A History of the World: Chapter 22: The Scientific Revolution and the Enlightenment

A theory is an explanation for how or why something happens. Theories are based on what people can observe about a thing or event.

For instance, during Roman times, the Egyptian-born astronomer Ptolemy stated that the sun and the planets moved around the Earth. His geocentric, or Earth-centered, theory was accepted in Europe for more than 1,400 years.

Gradually, scientific knowledge expanded in Europe.

Copernicus developed a heliocentric, or sun-centered, theory of the universe. Copernicus believed that the sun was the center of the universe. Earth and the other planets followed a circular path around the sun.

Kepler added the idea that the planets move in oval paths called ellipses instead of the circular paths in Copernicus's theory.

The apple's fall led him to the idea of gravity. Gravity is the pull of the Earth (or other bodies in space) on objects that are on or near the planet.

In the mid-1600s, the Irish scientist Robert Boyle proved that all matter is made up of elements. Elements are basic materials that cannot be broken down into simpler parts.

Descartes is viewed as the founder of modern rationalism. This is the belief that reason is the main source of knowledge.

He believed that unproven ideas from earlier generations should be put aside.

The scientific method consists of several steps. First, scientists observe facts. Then, they try to find a hypothesis, or an explanation of the facts. Scientists conduct experiments to test the hypothesis. These tests are done under all types of conditions. Repeated experiments may show that the hypothesis is true.

However, in the 1700s, many educated Europeans began to break away from tradition. They viewed reason as a "light" that uncovered error and showed the path to truth. As a result, the 1700s became known as the Age of Enlightenment.

In this work, Hobbes argued that natural law made absolute monarchy the best form of government. According to Hobbes, humans were naturally violent and selfish. They could not be trusted to make wise decisions on their own.

This political theory of Hobbes became known as absolutism, since it supported a ruler with absolute, or total, power.

The Glorious Revolution eventually turned England into a constitutional monarchy. This is a form of government in which written laws limit the powers of the monarch.

The Bill of Rights also guaranteed all English people basic rights.

Peter also improved Russia's military and created a navy.