Galileo
During the last unit, we saw the decline of science due to the fall of the Roman Empire and the rise of Christianity. A major contributor to this decline was also the plagues that struck Europe. However, after the depletion of the population of Europe in the 14th century, cities and towns began to sprout once again. Science spurred this growth, as mechanical inventions and trade were necessary to make up for the now missing populations. Gradually, scientists would also start experimenting due to the influences of Roger Bacon and St. Thomas Aquinas. This era would end with the founding of the Royal Society in England, which would once again unite scientific pursuits.
Science during this era formed a bridge between the absorption of classical learning and the adoption of Arabic mathematics. However, some science remained in the dark ages. Alchemy (the attempt to turn items into gold) and astrology still remained more popular than chemistry and astronomy. Aristotle’s ideas about physical science were once again brought to the forefront, but needed some serious refinement. Life science would experience a resurgence as explorers would reach the New World and discover many new plants and animals. With new plants and animals came a need for new classifications. The study of the human form would influence not only science but also art, as Michelangelo and Leonardo da Vinci would incorporate human anatomy into their art. These two would also influence the science world as Michelangelo was an engineer and da Vinci was an inventor and engineer. Leonardo made a great contribution to science of later eras with his notebooks filled with many technological ideas, which showed that da Vinci was a man way ahead of his time. Scientists have studied these notebooks for years, and recently made an interesting discovery. Using a “recipe” found in Leonardo’s notebooks, scientists make a natural form of plastic that Leonardo never did create. Leonardo also designed a helicopter (it never would have worked), a parachute and various flying machines. Sadly, Leonardo rarely made working models of his devices and kept his notebooks secret. Leonardo also wrote all his notebooks in the odd style of “mirror writing” or writing backwards. The ability of these men to function in many roles of life led to the coining of the term “Renaissance Men”.
As the Renaissance continued, trade experienced a boom with the exploration of new lands. We have already discussed the impact of trade on science. Francis Bacon wrote “the opening of the world by navigation and commerce and the further discovery of knowledge” would distinguish this age. Bacon also felt that science was a powerful tool in which to conquer nature. He wrote that science’s goal was “the enlarging of the bounds of the human empire, to the effecting of all things possible.”
What does it mean to be a “Renaissance Man”?
Do you agree that science should expand the bounds of the human empire to all things possible? Please explain.
In 1543, a book was published that would forever change the view of our world. Copernicus’s view on a heliocentric solar system was this book. His book was published postmortem, as he feared retribution from the church. Copernicus’ views would not be widely accepted for some time. Both the Catholic and Protestant Churches opposed a heliocentric solar system, but the Catholic Church took the stronger actions. In 1600, Friar Giordano Bruno was burned at the stake for his agreement with the heliocentric theory. In 1616, the Catholic Church banned Copernicus’ book De revolutionbus orbium coelestium (On the revolution of celestial bodies) where it would remain until 1835 and Galileo was warned not to promote Copernican ideas. When he did, he faced a trial and was placed under house arrest.
Galileo
Galileo was definitely the lead scientist of this era. He was truly a Renaissance man as he was involved in art, astronomy and physical science. He also invented a version of the telescope in 1609. However, he is often remembered for his arguments with the Pope and the Catholic Church.
Ironically, Galileo’s pursuit of science most likely began in a church. In 1581, at the age of 16, Galileo studied the hanging lanterns during a service at the cathedral in Pisa. As he watched them sway back and forth, this led him to formulate some ideas about pendulums, which would later help Christiaan Huygens invent a pendulum clock. Galileo would continue his study of physical science when he wrote a book entitled De motu (On Motion) in which he refuted, or denounced, Aristotelian physics. Much of what the people believed about science was still rooted in the thoughts of Aristotle. For example, many still used this quote from Aristotle to explain motion…
There is a natural place for everything to seek, as:
Heavy things go downward, Fire upward,
And rivers to the sea.
To prove Aristotle wrong, Galileo attempted to repeat an experiment that had been done by Simon Stevinus. Galileo dropped two balls of different weights off of the tower of Pisa. Galileo believed that the balls would hit the ground at the same time, which was different than Aristotle’s view that heavier objects fall faster than lighter ones. Galileo reported that the lighter ball originally fell faster and then the heavier ball caught up. They both hit the ground at almost the same time. Galileo claimed that without air resistance, the balls would hit the ground at the same time. However, scientists were stumped on why Galileo reported that the lighter ball originally fell faster. So, they repeated the experiment with cameras. What they saw explained Galileo’s report. When you hold two balls with outstretched arms, your muscles become strained. Without knowing it, you will always release the lighter ball (the one you are gripping less) a little bit earlier than the heavier ball. This proved to scientists that Galileo actually did the experiment.
The pursuit of proving Aristotle wrong would continue until four years prior to his death. In 1638, Galileo published a book in which he described a mathematical explanation for his laws of motion as well as the concept of friction. He was able to disprove the idea that heavier objects fall faster than lighter ones. Galileo also spent a great deal of time studying falling bodies and the rates at which they fell. He also worked on his principle of inertia.
Galileo is just as infamous for his studying of the heavens as he is for his descriptions of forces and motion. In 1597, he wrote a letter to Johannes Kepler in which he admitted that he accepted the Copernican system. In 1609, Galileo would make his own version of a telescope, based on the spyglass he had received from Hans Lippershey in Holland and with modifications and improvements would achieve a magnification of 30x. Lippershey was Dutch and at this time, the Dutch were great seas merchants. This spyglass would help the Dutch in there navigations. However, Galileo would not use his telescope to look across the seas, but rather turned the telescope towards the heavens. Using his telescope, he was able to draw the mountains and craters of the moon. He also noticed that the dark side of the moon was slightly illuminated by the reflection of sunlight off of the Earth, a concept he called Earthshine. In 1610, he described the moons of Jupiter, which proved that the Earth-Moon relationship was not unique to us. He would call these the Medicean Moons in honor of the Grand Duke Cosimo. He also saw the rings of Saturn, although he did not understand what they were. His best description was that the rings were “handles”. He also noticed that the sun had spots and rotated once every 25 days. Most importantly, he recognized the phases of Venus. Seeing that Venus would go through phases like our own Moon, Galileo was able to prove that Venus reflects the Sun’s light and that it revolves around the Sun. In Galileo’s opinion, all of his discoveries only went to prove the Copernican heliocentric theory to be true.
This is where Galileo would receive his most trouble. Galileo wrote a newsletter called The Starry Messenger, in which he told of his discoveries as well as defending the Copernican system. Within 9 days of printing, all 550 copies had been sold. He also claimed that the church had the burden of proving the Copernican system wrong. In 1616, Galileo received a letter from Cardinal Bellarmine warning him not to teach or defend the Copernican system. Privately, Galileo continued to teach the system and often tried to convince the Pope of his views. In 1632, Galileo published a book entitled Dialogue on the two chief world-systems, the Ptolemaic and the Copernican. The book consisted of a discussion between a defender for Ptolemy and Copernicus as well as an “idiot” named Simplico who was supposed to represent Pope Urban VIII. Needless to say, the Pope was not too thrilled by this book and summoned before the Inquisition in 1633. Galileo was found guilty of heresy and forced to recant the Copernican system, which he did. However, it is rumored that Galileo ended his recantation about the Earth not moving by saying “E pur se muove” or “Nevertheless, she moves.” This final disagreement with the church is highly believed to be fictional. Galileo was placed under house arrest until his death in 1642.
Prior to Galileo, it was near impossible to measure most things with any accuracy. Length and mass could be measured with some certainty, but time could only be measured in large amounts and temperature had no numerical attached to it. Galileo would often measure time by keeping beat with music, use a vessel that dropped water at certain intervals or used the human pulse. We have already seen how Galileo would affect the measurement of time with a pendulum. Galileo also had an impact on the measurement of temperature. He tried often to make a thermometer but often failed. However, his ideas were refined during the 17th century and then perfected by Fahrenheit in 1714.
How did Galileo begin his study of science?
Why did Galileo get in trouble with the church?
What did Galileo try many times to invent but never managed to perfect?
Dealing with the subject of astronomy, what was Galileo’s most important discovery? Explain why this was important.
The astronomy of this era began with the translation of Ptolemy into Latin. This allowed the knowledge of the past to carry on, but sadly this knowledge was full of incorrect information. The idea of a heliocentric solar system would still be an undercurrent at the beginning of this era, and become a full-fledged theory by the end of the era. Besides Galileo, the three major astronomers of this time were Tycho Brahe, Nicholas Copernicus and Johannes Kepler.
NICHOLAS
COPERNICUS
Nicholas Copernicus would lead astronomy with his heliocentric theory, although the work of Brahe and Kepler probably deserve more of the credit. In 1513, he built his own tower for observing the heavens. He came up with this theory in 1514, but would not publish this theory until 1543. Copernicus wrote, “The Earth carrying the Moon’s path, passes in a great orbit among the other planets in an annual revolution around the Sun.” In his book, he strongly objected to the Ptolemaic System claiming that it did not explain what was readily observed. Just the fact that the stars appeared closer and farther away at different times of the year was enough for Copernicus to dispute Ptolemy. However, Copernicus was working on calendar reform for the Church and was not quite ready to dispute Ptolemy, even though it was Ptolemy’s system that caused a need to revise the calendar. Copernicus feared the views of the church and waited until just months before his death to publish the theory. Since most of the publishing was still done in churches, the publisher added a preface that the Earth did not move, but calculations were easier to understand if one assumed that it does. The book was not a success from a publisher’s point of view as it was high priced and sold slowly. However, most scientists readily accepted a heliocentric solar system. Why the quick acceptance? First, Copernicus divided the planets into two simple groups, those inside the Earth’s orbit, and those outside. Second, he fixed the order of the planets while Ptolemy had the ordering be more arbitrary. Also, a heliocentric solar system now had a valid answer for Ptolemy’s epicycles. This now became know as retrograde motion. Again, while we often think of Copernicus as creating this heliocentric system, it is the works of Kepler and later Newton that would solidify Copernicus as a great astronomer.
TYCHO
BRAHE 
Tycho Brahe was one astronomer who did not originally believe in a heliocentric system, instead the argument could be made that he never switched to this view. In fact, his geocentric system would be compared to the Copernican system as late as 1651. Giovanni Riccoli wrote a book comparing the two systems and in the end favored the Brahe system in which the Earth was stationary, but the rest of the planets revolved around the Sun. Although Brahe was wrong in this aspect, he was still widely respected as an astronomer. Brahe is probably most famous for his observations of comets and supernovas. While Brahe was observing the great comet of 1577, he attempted to measure the distance of the comet from Earth using a parallax. Brahe determined that the comet was at least 4 times farther away from the Earth than the moon. He also noticed that the comet appeared to get brighter and dimmer, so he labeled its path as an ellipse. This proved that the comet was not of Earth and showed that the heavens could change, a thought that originated in 1550. Three years later, the King of Denmark built Brahe his own observatory.
In 1588, using the data from the great comet, Brahe rejected the idea of crystalline spheres. Brahe would go on to detail the positions of 777 stars. In 1600, a new apprentice would come to study under Brahe, and be named his successor the next year when Brahe died. The name of this apprentice was Johannes Kepler.
What did Brahe prove about comets?
Brahe was able to excel in astronomy due to having what built for him by the King of Denmark?
Brahe’s Instruments
JOHANNES
KEPLER
Kepler was already a pretty accomplished astronomer himself. In 1592, he attempted to explain how each of the planets would be contained in one of the five Platonic solids. To him and many others, this explained why there were six planets. Kepler spent a lot of time observing stars and supernovas, most likely due to the influence of Brahe. Kepler’s biggest accomplishment was his three laws of planetary motion, although many wonder if his ideas were his own or just extensions of Brahe’s ideas for after Brahe died, Kepler often petitioned Brahe’s family to release Brahe’s notes on observations to him. Included in this was his theory that planets did not revolve in circular orbits but rather ellipses. Kepler’s second law stated that the planets swept out equal areas for equal amounts of time. His third law stated that the square of the times of revolution was proportional to the cubes of their distances from the Sun. Another astronomer would prove that these laws applied to the moons of Jupiter as well. According to Kepler, these three laws supported the Copernican theory and wrote this in a book in 1619. This book was quickly placed in the Catholic Church’s banned book library. Also in 1619, Kepler would explain why a comet’s tail pointed away from the Sun, a concept that had been known for years. Kepler claimed that there must be something coming from the Sun pushing the tail away. We now know this to be solar wind. Kepler’s final contribution would be a star catalog in which he detailed 1005 stars, 777 that had already been detailed by his mentor, Tycho Brahe.
Although Brahe, Copernicus, Galileo and Kepler led the charge in astronomy, there were plenty of other contributions by other astronomers. Regiomontanus is the first to make a scientific study of a comet in 1472, by watching its orbit, motion and position of its tail. This comet was later to be known as Comet Halley. Inventor Hans Lippershey would set the astronomy world on fire with his invention of the telescope in 1608. Three years later, a French astronomer would discover the Orion Nebula. This has long been a joke among astronomers to have the great hunter Orion actually being a place where stars are given birth. The invention of the telescope would allow astronomers to watch the transit of Venus across the Sun (1639), maps to be made of the moon (1647), a description of Saturn’s rings (1656), and observe the surface features of Mars in 1659. The first ideas about traveling off our planet also surfaced during this era as Cyrano de Bergerac suggested 7 ways to travel to the Moon. Six of those ways would not have worked, but the seventh was traveling by rocket.
Even Christopher Columbus would get into the act. In 1504, Columbus scared a group of Native Americans by predicting a lunar eclipse on February 29th. Columbus was using an astronomy book by Regiomontanus.
Sadly, not everything about astronomy was good. In 1584, Friar Giordano Bruno said that the universe is infinite or never ending. Later that year, he would defend the Copernican system. Bruno would continue this defense and in 1600 he was accused of heresy. Bruno was burned at the stake in Rome on February 17th.
Tycho Brahe lost a section of his nose during a duel. A metal plate replaced this section
of his nose. During this time it was customary to not leave the room until the king had left. Well, Brahe was known for favoring the drink and he had to go to the bathroom. However, the king had not left and Brahe was forced to “hold it”. Brahe’s bladder would later burst, causing his death.
Galileo’s “house arrest” was spent in various country homes of his friends.
Who invented the telescope?
What causes a comet’s tail to point away from the Sun?
What is Kepler most famous for?
With the expansion of the world due to navigation, the mapping of the new lands became very important. Explorers such as Amerigo Vespucci, Christopher Columbus and Sebastian Cabot led the charge for this expansion. Columbus was one of the first to make it to the New World, which would receive its new name from Amerigo Vespucci, who was the first to realize they were a new land and not part of Asia. However, globes were introduced even before the Americas were known in Europe. Martin Behaim made one of the first globes around 1492, although he omitted the soon to be discovered Pacific Ocean and the Americas.
In 1507, the first map showing the Americas was made which would be followed by the first globe to show the Americas. Johannes Schoner made this globe in 1515. With all the new discoveries being made, many countries wished to claim the new lands. In 1493, Pope Alexander VI drew a line on a map that gave Spain all the undiscovered lands west of the line and Portugal all the lands east of the line. This line would be moved in order to give Portugal the land that is now known as Brazil. This is why the Brazilians speak Portuguese today.
Fossils became to be studied and understood better during this era. Previously, we had discussed that Xenophanes saw seashells at the top of mountains. Many religious leaders claimed that this proved Noah’s flood had occurred. Girolamo Fracastro would study fossils and explained that fossils were actually the remains of actual organisms. According to Fracastro’s calculations, he agreed that some fossils could have been buried during Noah’s flood. However, those fossils are buried at too many different geological strata for them all to have been buried at the same time. Fossils would actually get their name from a German metallurgist named Georgius Agricola in 1546. Agricola said this term should apply to anything dug from the ground. However, Agricola was not sure about the nature of fossils as he claimed that the term “fossil” should include “odd rocks that looked like bones or shells”. In 1565, Swiss naturalist Konrad von Gesner would follow this belief of odd-shaped rocks in his book De rerum fossilium. This book contained the first drawing of fossils to make it easier for so “students may more easily recognize objects that cannot be very clearly described in words”, although Gesner believed them to be rocks that just happened to look like bones or shells.
Finally, scientists would get knowledge of what would be the worst earthquake in history. An earthquake struck China in 1556, killing at least 830,000 people. Scientists would still have no knowledge of what caused earthquakes.
Questions
Why would it be decided to name the New World the Americas?
Why do the people of Brazil speak Portuguese?
How did Fracastro disprove that the fossils were all buried during the Great Flood?
We have spent a great deal of time discussing the contributions of Galen to the understanding of human anatomy and life processes. Galen would still have a large impact in those areas during this era, but the practice of dissecting corpses in front of medical students led careful observers to disagree with Galen at the end of the time period. The study of human anatomy got a boost from the artists and sculptors of the time such as Leonardo da Vinci. In 1552, Italian anatomist Bartolemeo Eustachio would describe a tube that connected the ears to the throat. The process of how the human body works became a little clearer with an understanding of blood circulation that was discovered by William Harvey in 1628. Harvey originally believed in the traditional views of Aristotle when it came to blood circulation. Then he noticed a connection between the heart and arteries and the liver and veins. He also noticed “one-way” valves in the veins, which seemed to permit blood flow in only one direction. If this were true, then the heart would pump out all of our blood within a half hour. How would the body make new blood so fast? He reasoned that the blood circulation may in fact be a complete cycle and blood would return to the heart. He performed many experiments to prove this fact. Sadly, he was not able to see the capillaries without a microscope, so he was not able to complete the cycle. In 1661, Marcello Malpighi would see these capillaries with the use of a simple single-lens microscope. The cycle was complete.
Konrad von Gesner wrote a series of three books called Historia animalium in which is credited with starting the study of Zoology. Zoology received a greater understanding due to a wide variety of studies. In 1555, naturalist Pierre Belon noticed homologies (similarities) between the bones of various vertebrates. Belon made these comparisons all the way from fish to mammals. Belon would use these similarities to help him classify these organisms. Belon would end up writing a classification for over 200 species. In 1623, the classification of animals also became more organized with binomial nomenclature, which was introduced by Gaspard Bauhin in 1623. Bauhin used the genus for the first name and the species for the second. Sadly, some scientists, such as Konrad von Gesner still wanted to include mythological creatures.
Botany also became a more diverse science as many authors published works about the structures, classifications and processes of plants. Otto Brunfel would start the botany of this era in 1530, when his described 230 species of plants that included detailed illustrations. As more and more journeys were made to the New World, many new plants were discovered. Leonard Fuchs would describe over 500 plants with over 100 of them being from the New World, including peppers, pumpkins and maize. In 1580, Prospero Alpini would be the first scientist to describe the two sexes of plants. Although, Alpini is the first scientist to describe this, it can be assumed that the common farmer or gardener had known this information for centuries. Although the classification of animals was fairly simple due to many distinguishing characteristics, the classification of plants was not that simple. In 1583, one of the first classifications of plants was created. This classification was based on roots and fruits.
Finally, just as astronomy had been greatly improved by the invention of the telescope, life science would be improved with the invention of the microscope in 1609. The microscope was invented by Zacharias Janssen and would be improved by Anton van Leeuwenhoek. We will discuss Anton van Leeuwenhoek more in the next unit.
Questions
How will Leonard Fuchs still be remembered today?
The physical science of this era was based on trying to replace Aristotle’s physics, which had existed for 1900 years. We have already discussed Aristotle’s views on natural, or up and down, motion. Aristotle claimed that objects simply wanted to return to their realm. Horizontal, or unnatural motion occurred because of an object being acted upon by a push or pull. Since we do not observe motion in a vacuum or without friction, objects on Earth continue to appear to obey Aristotle’s laws of motion. Simon Stevinus would start the challenge of Aristotle’s physics when he would drop two cannonballs of different weights off the leaning tower of Pisa. Stevinus was able to prove that all bodies fall equally fast and not proportional to their weight. Galileo would do similar experiments a few years later, although he would time balls as they rolled down inclined planes to “slow down their falling motion”. Galileo was able to deduce the following laws from his experiments:
1. Any body moving on a horizontal plane will continue at the same speed, unless a force opposes it.
2. In a vacuum, all bodies fall at the same rate, not matter what their weight or constitution.
3. A body falling freely or rolling down an incline undergoes uniform acceleration.
Isaac Newton would use these ideas as the basis for his laws of motion and gravitation. The early experiments of Galileo with moving bodies made physical science into an experimental science instead of an observational one. This also founded a field of science known as dynamics.
On a lighter note, in 1500, a Chinese scientist named Wan Hu would attempt to create one of the first flying machines. Wan Hu tied 47 gunpowder rockets to the back of a chair in an attempt to fly. The device exploded during testing, killing Wan Hu, who was the pilot.
Why do Aristotle’s laws of motion seen to still be true?
How would Stevinus be able to disprove Aristotle’s ideas about falling bodies? Please explain why this was able to disprove Aristotle’s ideas.
