Unit 4.2: Scientific Revolution

Topic 4.2 Explain how understanding of the natural world developed and changed during the Scientific Revolution and Enlightenment.

• A Scientific Revolution: Renaissance humanism and art laid the groundwork for new ideas in science to emerge in the 16th and 17th C.

Observation Based Science: This approach emphasizes the importance of empirical evidence and experimentation, leading to significant advancements in fields such as astronomy, biology, and physics.

• Reading a broader range of classical texts (Renaissance), provided a source of ideas that challenged the existing worldview. 

• Artists’ close observations of the natural world and use of math to develop techniques, such as perspective, established new ways to learn about the world.

• Later thinkers expanded use of experimentation that Da Vinci and others developed in late 15th C.

• These new methods for studying the natural world were the core of the Scientific Revolution

• Astronomy: Comes from Ancient Greek meaning “arrangement of the stars”, General term for the study of the universe beyond the earth

• COSMOLOGY -Branch of Astronomy concerned with the origins and structure of the universe

Medieval Worldview

• Ptolemy (2nd c. AD)  Greco-Egyptian mathematician & astronomer

• Aristotle (4th c. BC) Greek philosopher and scientist – authority on Physics

• Classical cosmology went unchallenged for 1,400 years

• This formed basis of medieval scholastic philosophers.

• Portrayed a Geocentric Universe—one with earth at the center of a system of concentric spheres, including the sun, circling around it. 

• Planets were bodies of light.

• Christian beliefs taught that God and the souls of those who had been saved existed beyond the outermost sphere of the

Nicolaus Copernicus (1473- 1543)

• Among the first Europeans to challenge the classical view. 

• Polish mathematician and natural philosopher—a scholar who studied the physical world. 

• Found references to ancient Greeks who questioned the geocentric views of Aristotle and Ptolemy. 

• Believed in a Heliocentric, or sun- centered universe.

• Using advanced mathematics, he proved that the perceived motion of the sun came from the earth’s spinning on its axis and its annual orbit around the sun

• Published On the Revolution of the Heavenly Spheres before death

Johannes Kepler (1571-1630

• Assistant to Danish astronomer Tycho Brahe 

• German astronomer who built on Copernicus’s work 

• Analyzed precise measurements of planetary orbits around sun and found them to be elliptical rather than circular

• By demonstrating these orbits Kepler further supported Copernicus’s heliocentric model and disputed the religious belief that the circle was the “perfect shape” and reflected the Divine order 

• Kepler shares his published work with Italian mathematician Galileo Galilei in 1597

Galileo Galilei: Italian Astronomer and Physicist (1564-1642)

• First European to build and use a telescope for the purpose of observing planets. 

• Discovered details never known such as the moons that circled Jupiter, and craters on the moon. 

• He showed that planets were not ethereal bodies but similar to Earth in their composition.

• This reaffirmed the heliocentric system and wide attention to these new ideas.

• Galileo’s improved Refracting Telescope allowed him to see things in space that others had not been able to see

• Galileo’s Telescopic Observations: The moon’s surface was not smooth as was traditionally believed, with mountains and craters

• Galileo discovered four moons orbiting Jupiter, proving that objects orbited planets other than earth.

Heliocentrism Debate

• Ptolemy (Roman) Egypt: GEOcentric Theory

• Copernicus 16th c. Poland: HELIOcentric Theory

• Galileo 17th c. Italy: CONFIRMED Heliocentric Theory

• Empiricism: Francis Bacon

Isaac Newton

• The Church’s condemnation of Galileo diminished the growth of science in Italy. •

• As Galileo dies in 1642, the English mathematician, Isaac Newton is born the same year and will bring together the ideas of Copernicus, Kepler and Galileo. 

• Newton is credited with discovery of the Universal Law of Gravitation and published his proofs for this law in Principia (1687).

• Newton Demonstrated that gravity applied to objects on earth and in space and was the force that held the planets in orbit around the sun

• Newton saw the universe as a giant machine with God as the prime mover who set the planets in motion.

• Newton’s ideas were accepted rather quickly in England, but they took a century before they were generally accepted on the European continent, due to skepticism. 

• Many in science community felt it sounded too much like mysticism (invisible force of gravity).

• Such rapid change from 1,400 years of beliefs shook foundation of knowledge. 

Anatomy and Physiology

• Medicine of medieval times was dominated from ideas from ancient Greece.

• Greek physician Galen (2nd C. BC) dominates field of anatomy and physiology.

• Anatomy – structure of the bodies of humans, animals, and plants.

• Physiology – refers to how those systems function

Galen’s Theories

• Galen dissected animals rather than humans, so his ideas of human anatomy were often incorrect.  Thought there were two different systems of blood flowing through the arteries and veins.

• Humoral Theory – body composed of four humors, blood, yellow bile, phlegm, and black bile.

• According to Galen disease was caused by an imbalance of the humors.

Challenges To Galen’s Ideas

• Three physicians most notably challenged Galen’s theories. 

• Paracelsus (N. Renaissance, 1520s) used observation and experiments to develop a theory based on chemical imbalances in organs rather than humoral, that could be treated with chemicals. 

• Andreas Vesalius publishes On the Structure of the Human Body (1543 ), 200 drawings of human anatomy disproving Galen’s anatomy.

• William Harvey corrected Galen’s ideas on the circulatory system with his On the Movement of the Heart and Blood, 1628.

• Demonstrated that the heart was the starting point of a single system of blood that completes circuit through the body’s arteries and veins and established that blood is pumped from the heart, rather than being consumed by organs as previously believed.

Francis Bacon

• Inductive Reasoning (empiricism) – moves from the specific to the general.

• Scholars should combine careful observation and systematic experimentation to collect small bits of information (data).

• Use the information to support valid general conclusions. Find truth at the end. Inductive can also be false in the end. “Harold is a grandfather. Harold is bald. Therefore, all grandfathers are bald.”

• The conclusion is not logical.

Renee Descartes

• Deductive Reasoning (rationalism) – moves from the general to the specific

• “I think, therefore I am.” Essential truth.

• Start with general principles and then apply them using strict logic to understand particular cases. “All men are mortal. Harold is a man. Therefore, Harold is mortal.”

• Though both reasoning’s had flaws, Newton was able to combine both and create Natural Laws, or general principles about the way the world worked

Science Through the Years

• Medieval science: Goal was To demonstrate the truth of traditional Christian beliefs, Most philosophers were clergy members, Relied on Aristotle, Ptolemy and Galen and logical analysis, Judged by Catholic church

• Post Renaissance Science: Goal was to understand natural world, most philosophers were secular, Drew on a broad range of classical sources, Combined observation and experiments with logic and mathematical calculations Science and religion were separate paths of inquiry

Alchemy and Astrology

• Alchemy – medieval and Renaissance approach to chemistry focused on discovering a method to turn common metals into gold.

• Astrology – during Renaissance came to mean the study of the heavenly bodies as they influenced human activity.

• Elites and natural philosophers were intrigued by both.

• Kepler studied astrology and was interested in the ideas of a sacred geometry in the universe. Newton wrote extensively about his alchemy experimentations.

• These views persisted because they supported the idea that humans could understand the universe and make predictions about it

Spain and New Discoveries

• Spain sought to profit early on from its New World holdings.

• Spanish crown sponsored many scientific expedition to gather specimens, expanding the fields of botany, zoology, cartography and metallurgy.

• Plants were of particular interest because of profits from spices, medicines, dyes and cash crops. •

• Spanish obtained a monopoly on the cinchona bark, native to the Andes which resulted in first treatment of malaria (quinine).

Natural History

• Other countries followed Spain’s lead. 

• Royal botanical gardens served as living laboratories for cultivating valuable foreign plants in multiple countries.

• New information about plant and animal species overwhelmed intellectual frameworks. 

• Carl Linnaeus of Sweden sent out his students on exploratory voyages to classify specimens they collected.

• New encyclopedias of natural history popularized this knowledge with realistic drawings and descriptions, which greatly enhanced public interest and understanding of the natural world.