Chapter 13 Section 5
The Renaissance and the Reformation facilitated the breakdown of the medieval worldview. In the mid-1500s, a profound shift in scientific thinking brought about the final break with Europe’s medieval past. Called the Scientific Revolution, this movement pointed toward a future shaped by a new way of thinking about the physical universe. At the heart of the Scientific Revolution was the assumption that mathematical laws governed nature and the universe. The physical world, therefore, could be known, managed, and shaped by people.
Changing Views of the Universe
Until the mid-1500s, Europeans’ view of the universe was shaped by the theories of the ancient writers Ptolemy and Aristotle. More than 1,000 years before the Renaissance, they had taught that Earth was the center of the universe. Not only did this view seem to agree with common sense, it was accepted by the Church. In the 1500s and 1600s, however, people began to question this view.
Copernicus Challenges Ancient Astronomy
In 1543, Polish scholar Nicolaus Copernicus (koh pur nih kus) published On the Revolutions of the Heavenly Spheres. In it, he proposed a heliocentric, or sun-centered, model of the universe. The sun, he said, stands at the center of the universe. Earth is just one of several planets that revolve around the sun.
Most experts rejected this revolutionary theory. In Europe at the time, all scientific knowledge and many religious teachings were based on the arguments developed by classical thinkers. If Ptolemy’s reasoning about the planets was wrong, people believed, then the whole system of human knowledge might be called into question. But in the late 1500s, the Danish astronomer Tycho Brahe (tee koh brah uh) provided evidence that supported Copernicus’s theory. Brahe set up an astronomical observatory. Every night for years, he carefully observed the sky, accumulating data about the movement of the heavenly bodies.
After Brahe’s death, his assistant, the brilliant German astronomer and mathematician Johannes Kepler, used Brahe’s data to calculate the orbits of the planets revolving around the sun. His calculations supported Copernicus’s heliocentric view. At the same time, however, they showed that each planet does not move in a perfect circle, as both Ptolemy and Copernicus believed, but in an oval-shaped orbit called an ellipse.
Scientists from many different lands built on the foundations laid by Copernicus and Kepler. In Italy, Galileo Galilei assembled an astronomical telescope. As you have read, he observed that the four moons of Jupiter move slowly around that planet—exactly, he realized, the way Copernicus said that Earth moves around the sun.
Galileo’s discoveries caused an uproar. Other scholars attacked him because his observations contradicted ancient views about the world. The Church condemned him because his ideas challenged the Christian teaching that the heavens were fixed in position to Earth, and perfect.
In 1633, Galileo was tried before the Inquisition, and for a year afterward he was kept under house arrest. Threatened with death unless he withdrew his “heresies,” Galileo agreed to state publicly in court that Earth stands motionless at the center of the universe. Legend has it that as he left the court he muttered, “And yet it moves.”
Bacon and Descartes: Revolutionary Thinkers
The new scientific method was really a revolution in thought. Two giants of this revolution were the Englishman Francis Bacon and the Frenchman René Descartes (day kahrt). Each devoted himself to understanding how truth is determined. Both Bacon and Descartes, writing in the early 1600s, rejected Aristotle’s scientific assumptions. They also challenged the scholarly traditions of the medieval universities that sought to make the physical world fit in with the teachings of the Church. Both argued that truth is not known at the beginning of inquiry but at the end, after a long process of investigation.
Bacon and Descartes differed in their methods, however. Bacon stressed experimentation and observation. He wanted science to make life better for people by leading to practical technologies. Descartes emphasized human reasoning as the best road to understanding. In his Discourse on Method (1637), he explains how he decided to discard all traditional authorities and search for provable knowledge. Left only with doubt, he concluded that doubt was the only thing he could not question, and that in order to doubt he had to exist as a rational, thinking being. Therefore he made his famous statement, “I think, therefore I am.”
A New Scientific Method
Despite the opposition of the Church, by the early 1600s a new approach to science had emerged, based upon observation and experimentation. During the Renaissance, the works of the ancient Greek philosopher Plato were rediscovered. Plato taught that man should look beyond simple appearances to learn nature’s truths. He believed that mathematics, one of the greatest human achievements, was the key to learning these truths. His teachings were rediscovered by Renaissance scientists and helped shape people’s view of the physical world.
A Step-by-Step Process
Over time, a step-by-step process of discovery evolved that became known as the scientific method. The scientific method required scientists to collect and accurately measure data. To explain the data, scientists used reasoning to propose a logical hypothesis, or possible explanation. They then tested the hypothesis with further observation or experimentation. Mathematical calculations were used to convert the observations and experiments into scientific laws. After reaching a conclusion, scientists repeated their work at least once—and usually many times—to confirm and refine their hypotheses or formulate better ones.
Breakthroughs in Medicine
The 1500s and 1600s saw dramatic changes in many branches of science, especially medicine and chemistry. The rapid changes in science and technology that began in this period still continue to this day.
Exploring the Human Body
Medieval physicians relied on the works of the ancient physician Galen. Galen, however, had made many errors, in part because he had limited knowledge of human anatomy. During the Renaissance, physicians made new efforts to study the human body. In 1543, Andreas Vesalius (vuh say lee us) published On the Structure of the Human Body, the first accurate and detailed study of human anatomy. Vesalius used whatever means he could to increase his knowledge of anatomy. He used friendships with people of influence to get invitations to autopsies. He also autopsied bodies that he himself obtained—counting on friends in the local government to look the other way.
In the early 1540s, French physician Ambroise Paré (pa ray) developed a new and more effective ointment for preventing infection. He also developed new surgical techniques, introduced the use of artificial limbs, and invented several scientific instruments. Then in the early 1600s, William Harvey, an English scholar, described the circulation of the blood for the first time. He showed how the heart serves as a pump to force blood through veins and arteries. Later in the century, the Dutch inventor Anton van Leeuwenhoek (lay wun hohk) perfected the microscope and became the first human to see cells and microorganisms. These pioneering scientists opened the way for further discoveries.
Isaac Newton Links the Sciences
As a student in England, Isaac Newton devoured the works of the leading scientists of his day. By age 24, he had formed a brilliant theory to explain why the planets moved as they did. According to one story, Newton saw an apple fall from a tree. He wondered whether the force that pulled that apple to Earth might not also control the movements of the planets. In the next 20 years, Newton perfected his theory. Using mathematics, he showed that a single force keeps the planets in their orbits around the sun. He called this force gravity.
In 1687, Newton published a book explaining the law of gravity and other workings of the universe. Nature, argued Newton, follows uniform laws. All motion in the universe can be measured and described mathematically. To many, Newton’s work seemed to link the sciences just as gravity itself bound the universe together.
For more than 200 years, Newton’s laws held fast. In the early 1900’s, startling new theories of the universe called some of his ideas into question. Yet his laws of motion and mechanics continue to have many practical uses. For example, calculus—a branch of mathematics partially developed by Newton and used to explain his laws—is still applied today.
The branch of science now called chemistry was in medieval times called alchemy. Alchemists believed that any substance could be transformed into any other substance, and many of them tried unsuccessfully to turn ordinary metals into gold. With the advances of the Scientific Revolution, the experiments of alchemists were abandoned. However, some of their practices—especially the manipulation of metals and acids—set the stage for modern chemistry.
In the 1600s, English chemist Robert Boyle refined the alchemists’ view of chemicals as basic building blocks. He explained all matter as being composed of tiny particles that behave in knowable ways. Boyle distinguished between individual elements and chemical compounds, and explained the effect of temperature and pressure on gases. Boyle’s work opened the way to modern chemical analysis of the composition of matter.