Magnet is not invented by man, it is natural magnetite. The ancient Greeks and Chinese discovered a naturally magnetized stone in nature and called it "magnetite". The stone can magically pick up small pieces of iron and always point in the same direction when swung at will.
Early navigators used this magnet as their earliest compass to identify directions at sea. The first people to discover and use magnets should be the Chinese, that is, they used magnets to make "the compass", which is one of the four great inventions in China.
After thousands of years of development, today magnets have become a powerful material in our lives. By synthesizing alloys of different materials, the same effect as magnetite can be achieved, but the magnetic force can also be improved.
Man-made magnets appeared in the 18th century, but the process of making stronger magnetic materials was slow until Alnico was made in the 1920s. Subsequently, ferrite (Ferrite) was produced in the 1950s, and rare earth magnets were produced in the 1970s [Rare Earth magnets include neodymium iron boron (NdFeB) and samarium cobalt (SmCo)]. So far, magnetic technology has developed rapidly, and strongly magnetic materials have also made components more miniaturized.
The earth itself has a very strong magnetic field, so people themselves have a kind of adaptation and even dependence on the magnetic field. Weak and stable magnetic fields are beneficial to the body, and magnetic therapy is often used in medical treatment. Electromagnetic waves, on the other hand, are high-energy waves whose frequencies can have adverse effects on the body. Therefore, magnets are not harmful to the human body.
Magnet bracelets are neither harmful nor beneficial to the human body. There are nuclear magnetic fields in medical equipment, and high magnetic fields of more than 3T are not harmful to the human body. It is generally accepted that NMR is the safest of all medical equipment in the radiology department. In other words, people are not afraid of magnetic fields, but more afraid of rays. The high magnetic field does have a certain negative impact on the human body, but the magnet content in the magnet bracelet is limited, so it is impossible to cause any impact on the human body. Some people claim that magnets provide a magnetic force that changes physiological tissues, and even believe that each cell has positive and negative poles, and others claim that magnets can improve blood circulation. In fact, there is no evidence that there is any interaction between human tissue cells or blood and magnetic fields. Iron ions in red blood cells are not only non-ferromagnetic, but even diamagnetic, and will not be attracted by magnetic fields. It is well known that hot compresses can promote blood circulation. The result is that the skin will turn red. If magnets can really promote blood circulation, why is there no redness on the skin that is in direct contact with the magnets?
The effect of magnetic therapy is only the so-called psychological suggestion ability, and there is no very direct and obvious medical effect. The magnet bracelet continuously stimulates the microcirculation system of the wrist through weak magnetic lines of force, which has a very weak effect on promoting blood circulation, improving the physiological magnetic field of the human body, and eliminating fatigue. It is indeed good for sleep, but not much. Wearing a magnet bracelet for a long time will not harm the human body.
But if the magnetic field strength of the magnet is very strong. Generally speaking, magnets with a magnetic field strength of more than 3000 are harmful to the human body. The harm to the human body below this standard is minimal.
The penetrating force of the magnetic field will harm the central nervous system, cardiovascular system, etc., and have an important impact on biological growth, life activities and behavior habits.
