Finding True North

Here’s some food for thought: what do your credit cards, washing machines, and headphone speakers all have in common?

Give up? Or did you guess it? All of these devices work using the properties of magnets. In the 21st century, magnetism has been harnessed to meet an impressive array of technological demands, from electromagnetic generators to advanced medical imaging. Astronomers can study the magnetic fields of celestial bodies to better understand their composition. Closer to home, the Earth’s magnetic field is responsible for the high concentrations of atmospheric ions that produce the aurora borealis, or Northern Lights. Eventually, magnets may be used in an effective long-term solution to Earth’s energy crisis: a controlled nuclear fusion reactor [1].

Magnetic technologies underly many of the 20th century’s most important inventions. However, it is only recently – within the last hundred years or so – that scientists have begun to understand how magnets work at all. For much of human history, magnets were a complete and total mystery, a bizarre abnormality that scientists could only guess at understanding.

And guess they did! For over two thousand years, scientists, philosophers, and laymen alike recorded their best guesses as to the origin of magnetism. This brief article will delve into how magnetism was understood throughout history, highlighting some of the funnier “theories” that developed along the way.

Table of Contents

Lodestone & The Ancient Greeks

The first mention of magnetism in recorded history can be found in the writings of the Ancient Greeks, who described the attraction of iron to lodestone in the 6th century BCE. Lodestone is a naturally occurring magnetic mineral, commonly known now as magnetite (Fe₃O₄).

Thales of Miletus, an ancient Greek philosopher, reasoned that lodestone may cause motion because it is imbued with “soul” or life force. This fit generally with the philosophy of Ancient Greek civilization; three hundred years later, Aristotle cited Thales’ theories in a treatise on the kinds of souls possessed by different living things [2].

Five hundred years after Thales first described magnetism, the poet Lucretius published his famous De Rerum Natura, a poem written to explain Epicurean philosophy – including atomic theory – to the Romans. Lucretius wrote:

First of all it must needs be that there stream off this stone
Very many seeds, or an effluence
Which, with its blows, parts asunder all the air which has its place
Between the stone and the iron.
When this space is emptied, and much
Room in the middle becomes void, straightway
First beginnings of the iron start forward
And fall into the void

(For the record, I think it should still be socially acceptable to publish major research findings in poem form. Anyone else? No?)
Lucretius asserted that the lodestone’s magnetic properties resulted from the discharge of a stream of particles (atoms) pushing air aside and creating a vacuum-like space, which iron fillings are then sucked into. He applied this “atomic stream” reasoning to other phenomena as well. Lucretius asserted that this same atomic stream was responsible for the smell of salt on an ocean breeze, or the cold sensation we feel when touching a frozen object.

Lodestone attracting iron filings. Image from Wikipedia.

While Lucretius’s theory of magnetism was entirely wrong, it was a creative expression of existing ideas toward the problem of magnetism, for which he should be given due credit. Lucretius’s guess as to the origin of lodestone’s mysterious powers would remain humanity’s most sensible endeavor on the subject for over a millenium.

The 17th Century & William Gilbert's "Little Earth"

Aristotle’s description of the “soul” being responsible for lodestone’s magnetic properties remained the dominant theory until the early 17th century. Given what relatively little was known about the stone at the time, society took it upon themselves to fill in the gaps with tall tales and nonsense. Some argued that, when placed under the head of a sleeping woman, a lodestone would “drive her out of bed if she be an adultress.” Some believed that having the stone on their person would enable them to speak eloquently. Others believed it would help them pick locks, or make their husbands more agreeable to them. Many believed that a weakened lodestone could be restored by the blood of a buck. Lodestone was even purported to save women from witchcraft [3].

Has your spouse been acting strangely? She might be a witch! Make sure to get that treated with some magic rocks.

Such superstition ruled dominantly until the year 1600. That year, William Gilbert, an English astronomer, physician, and physicist, published De Magnete, a treatise containing more knowledge about magnetism than all the rest of society had managed to accumulate up to that point.
Gilbert humorously began his work by launching into an enthusiastic tirade against the “disgraceful stupidities” often circulated on the subject of lodestone. A forward thinking Cambridge scholar, Gilbert published findings directly subverting Aristotelian philosophy, which common men beheld as the “wisdom of the ancients.” He seemed to take a sort of sadistic pleasure in tearing down each and every popular misconception about magnetism. On those who attempted to use magnetism in medicine, he remarked, “Thus do pretenders to science vainly and preposterously seek for remedies, ignorant of the true causes of things.”
Gilbert addressed the rest of his collection to those who “not only in books, but in things themselves look for knowledge.” His stance boiled down to, “If you doubt me, recreate my experiments and show me that I am wrong. I dare you.”
With his tirade out of the way, Gilbert reported on numerous significant experiments regarding lodestones. He found that iron, when drawn into a long wire, acts like a lodestone [3]. Based on his experiments with electricity, he correctly argued that electricity and magnetism were fundamentally different (although he arrived at this correct conclusion through incorrect logic). And, in his most substantial experiment, he demonstrated that the Earth itself had a magnetic field. He did so by first fashioning a small sphere made of lodestone – provocatively named a “terella,” meaning “little Earth.” Gilbert then positioned a compass needle in various locations around his terella. The compass needle, of course, pointed in different directions when moved around the sphere, in much the same way that a compass needle will point in different directions at different locations around the Earth.

William Gilbert's terella.

Angles of force on the terella.

Mesmer Magic

Gilbert’s experiments represented the first significant headway made on the subject of magnetism. However, this would not stop a wave of pseudoscientific magnetic therapies from sweeping across Europe in the early 19th century. Around this time, a gang of hustlers began to con their way to a dishonest living through the power of “magnetic healing.” The most notorious of these hypnotists was a German named Franz Mesmer. Mesmer claimed that his “animal magnetism” approach could cure nervous disorders, improve medications, and determine with great accuracy the origin, nature, and progress of even the most deadly diseases [1].

The practice of animal magnetism, in which ailments were treated by the removal of "obstructions" to the flow of "magnetic fluid" in the body, became popular in the early 19th century.

Of course, this was entirely rubbish. But animal magnetism became quite a popular form of alternative medicine. And given that much of conventional medicine throughout history was hardly any less off base, maybe Franz should be forgiven for the faults of his approach. In the 19th century, therapies were often more harmful than the diseases they were purported to cure. By comparison, having a “mesmerist” pass you over with some magnetic rocks would seem like an attractive option.
In fact, animal magnetism became so popular that competition from other “healers” threatened Mesmer’s business model. Franz angrily insisted that the other healers were frauds, and that only he possessed “the gift” required to treat patients. To sort out these disputes, the French Academy of Sciences created a committee to assess the veracity of animal magnetism. Among the committee’s members were some of the most respected minds of that generation – including Antoine Lavoisier, the “father of chemistry,” and the United States’ very own Benjamin Franklin.

Commission on animal magnetism, circa 1814. Image from Wikimedia Commons.

The committee arranged a series of tests, which included recruiting a 12-year old boy found particularly susceptible to “animal magnetism” treatments to help with their investigation. They had the boy, blindfolded, hug three trees, one of which had been “magnetized.” The boy convulsed upon hugging one of the trees, but it was not the one that had been treated. These and other tests informed the committee’s result: that so-called “animal magnetism” was not a legitimate phenomenon, and that “magnetic healing” worked entirely through the power of suggestion.

Into the Modern Era

James Maxwell first described the relationship between electric and magnetic fields, which results in the phenomenon we know as "light."

Later in the 19th century, a Scottish physicist named James Maxwell discovered that electric and magnetic fields are intimately linked. A changing magnetic field produces an electric field, and vice versa, and the two oscillate in tandem in an “electromagnetic wave” known as a photon. This illuminating discovery (heh) paved the way for a greater understanding of the origin of magnetism.
In the 1920’s, the transition of the field of physics from classical to quantum mechanics eventually empowered physicists to explain the majority of known magnetic phenomena. It is now generally understood that magnetism arises from the motion of electrical charges, be that via an electrical current or the inherent “spin” of electrons.
That said, skepticism is alive and well in the modern age. If you enter any local bookstore, you’re likely to find a section titled “Mind, Body, and Spirit” containing info on various alternative therapies, including animal magnetism.
So what can you do?
In all of these stories on magnetism, one theme held true: experiment reigns king. The proponent that tested their theories by way of experiment was eventually proven correct. So, as an observer to science, you should be encouraged to be critical. Make scientists earn your trust by proving and demonstrating their claims thoroughly with a well-designed experiment.

Anyone can claim to be a scientist! The most trustworthy source is a published experiment.

I hope you enjoyed this brief bit of science history! I always find that I’m more interested in topics when I know more about how humans came to understand them. As always, feel free to provide feedback or ask me questions about this writing, which was mainly inspired by my reading of Steve Blundell’s Magnetism: A Very Short Introduction (which I highly recommend).
Particularly, if you enjoyed the smaller, history-focused article format, let me know and I’ll produce more content like this!
Till next time!

References

S. Blundell. “Magnetism: A Very Short Introduction.” 2012. Oxford University Press.
Aristotle. “On The Soul.” 2011 (Distributed 350 BCE).
W. Gilbert. “De Magnete.” 1958 (Distributed 1600 CE).
P. Peregrinus. “The Letter of Petrus Peregrinus on the Magnet.” 1904 (Distributed 1296 CE). McGraw Publishing Company.