The Scientific Revolution The Beginnings of STEM

What is Truth? In the Middle Ages, scholars decided truth based on the Bible or from Greek or Roman texts.

The Search for Truth… In the Renaissance, people questioned how the universe worked. This caused the Scientific Revolution.

Until this time, scholars believed in the geocentric theory, that everything in the universe revolved around the earth.

Going In Circles??? This is commonly known as the GEOCENTRIC view where a motionless Earth is at the center of the universe while the moon, sun, planets, and stars revolve around the Earth. Ancient astronomers also believed the Earth was composed of “heavy” elements while the celestial bodies were composed of completely different substances and thus were weightless, allowing them to orbit the Earth.

Going in Circles… While Ptolemy was wrong, a positive consequence of his work was that it allowed stargazers and astrologers to track the planets with greater precision

1. Nicolaus Copernicus 1500’s Polish Astronomy Heliocentric theory – the earth and planets revolve around the sun!

The Copernican Hypothesis In the 16th century, the Polish monk, mathematician, and astronomer Copernicus (1473-1543) challenged the geocentric theory. His famous work On the Revolutions of the Heavenly Spheres, held the sun to be the center of the solar system aka, the HELIOCENTRIC theory. His ideas are attacked by religious authorities; Luther called him “the fool who wants to turn the whole art of astronomy upside down.”

Copernicus’ theory still didn’t explain why the planets orbited the way they did. Fearing ridicule or persecution, Copernicus did not publish his findings until 1543, the year he died.

2. Tycho Brahe (1546-1601) A Danish nobleman who received money from the king of Denmark to build an advanced observatory where he studied the stars and planets; collecting over twenty years of data. He had a very limited understanding of mathematics, but hypothesized a universe that was part Ptolemaic and part Copernican (figure to the left).

3. Johannes Kepler Late 1500’s German Math and astronomy Calculated the orbits of the planets (elliptical)

Johannes Kepler (1571-1630) Brilliant young assistant of Brahe Formulated THREE laws of planetary motion: Orbits of the planets are ELIPTICAL rather than circular Planets do NOT move at a uniform speed in their orbits The time a planet takes to make its orbit is precisely related to its distance from the sun Kepler’s contributions are HUGE; he had mathematically proved the relations of a sun-centered solar system, aka HELIOCENTRIC

4. Galileo Galilei 1609-1642 Italian Scientist & astronomer Invented the telescope

In Italy, Galileo confirmed Copernicus’ heliocentric theory through the use of his telescope.

Galileo (1564-1642) Using a telescope which he refined, he viewed the moon with all of it’s irregularities and stated that the moon is NOT a luminous object but is actually made of earth-like substances. Galileo’s greatest achievement was the elaboration and consolidation of the experimental method; …rather than speculate about what might or should happen, he conducted controlled experiments to find out what actually did happen.

Galileo (1564-1642) Using experiments, Galileo formulated the law of inertia stating that rest is NOT the natural state of objects. Galileo in 1591, according to the story, dropped a 10-pound and a 1-pound weight simultaneously from the top of the Leaning Tower of Pisa. Galileo showed that despite all previous speculation on the subject two bodies of different weights, when allowance was made for differences in air resistance due to differences of size or shape, struck the ground at the same time.

Galileo (1564-1642) Galileo was put on trial and condemned by the Catholic Church because his discoveries contradicted scripture. He was finally absolved by Pope John Paul II in 1992.

The Catholic Church warned Galileo, but in 1632 he published a heliocentric book!

The pope called Galileo to Rome to stand trial… Again.

Under the threat of torture and excommunication, Galileo knelt before the cardinals and read a confession that the heliocentric theory was false.

Galileo was never again a free man, living under house arrest and dying in 1642 in Florence. His books and ideas still spread throughout Europe.

5. Isaac Newton 1687- published book English Physicist Developed the law of gravity & laws of motion

What does an apple have to do with gravity? Ac-cording to George Stukeley, Newton’s biographer and friend, Newton was sitting in the shade of an apple tree when an apple fell nearby. Newton began to wonder why apples always fall to the ground. Why don’t they fall sideways or up? Newton reasoned that the earth must have a power that draws objects to it. That was the beginning of the law of gravity.

Newton established the law of universal gravitation. According to this law, every object in the universe attracts every other object. In 1687, Newton wrote Mathematical Principles of Natural Philosophy, full of his ideas.

6. Robert Boyle 1600’s English Chemist Distinguished elements and compounds

Although Boyle's chief scientific interest was chemistry, he developed a brilliant series of experiments in which he used an air pump to create a vacuum. He also developed what later became known as "Boyle's law" that the volume of a gas varies inversely with pressure. Boyle defined the term element in 1661 as " . . . certain primitive and simple, or perfectly unmingled bodies; which not being made of any other bodies, or of one another, are the ingredients of which all those called perfectly mixt bodies are immediately compounded, and into which they are ultimately resolved."

7. Andreas Vesalius 1500’s Italian Physician He accurately detailed the human body

8. William Harvey 1600’s English Biologist Developed theory of blood circulation (the heart pumps blood through the body) This illustration depicts one of William Harvey's experiments in his On the Circulation of the Blood (1628). Venal valves had already been discovered, but here Harvey shows that venal blood flows only toward the heart. He ligatured an arm to make obvious the veins and their valves, then pressed blood away from the heart and showed that the vein would remain empty because blocked by the valve.

9. Francis Bacon 1600’s English Writer Developed the Scientific Method

Not that bacon! This Bacon! An English writer, Sir. Francis Bacon believed that by better understanding the world, scientists would improve people’s lives. He urged scientists to experiment by observing the world and drawing conclusions. This Bacon!

10. Rene Descartes 1600’s French Scientist Supported idea that human reason should be used to find truth

A French researcher, Rene Descartes relied on mathematics and logic. He believed that everything should be doubted until proved by reason.

“I think therefore I am.” ~Rene Descartes