History

Archimedes: Greatest of the Ancient Scientists

Archimedes was famous in his lifetime as an inventor, yet he did not think his machines were special. He never wrote about them. He, like the Greeks of his time, believed that only ideas, the pure works of the mind, were truly important. As it happened, the world did not learn of Archimedes' important ideas until hundreds of years after his death.

Archimedes was born about 2,300 years ago (287 BC) in the Greek city-state of Syracuse in Sicily. He was the son of an astronomer named Phidias. Though not rich, Phidias had money enough to send Archimedes to Alexandria to study. This great Egyptian city was known throughout the known world for its library, its fine schools and its thinkers. Being educated in Alexandria would be like going to Harvard or Yale today.

Archimedes attended the school founded by Euclid, the father of geometry. No one knows how long he stayed in Alexandria, but he had friends there to whom he wrote throughout his life. His home and his heart were in Syracuse and it was there he chose to work.

When he was thinking about a new idea, or trying to solve a problem, he often became so absorbed that he forgot to eat, to drink, or to bathe! He would draw mathematical figures in the oil on his skin, in ashes on the hearth, and work arithmetic problems in sand strewn on the floor.

But Archimedes was not always serious. He liked to work puzzles for fun. He wrote that he sent some of his mathematical ideas (or theorems) to Alexandria once and purposely added mistakes to them, hoping to catch his friends in his joke.

Archimedes lived to be seventy-five. He died in 212 BC, when Rome invaded Sicily (Second Punic War). Several versions of his death exist. Each gives different details, but nearly every one illustrates Archimedes' remarkable gift of concentration that caused him to ignore the outside world.

All writers seem to agree that the Roman general, Marcellus ordered his soldiers to spare the life of Archimedes, for he held him in great respect. The basic story relates how a soldier found Archimedes. He was staring at the floor, working out a mathematical problem. Not realizing the city was taken, and, perhaps, ignoring questions put to him, Archimedes told the intruder, "Do not disturb my circles." This made the soldier angry and he killed Archimedes with his sword, not knowing he had slain the man his commander sought to save.

Archimedes can speak for himself about his accomplishments in mathematics, geometry and mechanics, for he wrote ten works that survive. Though thousands of years have passed, most people today are familiar with Archimedes' work, whether they realize it or not.

Archimedes first suggested that very large numbers could be represented by "orders" of 10,000. We use his idea when we write exponential notation, or raising a number to a power of ten. For example, if you want to work with a number as large as 1,000,000,000,000,000,000, writing it as 1018 is much easier!

Archimedes calculated the value of pi (the ratio of the circumference of a circle to its diameter) as 3.14. He used mathematics to find a more accurate value than was known before him. When you study geometry, you, too, will work with pi.

The most famous of his discoveries is known as Archimedes Principle, or the law of floating bodies (buoyancy). His insight enabled future scientists to explore Earth's atmosphere using hot-air balloons and to plumb the ocean depths in submarines.

Archimedes made a planetarium, a mechanical model that represented the sun, the earth, the moon and the five known planets (Mercury, Venus, Mars, Saturn and Jupiter). There were arranged so that he could turn a crank to set the bodies in motion. The historian, Cicero, tells us that the Roman general Marcellus found this object so wonderful that he carried it to Rome.

Archimedes improved a device, now called Archimedes' Screw, which is an efficient, human powered pump. It was an open tube with threads inside it, so that when it turned, it could raise water uphill. Egyptian farmers irrigated their fields with it for 2,000 years.

Though he did not invent it, Archimedes formulated the law of the lever. So confident was he of its power that he is reported to have said, "Give me a place to stand on and I will move the earth."

Hearing this, Hiero II, king of Syracuse, challenged Archimedes to put his great boast to the test. The men of the royal navy were having great difficulty trying to move a ship from land to water. Archimedes set up a system of cogs and pulleys that allowed him demonstrate his law. He moved the vessel, all by himself.

Archimedes also helped defend Syracuse against the forces of Rome. His war machines sent missiles flying near and far. He built cranes with an "iron hand" that could grab ships and pull them up from the water. Other cranes would drop great weights onto ships or onto soldiers who tried to scale the city walls. With Archimedes' help, the city held off the army of Marcellus for three years.

Archimedes' famous "eureka" moment is said to have occurred when King Hiero asked for his help. The king had given a weight of gold to a smith to make into a crown (or wreath) meant to be dedicated to the gods. When he received it, Hiero found the weight of the crown equaled the weight of gold, but he was suspicious. Could Archimedes test whether the crown was genuine, without harming it?

Weeks passed while Archimedes thought about the problem. One day, as he stepped into a tub at the public baths, he noticed the amount of water that overflowed depended on how deep he went. The deeper he went into the water, the less his body seemed to weigh. Archimedes realized a floating body would lose weight in the amount equal to the weight of the water it pushed aside. Thinking a little more, he saw that a body submerged under water should push away (or displace) water equal to its volume. All at once, he realized he had the answer. It was in his excitement and haste to test the idea, that Archimedes made his legendary dash without his clothes.

The tale goes on to say that Archimedes dunked Hiero's crown in a bowl of water and found that an amount of silver had been substituted for some of the more precious gold. He is said to have determined the exact amount stolen by the crafty goldsmith. However, experts don't credit this story as fact. Were it true, it is thought that the imaginative Archimedes would have employed a better method than the one described.

If it is not true, why do we repeat the story of Archimedes' bath today? In part, because it makes us giggle. In part, it prompts us to remember Archimedes, a man who loved thinking above all else, and whose ideas continue to help us understand how our world works.

Copyright ©  2005 Christine M. Roane

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