This is Shirley Griffith.
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.
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.
his life, Newton said of his work: "If I saw further than other men, it
was because I stood on the shoulders of giants. "
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.
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.
Newton built on the ideas of these two scientists and others. He found and
proved the answers for which they searched.
Isaac Newton was born in
Woolsthorpe, England, on December twenty-fifth, sixteen forty-two.
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.
father died before he was born. His mother married again a few years later. She
left Isaac with his grandmother.
was not a good student. Yet he liked to make things, such as kites and clocks
and simple machines.
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.
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.
Newton became a much better student after a boy kicked him in the stomach.
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.
Newton left school to help on
the family farm.
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
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.
completed his university studies five years later, in sixteen sixty-five. He
was twenty-two years old.
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.
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.
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.
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.
called the force "gravity. " He began to examine it carefully.
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.
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.
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
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.
Newton spent time studying light
and colors. He used a three-sided piece of glass called a prism.
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.
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
years later, Newton built a different kind of telescope. It used a curved
mirror to make faraway objects seem larger.
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.
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?
immediately gave Haley the answer: an egg-shaped path called an ellipse.
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.
Halley said Newton's scientific
discoveries were the greatest ever made. He urged Newton to share them with the
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
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.
in space continue to move, because nothing exists in space to stop them.
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.
third law says that for every action, there is an equal and opposite reaction.
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.
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. "
This Special English program was
written by Marilyn Christiano and Frank Beardsley. This is Shirley Griffith.
And this is Steve Ember. Listen
again next week for another Explorations program on the Voice of America.