User:Michael Hardy/Newton

Isaac Newton (1642–1727) is widely considered by scientists to be the most influential scientist who ever lived. This article will explain his system of basic laws of motion and gravity in non-mathematical terms.

Newton's system was the first that could explain both the behavior of physical objects on Earth and that of objects in the heavens, including planets, moons, and comets. Before Newton, the heavens and the Earth were understood only separately from each other. The laws of physics as identified by Newton are still the content of introductory parts of physics courses and the basis of innumerable practical applications such as those in engineering.

In one sense, Newton's system is considered superseded by that of Albert Einstein. However, the differences between Newton's and Einstein's theories become important only in situations not encountered in most practical applications, and in those commonplace applications Newton's system is used because of its relative simplicity. The differences are important in dealing with nuclear energy whether in nuclear power plants or within the sun. They are also important in astrophysics.

In the course of developing his theory, Newton needed to solve mathematical problems for which the methods known in his time were inadequate. For the purpose of addressing those problems, he developed differential and integral calculus. Some of those problems will be described here, but their solutions will not. (In Germany, Gottfried Wilhelm Leibniz also introduced the methods of calculus at about the same time.)

Newton's cannonball

Ball falling to the floor in an accelerated rocket (left) and on Earth (right)