The Great Scientists of the Ancient World

1. Euclid Archimedes Hipparchus Ptolemy Al-Khwārizmī IbnSina (Avicenna) Al-Biruni The Great Scientists of the Ancient World This presentation was partially developed from the 2005 book The Great Scientists, from Euclid to Stephen Hawking, by John Farndon, published by Metro Books, New York, NY.

2. The Great Ancients Over the centuries, from the ancient civilizations to modern times, countless scientists and mathematicians have contributed to the vast body of knowledge we now have at our disposal.

3. The Great Ancients Each in turn stood on the shoulders of those who came before, adding their own contribution to their world, and some even disproving long-standing beliefs, often causing great turmoil and controversy.

4. The Great Ancients Of the many, we will study just a few who really stood out, making truly significant impacts on their worlds and ours. We first take a look at The Ancients, the ones who started it all, and on whose shoulders we all stand.

5. EUCLID Euclid, known as the “Father of Geometry”, was a Greek mathematician who wrote the Elements, a book about geometry, the mathematics of shape. This book is the basic framework of geometry studied in high schools and colleges today.

6. EUCLID Euclid’s geometry is often called plane geometry, and is all about points, lines, shapes, and solid figures, including triangles, rectangles, circles, parallel lines, prisms, pyramids, cones, cylinders, spheres, and so on.

7. EUCLID The Elements used geometry to teach logic and deductive reasoning, using postulates and previously proven statements called theorems to show evidence and proof about what is true, and not just making intuitive leaps, claiming something is true just because it seems to be true or just makes sense.

8. EUCLID Euclid’s life is mostly a mystery, but it is believed he lived around 300 BC, probably in Alexandria, Egypt, the home of the great Museum and Library of Alexandria, the most remarkable intellectual and educational institution in the ancient world, where he most likely was a teacher.

9. EUCLID Euclid did not invent geometry. Previous civilizations like the Babylonians and Egyptians showed evidence of that knowledge with their structures, like the ziggurats of Babylon and the pyramids of Egypt. He was simply the first to codify all of that knowledge into a book.

10. ARCHIMEDES Archimedes was a Greek mathematician, inventor, engineer, and considered by many to be the greatest scientist of the ancient world.

11. ARCHIMEDES He was born in 287 BC and lived most of his life in Syracuse, a frontier seaport town on the east coast of the island of Sicily, an island at that time constantly caught between the warring powers of Rome and Carthage, who fought what are known as the Punic Wars. Syracuse, Sicily

12. ARCHIMEDES Legend has it that Archimedes declared to King Heiron II of Syracuse, “Give me a place to stand and I will move the Earth”, speaking of course of using his pioneering work in the study and application of leverage, one of the six simple machines we study in physics.

13. ARCHIMEDES To demonstrate this theory, the story goes that he setup a series of levers and pulleys, enough to launch a 4,064 ton luxury ship called the Syracusia, which had been beached. Many men with ropes had failed to move the ship off the beach, but Archimedes performed the feat all by himself with the system he had devised.

14. ARCHIMEDES As a young man Archimedes studied at the great Museum and Library of Alexandria, Egypt, the greatest center of learning of the ancient world, most likely studying with the great masters of the time, including Eratosthenes, the man who correctly calculated the circumference of the earth, as depicted by Carl Sagan in the first Cosmos episode.

15. The “Eureka” solution The most famous Archimedes anecdote is the “Eureka” story, when he made one of his most significant discoveries. He was asked by King Herion of Syracuse to determine whether a wreath had been made of pure gold, or if it was mixed with silver by the goldsmith to try and cheat the king out of some of the gold that was supplied to make it.

16. The “Eureka” solution It took him a while to figure it out, but as he was taking a bath one day, watching the water level rise as he lowered himself into the tub, it finally dawned on him, and that was when he uttered his famous cry, “Eureka”, which means, “I’ve got it!”

17. The “Eureka” solution Here is his solution: First he immersed in water a piece of pure gold that weighed exactly the same as the wreath and marked the water level that had been displaced. He then immersed the wreath itself into the same water container and noted that the water level of displacement was higher than the piece of gold!

18. The “Eureka” solution This proved that the wreath was NOT pure gold, and that the goldsmith had indeed cheated the king out of some his gold. Proof:Since silver weighs less than gold, it would take more silver mixed with the gold to create the same weight as the piece of pure gold, thus creating more volume, and thus displacing more water than the pure gold.

19. The “Eureka” solution The goldsmith was immediately executed for his dishonesty.

20. ARCHIMEDES Although his many engineering feats and inventions were remarkable, he considered his contributions to mathematics and geometry theory to be his greatest achievements. His favorite one, and the one he asked to be inscribed on his tomb, was his proof that the volume of a sphere is exactly two-thirds of the cylinder that contains it.

21. ARCHIMEDES’ Death Archimedes died in 212 BC when a Roman officer lost his patience waiting on him to finish some work and stabbed him to death. The Roman commander Marcellus, who had just invaded Syracuse during the Second Punic War between Rome and Carthage, had wanted very much to meet this legend, who was now a very old man, perhaps near 80 years old.

22. ARCHIMEDES’ Death Marcellus asked for someone to find him and bring him to his tent, and commanded that he was not to be harmed. Unfortunately, the word didn’t reach the Roman officer who was sent to get him, and when Archimedes refused to budge, he said, “Don’t disturb my circles!”, the last words he ever spoke.

23. HIPPARCHUS Hipparchus was a Greek astrologer, astronomer, geographer, and mathematician of the Hellenistic period. He is considered the founder of trigonometry.

24. HIPPARCHUS Not much is known about the life of Hipparchus, but he was apparently famous enough to have his face on Roman coins after his death.

25. HIPPARCHUS He was born in Nicaea (now Iznik, Turkey), and lived most of his life on the island of Rhodes, (home to the Colossus of Rhodes, one of the Seven Wonders of the Ancient World) studying weather patterns and how they were affected by the movements of the moon and stars.

26. HIPPARCHUS Working together with Ptolemy, another great scientist of that day, he compiled the first comprehensive catalogues of the stars in the sky, constructed systems for working out the motion of the Sun and Moon, and much more.

27. HIPPARCHUS In 134 BC, he spotted a rare phenomenon, a new star, or nova, in the night sky – there was not to be another such sighting until Tycho Brahe spotted one in 1572.

28. HIPPARCHUS This inspired Hipparchus to compile a catalogue of all the 850 or so stars whose positions were then known, which was so accurate that it was used for almost 1800 years as the definitive catalogue of the known stars.

29. HIPPARCHUS Hipparchus established the star rating system, giving each one a magnitude number from one to six, depending on how bright it looked. The brightest star he observed was Sirius (the Dog Star), which he called a First Magnitude star. The faintest stars he called Sixth Magnitude.

30. HIPPARCHUS Hipparchus biggest mistake was to assume that the Earth was the center of the solar system, the long held belief, shared and published by his colleague Claudius Ptolemy, that wasn’t corrected until the time of Galileo and Copernicus, many centuries later.

31. HIPPARCHUS His greatest contribution to mathematics was the early development of trigonometry, the mathematics of triangles, which he used to calculate precise positions of stars, and today is used for many more important applications.

32. HIPPARCHUS His most famous discovery was that the earth “wobbles” as it rotates on its axis.

33. PTOLEMY We know of Hipparchus’s work partly because it was developed by the astronomer Claudius Ptolemy (sometimes spelled Ptolemaeus - AD 90-168), who wrote four books summarizing Greek astronomical ideas, including the famous Almagest (Arabic for “The Greatest”).

34. PTOLEMY Ptolemy as a person is even more obscure than Hipparchus. We know he was Greek and lived in Alexandria, but that’s about it.

35. PTOLEMY Ptolemy was also the name used by the Egyptian family of rulers who followed Alexander the Great, and caused some confusion during that time, and still does today, causing some to think Claudius Ptolemy was of that family, which is not true at all.

36. PTOLEMY Ptolemy I, the first of that Egyptian dynasty, is credited for founding the great Library of Alexandria in the 3rd century BC, which flourished for 300 hundred years until Julius Caesar “accidentally” burned it to the ground in 48 BC.

37. DESTRUCTION OF THE ALEXANDRIA LIBRARY Parts of the library were salvaged and survived for several more years, but eventually, after repeated attempts to save the library, and later attempts to destroy it again, the entire library was completely obliterated, wiping out most of the knowledge of the ancient scientists and scholars.

38. PTOLEMY Ptolemy’s most famous book, Almagest, provided a complete system for the movements of the heavens, indicating an Earth centered planetary system.

39. PTOLEMY This became known as the Ptolemaic system, and was believed for 1500 years, until it was overturned in the 16th century by Copernicus and his followers, who correctly proposed the sun-centered theory.

40. AL-KHWARIZMI Muhammad ibnMūsā al-Khwārizmī was a Persian mathematician, astronomer and geographer, a scholar in the House of Wisdom in Baghdad, and made many significant contributions to the field of mathematics, including the invention of Algebra.

41. AL-KHWARIZMI It is believed that he was born in the year 786 and lived in what is now Uzbekhistan in Central Asia.

42. AL-KHWARIZMI One of his greatest contributions was to write a book called On Hindu Numerals, a comprehensive guide to the Hindu numbering system which originated in India around 500 AD.

43. AL-KHWARIZMI It is this system, later called the Arabic system because it came to Europe from al-Khwarizmi, that became the basis for our modern base ten number system.

44. AL-KHWARIZMI This system was a huge advance on every previous system, including the Roman system, which used I, V, X, and so on, very difficult to use and do even the simplest calculations.

45. AL-KHWARIZMI When the Arabic system reached Europe, it very quickly caught on and is now the one truly global “language”.

46. AL-KHWARIZMI When his book was translated into Latin, the new title of the book was based on his Arabic name, Algoritmi de numeroIndorum, which created another word, algorithm, which came to mean a logical step-by-step process for solving a problem or performing a task.

47. AL-KHWARIZMI In addition to his contribution of the Hindu/Arabic number system, al-Khwarizmi also is credited with the development of algebra, at the time a whole new branch of mathematics, and which today is the foundation for all higher level mathematics.

48. AL-KHWARIZMI The Arabic word al-jabr means “completion”and another word al-muqabalameans “balancing”, both key concepts in the transformation and simplification techniques that permeate the algebraic process.

49. AL-KHWARIZMI Although he most likely studied previous scholars who had similar ideas, like Euclid and the Hindu mathematician Brahmagupta, he was the first to codify the system of algebra, and is now correctly referred to as the “Father of Algebra”.

50. IBN-SINA (AVICENNA) AbūAlī al-ḤusaynibnAbdAllāhibnSīnā (also known by his Latinized name Avicenna) was a Persian scientist, mathematician, and physician, who wrote almost 450 treatises on a wide range of subjects, and wrote probably the greatest book on medicine for a thousand years.