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The Great Scientists of the Ancient World

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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.

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.

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.

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.

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.

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.

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.

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.

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.

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

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

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.

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.

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.

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.

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!”

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!

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.

The goldsmith was immediately executed for his dishonesty.

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.

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.

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.

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

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.

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.

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.

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.

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.

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.

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.

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.

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

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”).

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

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.

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.

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.

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

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.

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.

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

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.

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.

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.

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

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.

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.

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.

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”.

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.

Born around 980, he was a child prodigy who by the age of 10 had memorized the Koran and most of the known Arabic poetry, and by 16 was a qualified physician. His medical skills were legendary and he was the primary physician to the rulers of the day, the princes and caliphs.

Although he had many talents as a poet, astronomer, and physicist, his most notable work was his book entitled al-Qannfi al-Tibb (The Canon of Medicine).

Consisting of over a million words, this huge book was the definitive doctor’s guide to medicine for the next few centuries, not only in his area of the world, but also in Europe.

AbūRayḥān al-Bīrūnī was an Iranian scholar and scientist of the 11th century, and is regarded as one of the greatest scholars of the medieval Islamic era, well versed in mathematics, astronomy, physical and natural sciences, and also distinguished himself as a geographer, historian, chronologist and linguist.

Al-Biruni pioneered early studies comparing the speed of light and sound.

He lived around the same time as IbnSina, and had a special gift for languages.

Among his many contributions, he was the first to establish trigonometry as a branch of mathematics, originally introduced by the Greek mathematician and astronomer Hipparchus.

He was the first to introduce the idea that light travels faster than sound, that the Earth rotates on its axis, and he accurately measured the density of 18 precious stones and metals. He also noted that flowers have 3,4,5,6 or 8 petals, but never 7 or 9.

And now you know about:

Euclid, Archimedes, Hipparchus, Ptolemy, Al-Khwārizmī, IbnSina(Avicenna), and Al-Biruni

The Great Scientists of the Ancient World