Isaac Newton: One of the World’s Greatest Scientists
01 October 2008
VOICE ONE:
This is Shirley Griffith.
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And this is Steve Ember with the VOA Special English program, Explorations. Today we tell about one of the world’s greatest scientists, Isaac Newton.
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| Isaac Newton |
Much of today’s science of physics is based on Newton’s discovery of the three laws of motion and his theory of gravity. Newton also developed one of the most powerful tools of mathematics. It is the method we call calculus.
Late in his life, Newton said of his work: “If I saw further than other men, it was because I stood on the shoulders of giants. ”
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One of those giants was the great Italian scientist, Galileo. Galileo died the same year Newton was born. Another of the giants was the Polish scientist Nicholas Copernicus. He lived a hundred years before Newton.
Copernicus had begun a scientific revolution. It led to a completely new understanding of how the universe worked. Galileo continued and expanded the work of Copernicus.
Isaac Newton built on the ideas of these two scientists and others. He found and proved the answers for which they searched.
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Isaac Newton was born in Woolsthorpe, England, on December twenty-fifth, sixteen forty-two.
He was born early. He was a small baby and very weak. No one expected him to survive. But he surprised everyone. He had one of the most powerful minds in history. And he lived until he was eighty-four.
Newton’s father died before he was born. His mother married again a few years later. She left Isaac with his grandmother.
The boy was not a good student. Yet he liked to make things, such as kites and clocks and simple machines.
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Newton also enjoyed finding new ways to answer questions or solve problems. As a boy, for example, he decided to find a way to measure the speed of the wind.
On a windy day, he measured how far he could jump with the wind at his back. Then he measured how far he could jump with the wind in his face. From the difference between the two jumps, he made his own measure of the strength of the wind.
Strangely, Newton became a much better student after a boy kicked him in the stomach.
The boy was one of the best students in the school. Newton decided to get even by getting higher marks than the boy who kicked him. In a short time, Newton became the top student at the school.
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Newton left school to help on the family farm.
It soon became clear, however, that the boy was not a good farmer. He spent his time solving mathematical problems, instead of taking care of the crops. He spent hours visiting a bookstore in town, instead of selling his vegetables in the market.
An uncle decided that Newton would do better as a student than as a farmer. So he helped the young man enter Cambridge University to study mathematics.
Newton completed his university studies five years later, in sixteen sixty-five. He was twenty-two years old.
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At that time, a deadly plague was spreading across England. To escape the disease, Newton returned to the family farm. He did more thinking than farming. In doing so, he found the answers to some of the greatest mysteries of science.
Newton used his great skill in mathematics to form a better understanding of the world and the universe. He used methods he had learned as a boy in making things. He experimented. Then he studied the results and used what he had learned to design new experiments.
Newton’s work led him to create a new method in mathematics for measuring areas curved in shape. He also used it to find how much material was contained in solid objects. The method he created became known as integral calculus.
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One day, sitting in the garden, Newton watched an apple fall from a tree. He began to wonder if the same force that pulled the apple down also kept the moon circling the Earth. Newton believed it was. And he believed it could be measured.
He called the force “gravity. ” He began to examine it carefully.
He decided that the strength of the force keeping a planet in orbit around the sun depended on two things. One was the amount of mass in the planet and the sun. The other was how far apart they were.
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Newton was able to find the exact relationship between distance and gravity. He multiplied the mass of one space object by the mass of the other. Then he divided that number by the square of their distance apart. The result was the strength of the gravity force that tied them to each other.
Newton proved his idea by measuring how much gravity force would be needed to keep the moon orbiting the Earth. Then he measured the mass of the Earth and the moon, and the distance between them. He found that his measurement of the gravity force produced was not the same as the force needed. But the numbers were close.
Newton did not tell anyone about his discovery. He put it aside to work on other ideas. Later, with correct measurements of the size of the Earth, he found that the numbers were exactly the same.
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Newton spent time studying light and colors. He used a three-sided piece of glass called a prism.
He sent a beam of sunlight through the prism. It fell on a white surface. The prism separated the beam of sunlight into the colors of a rainbow. Newton believed that all these colors — mixed together in light — produced the color white. He proved this by letting the beam of rainbow-colored light pass through another prism. This changed the colored light back to white light.
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| Newton’s telescope used a mirror instead of a lens |
Newton’s study of light led him to learn why faraway objects seen through a telescope do not seem sharp and clear. The curved glass lenses at each end of the telescope acted like prisms. They produced a circle of colored light around an object. This created an unclear picture.
A few years later, Newton built a different kind of telescope. It used a curved mirror to make faraway objects seem larger.
Light reflected from the surface of the mirror, instead of passing through a curved glass lens. Newton’s reflecting telescope produced much clearer pictures than the old kind of telescope.
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Years later, the British astronomer Edmund Halley visited Newton. He said he wanted Newton’s help in finding an answer to a problem no one had been able to solve. The question was this: What is the path of a planet going around the sun?
Newton immediately gave Haley the answer: an egg-shaped path called an ellipse.
Halley was surprised. He asked for Newton’s proof. Newton no longer had the papers from his earlier work. He was able to recreate them, however. He showed them to Halley. He also showed Halley all his other scientific work.
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Halley said Newton’s scientific discoveries were the greatest ever made. He urged Newton to share them with the world.
Newton began to write a book that explained what he had done. It was published in sixteen eighty-seven. Newton called his book “The Mathematical Principles of Natural Philosophy.” The book is considered the greatest scientific work ever written.
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In his book, Newton explains the three natural laws of motion. The first law is that an object not moving remains still. And one that is moving continues to move at an unchanging speed, so long as no outside force influences it.
Objects in space continue to move, because nothing exists in space to stop them.
Newton’s second law of motion describes force. It says force equals the mass of an object, multiplied by the change in speed it produces in an object.
His third law says that for every action, there is an equal and opposite reaction.
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From these three laws, Newton was able to show how the universe worked. He proved it with easily understood mathematics. Scientists everywhere accepted Newton’s ideas.
The leading English poet of Newton’s time, Alexander Pope, honored the scientist with these words: “Nature and nature’s laws lay hid in night. God said, –’Let Newton be!’ – and all was light. ”
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This Special English program was written by Marilyn Christiano and Frank Beardsley. This is Shirley Griffith.
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And this is Steve Ember. Listen again next week for another Explorations program on the Voice of America.
Progress Seen Toward Making Objects Invisible
29 September 2008
VOICE ONE:
This is SCIENCE IN THE NEWS in VOA Special English. I’m Bob Doughty.
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And I’m Barbara Klein. This week, we will tell about evidence that some people can be both fat and healthy. We will also tell about brain aneurysms — a rare but deadly disorder. And, we will tell about materials that could help make objects seem to disappear.
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Two studies are suggesting that some overweight people do not always face an increased risk of developing heart disease. Researchers also found that some normal body weight individuals have an increased risk of the disease.
Being overweight does increase your risk of medical problems. But the studies found that not all heavy people are less healthy than thin people.
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In one study, American researchers examined medical records from more than five thousand men and women. Each person had taken part in a separate study from nineteen ninety-nine to two thousand four.
The researchers found that about fifty-one percent of the subjects were overweight or obese. About thirty-two percent were obese, but considered metabolically healthy. This means they had no evidence of problems in tests for high blood pressure or other measures linked to heart disease.
However, more than twenty-three percent of people who were at a healthy weight had two or more unhealthy measurements in the tests.
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Judith Wylie-Rosett helped supervise the American study. She is a professor at the Albert Einstein College of Medicine at Yeshiva University in New York. Professor Wylie-Rosett says the findings show that an obese person can still be healthy. She believes that having body fat is not as important to health as where the fat is found on body.
America’s Centers for Disease Control and Prevention notes that two-thirds of Americans are considered overweight or obese.
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A second study is suggesting that fat in the liver may be important to health risks. Norbert Stefan and his team work at Germany’s University of Tubingen. They closely examined three hundred fourteen people. They measured how much body fat each person had, and where it was on the body. To do this, they used medical imaging tests. They too discovered that obese people could have healthy hearts. Their results suggest that fat in the liver is more dangerous than fat in other areas.
The results of both studies were published recently in the Archives of Internal Medicine.
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Professor Wylie-Rosett says the findings do not mean that people should not be concerned about becoming obese. Experts say there are several diseases linked to obesity that make it more dangerous to be fat than thin. They say that people should see their doctor to learn what health risks they may be facing and what behaviors should be changed to improve health.
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We often hear the term brain aneurysm. Joseph Biden had two brain aneurysms twenty years ago. Doctors saved his life. Recently, the senator from Delaware was named the vice presidential choice of the Democratic Party.
Ohio’s first black congresswoman was not so lucky, however. Representative Stephanie Tubbs Jones died last month within hours after a brain aneurysm burst. Doctors said she may have had no warning.
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A brain aneurysm is a weak or thin area along an artery wall in the brain. It can become so thin that it ruptures and bleeds.
The most common form looks like a small, round berry hanging from the artery. The Mayo Clinic in Minnesota says as many as fifteen million people in the United States, or five percent, have a berry aneurysm. Fewer than thirty thousand will ever suffer a rupture.
The National Institute of Neurological Disorders and Stroke says forty percent of victims die within twenty-four hours. Another twenty-five percent die within six months.
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People may live a long and healthy life and never know they have an aneurysm. But sometimes, if it gets big enough, it can cause pain or other problems that lead to its discovery.
In Senator Biden’s case, his neck hurt for several weeks. Doctors thought he had a pinched nerve and a virus. But in February of nineteen eighty-eight, tests showed a leaking artery at the base of his brain. Doctors operated successfully, and again three months later for an aneurysm in another area.
Experts say most brain aneurysms happen in people born with an abnormality in an artery wall. Other causes can include head injuries, high blood pressure, infections, tobacco use and use of stimulant drugs.
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For years, scientists have dreamed of someday guiding or directing light in unusual ways. If they could, objects might seem to disappear. The objects would be invisible — hidden from sight.
Now, scientists in the United States have produced materials that may help to make invisibility possible. Researchers at the University of California in Berkeley performed the experiments. Their study took steps toward “cloaking”, or appearing to hide, objects.
The Lawrence Berkeley National Laboratory also took part in the experiments. Support for the work came from America’s National Science Foundation and the United States military.
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Before now, invisibility experiments succeeded in guiding light around only very thin objects of two dimensions. Such objects had length and width, but no depth. The new study marks the first time experiments have been successfully done in three dimensions using visible light, or light that can be seen.
We normally see objects because light strikes them. Then our eyes receive some of the light from the objects. To make an object seem to disappear, it is necessary to direct the light so it hides the object.
The California researchers successfully did this by using materials called metamaterials. Metamaterials are small almost beyond human imagination. They are made with a process called nanoengineering.
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It was thought that directing light with natural materials was not possible. But with nanoengineered materials, the researchers were able to build a special prism. Normally, a prism has many flat surfaces. It divides white light into colors. A nanoengineered prism does the opposite. It creates white light from colors.
Results of the experiment were reported in “Science” magazine. Results with the other metamaterial appeared in the publication “Nature.” University of California Professor Xiang Xhang led the research teams that developed both materials. They contained substances including metals, earthenware and fiber.
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The researchers designed one metamaterial like a net used to trap fish. It was made of silver nanowires. Each wire was about ten thousand times thinner than a human hair. The other metamaterial used twenty-one grids of silver and magnesium fluoride. The box-like grids formed lines. They were also unimaginably small.
Two years ago, two other researchers also reported on invisibility experiments. But they used microwaves instead of visible light. The two men were David Smith of Duke University in the United States and John Pendry of Imperial College in London.
Last year, scientists at America’s Purdue University reported success in guiding light around objects placed in a design. The design employs small needles called – you guessed it – nanoneedles. Mister Pendry, Mister Smith and David Schurig developed some of the required mathematics for that research. At the same time, so did Ulf Leonhardt of the University of Saint Andrews in Scotland.
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All this recent interest in invisibility is not surprising. People have been talking about making things invisible for thousands of years. In Plato’s “Republic”, there is an invisible ring. In the last century, “The Shadow” was a popular radio program. It told of a man who could become invisible. That meant he could defeat all evil.
More recently, the British secret agent of many films, James Bond, had an invisible car. And Harry Potter, hero of many books and films, sometimes had a magic cloak. He was able to protect himself by wearing it.
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This SCIENCE IN THE NEWS program was written by Jerilyn Watson, Caty Weaver and Brianna Blake, who also was our producer. I’m Barbara Klein.
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And I’m Bob Doughty. We would like to hear from you. You can read and listen to our programs at voaspecialenglish.com. Join us again next week for more news about science in Special English on the Voice of America.
‘Catch Shares’: A Better Way to Share the World’s Fish?
29 September 2008
This is the VOA Special English Agriculture Report.
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Too much fishing has reduced many fishery populations by ninety percent or more from their highest recorded numbers. Some fishing seasons last only a few days because the catch limit is quickly reached.
Two years ago, a Canadian scientist, Boris Worm, predicted the risk of a worldwide fishery collapse by two thousand forty-eight. But a new study says a management system called “catch shares” could offer a solution.
It divides the total permitted catch in a fishery into shares. These are bought and sold like shares of stock in a company. Shareholders in the fishery are each guaranteed a percentage of the catch.
Catch share systems are common in Australia, New Zealand and Iceland. And they have been gaining popularity in the United States and Canada.
Systems differ from place to place. But in general, experts set yearly limits, or quotas, on a fishery. The number of fish that each company or individual may catch is usually based on past averages.
Shares become more valuable as fish populations increase. With more fish in the fishery, catch limits also increase.
Human nature would tell us that shareholders are more likely to think about the long-term health of the fishery. They have a greater interest to protect the supply than in traditional, open access fisheries. But does that really happen?
Researchers looked at more than fifty years of records from eleven thousand fisheries worldwide. They compared open access fisheries with one hundred twenty-one fisheries that use catch share systems.
The study found that almost a third of the traditional fisheries have collapsed. But the number was only half that for the catch share fisheries. The findings appeared this month in the journal Science.
Researchers from the University of California, Santa Barbara, and the University of Hawaii did the study. The economist who led the research, Christopher Costello at Santa Barbara, called the results very hopeful. He says the system can improve the world’s fishing grounds and rebuild collapsed fisheries.
Still, not everyone likes the idea. Some environmental activists say the catch share system makes a public resource into a private enterprise. Generally speaking, anybody can work a traditional fishery. There is no need to organize into a group or company. Yet if scientists’ warnings are correct, those fisheries may not have many fish left to catch by the middle of the century.
And that’s the VOA Special English Agriculture Report, written by Jerilyn Watson. I’m Bob Doughty.
