Isaac Newton

Isaac Newton

Early Years

The great English scientist Isaac Newton was born in the little village of
Woolthorpe, not far from the old university town of Cambridge, on December
25, 1642. His father, a farmer, died before his son’s birth. Little Isaac
was left to the care of his mother, uncle and grandmother who sent him to
school.

In his early years young Isaac shone more as one who could make things
with his hands than a scholar. His neighbors watched him making various
things and thought ho would probably become a well-known clock maker. There
was ground for thinking thus became he had already made a clock of a kind
which his neighbors had never heard of before. It worked by water. Besides
the water-clock, Isaac also made a sundial. His grandmother was never at a
loss to know the hour; for the water-clock could tell it in the house, and
the sundial outside. It is said that the sundial is still at Woolthorpe, on
a wall of the house where Newton lived.

When he grew older, hhowever, he took a considerable interest in
mathematics.

Though Isaac Newton never lost his manual skill his ability as a
mathematician and a physicist was the most important in his life. According
to Newton himself, his first physical experiment was carried out in 1658,
when he

e was sixteen years old. Wishing to find out the strength of the wind
during a storm, he jumped against and before the wind and by the length of
his jump he could judge the strength of the wind. Thus, even in his boyish
sports, he was searching out the secrets of nature and could find out
difficult things in simple ways. His brain was always busy observing
different phenomena of nature.

[pic] Earth mass

Not far from his grandmother’s home there was a windmill. When the
windmill was not working he examined the mechanism and when the windmill
worked he watched the process of its work. Then he made a model of the
windmill; every part of the mill and its machinery was complete.

If Isaac was left to himself, hee was either making something’s or studying
some book. At night he looked up at the stars, and wondered if they were
worlds like our own, and how great their distance from the earth was. There
were a lot of questions in his mind but nobody was able to answer them.

When Isaac was fourteen years old, his mother took her son from school to
help her on the farm at Woolthorpe, where she lived with three other
children – Isaac’s brother and two sisters. For more t

than two years he
worked on the farm and then his mother sent him back again to school to
prepare for the University.

On June 5, 1551, Newton entered the University of Cambridge where he
studied mathematics. Soon he became famous having made a number of
important contributions to mathematics by the time he was twenty-one.

When Newton was twenty-two years old he began studying the theory of
gravitation. In 1665, while on a visit in his negative village, he saw an
apple fall from a tree and began wondering what force made the apple fall.
Probably this was influenced by his knowledge of Galileo’s experiment from
the Tower of Pisa.

[pic] Moon

The Problem of Gravitation

We know that the moon makes a circle round the earth in about every twenty-
eight days. We know also that our earth and other planets move around the
sun. Does it not seem probable that the earth pulls the moon, and it moves
in its orbit under the influence of the earth’s gravitation? Perhaps also
the sun pulls the earth and the other planets.

It was over such possibilities that young Isaac Newton was thinking in the
solitude of his Lincolnshire home when the Great Plague raged in London and
he, along with other students, was sent home from Cambridge because of this
plague. In that qu

uiet period of almost two years he finished considering
his discoveries which had perhaps the most far-reaching effect in the whole
history of science: the method of fluxions, decomposition of light and the
law of gravitation.

As a young man at Cambridge Newton had read with great interest the
writings of Galileo, he knew the geometry of Descartes, and he had already
partly worked out the methods of calculus, which he called the method of
fluxions. So when he began to think “of gravity extending to the orb of the
moon”, as he wrote, he immediately put this idea to the test of
calculation.

When Newton first began his calculations the available information of the
earth’s radius and of the moon’s distance were not accurate. The relative
distance between the various planets was not accurately known at the time.
Newton did not know whether he could treat the sun and the planets as
though they were points, concentrated at their respective centres through
which he could assume the forces acted so he put his calculations aside and
let the problem wait.

For some years he studied light, in which subject alone his work was
enough to place him in the first ranks among men of science.

Newton performed many experiments with light and found that white light
was made up o
of rays of different colors. He invented the reflecting
telescope, that was very small in diameter, but magnified objects to forty
diameters. Newton developed a mathematical method which is now known as the
Binomial Theorem and also differential and integral calculus.

In 1669 he was appointed professor and began lectures on mathematics and
optics at Cambridge.

Newton’s Theory of gravitation

Some years after Newton had begun to work on the problem of gravitation a
French observer made a new estimate of the earth’s radius, and reported his
results at meeting of the Royal Society. Newton then reviewed his old notes
and examined the information he had. He found that now he was nearer to the
solution of the problem than before, but he did not publish his results, he
was still not satisfied, because his theory was not completely worked out.

However, the time had come to publish his results on gravitation because
the problem was being discussed on all sides. An important work on
centrifugal force by a Dutch scientist Christian Huygens appeared in 1673.
The mathematical difficulties seemed insurmountable, so Huygens, together
with some Fellows of the royal Society approached Newton on the subject. He
was asked what path a body would take if it were attracted by a mass with a
force acting inversely as the square of the distance. And Newton’s
immediate answer was, “an ellipse.”

Newton gathered together all his earlier calculations, and succeeded in
completing his whole theory. First he examined the general problem of the
attraction of one mass by another. He showed that a massive sphere attracts
another as if the whole mass were concentrated at the centre. This was a
result of great importance. It enabled Newton to treat the problems of the
sun, moon and earth like problems of geometry, for the masses of these
bodies could he treated as if concentrated at points. Thus he at last
justified the method of treatment which he had first adopted for the
problem of the earth and moon. The proof of his inverse square law was now
complete. He had demonstrated that the gravitational pull of the earth
extends as far as the moon and keeps it in its orbit. He demonstrated that
this pull is in accordance with the same law as that by which a stone falls
to the ground, namely gravity.

[pic] Newton

Newton then showed that the inverse square law represents not only
Kepler’s third law, but his first two laws as well. Thus he not only
combined the three results of Kepler, but the extended his own theory of
gravitation to the movements of the planets round the sun. the whole
machinery of the solar system was thus brought under the sway of one law,
which states that every particle attracts very other particle with a force
which changes inversely as the square of the distance between them. This
statement is part of Newton’s law of gravitation, which, together with all
his other theories, was given to the world in his great work Elements of
Natural Philosophy published in 1687.

It is interesting to mote that Newton did not want to publish his book. He
locked it in his desk and decided to keep it there forever.

However, other scientists began to take interest in the subject of
gravitation. Astronomers, physicists and others talked about it at
conferences in London. Wren, the famous architect, offered a prize to any
scientists who could prove why the path of a planet must be an ellipse. But
nobody could solve the problem. Newton said he had already got the answer,
and promised to send his manuscript some time later. Halley received the
manuscript in the autumn of the same year but Newton’s great work, Elements
of Natural Philosophy, was published only in the middle of 1687. With this
book, a new period in the development of science began.

Newton’s law of inverse squares thus joined in one simple mathematical
statement the behavior of the planets as well as of bodies on this earth.
It was the first synthesis of physical knowledge. As such his contribution
to science is unique.

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