الرئيسية The Big Ideas That Changed the World
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THE BIG BIG IDEAS IDEAS THAT CHANGED THE WORLD Incredible inventions and the stories behind them 0+,(: ;/(; */(5.,+ ;/, >693+ Authors Julie Ferris, Dr. Mike Goldsmith, Ian Graham, Sally MacGill, Andrea Mills, Isabel Thomas, and Matt Turner Consultant Roger Bridgman LONDON, NEW YORK, MELBOURNE, MUNICH, AND DELHI Project editor Camilla de la Bédoyère Editors Sally MacGill, Theresa Bebbington Project art editor Ralph Pitchford Art editors Sandra Doble, Steve Woosnam Savage Senior editor Shaila Brown Senior designer Spencer Holbrook Designers Johnny Pau, Jane Thomas, Stefan Podhorodecki Managing editor Linda Esposito Managing art editors Diane Thistlethwaite, Jim Green Category publisher Laura Buller DK picture library Emma Shepherd Picture researcher Karen VanRoss Additional picture researchers Ria Jones, Jenny Faithful, Sarah Hopper Production editor Marc Staples Senior production controller Angela Graef Jacket designer Laura Brim, Sophia M.T.T. Jacket editor Matilda Gollon Development team Jayne Miller, Laura Brim Design development manager Sophia M. Tampakopoulos Turner First published in the United States in 2010 by DK Publishing, 375 Hudson Street New York, New York 10014 10 11 12 13 14 10 9 8 7 6 5 4 3 2 1 177397—06/10 Copyright © 2010 Dorling Kindersley Limited All rights reserved under International and Pan-American Copyright Conventions. 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, or otherwise, without the prior written permission of the copyright owner. Published in Great Britain by Dorling Kindersley Limited. DK books are available at special discounts when purchased in bulk for sales promotions, premiums, fundraising, or educational use. For details, contact: DK Publishing Special Markets, 375 Hudson Street, New York, New York 10014 SpecialSales@dk.com A catalog record for this book is available from the Library of Congress ISBN: 978-0-7566-6531-9 Hi-res workﬂo; w proofed by MDP, U.K. Printed by Leo Paper Products, China Discover more at www.dk.com 0+,(: ;/(; */(5.,+ ;/, >693+ GENIUS 10 Introduction Lightbulb 12 Antibiotics 14 Penicillin 16 Vaccination 18 Microscope 20 X-ray 22 DNA 24 Watson and Crick 26 Radioactivity 28 Tin can 30 Portland cement 32 Hoover Dam 34 PET bottles 36 Stainless steel 38 Telegraph 40 Who invented the telephone? 42 World Wide Web 44 Laser 46 LCD 48 Nylon 50 Wallace Carothers 52 Dynamite 54 Contents GREAT GIZMOS HANDY GADGETS 56 106 Engine 58 Microwave 108 Elevators 60 The first microwave 110 Elisha Otis 62 Digital camera 112 Refrigerator 64 Glasses 114 Wind turbine 66 Radio 116 Electric motor 68 Marconi 118 The father of electricity 70 Money 120 Spinning jenny 72 Credit card 122 Robots 74 Cash register 124 Robots in our world 76 James Ritty 126 Pendulum clock 78 Bar code 128 The master of time 80 Stapler 130 Crane 82 Stamp 132 Printing press 84 Post-its 134 Flushing toilet 86 Velcro 136 Television 88 Zipper 138 From script to screen 90 Cell phone 140 Solar cell 92 Going mobile 142 Clean energy 94 Battery 96 Microprocessor 98 From valves to microprocessors 100 Apple computer 102 Wozniak and Jobs 104 ON THE MOVE EXPLORE 144 178 Wheel Ford Model T Ford’s model factory Sailing ship Submarine Jet plane Helicopter Steam locomotive Full steam ahead Bicycle Cat’s eye Percy Shaw Electric car Metro London Underground 146 148 150 152 154 156 160 162 164 166 168 170 172 174 176 Saturn V Hubble Hubble in action Compass Mars rovers GPS Cassini Spacesuit Space helmet Submersible Scuba Jacques Cousteau Fiber-optic endoscope MRI 180 182 184 186 188 190 192 194 198 200 202 204 206 208 CULTURE 210 Ballpoint pen Umbrella LEGO® brick Play well Walkman Skateboard Newspaper Jeans Levi Strauss Kinetoscope What is 3-D? Video games Sunglasses Electric guitar Sports shoes Soccer 212 214 216 218 220 222 224 226 228 230 232 234 236 238 242 244 Time line Glossary Index 246 248 252 Contents As Thomas Edison stated, inventions are mostly hard work. But without a big idea to begin with, they would never happen at all. And without these big ideas and the inventions they lead to, our lives would be very different. They have changed the way we live and think and changed the course of history. Ideas in action Just look around you—how many of the things you can see didn’t have to be invented by someone? In fact, without inventions, many of us wouldn’t even be alive— medicines and machines start keeping us safe and healthy even before we are born and continue protecting us throughout our lives. Some inventions keep us in touch with our friends, allow us to explore our world, or help solve the mysteries of the universe, while others simply help us enjoy ourselves. Introduction 8 “ Genius is one percent inspiration and ninety-nine percent perspiration ” Thomas Edison, American scientist and inventor Changing the world For many centuries, most inventions started as the big idea of a single person. That began to change around a century ago, and soon colleges, big companies, and even entire governments were helping develop new ideas and turn them into reality. When they work together, large groups of people can do amazing things, from wiping out diseases to ﬂying to the Moon. It’s said that more things were invented in the 1900s than in all the centuries that came before, and it’s impossible to imagine just how many more things will be invented during this century. 9 Genius What does it take to be a genius? It might require years of study, endless experiments, the work of a lifetime. Or it might happen in a moment, with a single idea. An idea that changes the world. . . 1881 JOSEPH SWAN AND THOMAS EDISON The discovery of electricity sparked a race to design electric lights that were small and safe enough to be used at home. Englishman Joseph Swan and American Thomas Edison hit on the same bright idea: a glowing electric wire sealed inside a vacuum. They teamed up to sell their inventions, and in 1881, the ﬁrst commercial lightbulbs were produced. People were no longer limited to candlelight to see in the dark. For the ﬁrst time, doctors, craftspeople, and factory workers could see well enough to work at night. Streetlights made traveling safer. Miners no longer carried dangerous naked ﬂames. Within 25 years, millions of homes were lit by electric lamps. BRIGHT SPARKS Edison and Swan built upon decades of research to use electricity to make light. Sir Humphrey Davy made a key breakthrough in 1809. He found that an arc of electricity jumps between two carbon sticks to complete a circuit, heating the carbon until it glows. Electrical system Edison was one of the world’s greatest inventors and had 1,093 patents for his ideas. To make his lightbulb useful, he designed an entire system to generate and supply electricity to buildings. His inventions include safety fuses, light sockets, switches, and all the equipment that delivers electricity from power plants to homes in the right amounts. Edison and Swan both created vacuums inside their bulbs—with no oxygen around it, the ﬁlament can get white-hot without catching ﬁre The gas argon eventually replaced the vacuum inside bulbs Electricity passes through the ﬁlament, heating it to furnacelike temperatures The bulb had to be sealed after the air was carefully forced out, using a special pump In 1909, fragile carbon ﬁlaments were replaced by ﬁne tungsten wires, which were easier to handle and lasted longer Lightbulb 12 COOL SCIENCE If you uncoil a lightbulb ﬁlament, it is 20 in (51 cm) long Warnings At ﬁrst, people were suspicious of the new technology. Warning signs were necessary to remind them not to light bulbs with matches. Customers had to be reassured that electric lamps would not damage their health or affect their sleep. Wires heat up as electricity passes through them. If they get hot enough, they glow as electrical energy is changed into light as well as heat. Long, thin coiled wires produce the brightest light. Modern ﬁlaments have coils so small, they can be seen only with a microscope. Popular light source Lightbulbs made electric lighting affordable. Although they are more than 100 years old, Edison’s original bulbs look very similar to today’s incandescent bulbs. Easy to use, they have become the world’s most popular source of light. A good source of light? As countries around the world look for ways to reduce energy use, new types of lightbulbs are stepping into the spotlight. More heat than light Although cheap to produce, modern lightbulbs convert just 4–6 percent of their electricity supply into light. The rest is wasted as heat. The term “lamp” originally referred to the bulb, but today we use it to refer to the ﬁtting that holds it Early Swan lamp Energy-saving bulb Compact ﬂuorescent bulbs use one-quarter of the energy and last 10 times longer than ﬁlament bulbs. A coating on the glass glows as electricity passes through the gas inside. The bulbs slot into ﬁttings that make contact with the electricity supply Early bases, such as this wooden one, were eventually replaced by a screw-in base invented by Edison Lighting the future Light-emitting diodes (LEDs) produce little heat and have been used since the 1960s. New-generation LED bulbs are bright enough to light rooms and last for 25 years. SEE ALSO X-ray 22 · Television 88 13 1928 TOMORROW’S WORLD ALEXANDER FLEMING For most of human history, disease-causing bacteria were our deadliest enemies. During World War I, more soldiers died from infections than ﬁghting—even a scratch from a thorn could be lethal. Alexander Fleming’s accidental discovery of a substance that could kill bacteria without harming human cells changed the course of history. Antibiotics have helped people live longer, healthier lives and transformed the way in which new drugs are developed. Deadly invaders Bacteria are microscopic organisms. Many “friendly” bacteria live inside us without doing any harm, but disease-causing bacteria release chemicals that damage our cells. They cause some of the deadliest human diseases, including pneumonia, tuberculosis, and the plague. Bacteria, such as Salmonella (above), can rapidly change, making it difficult to treat the disease that they cause. Scientists are hoping to create new synthetic antibiotics that will target all types of bacteria even more effectively than natural ones can. U.S. doctors prescribe 150 million doses of antibiotics every year Seek and destroy Each antibiotic ﬁghts bacteria in a different way, stopping them from growing or reproducing normally. Penicillin, for example, stops bacteria from building their protective cell walls, so the bacteria are damaged or burst as they grow. The ﬁrst antibiotics were injected or used on skin wounds— most are now taken by mouth (orally) Antibiotics 14 Antibiotic capsules are made from gelatin or other digestible materials Miracle mold Fleming discovered the ﬁrst antibiotic when he left a dish of Staphylococcus bacteria uncovered for several days. Spores of Penicillium notatum mold, closely related to ordinary bread mold, drifted into the dish and began to grow. Fleming realized that the mold produced a chemical that was poisonous to bacteria—he called this penicillin. The ﬁght continues Penicillin’s success led to a scramble to ﬁnd new antibiotics. In the 1950s, the discovery of streptomycin and other antibiotics made diseases—including tuberculosis—curable. People pictured a world free of infections, but bacteria began to ﬁght back. Halos of dead and dying bacteria appeared around the blue mold Viruses Antibiotics don’t harm viruses. However, they are vital to the development of virus-busting drugs. They are added to eggs, which are used to grow viruses for research and stop bacteria from infecting them. Coatings can be added to capsules so that they dissolve in the intestine, protecting the penicillin from stomach acid A growing problem The use of antibiotics is not tightly controlled—doctors prescribe them for virus infections, patients take incorrect doses, while farmers feed them to livestock. All of these things help new, antibiotic-resistant bacteria evolve. Your body breaks down penicillin after around four hours, so capsules must be taken frequently SEE ALSO Vaccination 18 15 Penicillin Alexander Fleming was the ﬁrst person to investigate penicillin’s bacteria-busting effects. However, it was the work of two lesser-known scientists that gave doctors the ability to ﬁght bacteria with antibiotics. Ernst Chain and Howard Florey separated the antibacterial substance from the mold that produces it and used this to make a life-saving drug. Purifying penicillin Fleming tested his Penicillium mold on different types of bacteria and discovered that it killed those that caused pneumonia, syphilis, and diphtheria. It was also harmless to humans, unlike the antiseptics that were in use at the time—these chemicals killed bacteria but also damaged human cells. He published his research in 1929, pointing out that if penicillin could be extracted, it would be very useful in medicine. A decade later, Chain read Fleming’s paper and suggested that he and Florey try to purify penicillin. By 1940, having tested it successfully on mice, they had extracted and puriﬁed enough penicillin to try it out on a human patient. Ernst Chain Howard Florey German-born Chain was an excellent biochemist who had left Berlin a few years before joining Florey’s team in England. Florey led the Oxford University laboratory that rediscovered penicillin. Unlike Fleming, he did not like media attention. 16 Alexander Fleming Fleming was a bacteriologist at Saint Mary’s Hospital, in London, England. His ﬁrst major discovery was that mucus from the nose has mild antibacterial effects. This work helped him see the signiﬁcance of the moldy dish. New sources Florey and Chain had so little penicillin, they had to remove the drug from their ﬁrst patient’s urine and reinject him with it. Finding it difficult to extract enough penicillin from Penicillium notatum, Florey launched a worldwide search for a more productive strain of the mold. Finally in 1943, a lab worker brought in a moldy melon from a local market. This became the source of most antibiotics for the next decade. Making an antibiotic Florey and Chain’s successful trials with penicillin helped persuade companies to produce the drug on a large scale. Penicillin for all Production of penicillin was led by American companies, but it was not long before the technology was used by other countries, helping resolve the lack of supply. Prizes and predictions In 1945, Fleming, Florey, and Chain won a Nobel Prize for their work. Fleming made a speech predicting today’s problems of antibiotic resistance—taking too little could expose bacteria to small, nonlethal quantities of the drug and allow them to become resistant. Few took notice of Fleming’s warnings. Military orders The ﬁrst penicillin stocks were sent straight to soldiers wounded on the battleﬁelds of World War II. The “miracle drug” dramatically reduced deaths from infected wounds, and penicillin became a household name. 17 1796 The cowpox virus is still used to make smallpox vaccines EDWARD JENNER Smallpox was once a common disease, killing most victims and leaving survivors with terrible scars. In 1796, Edward Jenner discovered that exposing people to the milder disease of cowpox prevented them from catching smallpox. He called his technique vaccination. A century later, Louis Pasteur ﬁgured out how to make vaccines for other diseases, triggering a massive advance in the ﬁght against diseases. Vaccines have since been developed for many serious diseases, saving millions of lives. The test Jenner’s work was remarkable at a time when no one knew that microorganisms, such as viruses and bacteria, could cause diseases. Working as a doctor, Jenner discovered that milkmaids who caught cowpox became immune to smallpox. He tested his theory by infecting an eight-year-old boy with cowpox. Two months later, Jenner transferred some pus from a smallpox victim into a cut on the boy’s arm. The boy did not develop smallpox. Metal syringes are often used to vaccinate animals— humans are vaccinated with smaller, disposable needles or syringes Vaccines come in different forms—many are injected, but some are taken by mouth Vaccination prevents more than two million deaths every year Vaccination 18 Creating vaccines In 1879, Pasteur decided to try and make milder forms of other diseases to use as vaccines. He heated anthrax bacteria to stop them from causing a deadly disease. The damaged bacteria were injected into animals. Later, the animals were injected with real anthrax and survived. Vaccines are still made from dead or weakened microorganisms using Pasteur’s methods. Milestones in medicine Fighting diseases Pasteur’s pioneering work prompted research into new vaccines. Once-common diseases like tetanus, rabies, measles, polio, and diphtheria can now be controlled and prevented by vaccination. Newer vaccines target the viruses that cause certain cancers. Vaccination is a quick, easy, and cost-effective way to prevent diseases Vaccinations have given scientists and doctors a greater understanding of the immune system and how it destroys invading microorganisms and viruses. A plunger forces the liquid through the needle Protection on a large scale Vaccination prevents diseases from spreading, protecting entire communities as well as individuals. Mass vaccination for children is now routine in many countries. How vaccines work The weakened microorganisms are attacked and destroyed by your immune system. If the disease-causing microorganisms later invade your body, your immune system “remembers” how it fought the vaccine and quickly springs into action—killing the microorganisms. TOMORROW’S WORLD The end of smallpox The last death from smallpox (above) was in 1977, following a huge program of vaccination that was coordinated by the World Health Organization. Vaccines are biological products, so they have to be stored and used carefully Science is still searching for vaccines against many deadly diseases, including malaria, which is transmitted by mosquitoes. Malaria infects more than 240 million people per year and caused more than 860,000 deaths in 2008 alone. Organ transplants Immunology (understanding the immune system) made organ transplants possible. Doctors can stop the recipient’s body from treating the new organ like a disease. SEE ALSO Antibiotics 14 · Microscope 20 19 20 Microscope Hooke added a third lens inside this barrel to increase the visible area of the specimen The signal is displayed on a monitor Modern-day scanning electron microscopes use magnets to move a beam of tiny negatively charged particles, called electrons, across the object being examined. Electrons from the specimen are knocked loose and picked up by a detector, which feeds the information to a display. The electron beam hits the specimen, and electrons from the specimen are scattered The electrons reﬂected off the specimen are collected and turned into a signal Magnetic coils act like lenses, focusing the beam of electrons on to the specimen A beam of fast moving electrons is ﬁred into the microscope COOL SCIENCE HANS AND ZACHARIAS JANSSEN The barrel was made of wood, covered with thin leather The microscope’s barrrel was secured to a metal stand From spectacles to spectacular In the 1590s, magnifying lenses were used widely in spectacles, so it’s not surprising that a spectacle-maker invented the compound microscope. Hans Janssen and his son Zacharias realized that if one lens magniﬁed a little, two could magnify more. A compound microscope is one that uses more than one lens to magnify (make bigger) an image. Microscopes zoom in on details that are invisible to the naked eye. They are among the most useful of all scientiﬁc instruments, because they give us an insight into how things are structured and how they function. This 16th-century invention led to the discovery of cells and microorganisms and has unlocked many secrets of life, death, and diseases. Robert Hooke (above) and Anton van Leeuwenhoek began microscope-based research in the 1600s Hooke’s compound microscope had three lenses—the eye lens was at the top 1590 SEE ALSO Vaccination 18 · Spectacles 114 · Hubble 182 21 The image could be focused using this screw Better lenses led to more powerful microscopes. As microscopes improved, scientists delved deeper into the detail of life. Their discoveries were crucial to the development of science and medicine. Leeuwenhoek’s microscope In 1676, Leeuwenhoek used his simple microscopes to study plaque scraped off his teeth. He was amazed to see tiny “animals” moving around—he had discovered microorganisms. A magnifying lens was in the snout The barrel could be angled using a ball-and-socket joint Amazing discoveries The world’s most powerful microscope magniﬁes 14 million times, revealing individual atoms Light and lenses Lenses are pieces of glass with curved sides that bend light rays. The Janssens placed a lens at each end of a tube, creating a microscope that made objects appear 10 times bigger. In the 1670s, Anton van Leeuwenhoek made single-lens microscopes that could magnify objects 200 times. Germ theory Two hundred years later, Louis Pasteur used microscopes to study bacteria in diseased animals. His theory that microorganisms caused diseases revolutionized medicine. Modern microscopes Electron microscopes were invented in the 1930s, becoming so powerful that they allowed scientists to see atoms for the ﬁrst time. The latest models can reveal a specimen’s physical and chemical properties. Specimens were mounted on this pin and lit by light from an oil lamp Tiny worlds Robert Hooke used a compound microscope to examine thousands of objects and living things. In 1665, he published a bestselling book, called Micrographia, which was packed full of drawings of the strange and exciting details that he’d seen. His most important discovery was the cell, which is the building block of plants and animals. Hooke’s drawing of thin slices of cork from trees revealed that plants were made up of tiny structures, which he called cells 1895 WILHELM RÖNTGEN The accidental discovery of x-rays, a type of radiation, in 1895 astonished the world and changed science, industry, and medicine forever. Physicists, including Marie Curie, began researching new areas, leading to the discovery of radioactivity. Industry began using x-rays to ﬁnd faults in machines and materials. In medicine for the ﬁrst time, doctors could look inside people’s bodies without cutting them open. X-rays are now used worldwide to detect broken bones, bad teeth, swallowed objects, and even tumors. X-rays expose photographic ﬁlm in the same way that light does—the more rays that hit the ﬁlm, the darker it gets X-rays have more energy than light, so they can travel through different materials Discovering the unknown As Wilhelm Röntgen studied radiation from a cathode ray tube, he noticed a mysterious green light. He realized that unknown invisible rays had penetrated a cardboard barrier and were making a patch of ﬂuorescent paint glow. BRIGHT SPARKS In the mid-1800s, scientists began pumping the air out of glass tubes in order to study glowing beams known as cathode rays. In the 1870s, scientist William Crookes invented a better cathode ray tube that led to amazing breakthroughs in physics. Crookes tubes were used to discover electrons, plasmas, x-rays, radioactivity, and even led to the ﬁrst television sets. X-ray 22 X-rays are a type of electromagnetic radiation, like light and radio waves The x-rays leave a silhouette, or the shape, of objects that they can’t travel through, such as metal jewelry Penetrating power Röntgen excitedly experimented with the new rays. He found that they passed straight through many objects. The most startling result came when he placed his wife’s hand between the beam and some photographic ﬁlm. He’d discovered a way to photograph the bones inside the body. Bones let few x-rays reach the ﬁlm—these show up as white “shadows,” and help doctors see fractures X-rays were named after the mathematical symbol for an “unknown” Looking inside X-rays let us look inside things that are dangerous, difficult, or inconvenient to take apart—from the human body to gas pipelines and complex electronic equipment. Probing proteins An x-ray image can reveal the structure of miniscule molecules, such as this ﬂu virus. This helps scientists design effective medicines. Peering into the pelvis CAT scanners use multiple, moving x-ray beams to scan the body from every angle. A computer then builds detailed images, helping doctors ﬁnd unhealthy tissue. Soft tissues, such as ﬂesh, let more x-rays through, so they appear gray Invisible danger By 1927, scientists realized that radiation could kill cells and cause cancer. Doctors began to use shields and small doses to protect themselves and their patients. The harmful effects have also been harnessed to treat diseases, by zapping cancer cells with x-ray beams. Catching criminals X-rays are a quick and easy way to screen bags and luggage at airports and other places where both security and speed are important. SEE ALSO DNA 24 · Radioactivity 28 · Television 88 23 1953 BRIGHT SPARKS FRANCIS CRICK AND JAMES WATSON Humans have always been interested in what gives living things their characteristics, and how this information is passed from one generation to the next. The unraveling of DNA and the science of genetics was one of the greatest achievements of the 1900s. In the 1860s, Austrian monk and scientist Gregor Mendel experimented with pea plants. He ﬁgured out that simple characteristics, such as ﬂower color, are determined by two hereditary factors, one from each parent. Today, we call those hereditary factors genes. Information carriers Genes are carried on structures called chromosomes found in the nucleus of a cell. It was in the 1940s that scientists discovered chromosomes are made of long strands of tightly coiled deoxyribonucleic acid (DNA). The four letters are different chemicals called bases—shown as four different colors DNA is a simple four-letter alphabet that acts as a code, telling cells how to make proteins DNA 24 What is DNA? Scientists James Watson and Francis Crick discovered the structure of DNA in 1953, ﬁnally explaining how genes carry information. Each gene is a length of DNA that tells a cell how to make a speciﬁc protein. Humans, animals, and plants need many different proteins in order to live and grow. COOL SCIENCE DNA can make copies of itself, which is essential for living things to grow and reproduce. The double helix “unzips,” and each half of the ladder acts as a template. The separated bases attract new partners, building two identical double helices (plural of helix). The bases pair up like rungs on a ladder, linking together two chains of DNA A molecule of DNA is made up of two strands that twist around one another Each backbone and its bases make one chain The bases are linked together in long chains by a “backbone” made of carbon, hydrogen, oxygen, and phosphorus The science of genetics Genetics is the scientiﬁc study of genes—the hereditary factors in DNA. They affect almost everything about us, from how we look and behave to the illnesses that we might get as we grow older. Studying DNA helps us understand why some cells don’t work properly and could lead to cures for many diseases in the future. Genetics has also given us DNA ﬁngerprinting and genetic engineering (changing an organism’s DNA to give it useful new characteristics). TOMORROW’S WORLD The uncoiled DNA from a single human cell is almost 6 ft (2 m) long Colonies of bacteria can be given genes that make them light up every hour or so. If conditions change, the timing changes. Putting these bacteria into patients could warn doctors when body conditions change, so that every patient gets their medicine when they need it. SEE ALSO Antibiotics 14 · X-ray 22 25 k c i r C d n a n o s t a W DNA f o e r structu istory e h t r the h n scove i i s d e i r o o t g st ce ersity The ra he most excitin mbridge Univ how Ca ft os is one o . 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We have also learned how to release the enormous nuclear energy stored inside their atoms. There have been serious destructive consequences, but nuclear power now produces one-sixth of the world’s electricity. It does so without releasing global-warming gases, using a fuel found in rocks all around the world. Fuel rods contain pellets of uranium fuel Radioactive elements In 1896, the French physicist Henri Becquerel discovered that the metal uranium gives off radiation. Soon, other elements (substances that contain atoms of all one type) that are naturally radioactive were also found. In today’s nuclear reactors, we can also make some elements become radioactive. Over time, all these gradually change into different chemical elements. A uranium fuel pellet the size of a grape contains as much energy as three and a half barrels of oil When lowered into the reactor, the bundle of rods will provide energy for three or four years This French nuclear power plant produces enough electricity to boil 600,000 kettles at the same time The Curies French scientists Marie and Pierre Curie were interested in Becquerel’s mysterious rays. In 1898, they discovered three new elements that give off radiation. Marie realized that radiation comes from the atoms of these elements. She called this property radioactivity. In 1903, Marie became the ﬁrst woman to win a Nobel Prize, shared with Pierre Curie and Becquerel. Radioactivity 28 Nuclear power Radioactive atoms are unstable. Bombarding them with even smaller particles called neutrons can split them apart. This process—called nuclear ﬁssion—releases huge amounts of energy as heat and radiation. A nuclear reactor harnesses this to create steam for generating electricity. High-energy radiation is deadly, so power plant operators use machines to handle the fuel Wider uses of radioactivity We can detect even tiny amounts of radiation. Doctors use radioactive elements to trace the paths of chemicals inside the human body to study how the body works and diagnose diseases. Carefully targeted doses of high-energy radiation can also kill cancer cells. In industry, radioactive elements and sensitive detectors are used to check the thickness of materials like paper and plastic wrap as they are made. Scientists also use radioactive tracers. The amount of radiation given off by naturally radioactive elements tells us the age of ancient plant and animal remains. The water’s blue glow shows the strength of the nuclear reaction The splitting of uranium atoms takes place inside the reactor’s core TOMORROW’S WORLD Rocks that contain uranium are taken from mines (left), but mining can contaminate land and water with radioactive waste. This is harmful to living things. Scientists are exploring ways to clean up this waste. One possible method is to use a type of bacteria that “eats” radioactive uranium and makes it safer. SEE ALSO X-ray 22 · Solar cell 92 29 1810 BRIGHT SPARKS PETER DURAND First used by sailors, soldiers, and explorers, tin cans can still provide lifesaving food supplies. But since the 1920s, they have become essential, convenient, long-lasting food stock items in most households. Almost all foods can be canned, from the cheapest tomatoes to the ﬁnest caviar. Easily recycled and needing no refrigeration, cans are also one of the most environmentally friendly ways to preserve food. This means that people may still be using them in hundreds of years’ time. The ﬁrst tin cans In 1810, Englishman Peter Durand created tin cans by dipping sheets of metal into molten (melted) tin and connecting pieces together with a soldering iron. The ﬁrst canning factory was built near London, England, in 1812, and by 1815 British troops were eating canned food at the Battle of Waterloo. In the 1700s, many soldiers died of hunger while at war, so France offered a cash prize to anyone who could think of a new way to preserve food. In 1810, Nicholas Appert won the prize. It had taken him 14 years to ﬁnd a method that worked—boiling food that was then sealed inside glass jars. Gravy soup cans, 1899 Early cans were iron, but now most food cans are steel, and drinks cans are aluminum Workers rolled metal rectangles to form the cylinders—some cans are still made in this way In 1813, a can of meat cost nearly one-third of a laborer’s weekly income A slow start For years, production was very slow. Skilled tinsmiths made just six cans per hour by hand, which were then boiled for at least ﬁve hours. By 1846, machines could manufacture 60 cans per hour, but today’s machines can make a thousand per minute. We now boil the food very quickly, at high pressures and temperatures. A thin layer of tin stopped the inside from rusting Tin can 30 Tinsmiths soldered the ends of the can to the cylinder after hammering the edges down with a mallet Stopping the rot For many years, people canned food without knowing how the process worked. In the 1850s, Louis Pasteur showed that boiling food killed the bacteria and mold that cause decay. Sealing the cans prevented more live microorganisms from reaching the food. Old chicken On their 2006 wedding anniversary, Les and Beryl Lailey opened a can of chicken 50 years after receiving it as a wedding present; it still tasted ﬁne. Use-by dates are usually for two years, but if properly sealed, canned food may never go off. Preserving food People have been trying to preserve food since ancient times. This means either killing bacteria and molds or stopping them from growing. A small hole, soldered closed afterward, let air escape while the food boiled Opening cans involved a hammer and chisel until Ezra Warner invented the can opener in 1858 This gravy soup was for soldiers in the Boer War (1899–1902) to make beef tea Traditional methods The ancient Egyptians found that drying fruit in the sun made them last longer. For centuries, we have also smoked or salted meat and ﬁsh and pickled foods in vinegar. Freezing Microorganisms cannot function at freezing temperatures, and some die. But frozen food was not common outside cold countries until the invention of refrigeration. Much thicker than modern cans, early cans often weighed more than the food inside Tinsmiths used lead solder (a mixture of melted metals) to seal cans, not realizing that it was poisonous Freeze drying This method dries frozen food without damaging its structure. Adding water will return it to its original state, even years later. SEE ALSO Microscope 20 · Refrigerator 64 31 1824 JOSEPH ASPDIN Much of the modern world is built from concrete, as it is cheap, hard-wearing, and does not burn. Almost all of this concrete has been made with Portland cement. Cement is a vital ingredient of most civil engineering structures, such as roads, bridges, and sewers. We also use it in mortar, to plaster walls, and to lay bricks. Ancient civilizations used natural cements, but Portland cement is consistently strong and easy to produce, which is why it has been such a massive success. After water, concrete is the most widely used substance on Earth Most concrete and mortar mixes have more than twice as much sand as cement Cement, which makes up around 10 percent of concrete, is the glue that binds together sand and gravel Concrete hardens because of a chemical reaction— called curing—between cement and water Fortune seekers In the early 1800s, factories produced natural cements of limestone and clay. But their quality varied with the minerals found in the ground. Many people tried to make their fortunes with the perfect man-made cement. However, nobody understoond the chemistry of concrete, so they could only experiment by trial and error. Gravel gives concrete bulk and strength, but it is missed out when making mortar Fibers or chemicals can make concrete even stronger Portland cement 32 Early concretes In ancient times, many people used mud or dung as natural cements. Some also made long-lasting concrete from materials available locally. To cast concrete, builders pour well-mixed cement, sand, gravel, and water into molds known as formwork Success in the kitchen In 1824, British bricklayer Joseph Aspdin burned crushed limestone with clay in his kitchen and then ground it into a powder. He had found the recipe for an artiﬁcial cement that reacted with water to become much stronger. It made gray concrete that looked like high-quality Portland stone, so he called it Portland cement. Concrete-tipped pyramids Most scientists now agree that, rather than hauling huge stone blocks to the top of pyramids, the ancient Egyptians probably cast some in place using a clay-based concrete. Cables support the new concrete while the bridge is being built From strength to strength Aspdin’s son William, who ran Portland cement factories, improved the recipe with higher temperatures and modiﬁed ingredients. French gardener Joseph Monier invented reinforced concrete in 1867. His concrete plant pots with steel mesh paved the way for today’s massive reinforced concrete structures. Its curved shape helps the bridge carry more weight These are cast on site, but concrete blocks are often precast in factories Without steel reinforcement bars, this 2,120-ft(645-m-) long bridge would collapse Ancient Roman ash The Romans used ash from volcanos to make strong concrete. They changed its properties by adding blood, milk, and horsehair. BRIGHT SPARKS In 1756, John Smeaton built a stone lighthouse off the U.K. coast. He noted that unlike ordinary mortars of limestone and sand, those that also had a high proportion of clay became harder in water and could withstand the pounding of the waves. Shown here is the lighthouse, which was rebuilt on land as a memorial. SEE ALSO Stainless steel 38 33 Hoover Dam Built in the 1930s during America’s Great Depression, the Hoover Dam still stands as one of the most impressive feats of civil engineering ever. It took around 200 engineers and 20,000 construction workers to dam the Colorado River at Black Canyon. The concrete that they cast could have built a sidewalk 4 ft (1.2 m) wide all the way around the planet. Camping in Ragtown Months before dam building began in 1931, tens of thousands of men arrived at the site in search of jobs. They brought wives and children, but little money. Families camped in terrible conditions in a dry, barren spot that they called Ragtown. Diseases were rife, and the heat killed 25 people in the hot June and July of 1931. The following year, the government built Boulder City, where many of the workforce and their families lived until the dam was completed in 1936. Monkeys, Puddlers, and Scalers Work was far from easy, and 96 dam workers were killed in accidents. The men had speciﬁc duties: Powder Monkeys detonated dynamite, while Puddlers spread fresh concrete. High Scalers probably had the most dangerous job—they climbed down the cliffs on ropes to remove rocks. 34 Big blocks The dam workers built wooden formwork to cast more than 200 huge blocks of reinforced concrete. These joined like giant building bricks to form the dam. They were stuck together with a strong cement and water paste. “ I came, I saw, and I was conquered, as everyone would be who sees for the ﬁrst time this great feat of mankind U.S. President Franklin D. Roosevelt, 1935 Taming the river Upstream, the Colorado River (right) is still wild and unpredictable. In Boulder, the dam has blocked its ﬂow to create a huge man-made reservoir, called Lake Mead (below). To build the dam, workers had to divert the river away from the site, by building temporary dams and blasting tunnels through the canyon rocks. ” A new landscape Almost every year, the Colorado River had ﬂooded in the spring, and then slowed to a trickle during the summer months. Farmers struggled to water crops, and much of the area was a desert wasteland. Hoover Dam transformed the landscape around Boulder. It also now provides a steady water supply to four states and electricity to 1.3 million people. Producing power The hydroelectric power plant sits at the dam’s base. Water gushing through tunnels from Lake Mead turns massive turbine wheels 180 times per minute. These connect via shafts (pictured) to 17 electricity generators. Each can supply enough electricity for 100,000 homes. A huge attraction The curved Hoover Dam is an impressive 660 ft (200 m) wide and 730 ft (220 m) high and attracts more than seven million tourists per year. Half-buried deep underwater, the base is so thick that the concrete will probably continue to cure (harden) for hundreds of years. 35 1973 Lids are usually made from a different type of plastic and often cannot be recycled NATHANIEL WYETH Much lighter than glass, and virtually unbreakable, plastic bottles were obviously a very good idea. But making one for carbonated drinks was surprisingly difficult. The bottles that Nathaniel Wyeth designed were ﬁrst used for Pepsi Cola in the 1970s. We now use them for all types of things, such as peanut butter and makeup. Unlike most plastics, polyethylene terephthalate (PET) can be recycled, so it is becoming more and more popular. In Africa, some people make their water safe to drink using only PET bottles and strong sunlight An inquisitive man Wyeth worked as an engineer for the American company DuPont. One day at work, his colleague told him that plastic bottles were useless for carbonated drinks. That night, Wyeth ﬁlled one with ginger ale and put it in the fridge. The next day, the swollen bottle was wedged in—it was too weak to cope with the pressure. He decided to make a stronger one. BRIGHT SPARKS Belgian chemist Leo Baekeland made the ﬁrst synthetic plastic, called Bakelite, in 1907, which became fashionable in the 1920s for lamps, phones, and jewelry. PET, a type of polyester, was developed in 1941. PET bottles 36 Most water bottles are now made with PET Ridges make bottles stronger, so they can be thinner and use less plastic Hiding in the mold Plastic molecules are long, thin chains. Wyeth’s idea was to stretch these to line them up—a technique that made nylon thread stronger. Using air jets, he stretched hot plastic inside different shaped molds. After thousands of shapeless blobs, he found one mold empty. Then, looking closer at the sides of the mold, he spotted his ﬁrst plastic bottle. Unlike this modern PET bottle, early PET bottles had round bottoms, so they could not stand up without separate plastic bases Recycling PET PET comes from oil and takes centuries to degrade, but Wyeth did not really consider its environmental impact. Luckily, it is easy to recycle. The ﬁrst recycled bottle became a new Pepsi bottle base in 1977. PET is now the world’s most recycled plastic. The plastic is thicker at the top, as it needs to be more rigid PET is usually clear, but it can be colored to bottle light-sensitive liquids, such as beer As well as the recycling logo, PET bottles are stamped with “PET” or “PETE” and the number “1” Piles of old plastic PET recycling starts with sorting and squashing bottles into huge bales. These are sent to a recycling plant, where machines grind them into tiny ﬂakes. After washing, the ﬂakes are sold on to plastics factories. Recycling saves lots of energy, but most PET bottles are still buried The perfect plastic Wyeth tested different plastics for his bottle, ﬁnally settling on PET, which was normally used to make synthetic cloth and carpet. Strong, light, and cheap, PET is also very impermeable (leak-proof) to gases. This keeps the carbonated drinks inside very ﬁzzy. Although PET is cheap, 90 percent of the cost of bottled water is the cost of the bottle Thousand uses A surprising number of everyday things can be made from PET bottles. Most are turned into polyester ﬁbers for carpets and ﬂeece material. But we also make them into shoes, belts, bags, toys, ropes, containers, car parts, and, increasingly, new bottles. SEE ALSO Tin can 30 · Nylon 50 37 38 Stainless steel People have been making steel for thousands of years. In 1821, French mining engineer Pierre Berthier noticed that adding chromium metal made steel more resistant to chemical attack. But for years, scientists were not able to produce steel with enough chromium to make it stainless steel. Chrysler Building, New York, U.S.A. Stainless steel makes the building one of New York’s most stunning skyscrapers Stainless steel is strong and can withstand wind and rain When stainless steel is damaged, it does not rust because chromium reacts with air to form a protective scar The architect of the Chrysler Building had the 180 ft (55 m) ﬁnial (tip) added to make sure that it would be the tallest building in New York City Storage and transportation Stainless steel tanks do not develop leaks, even when they contain very corrosive (damaging) chemicals. So we use stainless steel to carry fuel, distil alcoholic drinks, and even carry household garbage. Surgical instruments Doctors use stainless steel instruments in surgical operations. Despite being repeatedly sterilized (boiled to kill germs), they do not rust. They are also resistant to the chemicals in blood. Most of us come across stainless steel many times each day—as nuts and bolts, exhaust pipes, saucepans, and even kitchen sinks. As well as being long-lasting, it is also hygenic. Stainless steel uses HARRY BREARLEY BRIGHT SPARKS Rust-free silverware Living among the steel factories of Sheffield in the U.K., Brearley immediately saw the potential of his “rust-less steel” in the local silverware industry. In 1914, factories started making knives from stainless steel. During World War I, it was used in the engines of ﬁghter planes. Englishman Harry Brearley was trying to develop a type of steel for riﬂe barrels that wouldn’t wear out quickly when bullets were ﬁred. To his amazement, among his many different steel samples was one that did not rust. It even resisted chemical attack from lemon juice and other acids. Unlike other steels, stainless steel lasts in most environments without having to be treated, painted, or renovated. It has revolutionized most modern industries, including food, medicine, and transportation. 1913 SEE ALSO Portland cement 32 39 Carbon is the black mineral found in coal, which can also form diamonds The main ingredient is iron, which is soft and rusts easily Chromium is very hard but also brittle (breakable) and can be poisonous What is stainless steel? Steel is an alloy (mixture) of iron with other substances. To be stainless, it must be at least half iron and at least one-tenth chromium, with a tiny amount of carbon. Other metals, such as nickel, can also be added. Builders attached each piece of stainless steel cladding separately Built in 1930 for the Chrysler motor company, the design was based on parts of cars, including hubcaps (wheel covers) Stainless steel looks much lighter in color on sunny days, as it reﬂects a lot of light Claiming credit Brearley is usually credited with the invention, but other scientists claimed to have made stainless steel ﬁrst. Fed up with using rusty razor blades, American Elwood Haynes may have made one type of stainless steel in 1911. There are other claims from the U.S.A., and also from Germany, Poland, and Sweden. 1830 When the contacts touched, electricity passed along the telegraph wire JOSEPH HENRY Operators tapped the key quickly or slowly to produce Morse code The key acted like a switch in a large electrical circuit with the telegraph receiver The spring lifted the key to break the electrical circuit Thousands of years ago, people sent signals using drums, smoke, and even pigeons. In the early 1800s, sending a letter was still the easiest way to contact someone far away. But telegraphs enabled people to send messages long distance along wires, with almost no delay. Kick-starting electronic communication, they paved the way for telephones, cell phones and even instant messaging. The receiver changed the key’s electrical signals into dots and dashes on paper tape Coils of wire wrapped around iron formed the electromagnets BRIGHT SPARKS French inventor and engineer Claude Chappe devised the ﬁrst nonelectric telegraph network in 1794. It crossed France and even branched into other countries. Relay towers with armlike pointers spelled out messages in semaphore code (a ﬂag-based alphabet). These were viewed by telescope from the next tower. Telegraph 40 Paving the way In 1830, American scientist Joseph Henry sent an electric current along more than 1 mile (1.6 km) of wire to strike a bell. His receiving device used an electromagnet. Many inventors then began designing telegraphs based on electromagnets, with varying success. In the U.K., railroads and post offices used telegraphs made by two British inventors, William Cooke and Charles Wheatstone. Morse and Vail In America, Samuel Morse was successful in improving Henry’s device. Morse abandoned a career as a painter to develop a practical electric telegraph. In 1836, young engineer Alfred Vail saw Morse’s crude device and offered to help improve it. They became partners, with Vail developing the working Morse telegraph seen here. A light metal arm moved down and up as the coils became magnetized and demagnetized Simply clever The Morse telegraph caught on, mainly because it was simple. It used just one telegraph wire to send messages, so the code was crucial. Using short and long electrical signals—dots and dashes—to make letters, Morse and Vail’s code became the standard language of longdistance communication. The other end of the arm rose to make small dents in the paper tape that fed through rollers The most famous message in Morse code is the international distress signal, SOS (... ___ ...) The tape came out here, embossed with Morse code The clockwork mechanism kept the tape moving steadily Telegraph wires being laid across the Atlantic Ocean by the S.S. Great Eastern Telegraph wires carrying Morse signals connected to the coils of wire Wiring the world Built in 1844, Morse’s ﬁrst telegraph line ran between Washington, D.C. and Baltimore, Maryland. Twenty years later, telegraph lines spanned America and Europe and were soon to cross the Atlantic Ocean. Even after the telephone was invented, the telegraph business thrived for decades. The last telegram was sent in 2006. SEE ALSO Cell phone 140 41 Who invented the telephone? Scottish scientist Alexander Graham Bell is famous for inventing the telephone. But he was not the ﬁrst person to transmit voices along wires. Nor was his telephone perfect—other scientists helped improve it. Many inventors also claimed to have invented the telephone before Bell, and some nearly beat him to receiving the recognition for this incredible device. In first place In 1874, Bell received funding to develop a telegraph that could send many messages down the same wire. But Bell and his assistant, Thomas Watson, also experimented with a talking telegraph. Bell applied for a U.S. patent for this on February 14, 1876. Three days after being given the sole right to make and sell telephones, he ﬁnally got the invention to work. Bell fought more than 600 lawsuits to defend his patent—the most valuable ever issued. But he won every case. “ I then shouted into M [the mouthpiece], ‘Mr. Watson, come here, I want to see you’ ” Alexander Graham Bell, March 10, 1876 42 Alexander Graham Bell Born in Scotland in 1847 to a deaf mother, Bell emigrated to Canada before settling in the U.S.A., where he taught deaf children to speak while investigating sound and electricity. A proliﬁc inventor, he is shown here with the telephone sketch he drew in 1876. Bell’s telephone After forming the Bell Telephone Company in July 1877, Bell gave lectures to promote his invention. By the end of the year, he had sold 3,000 telephones. He used the receiver pictured here to show Queen Victoria of England how the device worked. The outsider Antonio Meucci beat Bell to the patent office by ﬁve years. But he could only afford temporary arrangements to prevent others from patenting the telephone. He stopped buying these in 1874—the year that his laboratory, which he shared with Bell, claimed to lose his telephone prototypes (working models). In 2002, the U.S. government recognized Meucci’s work in the invention of the telephone. Antonio Meucci Meucci was an Italian inventor who moved to the U.S.A. in 1850. His wife suffered from crippling rheumatism, and in 1857 he built a telephone to talk to her from his basement laboratory. A photo ﬁnish Among the scientists ﬁghting Bell’s patent in court was Elisha Gray. He also took a design to the patent office on February 14, 1876 and accused Bell of stealing his ideas to make a working receiver. Most people believe that Bell beat Gray to the patent office by a few hours. Yet a patent officer signed a legal document saying that he had been bribed to award Bell the patent—and that he even showed Gray’s paperwork to Bell. Bell later denied that these events happened. Elisha Gray Elisha Gray was born in Ohio in 1835. He was a carpenter and blacksmith, before setting up an electrical company in 1872. He lost a long legal battle with Bell over his telephone design (above) but held 70 patents, including one for a fax machine. 43 1989 TIM BERNERS-LEE Tim Berners-Lee’s colleagues at the European organization for nuclear research (CERN) worked in many countries on different computer systems. He developed the World Wide Web to help them share scientiﬁc information. Now one quarter of the world’s population can access billions of web pages over the Internet—a network of linked computers. This has completely transformed business, culture, politics, shopping, and even the way that we socialize. The Internet network CERN ﬁrst used the web in 1991. But its network also linked to other institutes, via a network called the Internet. Soon, others connected to the Internet were setting up web servers. In 1993, CERN made its web development tools freely available. Six months later, there were 200 web servers, and the Internet itself had begun to grow. Berners-Lee worked on a black and white screen Each page has its own address, called a uniform resource locator (URL) A vague but exciting plan In 1989, aged 24, Berners-Lee proposed that information stored on central “web servers” could be browsed by people on networked (linked) computers using the simple point and click system, called Hypertext. Writing “vague The ﬁrst web browsers were also editors, so but exciting” on the proposal, his boss agreed people could make their own web pages to the project. Sitting at this NeXT computer, Berners-Lee put his ideas into practice. He developed HTML (Hypertext Markup Language) for writing web pages, HTTP (Hypertext Transfer Protocol), which is how servers and browsers talk to each other, and the very ﬁrst browsing program, simply called WorldWideWeb. Pointing and clicking on a hyperlink directed the browser to another web page address The average Internet user visits more than a thousand web pages every month NeXT computer World Wide Web 44 Easy browsers The ﬁrst web browsers were black and white and only worked on NeXT computers, but other versions were soon developed. Mosaic was the ﬁrst to become popular with the general public. It was very slow, but it already had sound, video, and bookmarks. TOMORROW’S WORLD Experts think we will soon be able to ask the web questions like, “Where can I get some lunch?” Knowing about us, and where we are, it could then point us toward a meal. How the web has changed us By making some things much easier, the web quickly changed people’s habits. Many with Internet access would now struggle to do without. Known as the Cube, this NeXT computer was the world’s ﬁrst web server The Cube once stored all the pages and ﬁles on the World Wide Web Buying things Online we can usually ﬁnd exactly what we want to buy, at the best price. Without it, we can only buy what nearby shops are selling. Computers linked via telephone wires or cables could browse the web A sticker asked people not to turn off the computer— if they did, no one could access the web Finding things out We all used to depend on asking each other or looking in books for answers. Now web pages cover almost every topic imaginable. The NeXT computer was powerful but expensive A new world The early web was for sharing information. But with the launch of Amazon.com in 1995, it also became a place to do business. Entire industries had to adapt to this. So even before broadband, mobile Internet, and countless web innovations like blogging, our world had already changed forever. Rather than a ﬁxed hard drive, the computer had removable optical disks Networking with friends Over the Internet, we can chat with friends, wherever they are, and also show them photos. SEE ALSO Microprocessor 98 45 1957 GORDON GOULD Based on a theory by physicist Albert Einstein, the invention of the laser was initially described as a solution looking for a problem. But people quickly found uses for its intense, narrow beam of light. Today lasers penetrate almost every aspect of life, from scanning bar codes to treating cancers, guiding missiles, and even replacing hair. Laser light is both bright and sharp A laser produces light waves with the same wavelength, so they are a single color Masers and lasers In 1954, Charles Townes built a maser. This used stimulated emission to amplify microwaves—similar to light waves, but with longer wavelengths. Adapting it for light waves was far from simple. In 1957, Townes’ student Gordon Gould started making a laser. But failing to understand the patent process, he did not protect his invention and his work was exploited by others. To trace the Moon’s path, scientists fire laser beams at mirrors that sit on the Moon’s surface Computer programmes can analyze a DJ’s music and produce laser effects to go with it The peaks and troughs of laser light waves are in step Theory of a genius We usually think of light as waves. Ordinary white light is a mixture of colored light waves, each one with a different wavelength. These are emitted (sent out) at random intervals in all directions. In 1917, Einstein theorized about making a much stronger light, using what he called stimulated emission. This would consist of waves with exactly the same wavelength that were perfectly in step, and all traveled in the same direction. Laser 46 Moving mirrors make fast ﬂashing laser beams look very dramatic The beams only shine at the audience brieﬂy, as they can damage people’s eyes Laser machines often have two or three lasers, for different colored beams Lasers big and small Lone operator There was a race to build a laser, with large research teams trying to create laser beams from different materials. However, it was Theodore Maiman, operating alone, who made the ﬁrst working laser in 1964, using a ruby crystal. Maiman’s laser used a ruby, but many other substances can also be used. Some lasers are delicate and precise, while others are extremely powerful. Light drilling Many dentists now use lasers rather than drills to whiten teeth, reshape gums, and remove decay. Surgeons also use lasers for delicate operations on the eyes and brain. COOL SCIENCE Photons of light bounce off the mirror at the back The ﬂash tube coils around the ruby crystal The semitransparent mirror reﬂects back most of the light, but lets some pass through Light industry Focused laser light can cut through most materials, including thick sheets of metal. Lasers can cut awkward shapes into delicate materials, and they never need sharpening. Strong red laser beam Bouncing photons stimulate the release of other photons, so the light gets stronger Aluminum reﬂecting cylinder White light from the ruby laser’s ﬂash tube gives the ruby’s atoms extra energy. Some release this as photons (small packets) of red light. When photons meet other high-energy atoms, they make them release energy, too, as photons that are in step. As photons bounce between the two mirrors, the new laser beam strengthens and ﬁnally emerges through the semitransparent end. Earth health check Scientists use lasers to study the atmosphere and monitor greenhouse gases. Lasers are also used to monitor pollution in rivers. SEE ALSO Bar code 128 47 1967 JAMES FERGASON The development of liquid crystal displays (LCDs) has been central to our increasingly digital lifestyle. These slim panels are used in most modern electronic gadgets. Many people contributed to the development of LCD technology. But the breakthrough that led to practical screens came in 1967, when American inventor James Fergason discovered a type of liquid crystal that could block or let through polarized light. Modern LCDs can display images, text, and video—and they are rapidly becoming smaller and more sophisticated. Glass sandwich LCD screens are layers of liquid crystal sandwiched between sheets of special glass, which—like sunglasses—polarizes (ﬁlters) light. They are thinner, lighter, and use less energy than the bulky cathode ray tubes of old-style screens. The liquid crystals are in segments, each with its own electricity supply Reﬂected light makes the display appear gray BRIGHT SPARKS Electricity stops the crystals from letting light through the glass, so these areas are dark Liquid crystals were discovered in 1888, but few scientists looked into their uses. Interest exploded in 1963, when George Heilmeier (above) and Richard Williams suggested using them for displays. LCD screens appeared four years later. LCD 48 Low-energy display A black and gray LCD does not need a backlight, making it perfect for low-energy, battery-powered devices. Instead, surrounding light simply bounces off a mirror at the back of the display. Liquid crystals are neither solid nor liquid; they exist in a state of matter between the two COOL SCIENCE Vertical polarizing ﬁlter Liquid crystal twists light A backlight makes color displays bright enough for us to see tones and details Color ﬁlter Glass The number of pixels in a display is known as its resolution Electricity applied Horizontal polarizing ﬁlter Display Touch-sensitive LCD screens are handy for everyone, but they also make it easier for people with language difficulties to communicate Light enters an LCD display and is polarized (to orient the rays in one direction) by a ﬁlter. When electricity is applied, the liquid crystals line up in a different direction, blocking light from passing through a pixel and making these sections appear dark. Pixel pictures More complex displays split the liquid crystals into millions of tiny elements called pixels. The more pixels a screen has, the more detailed its images. A computer screen can have more than one million pixels. Each pixel (made up of red, blue, and green) can display more than 16 million different colors Color ﬁlters cover the liquid crystals in each subpixel Each subpixel has a variable electricity supply with 256 brightness levels Creating colors Pixels are split into red, blue, and green subpixels, with liquid crystals controlling the brightness of each. They are so small that our brains see the combination of reds, blues, and greens as single colors. SEE ALSO Television 88 · Digital camera 112 · GPS 190 · Sunglasses 236 49 1935 DUPONT AND WALLACE CAROTHERS In 1935, a patent was granted to the American chemical company DuPont for a new material called nylon. Products made from nylon reached stores in 1938. They were an instant hit with customers. At ﬁrst, nylon ﬁbers were used in toothbrushes. They also replaced silk in stockings, which became known as nylons. Today, nylon is used in a variety of products and textiles. As well as nylon ﬁbers, solid nylon is used to make plastic products, including plastic pipes and some mechanical parts that used to be made from metal. Why is nylon so useful? Nylon is widely used because it is strong, tough, long-lasting, lightweight, easy to wash, resists scratches, and is not damaged by oil or a wide variety of chemicals. It can also be easily dyed different colors. COOL SCIENCE Nylon is a polymer. A polymer is a long chain of units made of groups of atoms. Nylon is made in a laboratory, but there are polymers in nature, too. Cellulose, found in the cell walls of plants, and natural rubber are polymers. Nylon 50 The bottom of the balloon is made of ﬁreproof material because nylon is sensitive to heat The downside of nylon Nylon has some disadvantages. If it gets too hot, it melts and burns. When it burns, it gives off poisonous fumes (gases). Once it is made, it is difficult to dispose of. Unlike natural ﬁbers, such as cotton and wool, nylon does not rot in the ground when it is thrown away. Nylon is made from petroleum—it was developed to be a substitute for silk, a more expensive material to make The balloon fabric is made from nylon panels stitched together The nylon fabric is coated with chemicals to make it more airtight and waterproof Nylon balloons Most hot-air balloons are made from nylon. It was ﬁrst chosen for this job because it had already proved to be a very good material for making parachutes. A type of fabric called ripstop nylon is used. Extra threads are woven into the material to stop tears from spreading. The very ﬁrst parachute jump using a nylon parachute was made in 1942 A versatile material Nylon can be made into different forms, making it a good material for products found in industry, sports, and the home. Pipes Nylon can be molded and formed into different shapes. Nylon pipes and hoses are used in car engines. Water and drainage pipes are also often made of nylon. Rope Nylon is used to make strong and ﬂexible ropes. In fact, nylon ropes are the strongest type in common use. They are used in mountaineering and to pull heavy loads. Woven and stitched Nylon ﬁbers are used in all types of products that are woven or stitched together, including clothing, carpets, upholstery, and tents. SEE ALSO PET bottles 36 · Umbrella 214 51 Wallace Carothers “ The story of nylon began when DuPont opened a new research center in the 1920s. They chose a brilliant young scholar and chemist, Wallace Carothers, to run it. Carothers was born in Iowa on April 27, 1896. After obtaining a science degree in 1920, he earned a doctorate at the University of Illinois. Carothers went to work at Harvard University in 1926, and two years later he moved to DuPont. Leaving Harvard When Carothers was offered the chance to run his own laboratory at DuPont, at ﬁrst he was unsure of whether or not to leave Harvard. He would have more research assistants of higher quality at DuPont, but he might be freer to follow the research that most interested him at Harvard. DuPont reassured him that he would be given all the support he needed to carry out his research. They also offered him nearly twice as much money as he was earning at Harvard. Wallace Carothers Carothers and his team of scientists at DuPont made new materials by combining different chemicals. They tried scores of combinations, searching for one that would produce a successful new material. 52 Nylon can be fashioned into ﬁlaments as strong as steel, as ﬁne as a spider’s web, yet more elastic than. . . natural ﬁbers DuPont Vice-President Charles Stine, 1938 ” An unhappy life Sadly, Carothers did not live to see the great success of the materials that he created. He rarely went out and hated the public speaking that he had to do as part of his work. He also had bouts of depression. In 1936, Carothers married Helen Sweetman, another DuPont worker, but his depression continued and he spent some time in a hospital. On April 29, 1937, at the age of 41, Carothers killed himself by taking poison—one year before the ﬁrst nylon products went on sale to the public. Neoprene Nylon wasn’t the ﬁrst new material to be made in Carothers’ laboratory at DuPont. In 1930, it developed neoprene, the ﬁrst successful mass-produced synthetic rubber. Wetsuits worn by divers are made of neoprene. First products The ﬁrst nylon product that people could buy was a toothbrush with nylon bristles. Until then, bristles had been made of animal hair. Mass production Nylon is ideal for making thousands of copies of the same product by forcing liquid nylon into molds. This DuPont worker is surrounded by 10,000 nylon combs, the number that one worker could make in a single day in the 1950s. 53 Dynamite 54 Scientists are developing new explosives that will make ﬁrework displays even more spectacular. Mixing chemicals in miniscule quantities— literally a few molecules at a time—makes them more powerful, so even more explosive. TOMORROW’S WORLD Killer chemical Italian chemist Ascanio Sobrero ﬁrst made the liquid nitroglycerin—dynamite’s explosive ingredient—in 1846. It was much more powerful than gunpowder, but deadly to handle. Even the tiniest knock could make it explode. It caused many fatal accidents, including one that killed Nobel’s younger brother, Emil. Dynamite was the first powerful explosive that was safe to handle. It transformed construction, mining, and quarrying, blasting a path into the 1900s. We use explosives to build railroads, roads, and tunnels. We blast through rocks to build dams and crack them open to extract coal. Alfred Nobel’s discovery also ignited research into more powerful explosives. These help us free up even more of Earth’s resources— the rocks and minerals used to make cars, computers, cell phones, and even medicines. Invented in 1878, blasting boxes used electricity to set off a blasting cap Pushing the plunger sent a powerful electric current down a wire Health and safety Nobel developed devices called blasting caps. These could be used to detonate (trigger) nitroglycerin explosions from a distance. But he also discovered that mixing nitroglycerin with kieselguhr (a chalky sand) made it much safer. He called this substance dynamite. 1866 ALFRED NOBEL SEE ALSO Hoover Dam 34 55 Born in Sweden in 1933, Nobel grew up in Russia, where his father made land mines for the Czar. He learned to speak ﬁve languages and developed wide interests. Although chemistry was his greatest passion, Nobel also wrote poetry in his spare time. Alfred Nobel The fuse allows explosions to be set off from a distance— this type burns The fuse triggers a small explosion in a blasting cap attached to its end The shock from the exploding blasting cap makes the dynamite explode Fireﬁghters use dynamite and other explosives to put out ﬁres in oil wells An inventive man Nobel started his dangerous experiments with explosives in 1860, continuing them long after he invented dynamite. When he died, aged 63, he held 355 patents— for inventions such as synthetic rubber as well as for other explosives. Shown here is his laboratory in Sweden. Dynamite does not have to contain kieselguhr—sawdust and other absorbent materials can also be used Nobel Prize Dynamite made Nobel a wealthy man, but he was sad that people used his inventions for war. In his will, Nobel left his fortune to set up the Nobel Prize. Since 1901, this has been awarded every year for work that most beneﬁts humankind. Detonating dynamite Dynamite was so stable that it could be dropped, hit, or burned without exploding. But it still exploded powerfully when detonated by a blasting cap. Demand for dynamite grew quickly, and Nobel eventually owned 90 dynamite factories in 20 countries. Dynamite can be shaped into tubes and safely packed in paper Great Gizmos A single amazing invention, like the clock or the printing press, can change people’s lives all over the world. Often, great gizmos like these go through many versions over the years, getting better and better all the time. 1860 ÉTIENNE LENOIR Engines are machines that burn fuel to make things move. The ﬁrst successful engines were all steam engines, which use steam from a boiler to move a piston in a cylinder. In internal combustion engines, the fuel is burned inside the cylinder. This makes them lighter and more efficient than steam engines, so they quickly replaced steam engines in machinery and vehicles. Lenoir’s gas engine In 1860, Belgian engineer Étienne Lenoir built the ﬁrst successful internal combustion engine (right). It was also the ﬁrst to be built in large numbers. Lenoir’s engine mixed gas with air inside the cylinder and was ignited (set alight) with a spark. The gas exploded, thrusting out the piston, which then turned the wheel. Once this ﬂywheel is turning, its weight makes it difficult to stop, helping the engine run smoothly Tiny explosions There are two types of internal combustion engines: those in cars and motorcycles are intermittent, which means that fuel burns in short bursts. Jet planes and rockets have engines in which the fuel burns constantly. Modern engines are more than 100 times as powerful as Lenoir’s engine The driving wheel turns a belt that powers another machine BRIGHT SPARKS In 1823, Samuel Brown patented a two-cylinder, gas-powered internal combustion engine, and in 1825 he used it to drive a vehicle, though it wasn’t very successful. It was too similar to a steam engine to work well. Engine 58 The piston pushes these rods to turn the ﬂywheel The engine evolves TOMORROW’S WORLD Tiny internal combustion engines can be used instead of batteries to produce electricity to power equipment such as computers. (Batteries need to be recharged about ﬁve times as often as these engines need to be refueled.) They are made of steel, but the scientists who made them want to use silicon to build much smaller versions, which will be the size of pinheads. From fuel to fumes Internal combustion engines convert the energy that is contained in fuel into other forms of energy, including motion and heat. They produce pollutants, including gases and tiny particles, during the process. These waste products are called exhaust. This rod connects the governor to an automatic control tap This pipe supplies gas to the engine Gas to liquid Nikolas Otto made an improved version of Lenoir’s gas-fueled engine. Then, in 1885, Daimler modiﬁed it to run on liquid fuel, and used it in the world’s ﬁrst motorcycle. Exhaust fumes leave through this pipe The governor controls the speed of the engine Air intake Over the years, engineers have worked hard to build engines that are reliable, quiet, light, run smoothly, and use fuel efficiently. The cylinder contains the piston Speed machine The Harley-Davidson company has been making motorcycles for more than a century. This one is from 1942—by then, engines were extremely efficient and powerful. Built for sport Today, supersport bikes perform well because they have “high revving” engines, which means their components move very quickly, producing a great deal of power. SEE ALSO Ford Model T 148 · Helicopter 160 · Electric car 172 59 Elevators 60 Walls and ceiling are made of toughened glass that is treated to keep out the Sun’s heat Clever machinery Today’s elevators are comfortable, fast, and safe. Many are connected to computer systems to ensure that they are in the right place at the right time. This is done by keeping elevators close to busy ﬂoors when not in use, and making sure that they stop more often on downward journeys when it’s time for people to leave the building. The first elevators were invented thousands of years ago in ancient Greece. For a long time they were not a very safe way to travel, and it was only after 1852—when Elisha Otis designed and demonstrated one that was equipped with a safety device— that people began to trust them. Without safe elevators, there could be no skyscrapers, and modern cities would look very different. INSIDE SAFETY BRAKE STAGE 2: IF SPEED IS TOO HIGH Arms locked into ratchet Wheel can no longer turn STAGE 1: AT SAFE SPEED Arm Ratchet Arm Four sets of rollers engage with a pair of rails that run up the side of the building Elevators are equipped with very reliable safety systems. If the elevator starts to fall, its cable spins the wheel inside the safety brake faster than usual, and the two arms inside the brake swing outward and interlock with a ratchet. This prevents the wheel from turning, bringing the elevator to a halt. Shock absorber Counterweight balances weight of passenger car Passenger car Computerized controller COOL SCIENCE 1852 ELISHA OTIS SEE ALSO GPS 190 61 One day, it may be possible to travel into space in an elevator! There are already thousands of satellites in orbit around our planet. Some orbit at the same rate that Earth turns, which means that they always remain above the same location. In theory, an elevator could take people up to satellites, as shown in this artist’s impression. TOMORROW’S WORLD Elevators everywhere It’s not just people who use elevators: they are often used for moving goods around, and some multistory parking lots have vehicle elevators, too. Aircraft carriers have huge versions, each large enough to hold two jet planes and able to lift more than 150,000 lb (70,000 kg). Special types of elevators, called stair lifts, can also be ﬁtted into the homes of people who ﬁnd it difficult to walk up stairs. The world’s fastest elevators are in the Burj Khalifa skyscraper in Dubai, United Arab Emirates—they travel at 40 mph (64 km/h) Cool views Occasionally, skyscrapers have external elevators that travel up and down the outside of their walls. This saves space inside the building and gives people amazing views as they travel. As these elevators are exposed to the weather, they have to be ﬁtted with special heating and cooling units. Ventilation, as well as heating and cooling systems, automatically keep conditions comfortable inside the elevator Metal rails provide extra safety Elisha Otis Many cities are dominated by huge and beautiful skyscrapers and famous landmarks. Skyscrapers allow huge cities to be built using only small amounts of land, and they provide safe, sheltered, and comfortable places for people to live and work. But without Elisha Otis’s big idea, we would not have these incredible buildings today. Global safety American inventor Elisha Otis installed his ﬁrst passenger-carrying safety elevator in a New York department store in 1857 and kept improving his invention until his death in 1861. His sons, Charles and Norton, then started the Otis Brothers Company, and by 1873 more than 2,000 Otis elevators had been installed. Their use in famous buildings helped make them popular, and there are now 1.7 million in use all over the world. Elisha Otis In 1853, Otis staged a dramatic demonstration of his safety elevator in an attempt to gain public conﬁdence. He cut the rope of an open elevator. Luckily, his safety system worked and led to the development of high-rise buildings. Eiffel Tower Statue of Liberty Otis elevators were installed in the curved legs of the Eiffel Tower in France. Completed in 1889, it was the world’s tallest structure until 1930. It is still the tallest in Paris and is one of the most recognizable buildings in the world. In 1886, the Statue of Liberty was given to the U.S.A. by the people of France. It has 324 steps, but in the early 1900s an Otis elevator was installed, making going to the top a lot easier! 62 The sky’s the limit What people call a skyscraper has changed over the years. In the 1880s, the Home Insurance Building in Chicago, Illinois, seemed amazingly high, but its 10 stories would not be very impressive today. However, it introduced the building technique that, together with the elevator, is key to skyscraper construction: it was built using a metal “skeleton” of iron and steel to support the weight of the building rather than its external walls. Later skyscrapers used all-steel frames. Burj Khalifa Dubai’s Burj Khalifa (which means “Khalifa Tower” in Arabic) is the tallest structure in the world. Completed in 2010, it is 2,717 ft (828 m) high and has 208 ﬂoors. The building contains 57 Otis elevators. Two of these are double-decked elevators (one cab mounted above the other) that take people to the 124th ﬂoor observation deck. “ A skyscraper is a boast in glass and steel ” Mason Cooley, American author Milan Cathedral Mori Tower For centuries, the highest city buildings were often cathedrals. This one in Milan, Italy, was started in 1386 but not ﬁnished until 1965! In 1997, a new Otis elevator was installed inside one of the 135 spires. Opened in 2003, the Roppong Hills Mori Tower is an important landmark in the Japanese city of Tokyo. People can work, shop, and play under one roof. There are 12 Otis elevators in this 54-storey building, all of which are double-decked elevators. 63 1927 A compressor unit transfers heat from the refrigerator into the room CHRISTIAN STEENSTRUP Many people helped develop the refrigerator, but they only became really useful machines when people could afford to buy them for their homes. The price of the General Electric all-steel model was what made it into a household item. Chilling food slows down the growth of bacteria that cause food poisoning, so food in a refrigerator lasts longer before going bad. It also means that less food is wasted, people suffer fewer health problems, and shopping no longer has to be a daily chore. Controls allow the temperature to be set The icebox is the coldest part of the refrigerator A cheaper chiller Christian Steenstrup worked for the American company General Electric, and designed the ﬁrst affordable refrigerator in 1927. At $525, it was still expensive, but it cost half the price of its competitors. Just three years later, it was by far the most popular refrigerator in the U.S.A. BRIGHT SPARKS Until the mid-1900s, people moved natural ice from cold parts of the world to warmer areas and stored them in underground “ice houses.” Chunks of ice from the ice houses were used to cool “iceboxes,” which were like unpowered refrigerators. Refrigerator 64 GE monitor-top refrigerator, 1927 COOL SCIENCE Put to good use Another advantage of the all-steel refrigerator was that it didn’t have the strong smell of ammonia that some other types had, so it could be kept in the kitchen. Since then, refrigerators have become common items—but they aren’t only used for food storage in homes. They are vital in hospitals to keep medicines cool, and every air-conditioner unit contains one. Refrigerators that can cool to below freezing point are called freezers and are used to store food for even longer. A coolant gas circulates in coils, absorbing heat An expansion valve converts liquid coolant into cold gas The condenser coil releases heat from the coolant The motor drives the compressor Compressor If you blow on wet skin, it feels cold. This is because the liquid water is changing into vapor—and it is using heat energy to do it. Refrigerators work in the same way: inside them liquid changes to gas, cooling the interior. The gas changes back to liquid in pipes outside the unit, releasing warmth into the air. Purple cold areas Green cool areas Seeing heat All objects send out infrared rays, which we can sometimes feel as heat. Although we can’t see these rays, special cameras can detect them and make heat-pictures of things, like the inside of this refrigerator. These heat pictures are called thermograms—in this one, the hottest objects are red and the coldest are purple. It’s important that refrigerators do not have hotspots, where food would go off, or cold spots, where it might be damaged by being frozen. A thermogram of the refrigerator could be used to check for warm or cold spots. The latch ensures that the door closes tightly, so that cool air does not escape The single-door refrigerator was the most popular model, but there were models with two doors—and even some with three doors A thick, insulated door stops the refrigerator from warming up Red warm areas A refrigerator warms the room that it is in, and if you open its door, the room will soon become even warmer Magnetic attraction In the future, refrigerators may be cooled by using magnetism. Some materials contain tiny structures called magnetic domains, which form patterns when a magnetic ﬁeld is present. When the ﬁeld is turned off, the domains become jumbled, which cools the material as part of the jumbling process. The cold material can then be used to cool a refrigerator. SEE ALSO Vaccination 18 · Tin can 30 65 1887 JAMES BLYTH AND CHARLES BRUSH Machines powered by wind have been in existence for thousands of years. Windmills have long been used to grind grain into ﬂour to make bread and to pump water. Yet it was not until 1887 that the wind was ﬁrst used to generate electricity. A Scottish inventor James Blyth used a horizontal windmill to generate enough electricity to light his own house, and, coincidentally, American inventor Charles Brush built a similar machine for his Ohio home. By the 1930s, there were wind-powered generators all over North America, mostly supplying electricity to remote farms. Generating interest James Blyth realized how useful his invention could be and offered to build a machine that would provide enough power to light the streets of his village. His neighbors, however, were not so easily persuaded. They thought electricity was the work of the devil and refused his offer. Eventually, Blyth’s invention was put to good use when wind-powered generators provided an emergency electricity supply for his local hospital. Turbines today Today, electricity-producing wind machines are called wind turbines. Each one produces only a little electrical power, so hundreds are needed to supply as much as a power plant. As a result, they are often built in groups, called arrays or wind farms. As the wind changes direction, the tops of the turbines turn to face the wind. Doubling the length of a wind turbine’s blades produces not just double, but four times as much electricity—so the best wind turbines are large ones The world’s largest wind turbine has a rotor 410 ft (125 m) across Most wind turbines are painted gray to blend in with the color of the sky A ladder allows access to the nose for maintenance COOL SCIENCE Gear wheels Low-speed shaft High-speed shaft Generator Nose Tower Rotor Electric cables from generator The blades of a wind turbine turn only once per second or two. Generators use electromagnets to turn motion into electrical power. They only work well at high turn speeds, so gear wheels are used to “step up” the rotation to around 20 turns per second. Above the waves The wind blows more strongly out at sea, because there are no hills, trees, or buildings to slow it down. So, many wind farms are built offshore, even though this is much more complicated and expensive than building them on land. However, it does mean that people are not bothered by the noise that they make. Wind turbine 66 Good or bad? Wind turbines are often regarded as one of the solutions to the energy crisis: unlike fossil fuels, wind energy will never run out. However, there are ﬁerce disagreements about whether their beneﬁts are worth the problems that they cause. The generator turns the motion of the blades into electricity. The turbine shuts down automatically at very high wind speeds to avoid damage Advantages of wind energy Wind turbines occupy only small areas and can share ﬁelds with crops or cattle. Unlike power plants that burn coal or oil, they make no waste gases, so they are considered a source of “green” energy. The wind turbine’s tower is a huge steel tube, up to 300 ft (90 m) high Disadvantages of wind energy Some people think that wind turbines are ugly and pose a threat to ﬂocks of birds that might ﬂy into them. When turbines are in remote places, it is expensive to transmit the electricity that they make to the people in towns and cities who will use it. SEE ALSO Solar cell 92 · Helicopter 160 67 1821 Electromagnets hug the rotating iron ring in the middle of the machine to intensify the magnetic forces acting on it MICHAEL FARADAY AND ZÉNOBE GRAMME Michael Faraday’s groundbreaking work with magnets and electricity led to simple electricity generators. The discovery by Zénobe Gramme that generators could also be used in reverse as electric motors gave people a new source of power for industry. Before electric motors were available, machines were powered by steam, water, or animals. Today, electric motors are used in a huge number of household items and are essential for industry. Faraday’s motor In 1821, Faraday showed that electricity and magnetism could produce motion when he invented a simple electric motor. Modern motors use electricity and magnetism, too. A motor contains coils of wire wound around pieces of iron. When electricity ﬂows through the coils, they become magnets. These “electromagnets” and other magnets push and pull each other to turn the motor. Two metal arms transfer direct current electricity to the metal barrel The barrel supplies electricity to the wire coils, alternating the direction of the current so that the motor keeps turning TOMORROW’S WORLD Gramme machine Tiny electric motors open up exciting new possibilities. The prototype Proteus motors are just 2½ times the width of a hair and small enough to travel through blood vessels. Surgeons will equip them with cameras so that they can be used to repair damage to the circulatory system. The coils of wire are wrapped around an iron ring that can rotate freely between the electromagnets above and below it Electric motor 68 When electric currents ﬂow through the wire coils, magnetic forces turn the iron ring Two electromagnets connected by a frame provide a north and south pole Reversal of fortune In 1870, Zénobe Gramme built the ﬁrst generator that produced enough power for industry. The Gramme generator, or Gramme machine, produced a smooth, constant current. While he was demonstrating it in 1873, his partner mistakenly hooked two generators together, so that one supplied electricity to the other. To their surprise, the shaft of the second generator turned—it had become an electric motor. The world’s largest electric motor turns a huge fan, which blows wind faster than the speed of sound The rotating iron ring is attached to a steel shaft, which turns as electricity ﬂows through the coils Driving the world Almost every electrical object with moving parts contains a motor, from vibrating cell phones to large industrial machines. Electric motors can be as small or large, as the job demands, and can be started and stopped with the ﬂick of a switch. Alternating current Most large machines in the home have motors that can use alternating current (AC )—a type of current that is supplied to wall outlets and constantly changes direction. In 1883, Nikola Tesla invented another type of AC motor, which is used to operate heavy machinery in factories. As the shaft rotates, it moves any object that it is connected to When the machine is used as a generator, this shaft is turned by an engine and the machine produces electricity Spark of genius Despite being designed to generate electricity, the Gramme machine was a very important discovery in the development of the electric motor. In fact, many motors used today are still based on Gramme’s machine. Direct current motors Batteries supply constant, direct current (DC ), and many battery-powered gadgets, such as electric toys, use DC motors ﬁtted with permanent magnets. We use another type—the stepper motor—in complex electronic equipment like computer disk drives, where movement needs to be precisely controlled. Laptops and other gadgets have adapters that convert AC electricity into a DC power supply to run these motors. SEE ALSO Battery 96 · Steam locomotive 162 69 The father of electricity From luxury gadgets to lifesaving machines, today’s electrical equipment depends on the discoveries made by the genius known as the “Father of Electricity”— Michael Faraday. His groundbreaking inventions include the ﬁrst electric motor and a method of generating electricity that lies at the heart of all power plants. Faraday’s ideas inspired other scientists to explore electricity and magnetism, sparking a golden age of invention that changed the world. Michael Faraday Faraday, an English Chemist, came from a poor family and left school at 13. In the 1800s, it was very difficult for someone like him to become successful. Yet Faraday achieved so much that, in 1858, Prince Albert awarded him a house at Hampton Court Palace, in southern England. Teaching science Faraday loved to share his excitement about science with everyone. In 1825, he began to give entertaining Christmas lectures for young people at the Royal Institution in London, Engand. The lectures continue today and are shown on television. Using electricity In the early 1800s, electricity was a laboratory novelty rather than a practical source of energy. Faraday changed this when, in 1821, he showed that electromagnetic energy could be used to produce motion— creating the ﬁrst electric motor. In 1831, he discovered that electricity begins to ﬂow in a conductor when it is moved between the poles of a magnet. Within weeks, he used this idea to invent the electric transformer and generator. For the ﬁrst time, electricity could be produced without a battery and in much greater amounts. Motor Faraday was inspired by the discovery of electromagnetism—the fact that a current passing through a metal wire produces a magnetic ﬁeld around the wire. His simple motor used this idea. He suspended a wire in a small cup of mercury with a magnet at the bottom (left). When a current was passed through the wire, it swung around the magnet in a circle. This was the ﬁrst time anyone had produced continuous movement from electricity. Transformer Faraday made the ﬁrst transformer by coiling two lengths of wire around an iron ring Transformers turn high voltages into low ones and vice versa. They are used in electrical gadgets, and to change the high-voltage electricity from power plants into safer voltages for our homes. Diary Passing electricity through one coil made an electric current ﬂow brieﬂy in the other coil Faraday researched many other areas of chemistry and physics. In 1822, he wrote in his diary (above) “Convert magnetism into electricity!” However, he was so busy that almost 10 years passed before he tried doing it. Generator Faraday’s generator uses magnets and motion to generate electricity. The copper wheel is turned by hand so that its rim passes between the poles of a permanent magnet. This continually cuts the magnetic force lines, causing an electric current to ﬂow in the copper. The current is led off through a wire and today can power a small lightbulb. 71 1764 JAMES HARGREAVES Moving the bar stretched the yarn The worker spun the wheel with one hand and the bar with the other James Hargreaves never meant to change the world—his invention, the spinning jenny, was simply a machine that made it quicker and cheaper to produce yarn from the ﬂuffy covering of cotton plant seeds. But cheap yarn was bad news for other yarn makers in the area, and they smashed his machine. Hargreaves ﬂed to Nottingham, England, and continued to work on automation, the process of replacing human labor with machines. “Jenny” was the name of Hargreaves’ daughter, who knocked over a spinning wheel and gave Hargreaves his big idea These helped twist together the ﬁbers BRIGHT SPARKS Some of the earliest spinning machines were spinning wheels, and they were probably invented in India. Spinning wheels were used to turn natural ﬁbers, such as wool and cotton, into a thread that could be woven or knitted into a textile. Spinning jenny 72 Cottage industry Before the invention of the spinning jenny and other textile machines, textiles were made at home. This is known as a cottage industry. Spinning was mostly done by women, while weaving—making ﬁnished cloth—was generally seen as men’s work. Yarn was wound around a row of spinning spindles Child labor One of the reasons for the success of the spinning jenny was that it could be operated by a child, unlike spinning wheels, which were more difficult to use. Hargreaves died in 1778, and by then more than 20,000 spinning jennies were in use all over Great Britain. Slow progress The invention of the spinning jenny was part of a slow process of developing textile machines, in which many inventors were involved. These cords attach the wheel to spindles The worker rotated the wheel with this handle Kay’s ﬂying shuttle, 1733 John Kay’s ﬂying shuttle, which was a device for holding thread, speeded up the process of weaving. Machines with these shuttles were faster at making more fabric, of greater width, and with fewer workers. A row of bobbins held the loose cotton ﬁbers in place, ready to be fed through the bars to the spindles Time for change The spinning jenny, and other machines used to make textiles, changed the way in which people lived and worked. Their use sparked the time known as the Industrial Revolution— a period when large factories were set up and people moved from the country to towns. Its effects spread from Europe and throughout the world. Although early spinning jennies had sloping wheels, later models had upright ones, which were more efficient Arkwright’s water frame, 1768 Richard Arkwright’s invention was an important improvement on the spinning jenny. It made stronger cotton threads, and was powered by a water mill. Crompton’s mule, 1779 The next signiﬁcant improvement was Samuel Crompton’s spinning mule; it could make many types of threads quickly and easily. SEE ALSO Robots 74 · Jeans 226 73 1961 GEORGE DEVOL AND JOSEPH ENGELBERGER For centuries, people have been fascinated with the idea of building lifelike machines. Until the 1900s, these were just clever toys, but, in the 1950s, engineers began to work on the idea seriously. Some of them wanted to build a machine that would be a step beyond the highly sophisticated factory machines that were in use at the time. They wanted to build an adaptable, ﬂexible machine that could do a range of tasks, just like a human being can—they wanted to build a robot. Pioneers of robotics Robots had been popular for many years in science-ﬁction magazines and movies when American engineers George Devol and Joseph Engelberger were inspired to change science ﬁction into science fact. In 1954, Devol patented his idea of a “general purpose machine:” a robot that could be programmed to transfer items from place to place in a factory. In 1956, he and Engelberger met, and they formed a company called Unimation Inc. (Unimation is short fo