The alchemists of this period were attempting to derive gold from other elements. Mathematical ideas were adopted from Arabian concepts. Astronomy was actually astrology during the Renaissance. The theory of Ptolemy, set forth in the second century, was still accepted by scientists of the Middle Ages. They believed that the earth was the center of the solar system. Science made great advances with the discoveries and inventions of such men as Bacon, da Vinci, Copernicus, Galileo, Kepler, and Newton.
Roger Bacon
As a thirteenth-century English scholar, Bacon believed in experimentation, rather than in a simple reasoning process. Bacon's most important mathematical contribution was in applying the science of geometry to optics. In his book, Opus Majus, Bacon described spectacles, or eyeglasses, which became popular toward the end of the Middle Ages. You can imagine the revolutionary change that came over visually handicapped people who could now see! Roger Bacon is to be credited with the original concept of eyewear. His interest in mathematics and science started when he was a student at Oxford. He dedicated his life to the study of languages, mathematics, optics and sciences, often merging the many facets of science and seeing how they worked together. One of his most well-known phrases is "Mathematics is the door and the key to the sciences."
Leonardo da Vinci
Da Vinci was not only one of the greatest inventor-scientists in all of Italy, he is considered possibly the greatest of all time. Even as a teenage apprentice painter, Leonardo developed his own artistic style and even devised his own special formula of paint! Some of the many occupations he engaged in included civil engineer, architect, and military weapons designer. Although many people classify the contributions of Leonardo da Vinci among the arts, some of his most interesting ideas occurred in the field of science. These fields included anatomy, botany, engineering, geology, and astronomy. His works reveal intricately detailed studies of bone and muscle. Other sketches show men "flying" with manmade "wings." Da Vinci's designs involve primitive prototypes for the helicopter, the parachute, the machine gun, armored tanks, and the catapult. Da Vinci also made geological studies of rock formations and water movement. His works were recognized and sometimes sponsored by the nobility in his country. He developed canal systems complete with locks, as a part of his job to divert rivers. Because of his versatility and genius, da Vinci is considered today to be the standing representative of the ideal Renaissance man. Da Vinci was able to write with either hand, and often wrote his notes backward so that they could only be deciphered in a mirror!
DaVinci's many artistic works included scientific sketches of the human anatomy.
Copernicus
By the mid-sixteenth century a Polish priest named Nicolaus Copernicus had published On the Revolution of Heavenly Bodies, in which he asserted that the sun was the center of the universe, or that the universe was heliocentric. Copernicus is universally acknowledged as the founder of modern astronomy. He was not limited, though, to astronomy, for he also studied mathematics, optics and perspective at Cracow University, as well as canon law (church law) at Bologna and even medicine at Padua. Copernicus served as a lawyer, doctor, bailiff, military governor, judge, tax collector, vicar-general, and physician. A scholarly man with a doctor's degree, Copernicus believed that the earth moved through the universe and was just one of the several planets.
Copernicus did not publish De Revolutionibus until late in his life because he was unsure of the response of the church. In De Revolutionibus, Copernicus presented evidence proving that the earth is not the center of the universe, as was commonly believed, especially in the Catholic church. He stated that the earth revolves around the sun, and theorized that the sun was the center of the universe. The Catholic church vehemently denied this to be so, for they felt that it trivialized the importance of the earth and of man, whom God created "a little lower than the angels" (Hebrew 2:7). The authorities of the church felt that Copernicus' works considered the earth a mere planet among other mere planets, rather than a central point around which the heavenly bodies revolved. Although most Renaissance people refused to accept this theory, his heliocentric theory influenced the other scientific developments by Galileo, Johannes Kepler, and later by Sir Isaac Newton.
Galileo
Galileo was an Italian scientist who at the turn of the seventeenth century made several important scientific discoveries. Galileo developed a way for determining the specific gravity of objects and discovered the laws of the pendulum. He also invented a type of compass that is still used by draftsmen.
Galileo is known primarily for his discoveries in the field of astronomy. His invention of the telescope enabled him to observe the heavens more closely. Galileo discovered that the moon did not generate its own light, but that light was reflected by a rough, mountainous surface. He also discovered four of Jupiter's moon's, naming them for members of the famous Medici family of Florence, Italy. Other astronomical discoveries, including sunspots and observations of phases of Venus, brought him fame as well as opposition from the church. After the publication of his A Dialogue on the Two Principle Systems of the World, Galileo was called before the Inquisition and publicly forced to deny the Copernican theory.
Johannes Kepler
Johannes Kepler, who lived at the same time as Galileo, publicly supported the Copernican theory. A German scientist and mathematician, Kepler made valuable contributions to the field of astronomy. He worked with Tycho Brahe, an earlier astronomer who had made many observations of the planet Mars unaided by telescope. While investigating Brahe's theories, Kepler discovered that the orbit of Mars was oval, rather than circular. His findings included three laws of planetary motion. These laws influenced Newton's later discoveries concerning gravity. His three laws were included in his work Astronomia Nova. The three laws became known as Kepler's Laws of planetary motion; chiefly because of this, Kepler is considered the founder of physical astronomy. The three laws state:
- The planets move in elliptical orbits with the sun at one focus
- The planets sweep out equal areas in equal times
- There is a mathematical relationship between the orbital periods of the planets and their distances from the Sun different from what is commonly accepted
Kepler believed that the planets were kept in their orbits by what he called "vis motrix'' (life force). He also developed the concept of a ray.
Sir Isaac Newton
The English astronomer Sir Isaac Newton, who worked at the end of the seventeenth and first part of the eighteenth centuries, was able to apply earlier scientific knowledge to discover laws of gravitation and motion. His discoveries were largely unrecognized until another English astronomer, Edmund Halley, consulted him about a problem. With Halley's financial aid, Newton published his laws in book form. Newton's laws are usually considered an outstanding contribution to modern scientific discovery. Newton also made discoveries concerning light and color, paving the way for the development of spectrum analysis.
Newton invented the mathematical discipline of calculus and gave much to the field of physics. He had accomplished so much that the poet Alexander Pope wrote a little dedication to him:
Nature and Nature's laws
lay hid in night;
God said, Let Newton be!
and all was light
Three major works centering on Newton are:
- Newton's Three Laws of Motion
- The Theory of Universal Gravitation
- The demonstration that Kepler's Laws follow from the Law of Gravitation
