1. World History Revolutions 5.2.A – Scientific Revolution

2. Scientific Revolution Before the 1500s, Europeans based their ideas about the world on Greek and Roman teachings, and on the Bible and the Catholic Church. The Age of Exploration caused a change in thinking, known as the Scientific Revolution. Explorers discovered new plants and animals in the Americas, not known to the Greeks or Romans, or mentioned in the Bible. People began to ask questions about these new discoveries. Before the Scientific Revolution, beliefs about the world were based mostly on teachings of experts such as Aristotle, the writers of the Bible, or Popes, and on logic and intuition. Scientists also use experts, logic and intuition; but mostly, they base their beliefs on evidence, which is obtained by observation, experimentation, and the testing of hypotheses and theories.

3. Scientific Revolution: Astronomy Old System of Astronomy: Geocentric Theory (Geos = Earth) of Ptolemy New System of Astronomy Heliocentric Theory (Helios = Sun) of Copernicus Proof: 1.Tycho Brahe’s naked eye observations 2.Kepler’s Laws of Motion 3.Galileo’s observations with a telescope 4.Newton’s Laws of Gravity

4. Ptolemy’s Geocentric Theory Ancient Greeks such as Plato and Aristotle believed the earth sat motionless at the center of the universe. Sun, moon, stars and planets circled it. In about 150 AD, a Greek thinker named Ptolemy noticed that the simple geocentric theory of Plato and Aristotle did not correctly explain the observed motions of of Sun, moon and planets. His Ptolemaic System kept Earth at the center, but added additional circles (called epicycles) to adjust for the observed movement of the Sun, moon and planets.

5. Copernicus & Heliocentric Theory In the early 1500s, a Polish churchman, Copernicus, developed a new, Heliocentric (sun-centered) model of the universe. Earth and planets moved around the sun, which was at the center of the universe, in circular orbits. Earth also rotated on its axis every 24 hours. Stars were stationary. Copernicus only published his theory while on his deathbed, for fear of criticism from other scholars, and perhaps from the church.

6. Proof of Copernicus’ Theory (1) A Dutch astronomer, Tycho Brahe, rejected Copernicus’ theory. He meticulously measured the movement of the planets with his naked eye, because telescopes had not yet been invented, and found many errors in Copernicus’ model. German mathematician Johannes Kepler, using Tycho Brahe’s measurements, discovered that the errors in Copernicus’ model could be corrected if the orbits of the planets were egg-shaped (elliptical), not circular. Kepler correctly developed 3 laws to explain the motion of the planets around the sun.

7. Proof of Copernicus’ Theory (2) In 1608, a German optician invented the telescope. A year later in Italy, Galileo built a telescope to observe the Sun, moon and planets. He saw sunspots, craters on the moon, and the rings of Saturn. His discovery of moons orbiting around Jupiter gave observational evidence for Copernicus’ theory. The Catholic Church condemned Galileo’s support for Copernicus and forced him to recant. However, the reasons for his trial were probably more political than scientific. The Pope and many bishops initially supported Copernicus and Galileo, until Galileo insulted the Pope in one of his books by implying that the Pope was a fool.

8. Proof of Copernicus’ Theory (3) In England in the mid-1600s, Isaac Newton developed the theory of gravity. This explained the motion of the Earth, sun, moon, stars and planets. Newton also invented calculus (which was invented simultaneously by Gottfried Leibniz, a German mathematician). Newton improved telescope design, using mirrors instead of a lense. He was first to measure distance of earth to a star other than the sun. And he used prisms to study spectra (rainbow colors and wavelengths) of light.

9. The Scientific Method Francis Bacon in England is credited with developing the scientific method in about 1620 - (1) hypothesis; (2) observation, experimentation; (3) revisions, theory, further testing. Bacon used “inductive reasoning,” starting with observations to arrive at logical conclusions. Inductive reasoning also is known as “bottom-up” reasoning. Rene Descartes, in France in the early 1600s, developed deductive reasoning, which starts with a first principle, then arrives at conclusions based on logic. Descartes’ famous 1 st principle was simply, “I think, therefore I am,” because “I cannot doubt that I am doubting.” Deductive reasoning also is used by scientists and is called “top- down” reasoning. Descartes also is credited with inventing Analytic Geometry and the use of Cartesian coordinates.

10. Next Steps in Science

11. After breakthroughs in astronomy and physics, scientists started to explore the earth and its age (geology), weather (meteorology), the elements (chemistry) and life (biology, botany, zoology). The study of medicine also began to advance. The microscope was invented in about 1590. This led to the discovery in 1675 of cells and bacteria by Anton von Leeuwenhoek. Scientists began to learn about human anatomy, including the circulation of blood. In the late 1700s, Edward Jenner developed the first vaccine, for small pox. Charles Darwin developed the theory of evolution in 1859, after a voyage of exploration around the world in the 1830s about the ship HMS Beagle. Modern genetics began with a Catholic friar, Gregor Mendel, in about 1860. Penicillin, the first antibiotic, was discovered in 1928. DNA was discovered in the 1940s and 1950s.

12. Words to Know Names Plato Aristotle Ptolemy Copernicus Kepler Galileo Isaac Newton Francis Bacon Rene Descartes Anton von Leeuwenhoek Edward Jenner Charles Darwin Gregor Mendel Sources of Knowledge: -Authority -Logic -Intuition -Evidence Terms Heliocentric Theory Geocentric Theory Telescope Microscope Scientific Method Gravity Geology Meteorology Chemistry Biology Genetics Evolution Cell Bacteria Vaccine / small pox Penicillin / antibiotic DNA