From Lodestones to Levitation: A History of Magnets

The Greeks and Thales of Miletus: According to legend, a Greek philosopher named Thales of Miletus noticed that a particular type of rock, later called magnetite, attracted pieces of iron. This marked the beginning of human recognition of the magnetic force. The word "magnet" comes from Magnesia, the region in Greece where this type of stone was found.

The Chinese and Lodestone: Around the same time, the Chinese were also discovering the properties of magnetism. They used a mineral called lodestone, another form of magnetite, for its ability to attract iron. Historical records suggest the development of the first compass, known as a "south-pointing chariot," around the 2nd century BC. This ingenious invention may have used lodestone suspended on a platform or in water to align with the Earth's magnetic field, aiding navigation on land and sea.

Sometime in the 11th century, it was discovered that a piece of iron rubbed against a lodestone would get magnetised. This led to the development of the magnetic compass, which, in turn, opened up the oceans to human exploration.

These early compasses were likely simple affairs, with a magnetized needle placed on a piece of wood or cork that floated in water. The needle would align itself north-south, and the user could read the direction from markings on the floating platform.

Over time, compass designs improved. In the 18th century, advancements were made in balancing the compass needle and compensating for magnetic declination, leading to more accurate readings.

The development of the magnetic compass caused a sea change (what else? 😊) in navigation. It allowed sailors to venture further out of sight of land, leading to the Age of Exploration and groundbreaking discoveries, including a complete New World!

Even today, despite the emergence of modern electronic navigation systems, the magnetic compass remains a valuable tool. Its simplicity, reliability, and low cost makes it a dependable backup for navigation, particularly in situations where electronic devices might fail.

For centuries, people used naturally magnetic rocks called lodestones. These weren't truly man-made, but they were harnessed for their magnetic properties.

The credit for the first documented artificial magnets goes to Englishman Servington Savery around 1730. His innovation involved combining multiple pieces of magnetic steel, creating a "compound magnet" with stronger and more permanent magnetism.

Gowin Knight produced the first artificial magnets for sale around 1740. These magnets could have been targeted towards scientific investigators or terrestrial navigators who needed compasses.

William Gilbert, a 17th-century English scientist, is widely regarded as a pioneer in the study of magnetism and electricity. A key invention of his was the Terrella, a magnetized sphere that acted as a miniature Earth. By observing compass needles interact with the terrella, Gilbert concluded that the Earth itself behaved like a giant magnet, explaining why compass needles consistently pointed north-south, a phenomenon that had puzzled philosophers for centuries.

Building on his observations of the terrella, Gilbert introduced the concept of magnetic poles. These are the regions on Earth where the magnetic force is strongest, analogous to the poles on a bar magnet. He identified the Earth's north and south poles as corresponding to these magnetic poles.

His influential book, "De Magnete," published in 1600, revolutionized our understanding of magnetism. He also recognized electricity as distinct from magnetism, noting it couldn't be continuously produced from the same material.

The book inspired other scientists like Galileo Galilei and Johannes Kepler. It laid the foundation for further exploration of electromagnetism and helped pave the way for future advancements in science.

The story of magnets is intricately entwined with that of electricity. Discoveries in electricity during the 18th century laid the foundation for later breakthroughs. Scientists like Benjamin Franklin, famous for flying a kite in a thunderstorm, began to unravel the nature of electrical charges. In 1820, Hans Christian Ørsted, a Danish physicist, made a monumental discovery. He observed that an electric current flowing through a wire could deflect a compass needle, proving a clear link between electricity and magnetism. This sparked a new field of study: electromagnetism. Building on Ørsted's work, André-Marie Ampère subsequently developed a theory of electromagnetism. He discovered how the strength and direction of a magnetic field depended on the current flowing through a conductor.

In 1831, Michael Faraday, a prolific English scientist, made several significant contributions. He discovered electromagnetic induction, where a changing magnetic field can induce an electric current in a conductor. This principle is the foundation for transformers and electric generators.

 

In 1865, James Clerk Maxwell, working closely with Faraday, published the set of four elegant equations that unified the concepts of electricity and magnetism, showing that they were different manifestations of the same underlying force, the electromagnetic force.

In 1905, Albert Einstein, with his Special Theory of Relativity, further solidified its principles and revealed the deeper connection between electricity and magnetism.

In 1824, William Sturgeon, a British scientist, built the first electromagnet by wrapping a wire around a horseshoe-shaped iron core and passing a current through it. This invention paved the way for more powerful and controllable magnetic applications.

Five years later an American inventor named Joseph Henry (1797 to 1878) made a far more powerful version of the electromagnet. Henry demonstrated the potential of Sturgeon's device for long distance communication by sending an electronic current over one mile of wire to activate an electromagnet which caused a bell to strike. Thus the electric telegraph was born, which made (almost) instantaneous communications over vast distances possible. Henry's name has since been immortalised in science as the unit of electrical inductance, as has Faraday's name for capacitance.

the 1930s, two scientists at the Tokyo Institute of Technology, unintentionally stumbled upon a new magnetic material. They were researching "soft" ferrites, which is a type of material prized for its ability to be easily magnetized and demagnetized, making them ideal for applications like transformers and inductors. However, they made a small mistake in the composition, which resulted in the creation of the first Ferrite permanent magnets. Even today, while other types of magnet materials like rare-earth magnets offer stronger magnetic fields, ferrites remain popular due to their cost-effectiveness and other desirable characteristics like low cost, good corrosion resistance and reasonable temperature tolerance.

Then came the revolutionary Alnico magnets. Made from a clever combination of aluminum, nickel, and cobalt, these magnets boasted a significant jump in strength compared to their predecessors. Their unique crystal structure allowed for a better alignment of magnetic domains within the material, essentially packing more punch into a single magnet. Being both powerful and affordable, this advancement propelled permanent magnets into widespread use, powering motors, loudspeakers, and even finding a place in musical instruments like electric guitars.

The 1960s saw the arrival of the first rare-earth magnets, with Samarium-Cobalt (SmCo) leading the charge. These magnets were not only substantially stronger, but also held their own against heat, making them ideal for high-performance motors and hot environments.

Finally, the 1980s witnessed the crowning achievement - Neodymium (NdFeB) magnets. Currently the strongest permanent magnets available, these tiny powerhouses are a marvel of material science. A combination of neodymium, iron, and boron, they offer exceptional strength in a compact size. This breakthrough revolutionized countless industries, allowing for the miniaturization of motors and electronic devices without sacrificing power.

The story of magnets isn't over yet. Imagine a world where clean energy flows freely. Powerful magnetic fields hold the key to achieving fusion power, a clean and sustainable energy source. Magnets could also revolutionize refrigerators (and not as fridge magnets!), using their properties to create a cooling effect without harming the environment. Storing all this clean energy wouldn't be a problem either. Scientists are developing magnetic materials that could store vast amounts of energy, making renewable sources like solar and wind power even more reliable.

Transportation is about to get a magnetic makeover too. Maglev trains, which use magnets to glide effortlessly, could become commonplace. Even electric vehicles could get a boost from advancements in magnets, making them travel farther and perform even better.

In the world of medicine, tiny magnetic nanoparticles could become doctors' new allies, delivering medicine directly to diseased areas. Improved MRI machines, powered by cutting-edge magnetic materials, could provide doctors with a clearer picture of what's happening inside our bodies.

So next time you see a magnet, remember, it's not just holding up a grocery list. It's a tiny seed holding the promise of a future filled with incredible advancements, all thanks to the invisible force of magnetism!