Page iii           Scientific American Science Desk Reference

Page iv         This book is printed on acid-free paper.             Copyright © 1999 Helicon Publishing Ltd. All rights reserved Original title: The Hutchinson Science Desk Reference             Published by John Wiley & Sons, Inc. Published simultaneously in Canada             Albert EinsteinTM licensed by the Hebrew University. Represented by The Roger Richman Agency, Inc., Beverly Hills, CA             No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, scanning or otherwise, except as permitted under Section 107 or 108 of the 1976 United States Copyright Act, without either the prior written permission of the Publisher, or authorization through payment of the appropriate per-copy fee to the Copyright Clearance Center, 222 Rosewood Drive, Danvers, MA 01923, (978) 750-8400, fax (978) 750-4744. Requests to the Publisher for permission should be addressed to the Permissions Department, John Wiley & Sons, Inc., 605 Third Avenue, New York, NY 10158-0012, (212) 850-6011, fax (212) 850-6008, E-Mail: PERMREQ @ WILEY.COM.             This publication is designed to provide accurate and authoritative information in regard to the subject matter covered. It is sold with the understanding that the publisher is not engaged in rendering professional services. If professional advice or other expert assistance is required, the services of a competent professional person should be sought.             Library of Congress Cataloging-in-Publication Data:             Scientific American science desk reference. p.    cm. Includes index. ISBN 0-471-35675-1 (alk. paper) 1.  Science Miscellanea.  2. Science Handbooks, manuals, etc. I.  Title: Science desk reference. Q173.S427    1999 500-dc21                                                                                  99-32007                                                                                                           CIP             Printed in the United States of America             10  9  8  7  6  5  4  3  2

Contents

1. Measurement 1
Systems of Measurement
Scientific Notation of Standard Form
Types of Measurement
Chronology
Biographies
Glossary
Further Reading

2. Mathematics 23
Numbers
Arithmetic
Algebra
Geometry
Trigonometry
Calculus
Statistics
Chronology
Biographies
Glossary
Further Reading

3. Chemistry 61
Molecules, Atoms, and Elements
Organic Chemistry
Inorganic Chemistry
Physical Chemistry
Analytical Chemistry
Applications of Chemistry
Chronology
Biographies
Glossary
Further Reading

4. Physics 119
The Atom
Splitting the Atom
Subatomic Particles
Radioactivity
Electricity and Magnetism
Matter
Mechanics
Thermodynamics
Radiation
Waves
Fundamental Forces
Relativity
Chronology
Biographies
Glossary
Further Reading

5. Astronomy 165
The Universe
The Celestial Sphere and Constellations
Stars
Galaxies
Other Astronomical Objects
The Solar System
Planets
Telescopes
The Exploration of Space
Directory of World Space Agencies
Chronology
Biographies
Glossary
Further Reading

6. Earth Science: Evolution and Structure of Planet Earth 215
Structure and Composition of the Earth
Plate Tectonics
Major Physical Features of the Earth's Surface
Earth phenomena: Earthquakes, Volcanism, and Magnetism
Rocks
Minerals
Geological Record: Divisions of Geological Time and Dating
Geological Timescale
Chronology
Biographies
Glossary
Further Reading

7. Earth Science: The Atmosphere and the Hydrosphere 265
Earth's Atmosphere
Earth's Hydrosphere
Chronology
Biographies
Glossary
Further Reading

8. Environment and Ecology 307
Elements of an Ecosystem
Biomes
Environmental Issues
Resources
Conservation
Chronology
Biographies
Glossary
Further Reading

9. Biology 349
Origins of Life
The Cell
The Molecules of Life
The Chemical Processes of Life
Genetics
Evolution
Classification and Nomenclature
Chronology
Biographies
Glossary
Further Reading

10. The Animal Kingdom 385
Classification
Mammals
Birds
Reptiles
Amphibians
Fish
Other Major Phyla
Feeding
Life Cycles
Animal Behavior
Chronology
Biographies
Glossary
Further Reading

11. Plant Kingdom 421
History of Botany
Classification
The Plant Cell
Plant Tissues
Roots, Stems, and Leaves
Reproduction in Angiosperms (Flowering Plants)
Alternation of Generations
Nutrition
Transpiration
Chronology
Biographies
Glossary
Further Reading

12. Human Body 457
Skeletal System
Muscle System
Circulatory System
Respiratory System
Nervous System
Endocrine System
Digestive System
Urinary System
Chronology
Biographies
Glossary
Further Reading

13. Health and Disease 497
Infectious Diseases
Noninfectious Diseases
Complementary Therapy
Chronology
Biographies
Glossary
Further Reading

14. Computer Science 553
Parts of a Computer
Peripheral Devices
Types of Computer
Computer Programming
The Computer—Human Interface
Computer Applications
Communications and the Internet
Computers and the Future
Chronology
Biographies
Glossary
Further Reading

15. Technology 603
Muscle to Microelectronics
Technology of Energy Conversion
Engineering and Technological Science
Technology of Machines
Technology of Industry
Technology of Construction Industries
Technology of Transportation
Technology of Telecommunications
Key Technological Inventions
Chronology
Biographies
Glossary
Further Reading

16. Discoveries, Inventions, and Prizes 651

Page ix           Foreword             Readers of Scientific American are curious, virtually by definition, so it's scarcely a surprise that they regularly call or write to our magazine's offices for answers to their questions on science and technology. The subjects of their queries can range from the commonplace ("How does the fluoride in toothpaste prevent cavities?") to the provocative ("Who gets to name the newly discovered planets orbiting other stars?") to the subtly profound (''Why is the night sky dark?").             Answering questions like those is what Scientific American does best. As the oldest continuously published consumer magazine in the United States, Scientific American has been explaining science to the public for more than 150 years, since 1845. We've developed a reputation for telling complex scientific tales that inquisitive nonscientists can understand.             To save some of you the trouble of a phone call or a letter, we are now pleased to present this single-volume desk reference on the exciting and ever-changing world of science and technology. Many of the facts and anecdotes you'll read in this volume are the legacies of pioneering scientists who've graced our pages over the decades. What's always made Scientific American different from other popular magazines is that we deliver stories from the frontiers of science straight from the mouths of the experts who did the work.             Take British molecular biologist Francis H. C. Crick, for example. In 1953 he and U.S. biologist James Watson revolutionized genetic research by describing the double helical structure of the DNA molecules that are the hereditary instruction manuals of most life. A few months later, Crick told his story in the pages of Scientific American. As the years passed, he kept our readers apprised of research developments with half-a-dozen more articles.             Research that was on the cutting edge almost forty years ago is what drives the biotechnology industry and a gamut of other genetic explorations today. This desk reference is a wonderful springboard for your own plunge into the field. You can read short biographies of Crick and Watson; a summary of their Nobel Prize-winning work; and a timeline of how their findings tie into the historical mesh of biology, genetics, and evolution. And if you find yourself yearning to know more about what makes Crick tick, a World Wide Web address will lead you to an online pool of facts about his upbringing, education, and recent research.             I think that what you'll enjoy about this book is that it conveys not only what we know about science but also how we know it. It's just the thing for helping you get a concise overview because it introduces the pioneering investigators who developed and structured the network of knowledge over time. And yet it's also great as a quick reference for converting miles to kilometers, or labeling the parts of the human digestive tract, or distinguishing between a black hole and a neutron star. When readers contact us with their questions, this book may be one of the first places we turn for an answer.           —JOHN RENNIE EDITOR-IN-CHIEF SCIENTIFIC AMERICAN             P.S. The answers to those questions I posed at the beginning? Fluoride strengthens teeth by fortifying the crystalline matrix in their enamel covering. New planets are named by the International Astronomical Union. Explaining why the night sky is dark is surprisingly complex, but essentially it's because light has a finite speed, stars have a finite life span, and the oldest parts of the universe may be too far away to see. Thanks for asking!           —J.R.

Page xi           Introduction             Science is one of the fastest changing areas of human knowledge and one of the main aims of Scientific American Science Desk Reference is to enable the reader to make sense of the vast amount of fascinating information and data that comprise modern science. The editors have produced a readable, accurate, and accessible reference book that will appeal to the specialist and general reader alike. In every chapter the reader will find a clear overview of the subject; easily accessible facts displayed as tables and diagrams; key vocabulary in the individual subject glossaries; historical context in the form of a chronology; outlines of the achievements of notable scientists; and numerous weblinks and bibliographies to aid further research.             Definition of Science             Science is represented within this book at its very broadest. Pure science does not exist in a vacuum, but requires the back up of technology, computing science, and mathematics; in addition, no science desk reference would really be complete without some information on medicine and the natural world.             How to Use Scientific American Science Desk Reference             The book is arranged thematically with each chapter covering one scientific discipline or an area within a discipline. Every chapter follows the same structure (except the final chapter "Discoveries, Inventions, and Prizes," which consists of tables):             • subject overview with tables, illustrations, weblinks, topic features, interesting facts, and memory joggers to complement the main text;             • chronology to provide a brief history of the subject, listing milestones such as groundbreaking experiments and important publications;             • biographies of important figures, outlining their contributions to the field;             • glossary of key vocabulary used within the chapter;             • further reading for those who would appreciate some pointers for additional research.             Cross-References             Cross-references (indicated by ) are self-contained within each chapter and refer to glossary or biography entries at the end of that chapter only.             Subject Overlap             Some amount of subject overlap is inevitable when one attempts to carve up the interrelated world of science into chapters—indeed Austrian-born British scientist and mathematician Hermann Bondi summed this up very neatly with his observation that science is "above all a cooperative enterprise." For reasons of space, glossary and biography entries that have bearing in a number of areas normally appear in one chapter only. The extensive index ensures readers can locate all relevant information, even if they are unsure in which chapter to look.