What are the records of magnetic and electrical phenomena in China?

Ancient knowledge about magnetism was quite rich. Our ancestors' understanding of magnetism began in the iron smelting industry. A lot of knowledge about magnetism is recorded in ancient books. There is an essential connection between magnetism and electricity. Some ancient records of electrostatic phenomena, such as triboelectrification, electromagnetic phenomena of terrestrial light and aurora, are only juxtaposed with magnetic phenomena.

In ancient China, Guanzi was published in the late Spring and Autumn Period. Tujiao, Guiguzi in the Warring States Period, Lu Chunqiu at the end of the Warring States Period, etc. , all describe the natural magnet and its iron absorption phenomenon, and also describe the world's oldest compass "Sina". After Qin Shihuang unified the whole country, his conscious achievements can be compared with those of the three emperors and five emperors. He thinks the palace in Xianyang, the capital, is too small to show his majesty to the world. In 2 12 BC, he ordered the construction of a huge palace community, Epang Palace, in the south of Weihe River and west of Zaohe River, where the Shanglin Garden in Wangjiayuan is located.

According to legend, when Qin Shihuang built the north gate of Epang Palace, he made skilled craftsmen "tired of magnets", so it was called "magnet gate". The magnet door adopts the principle of "magnet summons iron", which is similar to the modern security door.

The function of the magnet door is: first, to prevent assassins, the iron absorption of the magnet makes the hidden armor unable to pass; Second, it is also called "Bird Humen" in order to show the magical power to the "four foreign dynasties" and make them afraid of infidelity.

The construction of the magnetic gate reflects the superb scientific and technological level of Qin State. This is the first time in the history of our country and even the world, and it can be said to be a great pioneering work in the history of world science and technology.

In fact, as early as 2000 years ago, the working people in ancient China began to deal with magnetism. In the constant contact with magnets, people gradually understand some of its characteristics and use these characteristics to serve mankind.

In the process of searching for iron ore, the ancients will inevitably encounter magnetite, which is a magnet. The earliest record of magnets in China's ancient books is in The Tube? In "Tujiao": "Those who have compassion stones on the top have copper and gold on the bottom. "

The ancients compared the iron absorption characteristics of magnets to the love between mother and child, and thought that "stone is also the mother of iron." Because there is a kind stone, it can lead its son; Stone is unkind and cannot be cited. Therefore, in the early Han Dynasty, the "magnet" was written as a "ci stone". Chen Wei, a Taoist priest in the Song Dynasty, and Yan Yu, a Taoist scholar, both discussed the problem of magnets absorbing iron.

After discussion, it is considered that the magnet attracts iron because of the inherent reason of the magnet itself, which is determined by the internal "qi" relationship and "harmony of spirit" between iron and magnet.

Liu Xianting, a geographer in the late Ming Dynasty, also thought in his Miscellanies of Yang Guang that magnets attract iron because they have the characteristics of "blocking each other". Liu Xianting also understood the magnetic shielding effect of iron as "the principle of nature".

This view of trying to explain natural phenomena by nature itself is materialistic. Considering the scientific level at that time, this is the only explanation.

In ancient China, the absorption of iron by magnets was also used in production. Zhu Yan, a scholar in Qianlong period of Qing Dynasty, wrote A Shuo, which recorded that when white porcelain was burned in ancient times, iron filings in glaze water were filtered by magnets. Because if the plain porcelain is stained with iron filings, there will be black spots after firing.

Magnets are also used for medical treatment. In the Compendium of Materia Medica written by Li Shizhen, a medical scientist in the Ming Dynasty, it is recorded that people in the Song Dynasty used magnets to attract iron to perform some surgical operations, such as sucking some tiny iron foreign bodies into their eyes or mouths. This has developed into a special magnetic therapy in modern times, showing good curative effect on arthritis and other diseases.

China's record that the earth's magnetic field can magnetize iron objects can also be found in some works. For example, Ito quoted in the eighth volume of Fang Yizhi's Physical Notes that "the iron bar is long and uniform, and it also guides it."

The horizontal components of declination, inclination and geomagnetic field are called "three elements of geomagnetism". Europeans discovered the magnetic declination during Columbus' voyage in 1492, and the magnetic declination was discovered later. In China, magnetic declination and magnetic dip were discovered much earlier.

The method of making a compass described in the official military work General Theory of Jason Wu in the Northern Song Dynasty contains some geomagnetic knowledge. Even the knowledge about magnetic dip angle is embodied in this magnetization method. Because the northern end of the compass is inclined downward when magnetized, it implies that people at that time have realized the existence of inclination.

The authoritative document on magnetic declination discovered so far is Meng Qian Bi Tan written by Shen Kuo in the Northern Song Dynasty.

Shen Kuo's contributions to magnetism are as follows: first, he gave the artificial magnetization method; Second, he pointed out for the first time in history that the geomagnetic field has a magnetic declination; Thirdly, he discussed four installation methods of compass, which laid the foundation for making compass for navigation. In addition, Shen Kuo also studied the phenomena of light and electricity in the atmosphere.

From the later development of geomagnetism, we know that the magnetic declination changes with the change of position, and the magnetic declination of the same position changes with the passage of time. These changes are caused by the constant changes of the earth's magnetic poles.

In the Southern Song Dynasty, the situation that the magnetic declination varied from place to place was recorded more clearly and applied to the Kanyu compass.

In Yuan, Ming and Qing Dynasties, the compasses of Kanyu were also equipped with sewing needles, and the directions of sewing needles of compasses made in different periods and regions were also different. This can be regarded as the original record of China's ancient deflection angle changing with time and place.

In physics, magnetism and electricity are essentially related. It is meaningful for the ancients in our country to link magnetic phenomena with electrostatic phenomena and unify them into "Qi". Later, people observed electrostatic attraction more deeply and found some special situations.

For example, during the Three Kingdoms period, people already knew that "amber does not take rotten mustard". Amber is a kind of resin fossil, which has good insulation performance and can attract light and small objects after friction. This phenomenon has been widely known since the Han Dynasty.

"Rotten mustard" refers to rotten mustard seeds, which must be full of water, so they are sticky, easy to stick to other objects and difficult to absorb.

In addition, the water vapor evaporated from rotten mustard makes the surrounding air and the desktop in contact with it wet, which makes it easy to conduct electricity. When the rotten mustard is close to the charged body, the induced charge is easily taken away by the humid air around it, so the electrostatic attraction must be very small.

It can be seen that "amber doesn't take rotten mustard" is not only a fact, but also in line with the electrical principle, and it is also a conclusion drawn by people's in-depth observation and research on triboelectrification.

The ancients thought that amber was really amber when it was easily charged under human friction. It can be seen that the ancients already knew whether there were obvious electrostatic properties as the standard to distinguish between true and false amber, which was the practical application of preliminary electrical knowledge.

Under certain conditions, triboelectrification will cause Mars with slight noise. This phenomenon called "electroluminescence" was also found and recorded from time to time in ancient times.

Zhang Hua's "Natural History" in the Jin Dynasty records: "People comb their hair and undress, and there is a hiss when they comb their hair." Two phenomena are recorded here, one is friction electrification between comb and hair, and the other is friction electrification between coats and underwear made of different materials.

Ancient combs, with lacquer wood, bones or keratin, are easy to get charged when rubbing hair; Silk, fur and other clothes are easy to get charged when they rub against each other. When the weather is dry and the friction is high, there can be sparks and sounds.

Of course, this Mars and sound are very weak, and the ancients can detect it, which shows that it is very careful and serious.

Besides thunder and lightning, electromagnetic phenomena observed in ancient times also has the characteristics of terrestrial light and aurora.

China ancient local chronicles recorded the most terrestrial light. For example, Chengdu Records records that1before the Chengdu earthquake on February 4, 993, "a fire went into the ground"; According to Zheng De, on February 30th, 15 13, Sichuan "saw a fireboat in the air, which sounded like thunder, and the Wusu earthquake occurred the next day"; According to the records of Yingshang County, 1652 On March 24th, when Yingshang earthquake occurred in Anhui Province, "red light spread all over the city".

In all these words, "firelight", "fireboat" and "red light" are all nouns used by the ancients to describe terrestrial light.

These records are accurate and vivid, and they are extremely precious materials in the history of science. Their significance lies in that the ground light can reflect the activity of rock strata, which is closely related to earthquakes, especially helpful to the prediction of impending earthquakes.

Aurora is divided into northern lights and southern lights. Our country is located in the northern hemisphere, so we can only see the Northern Lights. There are many opportunities to see aurora in high latitudes, and occasionally in middle and low latitudes, but the brightness is much weaker.

It is generally believed that the aurora is caused by the influence of the earth's magnetic field on countless charged particles emitted by the sun, and their moving directions have changed. They descend to the upper layer near the north and south poles along the earth's magnetic field line and drill into the atmosphere at high speed. These charged particles collide with molecules and atoms in the atmosphere, causing the atmosphere to ionize and emit light. This is Aurora.

All kinds of atoms emit different colors of light, so the aurora is colorful, usually yellow-green, but there are also white, red, blue, gray-purple, or both.

Aurora has been recorded for a long time in ancient China. Thousands of years ago, during the legendary period of the Yellow Emperor, there was a "big lightning around the big dipper".

The bamboo annals of the Warring States recorded an aurora around 950 BC: "In the last years of King Zhao of Zhou, the night was bright and colorful. That year, Wang Nan did not come back. " It describes the time, direction and color of the aurora, and is the earliest and most detailed aurora record in China, more than 600 years earlier than in the west. There are abundant records about aurora in ancient China. At that time, there was no name for aurora, but it was named according to the shape, size, movement, change and color of various aurora phenomena.

This classification nomenclature was first seen in historical records? Official books show that it has a history of at least 2000 years.

Aurora is an important topic in the study of the relationship between the sun and the earth, which is closely related to astrophysics and geophysics. The historical materials of aurora recorded in ancient times can help people understand the changing laws of solar activity, geomagnetic field and ionosphere in the past, and also explore the changing process of paleomagnetic pole position.