2017年1月22日星期日

The History and Legend of Magnets

Magnetism was discovered thousands of years ago, and magnets have been used for many purposes ever since.  However, there is a great deal of mystery and controversy surrounding the discovery of magnetism.  We'll explore some of the various legends about magnets, including how they were discovered and some of their first uses.

Around approximately 2500 B.C.E., a young shepherd boy named Magnes lived near Mount Ida in Greece, a mountain commonly mentioned in Greek mythology.  According to the legend, Magnets used to wear sandals with iron soles.  He often found it difficult to climb up the mountain where he tended his sheep because of the excessive amounts of natural magnetic mineral, or lodestone, that was present in the rock and soil of the mountain.  The Greeks called the material "magnets" in honor of his discovery, and this is how we have come to use the word "magnet" today.

The first historical use of lodestones was the development of the compass around the 8th century AD by the Chinese.  The first recorded use was documented by Zheng He of the Yunnan province.  Between the years 1405 and 1433, Zheng He recorded his voyages across seven oceans.  The compass Zheng used had markings for points of the constellations found by the use of the Sextant, but the center of the compass was a spoon shaped device made from lodestone.  In later centuries, the lodestone was replaced with a metal needle that was magnetized by vigorously rubbing it against a piece of lodestone.  From Zheng He's time forward, no wise sailor would venture out into the ocean without two critical navigational instruments, the compass and the sextant.

The Greek philosopher Aristotle spoke about magnets more than 300 years before the birth of Christ.  He wrote about magnets and their use in pain reduction.  During that time, it is said that doctors used magnets therapeutically to reduce muscle spasms and treat gout.

Cleopatra reportedly wore a piece of magnetic jewelry on her forehead to suppress wrinkles and preserve youth.  It is said that she believed so strongly in the value of magnetic power, that she routinely slept on bed constructed of lodestone to enhance her youthful appearance.  Who knows how well this did or did not work, given that she only lived to the age of 39.

In 1777 A.D., France's Royal Society of Medicine conducted an in depth study about the history of magnets and their use in medical practice.  In spite of some skepticism and ridicule from mainstream medical authorities of that time, the Royal Society concluded that magnets could be used medicinally to cure back and neck pain, headaches, circulation problems, sore throats, and numerous other complaints.

Prior to 1820, the only magnetic substances know to man were lodestone and other metals that had been rubbed against a lodestone to magnetize them.  In 1820, a scientist named Hans Christian Oersted, a professor of Science at Copenhagen University, noted that every time he switched on an electric current near a compass, the direction of the needle moved.  Over the next several months he worked diligently to try to explain and understand the logic of what he had observed.  His studies led to the electromagnet as we know it today.  Though Hans Christian Oersted did not develop the electromagnet, his experiments directly led to this new and important technology and a newfound understanding of physics.
Flat neodymium rectangular magnets for industry

From the earliest recorded knowledge of lodestone and magnetism thousands of years ago, our understanding of magnets has grown exponentially.  Today magnets play a role almost every technologically advanced device we use, including computers, automobiles, and cell phones.  While we do not know what new magnet technologies the future will hold for human kind, we can be certain of one thing.  As our understanding and knowledge of magnets continues to improve, the way we harness and utilize magnetism will continue to expand and develop as well.

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