life Everywhere: The Maverick Science of Astrobiology
The Complete Book of Spaceflight
The Universal Book of Astronomy
The Universal Book of Mathematics
Teleportation: The Impossible Leap
Gravity s Arc
The Story of Gravity, from Aristotle to Einstein and Beyond
DAVID DARLING


John Wiley Sons, Inc.
To Jill, forever
Copyright 2006 by David Darling. All rights reserved
Published by John Wiley Sons, Inc., Hoboken, New Jersey
Published simultaneously in Canada
Design and composition by Navta Associates, Inc.
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Library of Congress Cataloging-in-Publication Data:
Darling, David.
Gravity s arc : the story of gravity from Aristotle to Einstein and beyond / David Darling.
p. cm.
Includes bibliographical references and index.
ISBN-13 978-0-471-71989-2 (cloth)
ISBN-10 0-471-71989-7 (cloth)
1. Gravitation-History. 2. General relativity (Physics)-History.
3. Physicists-Biography. I. Title.
QC178.D373 2006
531 .14-dc22
2005030772
Printed in the United States of America
10 9 8 7 6 5 4 3 2 1
The roots of the Academy of twelve olive groves, millennia later-the olives-Newton s laws; today, the black olives, dark energy, in a hurry to arrive beyond the barren terrain and isolated tranquility of spacetime.
- ANNA KANCHEVA, BULGARIAN POET
Contents
Acknowledgments
Prelude: The Weighting Game

1 No Laughing Matter

2 The Path of Dissent

3 The Parabolic Man

4 The Day the Sky Fell

5 Escape from Earth

6 One of Our Planets Is Missing

7 When Gravity Became Geometry

8 Alpha and Omega

9 The Ripples of Space

10 Disturbing News

11 In the Dark

12 All Together Now

13 Engineers of the Continuum

References
Bibliography
Index
Acknowledgments
Among those have who been kind enough to provide technical advice and information are Stuart Anderson, Sasha Buchman, Bill Folkner, Joshua Gilder, Gary Page, Michael Salamon, Robert Soberman, and Robert Wald. Any errors that appear in the book are, of course, my responsibility alone.
I m once again very pleased to thank my outstanding editor, Stephen Power, and my production editor, Lisa Burstiner, at John Wiley Sons, and my wonderful agent, Patricia Van der Leun.
Lastly and mostly, I m grateful to my family for their love and support.
Prelude: The Weighting Game
We live in uneasy tension with gravity. Without gravity we wouldn t be here; it holds the atmosphere and the oceans to the earth, and it keeps the earth in orbit around the sun. It was the very reason the sun and Earth formed in the first place. Ultimately, gravity creates the conditions needed for life like ours to appear and survive. But it also creates enormous problems for those who live in its thrall.
Take our buildings, for example. The greatest of them soar elegantly in seeming defiance of the relentless force that tries to flatten them. But every one of them is a compromise, a visible, titanic struggle between aspiration and load. We want our buildings to float, to fly, to be filled with space and light. At the most basic level, however, gravity insists that you can t have a roof without support, so when the roof is too wide or weighty to be upheld by four simple walls, we need some other way to stop the edifice from crashing down around us.
The easiest answer to this problem of support is the column. Yet, however tastefully adorned, the column is the most pathetic of all supporting elements because it brutally exposes the architect s impotence. Those who built the Parthenon above Athens didn t want its interior to be so crowded with massive pillars, but they knew no other way to prevent the thing from collapsing. Only gradually, through trial and error, did the designers of buildings come to understand more intimately the play of forces and the use of shape and design to conduct gravity more subtly from rooftop to ground.
In the hands of the Arabs, the beam evolved to become the arch, which allows the supporting columns to be pushed further apart. The semicircular arch became the pointed arch, which adds strength and height. The arch was rotated in three dimensions to give the dome. Block-built pyramids and column-crammed, flat-beamed Greek temples gave way to spacious, sunlight-filled cathedrals with lofted ceilings, fan vaulting, and flying buttresses. The builders and designers of these finely tuned structures, the freemasons, carried in their heads a stock of ideas about how to control gravity, how to make stress flow to the outside of a building, that had grown from experience. The aqueduct at Segovia, the cathedral at Reims, and the Duomo of Florence reveal in their curved, ribbed, soaring forms the solution to one of gravity s challenges: how to build gracefully on a grand scale and at the same time manage the loading that gravity imposes.
Gravity is manifest not just in our buildings and in the natural landscape of mountains, caves, and rock bridges and cantilevers, but in our own bodies. It s literally in our bones, in their size and shape and arrangement. Millions of years of evolution have sculpted our bodies and internal processes, and those of other creatures, to survive and thrive in a one- g environment. When life emerged from the sea and became many-celled, it had to deal with the serious consequences of weight for the first time. Land species shifted their orientation with respect to gravity, or gained height, and so began to develop ways to cope with directional changes and to move structures and fluids against this load.
A fascinating instance of gravity playing a direct role in evolution concerns snakes. The orientation of a snake to the direction of gravity depends on habitat: tree snakes spend their days crawling up and down trees; land snakes spend most of their time in a horizontal position; sea snakes are neutrally buoyant. Researchers have found that of all snakes, the tree snake has its heart closest to its brain-an adaptation that allows it to get sufficient blood to its brain against gravity s pull. In humans, many of the most obvious signs of aging, such as sagging faces and bodies, rickety joints, and stooping, can be blamed on the relentless downward drag.
Everything around and inside us is adapted to existence in normal Earth gravity. Before the dawn of the space age, people wondered what would happen to human beings and other life-forms when thrust into a situation where the old rules didn t apply. In orbit, and while traveling at a steady speed through space, objects are weightless. While accelerating into space and reentering, spacecraft, and everything in them, experience several times Earth s gravity. Of prime concern was how well humans could tolerate such conditions, and for how long. The American physician John Stapp, as we ll discover, did some remarkable experiments on himself involving rocket-powered sleds that subjected him to several tens of g s for brief periods. Prospective astronauts were whirled around in centrifuges and other disorienting devices. Animals were sent on test flights to the edge of space. Eventually, humans spent many months at a time aboard space stations. The effects of microgravity on the human body became clear: muscle degeneration, space motion sickness, and bone demineralization.
Other animals, too, have trouble adapting to unearthly regimes. Spiders can t build proper webs without gravity as a guide. Zebra fish don t develop a normal vestibular system, essential for balance, if they grow up in a zero-gravity environment. Spaceflight studies in general show that gravity plays a crucial role in the development and health of vertebrates. Very-long-duration manned missions in zero-gravity will need some form of artificial gravity. Further down the road, other questions remain to be answered: Is the lower gravity on the moon and on Mars enough for people to live under for years