Enlightenment and Revolution Chapter 6. The Roots of Modern Science.

Enlightenment and Revolution

Chapter 6

The Roots of Modern Science

• In the mid-1500s, attitudes began to change. Scholars started what is called the Scientific Revolution. It was a new way of thinking about the natural world. It was based on careful observation and the willingness to question old beliefs.

A Revolutionary Model of the Universe

• During the Middle Ages, few scholars questioned beliefs that had been long held. Europeans based their ideas on what ancient Greeks and Romans believed or on the Bible. People still thought that the earth was the center of the universe. They believed that the sun, moon, other planets, and stars moved around it.

• The first challenge to accepted thinking in science came in astronomy. In the early 1500s, Nicolaus Copernicus, a Polish astronomer, studied the stars and planets. He developed a heliocentric theory.

• Heliocentric meant sun-centered. It said that earth, like all the other planets, revolved around the sun. And the moon revolved around the earth

Tycho Brahe

• One of the scientists to follow Copernicus’ work was an astronomer named Tycho Brahe. He produced a massive amount of data from recording the movements of the planets.

• After Tycho Brahe passed away in 1601, his work was continued by his assistant, Johannes Kepler. Kepler was a brilliant mathematician. Using Brahe’s data, Kepler determined that there were certain mathematical laws which govern planetary motion.

• One of these laws showed that planets had elliptical orbits around the sun rather than circular. Kepler’s laws mathematically demonstrated that Copernicus’s ideas were true.

• An Italian scientist, Galileo Galilei, made several discoveries that also undercut ancient ideas.

Galileo’s Discoveries

• Galileo discovered the law of the pendulum

• He also found that when you drop two objects, they fall at the same rate of speed.

• In 1610, Galileo published a series of newsletters called the Starry Messenger, which described the observations he had made with his telescope.

• In them, he described the following:– How Jupiter had

four moons– The sun had dark

spots– The moon had an

uneven surface

• His observations of the moon proved Aristotle was wrong as he had hypothesized that the moon and the stars were made of a pure and perfect substance.

• Some of his ideas about the earth, the sun, and the planets went against the teaching of the Catholic Church. Church authorities forced Galileo to take back his statements. Still, his ideas spread.

Galileo upsets the Church

• Both protestant and catholic authorities were troubled by the work of Galileo. They worried that if the Church was wrong about this, that people might question other Church teachings.

• In 1616, the Catholic Church warned Galileo not to defend Copernicus. For years he remained silent, but he continued his work. In 1632, he published Dialogue Concerning the Two Chief World Systems. This book compared the theories of Ptolemy and Copernicus, but it clearly defended Copernicus.

Galileo faces the inquisition

• The pope became furious with Galileo, and summoned him to stand trial and face the Inquisition in Rome. Under the threat of torture, Galileo stood in front of the court and signed a confession which stated that the ideas of Copernicus were not true.

• He escaped torture, but from this point until his death he was forced to live under house arrest.

The Scientific Method

• Interest in science led to a new approach, the scientific method. With this method, scientists ask a question based on something they have seen in the physical world.

• They form a hypothesis, or an attempt to answer the question.

• Then they test the hypothesis by making experiments or checking other facts. Finally, they change the hypothesis if needed

• The English writer Francis Bacon helped create this new approach to knowledge. He said scientists should base their thinking on what they can observe and test.

Newton Explains the Law of Gravity; The Scientific Revolution Spreads

• In the mid-l600s, the English scientist Isaac Newton described the law of gravity. Using mathematics, Newton showed that the same force ruled both the motion of planets and the action of bodies on the earth. In 1687, wrote Mathematical Principals of Natural Philosophies. This is one of the most important scientific books ever written.

Newton felt that the universe was like a giant clock. Its parts all work together perfectly in ways that could be expressed mathematically. He believed God was the creator of this ordered universe, the one who had set everything in motion.

• Other scientists made new tools to study the world around them. Robert Hooke invented a microscope and studied everything he could with it. He wrote about these observations in his book Micrographia .

• Doctors also made advances. Andreas Vesalius made drawings that showed the different parts of the human body.

• In the late 1700s, Edward Jenner first used the process called vaccination to prevent disease. By giving a person the germs from a cattle disease called cowpox, he helped that person avoid getting the more serious human disease of smallpox.

New Scientific Tools

Anton van Leeuwenhoek• In the 1670’s, a Dutch

drapery merchant and moonlight scientist named Anton van Leeuwenhoek (LAY vuhn HUK) used a microscope to observe bacteria and red blood cells.

• He also saw that after studying maggots, and other such organisms, that they did not come to life spontaneously, but that they were in fact immature insects.

Evangelista Torricelli

• Torricelli developed the first mercury barometer, a tool for measuring atmospheric pressure and predicting weather.

Gabriel Fahrenheit

• In 1714, this Dutch physicist made the first thermometer to use mercury in glass.

• This thermometer showed water freezing at 32°.

Anders Celsius

• In 1742, this Swedish astronomer created a mercury thermometer which showed water freezing at 0º.

Discoveries in Chemistry

Robert Boyle

• Pioneered the use of the scientific method in chemistry.

• Considered the founder of modern chemistry.

• In his book The Skeptical Chemist, he challenged Aristotle’s idea that the physical world consisted of four elements – earth, air, fire, and water.

• Proposed that matter was made up of smaller particles that joined together in different ways.

Robert Boyle (cont.)

• His most famous contribution to chemistry is Boyles Law.

• This explains how the volume, temperature, and pressure of gas effect each other.

Joseph Priestly

• Separated one pure gas from air in 1774.

• He noticed that he felt better after breathing this special air.

• “This pure air may become a fashionable luxury.”