The Physics of War Read online

  ALSO BY BARRY PARKER

  Einstein's Brainchild

  Quantum Legacy

  Einstein: The Passions of a Scientist

  Albert Einstein's Vision

  Published 2014 by Prometheus Books

  The Physics of War: From Arrows to Atoms. Copyright © 2014 by Barry Parker. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, digital, electronic, mechanical, photocopying, recording, or otherwise, or conveyed via the Internet or a website without prior written permission of the publisher, except in the case of brief quotations embodied in critical articles and reviews.

  Interior artwork by Lori Scoffield Beer

  Cover image © 2013 Media Bakery and BIGSTOCK

  Jacket design by Grace M. Conti-Zilsberger

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  Library of Congress Cataloging-in-Publication Data Pending

  ISBN 978-1-61614-803-4 (hardcover)

  ISBN 978-1-61614-804-1 (ebook)

  Printed in the United States of America

  PREFACE

  CHAPTER 1: INTRODUCTION

  Summary of the Book

  CHAPTER 2: EARLY WARS AND THE BEGINNING OF PHYSICS

  Battle of Kadesh

  The Wonder Weapon

  Copper, Bronze, and Iron

  The Assyrians

  Greeks and the Beginning of Physics

  The New Wonder Machines

  Alexander the Great

  Archimedes

  CHAPTER 3: BASIC PHYSICS OF EARLY WEAPONS

  Velocity and Acceleration

  Force and Inertia

  Momentum and Impulse

  The Effect of Gravity

  Energy and Power

  Angular Momentum and Torque

  Machines

  Physics of the Bow and Arrow

  Physics of Other Early Weapons

  CHAPTER 4: THE RISE AND FALL OF THE ROMAN EMPIRE AND THE EARLY ENGLISH-FRENCH WARS

  The Romans and Their Weapons

  Early English-French Wars

  Origin and Physics of the Longbow

  CHAPTER 5: GUNPOWDER AND CANNONS: THE DISCOVERIES THAT CHANGED THE ART OF WAR AND THE WORLD

  Roger Bacon

  Development of the Cannon

  The Hundred Years’ War

  The Basilica and the Siege of Constantinople

  Cannons in the English-Scottish Wars

  The French

  Charles VIII and Victory over Naples

  CHAPTER 6: THREE MEN AHEAD OF THEIR TIME: DA VINCI, TARTAGLIA, AND GALILEO

  Leonardo and Physics

  Leonardo's Military Inventions

  Leonardo's Attitude toward War

  Tartaglia

  Galileo

  CHAPTER 7: FROM EARLY GUNS TO TOTAL DESTRUCTION AND DISCOVERY

  The Guns of War

  The War at Sea

  Henry VIII of England

  William Gilbert

  The Problem of Longitude

  The Thirty Years’ War

  Swedish Intervention

  A New Era of Discovery: Isaac Newton

  CHAPTER 8: THE IMPACT OF THE INDUSTRIAL REVOLUTION

  Introduction

  The French Revolution

  The English Revolution

  James Watt and the Steam Engine

  John “Iron Mad” Wilkinson

  Benjamin Robins

  The Flintlock

  Christiaan Huygens

  Physics and the Industrial Revolution

  CHAPTER 9: NAPOLEON'S WEAPONS AND NEW BREAKTHROUGHS IN PHYSICS

  The French Revolution

  Jean-Baptiste Vaquette de Gribeauval

  Napoleon and His Weapons

  Count Rumford

  New Breakthroughs in Physics

  How This Affected Warfare

  CHAPTER 10: THE AMERICAN CIVIL WAR

  Development of the Percussion Cap

  The Minié Ball

  A Revolution in Rifles and Cannons

  The War

  The Role of the Telegraph

  The Dynamo (Generator)

  The Gatling Gun

  The War at Sea

  Physics of the Propeller

  “Damn the Torpedoes”

  Submarines

  Balloons

  CHAPTER 11: WHERE DOES THE BULLET GO? BALLISTICS OF RIFLE BULLETS AND CANNON SHELLS

  Internal Ballistics

  Recoil

  Transitional Ballistics and the Sonic Boom

  External Ballistics

  Stability of the Bullet

  Terminal Ballistics

  CHAPTER 12: HEY, LOOK…IT FLIES! AERODYNAMICS AND THE FIRST AIRPLANES

  Discoveries That Led to the Airplane

  The Wright Brothers

  What Makes an Airplane Fly?

  The Physical, More Exact Explanation of Lift

  Details of Drag

  Steering and Maneuvering the Airplane

  First Use of Airplanes in War

  CHAPTER 13: THE MACHINE GUN WAR—WORLD WAR I

  Development of the Machine Gun

  Other Weapons

  How the War Started

  The First Warplanes

  The War at Sea and the Menace beneath the Sea

  The Final Horror—Poisonous Gas

  The First Tanks

  America Enters the War

  CHAPTER 14: THE INVISIBLE RAYS: THE DEVELOPMENT AND USE OF RADIO AND RADAR IN WAR

  The Production and Detection of Electromagnetic Waves

  The Electromagnetic Spectrum

  Radio Waves

  X-rays

  Light and Infrared

  Radar

  An Amazing Discovery

  CHAPTER 15: SONAR AND THE SUBMARINE

  Archimedes’ Principle

  Physics of Submarines

  Power for the Propellers

  Shape and Periscopes

  Navigation

  Sonar

  Torpedoes

  How Torpedoes Work

  Submarines in World War II

  CHAPTER 16: THE GREAT WAR: WORLD WAR II

  How the War Started

  Ready for War

  The Battle of France, and Dunkirk

  The Radar Advantage

  The Battle of Britain

  American Entry into the War

  Advances in Aviation

  The First Rockets in War

  Other Weapons and Small Arms

  Computers and Intelligence

  CHAPTER 17: THE ATOMIC BOMB

  The Beginning

  Einstein's Role

  The Italian Breakthrough

  Hahn, Meitner, and Strassmann

  Christmas 1938

  A Chain Reaction

  The Letter to Roosevelt

  The War Begins

  Meanwhile in England

  Heisenberg and Bohr

  The Manhattan Project

  The First Reactor

  The Continuing Manhattan Project

  Trinity

  The German Bomb

  Decision to Use the Bomb on Japan

  CHAPTER 18: THE HYDROGEN BOMB, INTERCONTINENTAL MISSILES, LASERS, AND THE FUTURE

  Development of the Hydrogen Bomb

  The Ulam-Teller Breakthrough

  The First Test: Mike

  Physics of the Hydrogen Bomb

  Long-Range Missiles

  Other Weapons: Lasers

  Transistors, Microchips,
and Computers

  Satellites and Drones

  Futuristic Weapons of War

  NOTES

  SELECTED BIBLIOGRAPHY

  INDEX

  I mentioned to a friend that I was writing a book on the physics of war. “What does physics have to do with war?” he asked. “Oh, you mean the atomic bomb,” he added. And indeed most people know that physics had something to do with the atomic bomb. But in reality it has made many contributions other than the atomic bomb, and not all of them have led to the creation of offensive weapons that have caused damage and grief. It has also been helpful for defense, and one of the best examples of this was the invention of radar just before World War II. It allowed the British to track incoming German planes and take action to defend themselves. The invention of radar no doubt saved thousands of lives during the Battle of Britain. The discovery of x-rays by Röntgen has also played a large role in war, and there's no doubt that it has saved lives.

  And it's not just modern weapons that have been based on the principles of physics. Even though they knew little physics, early civilizations, such as the Egyptians, Assyrians, Greeks and Romans, used physics in devising their weapons. Indeed, all through history physics has played an important role in the development of weapons.

  As the basic principles of physics were discovered by such people as Galileo, Newton, Huygens, Einstein, and others, it became a science that was solidly based on a firm foundation. At the same time, however, it became more complex and more difficult for the layperson to understand. But it is important that people other than scientists understand, at least to some degree, what is going on in the world of science, and I'm hoping that the present book will help in this respect. I would like to also mention that although physics has been used extensively in war, it has been found to have many applications for the betterment of humankind.

  In as many places as possible I've tried to use a story format to make the book more readable and interesting. I've used a few formulas; I hope they don't scare you. I've added them for anyone that is particularly interested in the details of the physics behind the weapons. You can ignore them without losing much.

  Finally, I would like to thank my artist, Lori Beer, for an excellent job on the diagrams. I'm sure they will be helpful to most people.

  The first well-documented battle in the history of the world took place in 1457 BCE on the Plain of Esdraelon, near the city of Megiddo in modern day Syria. It is usually referred to as the Battle of Megiddo. Megiddo, along with several other cities in the region of Palestine and Syria, had formed a coalition under the Prince of Kadesh, and had decided to break away from Egypt. Egypt's pharaoh, Thutmose III, was determined to stop the rebellion. With an army of ten thousand to fifteen thousand men, including infantry, archers, and cavalry, he marched toward Megiddo, arriving within a few miles of it in April. As the army camped at a place called Yaham, Thutmose conferred with his generals. There were three routes from Yaham to Megiddo; two were relatively easy, but a third, more direct route through the mountains, was quite difficult. Part of the route passed through a very narrow pass where his soldiers would have to travel single file. In addition, the cavalry would have to dismount and lead their horses. Strung out in this way, they would be vulnerable if the Prince of Kadesh decided to attack. Thutmose's generals encouraged him to take one of the easy routes. As he thought about it, however, he realized that the Prince of Kadesh and his troops would not expect them to come through the mountains because of its difficult terrain. They would likely be waiting at some point along the other two routes. So, to the disappointment of his generals, he decided to take the route through the mountains.1

  And indeed, Thutmose was right. The Prince of Kadesh's men were waiting for them at the ends of the two easy routes. The prince had split his army into two groups, with one half of it in the south and the other half in the north. Furthermore, he had left almost no men to guard the city of Megiddo.

  The following day Thutmose led his men through the treacherous pass, and when they broke out into the open, with the city of Megiddo directly ahead, they saw that it was lightly guarded. But Thutmose didn't want to attack the city at this point. He still had to defeat the prince's army. It was late in the evening, so he camped overnight and was ready for battle the next morning. He split his men into three wings and moved quickly to attack the flanks of both sections of the prince's army. They were so surprised by an attack coming from an unexpected direction that most of the men broke rank and fled. Most of them ran for the shelter of the city.2

  Thutmose pursued them, and by the time he got to the city he could see that many of them were trapped. The defenders of the city had seen the fleeing men coming and had opened the gate, but as Thutmose's army came into view they immediately shut it, leaving many outside. The citizens inside, however, acted quickly; they lowered ropes made of clothes to pull the stranded soldiers over the walls.

  Thutmose wanted to attack the city, but by now most of his soldiers were plundering the enemy camp, taking whatever they could find. By the time he got his army reorganized most of the enemy, including the Prince of Kadesh, were safe in the city, which had a high, strong wall all around it. Thutmose could see that it would be suicidal to attack it directly, so he decided on a siege. His troops had plenty of supplies, and there were more supplies available in the surrounding area. But the people within the city were cut off, so it was only a matter of time before they ran out of food and other supplies. The siege lasted for seven months, but finally the citizens and what was left of the army surrendered. By this time, however, the Prince of Kadesh had somehow escaped.

  It had taken longer than he had hoped. Nevertheless, Thutmose had soundly defeated the prince's army, and he had captured Megiddo.

  SUMMARY OF THE BOOK

  Like all rulers or generals going to war, Thutmose III was looking for something that would give him an advantage, and he found it. In his case it was a tactic that gave him an element of surprise. Throughout history, and even today, military leaders contemplating war, or involved in it, are still looking for some sort of advantage over their enemy. Whereas Thutmose used a surprise tactic to his advantage, throughout most of history military leaders have searched for a new “wonder weapon”; in essence, a weapon the enemy does not have. As we'll see in this book, it is usually physics that provides a path to this new weapon. Physics and science in general has indeed been of tremendous value to military leaders. It has given them a better understanding of ballistics so that they can aim their guns better; it has given them radar so that they can detect the enemy before they are detected; it has given them an understanding of the electromagnetic spectrum so they can use radiation in various military applications; it has given them an understanding of rocketry and jet engines, and an understanding of the secrets deep within the atom so they are able to build super bombs.

  This book gives an overview of most branches of physics, and it shows how they are used for military applications. It also gives a summary of the history of war all the way from the first bows and arrows and chariots through to the atomic and hydrogen bombs. We begin in chapter 2 with the Egyptians, Assyrians, and early Greeks. We'll look at some of their interesting weapons, such as the ballista, the onager, and the trebuchet, all of which involve basic principles of physics.

  In chapter 4 we look at the rise and fall of the greatest military establishment ever seen up to that time, namely the Roman Empire. The early English-French battles are also included in this chapter; one of the most famous of these was the Battle of Agincourt, where the English used the longbow to overcome a much larger and more powerful army. It was their secret new weapon.

  In chapter 5 we see the introduction of new technologies that completely changed the nature of war: gunpowder and cannons. Cannons were, in fact, so effective that they led to wars that lasted for a hundred years. At this stage, however, we can't say that physics made large contributions to the art of war because, for the most part, it didn't exist. But as we'll
see in chapter 6, three men, including Galileo, made important advances and helped put physics on a much better footing.

  With these advances and others, war became even more prevalent throughout Europe. Rifles improved significantly, beginning with the matchlock and ending with the flintlock a few years later. In addition, ships were now getting larger, and they were soon equipped with cannons. Furthermore, with William Gilbert's discoveries in relation to magnetism came a better understanding of navigation at sea, so sailors could now head out into the unknown without worrying about getting lost.

  Then came the magnificent discoveries of Isaac Newton, and physics was raised to new heights of understanding. His discoveries are discussed in chapter 7. Following this came the Industrial Revolution, discussed in chapter 8. In a period of less than one hundred years the civilized world changed significantly. In particular, several new techniques, including mass production, made war even more devastating.

  In chapter 9 we look at Napoleon and his weapons and tactics. Without doubt, he is one of history's greatest military tacticians, but strangely he didn't introduce many innovative new weapons. About this time another revolution in physics was occurring, and it would lead to a tremendous change in warfare. It began with the discovery that a “current” of electricity could be produced by a simple device called a pile. Soon the new phenomenon was all the rage throughout Europe, and it quickly attracted some of the best minds in physics: Oersted, Ohm, Ampere, and Faraday. Electric generators, motors, and other electrical devices followed, and of course, they eventually became central to war.

  In chapter 10 we come to the American Civil War, which was the most devastating war ever fought on American soil. By this time tremendous advances had occurred, including the percussion cap, which quickly led to much more accurate and deadly rifles, along with the first use of submarines, balloons, and the telegraph in warfare.

  In chapter 12 we discuss the airplane. World War I erupted only a decade after the first flight of the Wright brothers. And it didn't take long before airplanes were used in the war. “Dogfights” were soon common, and the airplane has played a central role in warfare ever since. Many other new weapons were also developed in World War I. They included huge new cannons, the first tanks, poisonous gas, and flamethrowers.