The history of the development of electrodynamics. Magnetism

Two years ago, for graduate school, he wrote an essay on the history of the development of electrodynamics. And then I remembered about him and decided to make several blog entries out of him, which is good enough to disappear. :) True, while preparing this post from the essay, little remained in its original form, but this is even good. But then the main thing for me was to pass it, and now you can dig into all sorts of interesting books and links and supplement it with interesting facts.

Magnetism

When exactly the permanent magnets were discovered is unknown, but already in the 5th century A.D. magnetism was famous. At least at that time they already knew that the pieces of magnetite suspended on a rope, the large deposits of which were in the ancient city of Magnesia, are always oriented in the same direction. Actually, the name “magnetism” comes from the name of the city of Magnesia, which was located on a tributary of the Meander river. This city is often called Magnesia on Meander, because there was another city with the same name - Magnesia at Cypilus. Now Magnesia on Meander is called Manissa and is located in Turkey.

In China, the first magnetic compass began to be used already in the II century BC. to indicate the direction of movement in the deserts, it can therefore be said that the Chinese used magnetism even then, although for Europe the invention of the compass occurred in the 12th – 13th centuries AD (according to other sources in the 9th century).

Thales of Miletus

By this time, magnets were used, but not particularly studied. In addition, then they already knew that amber is able to attract pieces of wool, and this was also attributed to magnetic phenomena. The first researchers include, for example, Thales of Miletus (640/624 - 548/545 BC). He suggested that the magnet has a “soul” and declared the properties of the magnet precisely with the help of it. Actually, this is where his achievements in magnetism end.

Averroes

The Arab thinker Abu al-Walid Muhammad ibn Ahmad ibn Rushd, also known as Averroes (1126 - 1198), made an interesting assumption at that time that the magnet distorted the space around it in accordance with the shape of the magnet.

In 1269, Pierre Peregrin from Maricourt published the manuscript “A Treatise on Magnets,” in which he described many of the properties of a magnet. In fact, this manuscript was originally just a letter to a friend. Peregrine is not a surname, but a nickname that can be translated in a modern way as a pilgrim, pilgrim, wanderer, traveler to holy places. Then, during the time of the Crusades, such a nickname was not difficult to get. Moreover, Peregrin took part in hostilities, and wrote a treatise letter in the military camp of Karl of Anjou, who besieged the city of Lucher.

It was Peregrin who discovered (or at least described) that there are poles of a magnet, and wrote that two magnets should be attracted, or, as he put it, “copulate,” with opposite poles. He also talked about the repulsion of magnets, if they are brought to each other by poles of the same name. He also noticed that if a piece of magnetic ore is broken in half, then each of the fragments also has two poles. True, the word “pole” Peregrin did not use, he talked about the places of the magnet, where the “magnetic effect” is especially great. Besides Peregrine with the help of magnets was going to make a perpetual motion machine.

William Hilbert

But William Hilbert (1540 - 1603) did especially much for the development of magnetism. Moreover, he was a doctor of medicine, but became interested in magnets after reading the “Treatise on Magnets” of the same Peregrin (and also, perhaps, because then magnets were used as a laxative :)) and later published his work “On a magnet, magnetic bodies and a large magnet - Earth ”, in which he accurately classified the known properties of the magnet. His most famous experiment was set up to explain the magnetism of the Earth. Hilbert made a ball from magnetic ore and investigated how the ball does not operate a small iron arrow. He found a similarity between the behavior of this arrow and the behavior of the inclinator arrow (a compass needle rotating on a horizontal axis) near the Earth and concluded that the Earth is a giant magnet. Hilbert also suggested that “a magnetic action spills out on each side” of a magnetic body (a concept that vaguely resembles the lines of force that Faraday would discover in the 19th century). He discovered that when a magnet is heated above a certain temperature, its magnetic properties disappear; subsequently, this temperature (588 ° C) was called the Curie point, in honor of Pierre Curie. Hilbert discovered that when a piece of iron is brought closer to one pole of a magnet, the other pole begins to attract more. This idea was patented 250 years after the death of Hilbert. Here is another stone in the garden of patents, be they wrong. :) He also discovered the magnetization of iron, if it lies near a magnet. which will be discovered by Faraday in the 19th century). He discovered that when a magnet is heated above a certain temperature, its magnetic properties disappear; subsequently, this temperature (588 ° C) was called the Curie point, in honor of Pierre Curie. Hilbert discovered that when a piece of iron is brought closer to one pole of a magnet, the other pole begins to attract more. This idea was patented 250 years after the death of Hilbert. Here is another stone in the garden of patents, be they wrong. :) He also discovered the magnetization of iron, if it lies near a magnet. which will be discovered by Faraday in the 19th century). He discovered that when a magnet is heated above a certain temperature, its magnetic properties disappear; subsequently, this temperature (588 ° C) was called the Curie point, in honor of Pierre Curie. Hilbert discovered that when a piece of iron is brought closer to one pole of a magnet, the other pole begins to attract more. This idea was patented 250 years after the death of Hilbert. Here is another stone in the garden of patents, be they wrong. :) He also discovered the magnetization of iron, if it lies near a magnet. This idea was patented 250 years after the death of Hilbert. Here is another stone in the garden of patents, be they wrong. :) He also discovered the magnetization of iron, if it lies near a magnet. This idea was patented 250 years after the death of Hilbert. Here is another stone in the garden of patents, be they wrong. :) He also discovered the magnetization of iron, if it lies near a magnet.

Hilbert did a lot and discovered. But Hilbert could hardly explain anything. No, he tried to explain, but it turned out quite original. Here, for example, is how Hilbert explains the fact that when cutting one long magnet, many short ones are formed, which have the original direction of magnetization and tend to maintain their former position in space. He compares the magnet to a tree branch:

“Let AB be a leafy twig of willow ... A is the top, B is the bottom, toward the root. They divided it into C. I affirm that the end A, inserted again in B following the rules of vaccination, adheres to it; in the same way, if B is inserted into A, then they are bonded to each other and give sprouts. But if D is inserted into A or C in B, then they enter into a struggle and never grow together, but one end dies as a result of an improper and inappropriate connection, since the plant power that follows one path now tends to go in opposite directions ... ”

And indeed he tried to explain magnetism with the help of the very same “soul of magnet” that Thales spoke of.

And it was Hilberg who first separated electricity from magnetism, and it was after this that electricity and magnetism began to be studied separately. Moreover, it was Hilbert who introduced the very concept of “electricity”. By electricity, he began to understand the attraction of a piece of amber wool. Before him, this phenomenon was considered a kind of magnetism. He tried to establish which substances resemble amber in their electrical properties and which are not. Here is the first use of the word “electric” in history:

“Electric bodies are those that attract in the same way as amber” (Gilbert V. “On the magnet”, chapter “Explanation of some words”).

And the Latin word “electricus” means “Amber”. He showed that diamonds, sapphires, rock crystal, glass, sulfur, salt, etc. can also attract wool and other small objects.

But about electricity (or rather, about electrostatics) will be next time.

References

G. Linson. Great experiments in physics. 1972
Magnesia on Meander
V. Kartsev. A magnet for three millennia
William Gilbert
Thales of Miletus
Abu al-Walid Muhammad ibn Ahmad ibn Rushd

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