Inventions and Discoveries of Ancient Greek Scientists

Thales of Miletus (c. 620 - c. 546 BCE)

Thales was a geometer, military engineer, astronomer, and logician. Probably influenced by Babylonians and Egyptians, Thales discovered the solstice and equinox and is credited with predicting a battle-stopping eclipse thought to be on 8 May 585 B.C. (the Battle of Halys between Medes and Lydians). He invented abstract geometry, including the notion that a circle is bisected by its diameter and that the base angles of isosceles triangles are equal.

Anaximander of Miletus (c. 611- c. 547 BCE)

The Greeks had a water clock or klepsydra, that kept track of short periods of time. Anaximander invented the gnomon on the sundial (although some say it came from the Babylonians), providing a way to keep track of time. He also created a map of the known world.

Pythagoras of Samos (Sixth Century BCE)

Pythagoras realized that the land and sea are not static. Where now there's land, there once was sea and vice versa. Valleys are formed by running water and hills are eroded by water.

In music, he stretched the string to produce specific notes in octaves after having discovered the numerical relations between the notes of the scale.

In the field of astronomy, Pythagoras may have thought of the universe as rotating daily around an axis corresponding to the axis of the Earth. He may have thought of the sun, moon, planets, and even the earth as spheres. He is credited with being the first to realize the Morning Star and Evening Star were the same.

Presaging the heliocentric concept, a follower of Pythagoras, Philolaus, said the Earth revolved around the "central fire" of the universe.

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A History of Ancient Greek Physics

By Andrew Zimmerman Jones

Anaxagoras of Clazomenae (born about 499 BCE)

Anaxagoras made important contributions to astronomy. He saw valleys, mountains, and plains on the moon. He determined the cause of an eclipse—the moon coming between the sun and Earth or the Earth between the sun and the moon depending on whether it's a lunar or solar eclipse. He recognized that the planets Jupiter, Saturn, Venus, Mars, and Mercury move.

Hippocrates of Cos (c. 460-377 BCE)

Previously, illness had been thought to be a punishment from the gods. Medical practitioners were priests of the god Asclepius (Asculapius). Hippocrates studied the human body and discovered there were scientific reasons for ailments. He told physicians to watch especially when fever peaked. He made diagnoses and prescribed simple treatments like diet, hygiene, and sleep.

Eudoxus of Knidos (c. 390–c. 340 BCE)

Eudoxus improved the sundial (called an Arachne or spider) and made a map of the known stars. He also devised:

• A theory of proportion, which allowed for irrational numbers
• A concept of magnitude
• A method for finding areas and volumes of curvilinear objects

Eudoxus used deductive mathematics to explain astronomical phenomena, turning astronomy into a science. He developed a model in which the earth is a fixed sphere inside a larger sphere of the fixed stars, which rotate around the earth in circular orbits.

Democritus of Abdera (460-370 BCE)

Democritus realized the Milky Way was composed of millions of stars. He was the author of one of the earliest parapegmata tables of astronomical calculations. He is said to have written a geographical survey, as well. Democritus thought of the Earth as disk-shaped and slightly concave. It was also said that Democritus thought the sun was made of stone.

Aristotle (of Stagira) (384–322 BCE)

Aristotle decided the Earth must be a globe. The concept of a sphere for the Earth appears in Plato's Phaedo, but Aristotle elaborates and estimates the size. 

Aristotle classified animals and is the father of zoology. He saw a chain of life running from the simple to more complex, from the plant through animals.

Theophrastus of Eresus - (c. 371–c. 287 BCE)

Theophrastus was the first botanist we know of. He described 500 different types of plants and divided them into trees herbs and shrubs.

Aristarchus of Samos (? 310-? 250 BCE)

Aristarchus is thought to be the original author of the heliocentric hypothesis. He believed the sun was immovable, like the fixed stars. He knew that day and night were caused by the Earth turning around on its axis. There were no instruments to verify his hypothesis, and evidence of the senses—that the Earth is stable—testified to the contrary. Many did not believe him. Even a millennium and a half later, Copernicus was afraid to reveal his heliocentric vision until he was dying. One person who did follow Aristarchus was the Babylonian Seleucos (fl. mid 2nd century BCE).

Euclid of Alexandria (c. 325-265 BCE)

Euclid thought that light travels in straight lines or rays. He wrote a textbook on algebra, number theory, and geometry that is still relevant.

Archimedes of Syracuse (c. 287-c. 212 BCE)

Archimedes discovered the usefulness of the fulcrum and lever. He began the measurement of the specific gravity of objects. He is credited with having invented what is called the screw of Archimedes for pumping up water, as well as an engine to throw heavy stones at the enemy. A work attributed to Archimedes called The Sand-Reckoner, which Copernicus probably knew, contains a passage discussing Aristarchus' heliocentric theory.

Eratosthenes of Cyrene (c. 276-194 BCE)

Eratosthenes made a map of the world, described countries of Europe, Asia, and Libya, ​created the first parallel of latitude, and measured the circumference of the earth.

Hipparchus of Nicaea or Bithynia (c.190-c.120 BCE)

Hipparchus produced a table of chords, an early trigonometric table, which leads some to call him the inventor of trigonometry. He cataloged 850 stars and accurately calculated when eclipses, both lunar and solar, would occur. Hipparchus is credited with inventing the astrolabe. He discovered the Precession of the Equinoxes and calculated its 25,771-year cycle.

Claudius Ptolemy of Alexandria (c. 90-168 CE)

Ptolemy founded the Ptolemaic System of geocentric astronomy, which held for 1,400 years. Ptolemy wrote the Almagest, a work on astronomy that provides us with information on the work of earlier Greek astronomers. He drew maps with latitude and longitude and developed the science of optics. It is possible to overstate the influence of Ptolemy during much of the next millennium because he wrote in Greek, while western scholars knew Latin.

Galen of Pergamum (born c. 129 CE)

Galen (Aelius Galenus or Claudius Galenus) discovered nerves of sensation and motion and worked out a theory of medicine that doctors used for hundreds of years, based on Latin authors like Oribasius' inclusion of translations of Galen's Greek in their own treatises.