A Short History of Science – Part I
By Tim Lambert
Ancient Greek Science
The Ancient Greeks were the first scientists. Greek philosophers tried to explain what the world is made of and how it works. Empedocles (c. 494-434 BC) said that the world is made of four elements: earth, fire, water and air. Aristotle (384-322 BC) accepted the theory of the four elements. However he also believed that the Sun, Moon and planets are made of a fifth element and are unchanging. Aristotle also studied zoology and attempted to classify animals.
Aristotle also believed the body was made up of four humors or liquids (corresponding to the four elements). They were phlegm, blood, yellow bile and black bile. If a person had too much of one humor they fell ill.
Although some of their ideas were wrong the Greeks did make some scientific discoveries. A man named Aristarchros believed the Earth revolved around the Sun. Unfortunately his theory was not accepted. However Eratosthenes (c.276-194 BC) calculated the circumference of the Earth.
Arab Science
Among Arab scientists was a mathematician called al-Khwarizmi (790-850), the philosopher al-Kindi (801-866) and the astronomer al-Farghani. Two great Arab doctors were al-Razi (824-925) and Ibn-Sina (980-1037).
Another Arab scientist was the astronomer al-Sufi (903-986). Another man named al-Haytham (965-1040) realized that light is reflected off objects into the eye. He also discovered that light travels in straight lines.
The Scientific Revolution of the 16th Century and 17th Century.
In the 2nd century AD a man called Ptolemy stated that the Earth is the center of the universe. The sun and the other planets orbit the Earth. In the 16th century a Pole called Nicolaus Copernicus (1473-1543) realized this is untrue. The Earth and the other planets orbit the Sun. However his theory was not published until just before his death.
Another great astronomer of the 16th century was Tycho Brahe (1546-1601). He made accurate observations of the positions of stars. However Brahe did not accept the Copernican theory. Instead he believed that the Sun revolved around the Earth and the other planets revolved around the Sun.
Moreover in 1572 Brahe saw a new star (a nova). The Greek philosopher Aristotle said the heavens were unchanging. Change and decay, he said, only happened on Earth. Obviously Aristotle was wrong.
Tycho Brahe was followed by Johannes Kepler (1571-1630). In the 16th century people believed that the planets move in circles. Kepler showed they orbit the Sun in ellipses and they move faster as they approach the Sun. Kepler published two laws of planetary motion in 1609. He published a third in 1619. Furthermore in 1604 Kepler published a book on Optics.
One of the most famous early scientists was Galileo. Aristotle said that if two objects, a heavy one and light one both fall from a height the large one will reach the ground first. According to legend Galileo tested the theory by dropping two different weights from the leaning Tower of Pisa. Both hit the ground at the same time.
However many people now believe this famous experiment is a myth. it never actually took place. In any case other scholars had already reached the conclusion that Aristotle was wrong.
Then in 1609 Galileo heard of a new invention from Holland. A man named Hans Lippershey had invented the telescope. Galileo made his own telescope and soon improved it.
Using a telescope Galileo was able to see several things invisible to the naked eye. Firstly he could see many stars not visible without a telescope. Secondly the ancient Greeks believed that the Moon was smooth. Looking through a telescope Galileo could see the Moon's surface is actually rough, with mountains and craters. He also discovered four small 'moons' orbiting the planet Jupiter. At the time these were astonishing discoveries. Until then nobody knew that any of the other planets, apart from Earth, had 'moons'.
In 1610 Galileo wrote a book called Siderius Nuncius or the Sidereal Messenger.
At that time astronomers were debating sunspots. A German named Christoph Scheiner claimed that they were satellites of the sun. In 1613 Galileo argued that sunspots are actually on the surface of the sun.
Copernicus also argued that the earth and the other planets orbit the sun. At first the church did not have a problem with his theory. However opinion gradually hardened and in 1616 the Copernican theory was declared heretical.
There is a passage in the Old Testament where a prophet named Joshua commanded the sun to stand still in the sky (Joshua 10:12-13). Some scholars said this meant the sun must move. Of course, Joshua knew nothing about Astronomy. To him the sun appeared to move across the sky. Naturally he would command the sun to stand still and to him it would have appeared to stand still. The church's objection to the Copernican theory was based on a misinterpretation of the Bible.
However Galileo was a resolute supporter of the Copernican theory. In 1632 he published a book called Dialogue Concerning the Two Chief World Systems. As a result he was summoned to Rome to be examined by the Inquisition. He arrived in January 1633. Galileo was threatened with torture unless he renounced the Copernican theory. Not surprisingly he agreed to do so. Nevertheless he was put under house arrest for the rest of his life.
In 1634 Galileo published a book about mechanics called Dialogue Concerning Two New Sciences. Then in 1637 he noticed that the moon moves slightly from side to side.
At this time doctors made great progress in understanding how the human body works. In 1628 William Harvey published his discovery of how blood circulates around the body. The Roman writer Galen said that blood passes from one side of the heart to the other through the septum. However by 1555 the great surgeon Vesalius had reached the conclusion that no such holes exist and that blood cannot pass from one side of the heart to the other in that way.
In 1559 a man named Realdo Colombo demonstrated that blood actually travels from one side of the heart to the other through the lungs.
Eventually William Harvey realized that the heart is a pump. Each time it contracts it pumps out blood. Harvey then estimated how much blood was being pumped each time.
A Roman writer named Galen believed that the body constantly makes new blood and uses up the old (rather like an engine using up petrol). However Harvey realized this is not true. Instead the blood circulates around the body.
In the 17th century medicine was helped by the microscope (invented at the end of the 16th century). In 1658 a man named Jan Swammerdan first observed red blood corpuscles. In 1661 Marcello Malpighi discovered capillaries. Then in 1665 Robert Hooke was the first person to describe cells in his book Micrographia.
Meanwhile Britain's oldest scientific society began in 1645 a when group of philosophers and mathematicians began holding meetings to discuss science or natural philosophy as it was called. Charles II was interested in science and in 1662 he granted them a charter and they became the Royal Society.
Isaac Newton is Britain's greatest scientist. In 1668, he invented a reflecting telescope.
Newton published his masterpiece Philosophiae Naturalis Principia Mathematica in 1687. It set out his theory of gravity and his laws of motion. Newton realized that there is a universal force (gravity) that attracts all objects in the universe to each other. His theory of gravity explained the movements of the planets. In 1704 Newton also published a book on light called Optics. Newton showed that white light is made up of several colors.
Meanwhile in 1704 he published another great work about light.
Many other scientists worked in the late 17th century. Christiaan Huygens (1629-1695) discovered Titan, the moon of Saturn. In 1656 he made the first pendulum clock, which made accurate measurement of time possible.
A man named Antonie van Leeuwenhoek (1632-1723) made his own microscopes and through them he made many observations.
Meanwhile in 1661 Robert Boyle (1627-1691) published the Skeptical Chemist, which laid the foundations of modern chemistry. Boyle rejected the Greek thinker Aristotle's idea that the world is made up of four elements, water, earth, fire and air. Boyle is also famous for Boyle's law (The volume of a gas kept at constant temperature is inversely proportional to its pressure).
We would like to thank Tim Lambert, author of this article, for the permission to republish his article on our website. To see the original article and many more on history, please visit http://www.localhistories.org
A Short History of Science – Part I – Comprehension Questions
1. What was the theory of four humors?
2. What was Copernicus' great discovery and why was it declared heretical by the Church?
3. Which discoveries were helped by the invention of the telescope and the microscope?