Most scholars would agree that the first “true” science was done during the time of the Greeks. It was during this era that mere observations were not enough. Instead, the “scientists” of this time tried to explain what they were observing. The construction of theories and an overwhelming desire to know and understand their universe was the impetus behind Greek science. The Greeks would introduce a scientific method, but it was based on observation and reasoning instead of experimentation.
There are two main factors that could be considered the cause for Greek science. The area of Greece was settled around 1400 B.C. by seafaring traders. The exchanging of materials as well as ideas would be a spark for science. Often they would encounter people whose explanations of the universe differed from their own. This would lead them to challenge and question their beliefs. Navigation would lead to the understanding of space and a sense of geometry. Secondly, the Greeks were the first to build institutions such as the Academy, Lyceum and Museum that were places of scientific research. In fact, it is the closing of these institutions around 529 AD that gives us the ending bookmark for this era. Hence, the Greeks can be considered as the place for the Dawn and Death of Science. However, the writings of the Greeks would continue to have a great influence on science for another 1000 years.
Although many Greeks believed in the gods, religion did not play a strong part in their everyday lives. They lacked a monotheistic religion and sought to explain the universe without the interaction of deities. Science would become something that was done by the common people, rather than the priests, as it was in Egypt and Babylonia. The theory of creation was absent in Greek religion and this allowed science to assume that role as science tried to explain the origins of various phenomena. However, established religions and natural philosophers did clash. This resulted in the condemnation of Anaxagoras, the death of Socrates by suicide, and the attacks and exile of Aristotle.
1. What two factors caused science to begin with the Greeks?
2. What caused science to come to an end during this era?
3. How did Greek science advance from that of the previous era?
4. How is the trading done by the Greeks similar to receiving an education?
While it is true that his religious contemporaries often attacked Aristotle, it is also true that no one was held in higher regard, scientifically and in some religious circles, than Aristotle. He shaped the thoughts and views of others during his time, and since it was difficult to disprove many of his theories, he shaped the thoughts of others well after he had passed. His views were so well received that often if Aristotle had claimed something to be true, it was believed to be true. Amazingly, Aristotle made many of these theories without the benefit of experimentation. Later, many scientists who did perform experiments would become famous by proving Aristotle was incorrect. Aristotle began his studies under the tutelage of Plato. He excelled so much that Plato once called him “the intelligence of the school.” At this time, Aristotle concentrated his studies on biology and natural history. After leaving Plato’s school, Aristotle served as tutor for a child that would come to be known as Alexander the Great in 343 BC. As Alexander conquered various parts of the world, he would bring back plants and animals for Aristotle to study. By the time Aristotle had died, he had classified over 500 animals and dissected nearly 50 of them. In 340 BC, Aristotle went on to form his own school, the Lyceum. It was during this time that he wrote over 150 volumes of the knowledge of this time. Sadly, only about 50 of them still exist today.
Aristotle enjoyed studying nature and was careful to write down what he had observed. He classified animals, first on the basis of their movement, then on their anatomy. He was the first to classify a dolphin as a “beast of the land” due to the fact that it nourished its young with a placenta. No fish did this, but mammals did. He also saw that these animals may have changed over time, but he came nowhere close to the theory of evolution. However, he did make some mistakes. He said plants lacked sexuality, a view many still hold true today. He also believed that the heart was the center of life and that the brain was merely for cooling blood.
His studies on physical science were nowhere near as good as his studies of biology. However, many of his theories were difficult to disprove. He believed that there were 5 elements…earth, water, air, fire and ether. He proposed that the heavens were made of ether and were unchanging and perfect. He believed that motion was caused by the inherent “need” of an object to return to its realm. His reasoning made good sense… rocks fall back to earth, bubbles floats on water, rain falls while fire rushes upward. Again, this thought is wrong, but without experiments; it is tough to disprove. Aristotle also believed that heavier objects fall faster than lighter ones. Watching a rock and a feather fall seems to prove this theory. It would take 19 centuries and scientists named Simon Stevinus and Galileo Galilei to prove him wrong. He also believed that an object could move on its own, without being pushed or pulled. According to him, your desk could be in a state of rest now, but later on your desk could move on its own. Amazingly, this is true to a certain extent. Many consider the only thing that Aristotle got right about physical science was the fact that it takes a certain amount of force to move an object. Aristotle claimed, “Moving an oxcart with one’s finger is inherently impossible.” This statement would become very important in the days of Isaac Newton.
In 323 BC, Alexander the Great died at the age of 33 after carrying the Greek Empire to the limits of the known world. Aristotle, fearing for his own life, fled to the island of Euboea, where he died in 322 BC.
A continuing theme that we will investigate throughout the year will be “having time to sit around and think.” This theme begins with Aristotle. Aristotle was an orphan who actually lived in the school where he studied. Aristotle also spoke with a lisp. This may have made it difficult to make friends. These two items would have given Aristotle plenty of time to “sit around and think.” We will see this happen with various other “scientific geniuses.”
Finally, the works of Aristotle were translated into Latin around 480. This allowed the thoughts and ideas of Aristotle to be the source of Greek ideals throughout the middle ages.
What did Aristotle mean when he said, “Moving an oxcart with one’s finger is
inherently impossible”?
Describe the scientific relationship that Aristotle had with Alexander the Great.
Why would Aristotle think that the brain was used for cooling blood?
Why did Aristotle consider a dolphin a beast of the land?
On May 25, 585 BC, a solar eclipse occurred during the war between the Medes and the Lydians. This eclipse was predicted earlier in the year, (the year not the actual date) by a philosopher named Thales. The two warring countries viewed the eclipse as a bad omen and called off their war. This event is also believed to be the first actual known date. The only time a solar eclipse could be seen in the Middle East was on May 25, 585 BC.
One of the first Greek leaders in astronomy was Hipparchus. Hipparchus lived from 190-120 BC. He was responsible for combining new Greek astronomy with the older Babylonian astronomy. He was a meticulous observer. He measured the length of a year to be 365 days, 5 hours and 55 minutes. He also realized that the seasons had different lengths. According to Hipparchus, spring was 94.5 days, summer was 92.5 days, autumn was 88.125 days and winter was 90.125 days. He calculated that the Earth was farthest from the Sun on July 4 and closest to the Sun on January 4th. By watching the moon, he calculated the length of a month to be 29 days, 12 hours, 44 minutes and 2.5 seconds. Amazingly, he was only off by 1 second. Finally, Hipparchus noticed that some stars appeared to be brighter than others and derived a system to classify them. We still use a “magnitude” system today. It was the work of Hipparchus that would be the springboard for the observations and ideas of Ptolemy.
However, the Greeks did struggle to explain the observations of the skies. Probably the biggest argument among the Greeks was where the Earth was and what shape it was.
Most Greeks believed that the Earth was at the center of the universe, or what is known as a geocentric universe, “Geo” meaning Earth and “centric” meaning center. The Pythagoreans who believed that the Earth traveled around a central fire did not hold this view true. However, they did not identify that central fire as the Sun. Aristarchus also held this view, in 270 BC, but was rebuked by Aristotle. As we read earlier, if Aristotle said it was true, it was. Another philosopher named Seleucus would make a final attempt to prove a heliocentric or sun-centered solar system in 190 BC. Sadly, this theory would not take hold until the time of Copernicus. In the end, Ptolemy had the final say and the Earth was at the center of the universe. The shape of the Earth was also of great debate. Most agreed with the Pythagoreans that the Earth was a sphere. They claimed this around 500 BC. Anaximander said the Earth was a disk or cylinder around 525 BC. He came upon this conclusion after watching the shadow of the Earth move across the moon during a lunar eclipse. Thales thought the Earth was a disk floating in water. Again, in the end, Ptolemy had the final say and the Earth was a sphere. Ptolemy would write a book called the ALMAGEST, or “the greatest” which included all the Greek theories on astronomy. Most importantly, the Almagest included Ptolemy’s model of the solar system, which placed the Earth at the center with all other planets moving about in perfect circles. However, observations claimed that the planets seemed to move backwards some of the time. Ptolemy explained that the planets themselves moved in tiny circles that he called “epicycles”. Sadly, this was another incorrect explanatory story. Ptolemy would go on to insist that the Earth was not spinning (the birds and clouds would be left behind). In the end, this book was later translated into many languages and became the standard for astronomy for many years to come.
All in all, the Greeks did a decent job with astronomy. Erastothenes correctly calculated the circumference of the Earth, while he was the director of the great library in Alexandria. He read that in Syrene, vertical sticks cast no shadow at noon on the Summer Solstice, or June 21. Also, the sun was visible in the water at the bottom of the wells. Erastothenes knew that in Alexandria, vertical sticks did cast a shadow at the same time. This led him to believe that the Earth is spherical and not flat. By measuring the length of the shadow in Alexandria, he calculated that the angle was 1/50th of a circle or 7 degrees. So he hired a man to walk from Alexandria and Syrene to measure the distance. The distance was measured to be 5,000 stadia or 800 kilometers. This distance must then be 1/50th of the circumference Earth. So the distance around the Earth would be 40,000 km or approximately 24,000 miles. All this was calculated from shadows and sticks. Other Greek astronomers determined the distance to the Moon, as well as where the planets would be at certain times of the year.
Many theories that we now hold true began during the Greek era. In 480 BC, Oenopides believed that the Earth was actually tilted. Using shadows, he claims that the Earth is tilted around 24 degrees. This is only a ½ degree from the accepted value of 23 ½ degrees. In 450 BC, a Pythagorean philosopher argues that the Earth rotates. Again, with the Greeks considering the Earth to be immovable, this view was not widely accepted. However, Aristotle claimed that this could be the reason for the winds. Greek astronomer, Heracleides, claims that Mercury and Venus orbit the Sun instead of the Earth around 390 BC. Later, actually seeing Mercury and Venus as they passed in front of the Sun would prove this fact. Around 330 BC, Pytheas, a Greek geographer traveled to Norway by boat. After observing the strong Atlantic tides, he claims that the Moon causes the tides, but could not explain why.
The people of this era are probably most famous for the constellations. They would play “connect the dots” with the stars and then create myths to explain why the constellations were up in the heavens. Today, we still use these constellations and the names of planets are derived from Greek and Roman gods.
Obviously, the strength of Greek science, especially in astronomy was their ability to observe and document these observations. They would use this information in a variety of ways such as the creation of star maps. These observations were also used to fine-tune the calendar. The basis for calendars was discussed in the previous unit, however, a unique occurrence happened with the construction of the Julian calendar. The Greek astronomer, Sosigenes offered advice to Julius Caesar in 46 BC to adopt a calendar of with three years of 365 days followed by a year of 366 days. We now call this the Julian Calendar. However, in order to make the seasons correct, the year 46 BC had 445 days making it the longest year on record. While we are on the subject of Julius Caesar, he was assassinated in 44 BC. In May of 44, astronomers report seeing a red comet that was visible during the daylight. The comet appears red due to the volcanic ash of Mount Etna, which is erupting during this time. However, many Romans considered the comet to be Caesar who had become a god after his assassination.
Finally, the Chinese also added a great deal to astronomy during this era. In 352 BC, they documented a supernova or the birth of a star. This was the first such recording. They were also famous for compiling star maps starting in 300 BC, which would last for hundreds of years. In 240 BC, the Chinese would record the first visit of Halley’s Comet, as it would later come to be known. They would be the first to record sunspots in the year 165 BC as well as the first to construct a planetarium in 132 AD to keep track of where the stars should be. Lastly, in 300 AD, Chen Zou would combine all the previous star maps into a single map.
What were some astronomical theories that began with the Greeks that were
correct?
What is special about the year 46 BC?
What does “heliocentric” mean?
What does “geocentric” mean?
Why is May 25, 585 BC considered to be the first actual date?
During the Greek civilization we find the true beginnings of earth science or geology. Previous civilizations had used the products of the Earth for their benefit and it is with little speculation that the volcanoes and earthquakes of their time would shock and amaze them. However, it is during the Greek civilization that we get a start at understanding the true dynamics of the Earth. Probably the first incidence of this is in 570 BC when Greek philosopher Xenophanes discovers sea fossils on the tops of mountains. He speculates that the surface of the Earth must have risen and/or fallen in the past.
Most of the geology that took place during this era was in the area of mapping. Navigation about the seas, conquering various civilizations and expanding the Greek and Roman empires were all vital to the construction of maps of the known world. In 500 BC, Greek historian Hecateus developed a map that showed Europe and Asia as semicircles surrounded by an ocean. Obviously, they still had a long way to go. This trait would continue when Poseidonius would incorrectly calculate the world’s circumference. This data would be used 1500 years later in a map made by Paolo Toscanelli and later given to Christopher Columbus. Columbus, using this map, believed that Asia was only 3000 miles west of Europe. As they say, the rest is history. Too bad Columbus didn’t use Strabo’s Geography, which was written in 20 AD. This text combined all known geographical information, including a correct measurement of the size of the Earth. Strabo also speculated that there must be continents occupying the unknown parts of the Earth. Shortly before Strabo’s book came out, around 1 BC, a Roman geographer named Mela claimed that the Equator was so hot that you were unable to cross it. Ptolemy would also play his part as he wrote a book entitled Geographia, which included an atlas of the known world based on the travels of the Roman legions.
The people of this era were also concerned with the volcanoes and earthquakes they experienced, although they had very little knowledge of their causes. Volcanoes were definitely a major source of investigation. In fact, the oldest known record of a volcanic eruption was of Mount Etna in 479 BC. This volcano was responsible for major eruptions in 44 BC that caused so much volcanic ash that the skies were darkened across many continents. The Chinese report crop failures for three years as a result. Mount Etna is still active today and had many eruptions during the summer of 2001. Mythology explained volcanoes as the work of Vulcan, a god who lived underground. Vulcan was a blacksmith and the volcanoes were an aftereffect of his work. Vulcan supposedly lived under Stromboli, a major volcano during ancient times. The Greeks often tried to explain volcanoes. Aristotle noticed that volcanoes were often located near the ocean shore. He claimed that air was forced underground by the action of the waves. The air would reach a mineral that could burn, and the fire would then wish to return to its realm above the Earth. Thus, it would explode from the ground and produce volcanoes.
Romans were inquisitive about volcanoes as well. Sadly, they often found out about volcanoes only after it was too late. The people of Pompeii did not realize that Mount Vesuvius was a volcano, even though Strabo had described its volcanic nature over 300 years earlier. Pompeii was a summer resort city and when the eruptions began on August 24, 79 AD, the city was full of people. Part of the Roman Navy was also anchored outside of Pompeii. The admiral of the fleet, Pliny the Elder was also a scientist and was interested in the volcano. As Vesuvius started to erupt, Pliny went closer for a better look. The city and people of Pompeii would actually be destroyed twice due to Vesuvius. First, clouds of poisonous gas rolled into the city, as people were packing to escape. The people outside of their homes were killed by either falling rocks or the poisonous gases. Those inside their homes died from lack of oxygen. Pliny, himself, escaped to reach the nearby town of Stabiae, where a friend needed rescue. Pliny would meet his death here as he was overcome by poisonous gas. Meanwhile, Pompeii was being destroyed a second time as volcanic ash covered the city. Rain was also falling at this time and turned the ash into cement. This preserved the bodies so well that we can see the clothing and sometimes the expressions on their face as they died. Eventually this would be used as a benefit to Greeks and Romans as they would use volcanic ash mixed with water to make cement as early as 100 BC. The nearby town of Herculaneum was also destroyed. Luckily for science, Pliny the Elder’s nephew, Pliny the Younger, documented all of this. Up until 1982, it was believed the people of Herculaneum had all escaped the destruction. It was at this time that an excavation uncovered a hidden shelter full of the remains of many of the people.
Finally, earthquakes were also studied in this era, but not nearly to the extent that volcanoes were. Earthquakes strike without warning and last only a short period of time. This made earthquakes difficult to study. Because of this, the prediction of earthquakes became the first attempts to study earthquakes. In 132 AD, Zhang Hen constructed the first seismograph to predict earthquakes. This seismograph consisted of a bronze dragon that would drop a ball into the mouth of a bronze frog, depending on the direction the earthquake came from.
How might religious leaders interpret the fact that sea fossils were found on the
tops of mountains?
How did Aristotle claim that volcanoes were formed?
A major area of study during the Greek era was that of natural science. This was an area that the Greeks truly wished to understand. Aristotle, himself, was considered a naturalist. An impetus for much of this study came from the desire to understand from where we came. In 520 BC, Anaximander wrote a book entitled On Nature. This text was the first to introduce any type of evolution. Anaximander assumed that life starts out in slime and eventually moved to drier places.
If you could study anything dealing with nature, what might you pick? If you answered “the human body”, you would be in the largest group. Probably since the dawn of man, we have been trying to understand the workings of the human body. Often, we would study other animals and see how they compared to us. This is called comparative anatomy. In 500 BC, we have record of probably the first experiments done on human cadavers for scientific purposes. The person to conduct these experiments was a Pythagorean physician named Alcmaeon. He discovered the optic nerve, the Eustachian tubes and he described the brain as the center of intellect. A Greek philosopher named Empedocles would later recognize the heart as the center of a system of blood vessels. However, he was mistaken in agreeing with common culture that the heart was also the center of emotions. This view still remains in folk tradition today. Another view of the heart that remains today is the actual shape of the heart. The heart that we picture on Valentine’s cards looks nothing like a human heart. However, the heart’s shape does resemble the shape of a frog’s heart. Perhaps after the dissection of many frogs, this became the standard for the shape of hearts. Praxagoras would take the information about blood vessels a step further in 340 BC, when he distinguished between arteries and veins. Erroneously he claimed that the arteries were responsible for carrying air while the veins carried blood. He made this claim based on the fact that he felt a pulse at the veins. Further study in 280 BC would link the lungs to the circulatory system. The Chinese would lead the way in studying the circulatory system. In 91 BC, they described blood circulation better than any other version prior to William Harvey in 1628. Finally, Roman anatomist Galen became the first physician to use the pulse as a diagnostic aid. He would later compile all medical knowledge in a book. Galen was an excellent observer, although many of his theories were incorrect. He held many public lectures on his knowledge. He was not allowed to perform human dissections and often tried to relate what he saw in animals to humans. His work on digestion, nerve impulses, the spinal cord, blood formation, respiration and the heartbeat would all be contained in his book. This book became the standard for physicians and medicine until the end of the Middle Ages.
Once we decided to study humans more closely, the Greeks wished to do this uniformly and accurately. Hippocrates founded the profession of physicians and created the Hippocratic Oath that doctors still take today. This oath simply states that doctors will use their knowledge to heal and never to harm. Hippocrates also encouraged the separation of medicine and religion.
You read earlier how Alexander the Great brought Aristotle a wide variety of plants and animals. However, Aristotle made many discoveries on his own while he was young. Aristotle spent most of his life along the seashores of Greece. He was able to study the shallow tide pools and was able to witness a wide variety of life forms. His works show us that he studied crabs, starfish, sea anemones and fish very carefully. His writings also tell us that he distinguished about 560 different types of organisms. He dissected many of these animals and was very good at describing the internal anatomies. Aristotle would do such a good job of describing the mouth of a sea urchin that this structure is still called “Aristotle’s lantern” today. Aristotle would then attempt to classify these plants and animals. He divided the animals into eight classes. His first attempt at classifying was based on where the animal lived and how it moved. He realized that this produced many conflicting results and later switched to classifying them by their anatomy and characteristics. Aristotle also had a great interest in blood, the heart and blood vessels.
Aristotle’s student, Theophrastus, would continue this work, especially in the area of plants. Theophrastus was the founder of the Lyceum with Aristotle. Two of his books became the authority on plants and would remain so for 1,500 years. He was one of the first to propose the sexuality of plants, but Rudolph Jakob Camerarius would not experimentally prove this until 1694. Research claims that most of Theophrastus’ knowledge of plants came from the Lyceum’s own garden. However, some of his information must have come from plants brought back by the travels of Alexander the Great.
Why would Praxagoras think arteries carried air and veins carried blood?
What is the function of Eustachian tubes?
How did Aristotle classify organisms?
The major flaw of science during this era was the lack of extensive experimentation. The Greeks tried to use only reason to explain the observations of their world. The use of tests and experiments to prove their theories were not performed. This flaw would hinder most science, but especially that of physical science. In 370 BC, an incorrect statement was made that would hold true for 2000 years. Aristotle claimed that heavier objects fall faster than lighter ones. Simple observation would seem to hold this statement true. It makes perfect sense to believe that rocks fall faster than leaves. Thirty years later, a Greek scientist did conduct an experiment and proved that bodies accelerate during free fall. However, he also supported the thoughts of Aristotle that heavier objects fall faster than lighter ones.
Archimedes would also have an impact on forces and motion, but more for the practical applications of this knowledge. Archimedes built a screw that could be used to raise water, lever and pulley systems to move large objects and proposed many military applications of his inventions. Archimedes is often viewed as an “odd” man. Legend tells us that Archimedes filled a bath, and when he climbed into it, the water overflowed. A naked Archimedes then ran through the streets of Syracuse screaming “Eureka” or “I have discovered it”. What had Archimedes discovered? If you were to weigh the water that spilled out of the tub, you would find it to weigh the same amount as the object floating in the water. Another fun fact is that Archimedes was often plagiarized or copied. Archimedes knew this and would often release false theorems. He would then debate the plagiarist to prove his point.