Chapter 22 – Scientific Revolution

•A new way of thinking about the natural world based upon careful observation and a willingness to question accepted

beliefs

• During the Middle Ages & the Renaissance, scholars not only translated Muslim works, but uncovered many classical manuscripts.

• Navigation & astronomy which were necessary to help with exploration were certainly the beginning, but scholars began to discover that not everything they believed was true.

• Nicolaus Copernicus, 1473 – 1543, a Polish astronomer, became interested in ancient Greek ideas that the sun, not the earth, stood at the center of the universe.

• After 25 years he came up with the concept called the heliocentric theory.

• It really didn’t answer the question about why planets orbited the way they did

• It also contradicted the church’s position that the earth was the center and all revolved around it. Knowing how this might be damaging to himself he didn’t come out

publicly until the year before he died.

• German mathematician Johannes Kepler was able to use data compiled by his boss, Tycho Brahe, and show that the planets revolved around the sun elliptically, not in circles.

• Galileo Galilei, 1564 – 1642, contradicted Aristotle’s theories of the pendulum and rate of falling objects

• He created his own telescope and was able to proclaim that Jupiter had 4 moons, that the sun had dark spots, that the moon had an uneven surface and disproved Aristotle’s concept that the moon and stars were made out of pure, perfect substance

Galileo facing the Roman Inquisition

• If the church was wrong about the earth and sun, then people may doubt other church teachings

• He was warned in 1616 not to support Copernicus’ ideas, but in 1632 he published a book that supported Copernicus & Ptolemy

• Even though he signed a confession that Copernicus’ ideas were false he was put under house arrest where he died in 1642

• Scientific Method – a logical procedure for gathering and testing ideas

• Helping to advance the scientific method approach was Francis Bacon, English politician and writer. Criticizing Aristotle and other ancients, he supported experimentation vs. abstract theories

Like Bacon, Rene Descartes believed

that scientists needed to reject old assumptions

and teachings. But instead of

experimentation, he supported use of mathematics

and logic. Descartes developed analytical

geometry (a linking of

geometry and algebra.

Descartes famous line, “I think, therefore I

am”, means that thought cannot be

separated from me, therefore, I exist. He

discards perception as unreliable and instead

admitting only deduction as a method.

• Another Englishman disproved another of Aristotle’s ideas that there was one set of physical laws governing earth and another for the rest of the universe. His name was Isaac Newton

• His laws of gravity would not be improved upon for over 200 years. He is considered the greatest figure in the history of Science.

Janssen’s 1st microscope

• Microscope used by Anton van Leeuwenhoek in 1670s (its about the size of a postage stamp, now missing its lens) to view bacteria swimming in tooth scrapings

Scientific Instruments

o Italian Evangelista Torricelli (1643) – 1st mercury barometer, a tool for measuring atmospheric pressure and predicting weather

o Dutch physicist Gabriel Fahrenheit (1714) made the 1st thermometer to use mercury in glass. Water freezes at 32º

o Swedish astronomer Anders Celsius creates another mercury thermometer . Water freezes at 0º

Medicine & the Human Body

• Flemish Physician Andreas Vesalius (1514 – 1564) dissected human corpses (this is actual picture from his book). Vesalius refuted Galen’s previous assumptions that the human body was similar to pigs and other animals.

• William Harvey, an English doctor, published in 1628 a book that showed that the heart acted as a pump to circulate blood and described the function of blood vessels. Was the 1st to apply scientific method to biology.

• In the late 1790’s, British physician Edward Jenner introduced vaccine to prevent smallpox. He discovered that inoculation from a milder disease, cowpox, would inoculate the patient. Smallpox was a leading cause of death in the 18th century, respecting no social class, it left many of the patients who recovered disfigured.

• Robert Boyle – Irish - scientific method in chemistry & considered the founder of modern chemistry.

• Englishman Joseph Priestley, in 1774 he separated pure gas from air. Not only that, but he:

• Was a pastor of a Calvinist church

• Was a lifelong friend of Benjamin Franklin

• Discovered graphite can conduct electricity - 1767• Mixing heavy gas with water, he created soda water - 1772• Created nitrous oxide (laughing gas) – 1772

Chemistry

• Documented the process of photosynthesis – 1774• He also isolated and described the properties of

ammonia, sulphur dioxide, hydrogen sulphide, oxygen gas, and carbon monoxide for the first time.

• Priestley discovered that India gum could  be used to rub out lead pencil marks.  Yes, he had invented the eraser and gave the material its common name - rubber.

• Openly supported American & French Revolutions. His home & church were burned to the ground & he and his

family fled to America