The Scientific Revolution pg. 356

Why look up at the stars? Once seen as omens and used for fortune telling Help us see our place in the universe We are explorers Help us to understand religion

The Starting Point Our knowledge of the universe begins with the ancient Greeks. Some thought the sun was in the center of everything. This is called a heliocentric theory. Most thought the earth was in the center of everything. This is called a geocentric theory.

Ptolemy (c CE) Claudius Ptolemaeus Furthered the work of Aristotle who argued for a geocentric universe. Earth stands still and everything else rests in concentric spheres around the earth.

Ptolemaic System Geocentric Believed for about 1500 years. Works mathematically with some difficulty

The New Astronomers Could make a living because of the belief in the importance of astrology. Nobles would have royal astronomers who charted the skies while on the noble’s payroll. Charting the skies was important in navigation, so mercantilist governments funded astronomers.

Nicolaus Copernicus ( ) Polish astronomer educated in Cracow and Italy Questioned the difficult math of the geocentric theory Published On the Revolutions of the Heavenly Spheres in 1543

Heliocentric Theory Copernicus stated the SUN was in the middle of the universe. Used reason and math, no telescope as of yet.

Importance of Copernicus Opened the door for others to take his theory further. Showed the importance of questioning the accepted theories. His theories were nearly as difficult to work out as Ptolemy however.

Tycho Brahe ( ) Son of a wealthy Danish noble (Denmark). Built the greatest observatory in the world. Astronomer to the Holy Roman Emperor.

Brahe’s Importance He believed in a modified version of the geocentric theory. His observational data was used by Kepler and others to develop later theories.

Johannes Kepler ( ) German astronomer who assisted Brahe. Was a Copernican theorist who used Brahe’s data. Published Astronomia Nova (New Astronomy) in 1609.

Kepler’s Laws of Planetary Motion Planets travel in ellipses around the sun, not circles as everyone had always thought. The closer the planet is to the sun, the faster the planet moves. You can calculate this in a mathematical formula. The time it takes a planet to travel around the sun is proportional to the distance it is from the sun in the same way for all the planets.

Galileo Galilei ( ) Italian astronomer. Used a telescope he improved from Dutch designs. His telescope saw 10x power and that was pretty good.

Importance of Galileo Felt the universe was based on mathematic natural laws. Everything was quantitative. Was very public in his support of Copernicus and Kepler. Made important contributions to the nature of motion.

Isaac Newton ( ) One of the most influential thinkers of all time. Studied in England. Developed calculus. Published Principia Matematica in 1687.

The Theory of Gravity Newton speculated that every mass attracted every other mass in the universe. The larger the mass, the greater the attraction. Created mathematical equations that explained the theories of Kepler and of Galileo.

Newton’s Theories Described a mechanistic universe. Would be considered untouchable until Einstein in the 20 th century. Helped land men on the moon and are still used today. Influenced science, philosophy, math, and religion.

The End