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 Aristarchus 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.
Advances in Astronomy
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 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. 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 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 Aristotle. He said that if two objects, a heavy one and a 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 concluded that Aristotle was wrong.
Galileo
Then in 1609, Galileo heard of a new invention from Holland. A man named Hans Lippershey 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 rough, with mountains and craters. He also discovered 4 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 Sidereus 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.
Advances in Medicine
At that time doctors made great progress in understanding how the human body works. In 1628 William Harvey published his discovery of how blood circulates 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 concluded 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 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 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 Swammerdam 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.
Britain’s oldest scientific society began in 1645 when a 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.
Science in the 17th Century
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.
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.
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 a constant temperature is inversely proportional to its pressure).
Science in the 18th Century
During the 18th century, chemistry made great advances. In 1751 a man named Axel Cronstedt discovered nickel. In 1766 Henry Cavendish (1731-1810) isolated hydrogen and studied its properties. (He also calculated the density of the Earth). In 1772 Daniel Rutherford (1749-1819) discovered Nitrogen. In 1774 n discovered oxygen. In 1756 Joseph Black (1728-1799) discovered carbon dioxide.
Perhaps the greatest chemist of the 18th century was Antoine Lavoisier (1743-1794). He discovered that during combustion oxygen combines with substances. He also discovered the role of oxygen in respiration and the corrosion of metals. Meanwhile, during the 18th century, people began to realize that the Earth is very old. A landmark in geology came in 1785 when James Hutton (1726-1797) published his book Theory of the Earth.
In 1781 the astronomer William Herschel (1738-1822) discovered the planet Uranus. In 1784 John Goodricke (1764-1786) discovered variable stars. Two great biologists of the 18th century were Georges Leclerc, Comte de Buffon (1707-1788), and Karl Linnaeus (1707-1778). Linnaeus invented a method of classifying living things.
Meanwhile, people began to investigate electricity. In 1746 a man Petrus van Musschenbroek (1692-1761) invented a way of storing electricity called a Leyden jar. In 1800 Alessandro Volta (1745-1827) invented the first chemical battery.
However, during the 18th century medicine made slow progress. Doctors still did not know what caused diseases. Some continued to believe in the four humors (although this theory declined during the 18th century). Other doctors thought infectious diseases were caused by ‘miasmas’ (odorless gases in the air).
Science in the 19th Century
During the 19th century, science made great progress. In 1808 n (1766-1844) published his atomic theory. According to the theory, all matter is made of tiny, indivisible particles. Dalton also said that atoms of different elements had different weights. John Dalton also studied color blindness. In 1827 the German chemist Friedrich Wohler (1800-1882) isolated aluminum. In 1828 he produced urea, an organic compound from inorganic chemicals. A Russian, Dmitri Mendeleev (1834-1907) formulated the Periodic Table, which arranged all the known elements according to their atomic weight.
Meanwhile, people continued to master electricity. In 1819 a Dane, Hans Christian Oersted discovered that an electric current in a wire caused a nearby compass needle to move. The Englishman Michael Faraday (1791-1867) invented the dynamo. In 1847 the German Hermann von Helmholtz (1821-1894) formulated the law of the Conservation of Energy, which states that energy is never lost but just changes from one form to another. In 1851 he invented the ophthalmoscope.
Meanwhile, geology made huge strides. Charles Lyell (1797-1875) saw that rocks were formed by processes we see today. In 1830 he published his book Principles of Geology. In 1837 a Swiss, Louis Agassiz (1807-1873) realized that a vast sheet of ice had once covered northern Europe. Furthermore, scientists discovered more and more fossils and the word Dinosaur was coined in 1842.
In 1831 Darwin sailed on the Beagle. In February 1832 the Beagle reached Brazil. Darwin spent three years in different parts of South America collecting specimens. Then in September 1835, the Beagle sailed to the Galapagos Islands. Darwin was surprised to learn the local people could tell by looking at a tortoise on which island it came from. Darwin also studied finches. Each island had a different species of finch. Later Darwin concluded that all were descended from a single species of finch. On each island, the finches diverged and became slightly different.
By 1836 Darwin believed that species of animals could change. In October 1838 Darwin thought of a way in which one species could change into another. He noticed that individual members of a species vary. Furthermore, all animals are competing with each other to survive. If the environment changed in some way, say if a new, faster predator appeared then any herbivores that could run slightly faster than other members of its species would be more likely to survive and reproduce. Any herbivores that ran slightly slower than most would be more likely to be eaten. Slowly a new, faster herbivore would evolve. This was later called the survival of the fittest. Darwin’s monumental work On the Origin of Species was published in 1859. It proved to be a bestseller.
In 1866 an Austrian monk named Gregor Mendel discovered the laws of hereditary by breeding peas.
Furthermore, medicine and surgery made great advances in the 19th century. There were several outbreaks of cholera in Britain. It struck in 1832, 1848, 1854, and 1866. During the 1854 epidemic, John Snow (1813-1858) showed that cholera was transmitted by water. However, doctors were not certain why. Later Louis Pasteur (1822-1895) proved that microscopic organisms caused disease. In the early 19th century many scientists believed in spontaneous generation i.e. that some living things spontaneously grew from non-living matter. In a series of experiments between 1857 and 1863, Pasteur proved this was not so. Once doctors what caused disease they made rapid headway in finding cures or prevention.
In the late 19th century physics made great strides. In 1873 James Clerk Maxwell (1831-1879) showed that light is an electromagnetic wave. He also predicted there were other electromagnetic waves with longer and shorter wavelengths than light.
Then in 1888, Heinrich Hertz (1857-1894) proved the electromagnetic waves predicted by Maxwell exist. In 1896 Henri Becquerel (1852-1908) discovered radioactivity. Then in 1898 Marie Curie (1867-1934) and Pierre Curie (1859-1906) discovered radium and polonium.
At the end of the century, scientists began to investigate the atom. In 1897 Joseph Thomson discovered the electron. In astronomy, Giuseppe Piazzi discovered the first asteroid, Ceres in 1801. In 1838 Friedrich Bessel (1784-1846) measured the distance to a star (61 Cygni) for the first time. The planet Neptune was discovered in 1846.
Science in the 20th Century
During the 20th century, science continued to go forward at fantastic speed. Scientists came to understand the atom. In 1910 Ernest Rutherford (1871-1937) discovered the atomic nucleus. He realized that almost all the mass of an atom is in the nucleus with electrons orbiting it. In 1932 James Chadwick (1891-1974) discovered the neutron.
Physics was revolutionized by two men, Max Planck (1858-1947) and Albert Einstein (1879-1955). In 1900 Planck proposed quantum theory, which states that energy is exchanged in discrete packets he called quanta. Einstein published his theory of Special Relativity in 1905 and his General Theory of Relativity in 1915. In 1927 Werner Heisenberg (1901-1976) published his uncertainty principle, which states that is impossible to determine the position and speed of a subatomic particle.
In 1915 Alfred Wegener proposed continental drift. He said that all continents were once joined and they have drifted apart.
In 1926 Arthur Eddington (1882-1944) suggested that stars are powered by nuclear fusion. Also in the 1920s, Edwin Hubble (1889-1953) showed that our galaxy is only one of many galaxies. He also proved that the universe is expanding. In 1930 Clyde Tombaugh discovered Pluto. The first radio telescope was built in 1937.
Medicine was making great advances. In 1928 Alexander Fleming (1881-1955) discovered penicillin. Meanwhile, genetics was making great strides. In 1953 Francis Crick and James Watson discovered the double-helix structure of DNA. At the end of the 20th century, genetic engineering became possible.
In astronomy, quasars were discovered in 1963 and pulsars were discovered in 1968. The Hubble Space Telescope was launched in 1990.
At the end of the 20th century, the first extrasolar planets were discovered. At the other end of the scale, scientists discovered many new sub-atomic particles. In 1964 Murray Gell-Mann (1929-) suggested that quarks exist. The most famous physicist of the late 20th century and early 21st century was Stephen Hawking (1942-2018). Hawking was known for his research into black holes, relativity, and cosmology.
Last revised 2024