Place: Russian Federation
Subject: biography, physics
English physician and physicist who performed fundamental pioneering research into magnetism and also helped to establish the modern scientific method.
Gilbert was born in Colchester, Essex, on 24 May 1544. He was educated at St John's College, Cambridge, where he graduated in medicine in 1569 and later became a fellow. In about 1573 he settled in London, where he established a successful medical practice, and in 1599 he was elected president of the Royal College of Physicians. In the following year he was appointed personal physician to Queen Elizabeth I, and was later knighted for his services to the queen. On Elizabeth's death in March 1603 he was appointed physician to her successor, James I, but Gilbert held this position for only a short time because he died on 10 December of that year.
Although successful as a physician, Gilbert's most important contribution to science was his research into magnetism and electrical attraction, which he described in his book De magnete, magneticisque corporibus, et de magno magnete tellure/Concerning Magnetism, Magnetic Bodies, and the Great Magnet Earth (1600). This work gave a detailed account of years of investigations (on which he is thought to have spent some £5,000 of his own money), which were rigorously performed. The importance of this work was recognized by Galileo, who also considered Gilbert to be the principal founder of the experimental method - before the work of Francis Bacon and Isaac Newton. Not only did Gilbert disprove many popular but erroneous beliefs about magnetism - that lodestone (naturally occurring magnetic iron oxide, the only magnetic material available until Gilbert discovered a method for making metal magnets) cured headaches and rejuvenated the body, for example - but he also discovered many important facts about magnetism, such as the laws of attraction and repulsion and magnetic dip. From his studies of the behaviour of small magnets, Gilbert concluded that the Earth itself acts as a giant bar magnet, with a magnetic pole (a term he introduced) near each geographical pole. He also showed that the strength of a lodestone can be increased by combining it with soft iron, that iron and steel can be magnetized by stroking them with lodestones, and that when an iron magnet is heated to red-heat, it loses its magnetism and also cannot be remagnetized while it remains hot. So extensive were Gilbert's investigations of magnetism that not until William Sturgeon made the first electromagnet in 1825 and Michael Faraday began his studies was substantial new knowledge added to the subject.
Gilbert also investigated static electricity. The ancient Greeks had discovered that amber (elektron), when rubbed with silk, can attract light objects. Gilbert demonstrated that other substances exhibit the same effect and that the magnitude of the effect is approximately proportional to the area being rubbed. He called these substances ‘electrics’ and clearly differentiated between magnetic attraction and electric attraction (as he called the ability of an electrostatically charged body to attract light objects). This work eventually led to the idea of electrical charge, but it was not until 1745 that it was discovered - by the French physicist Charles du Fay (1698-1739) - that there are two types of charge, positive and negative.
Gilbert also held remarkably modern views on astronomy. He was the first English scientist to accept Copernicus' idea that the Earth rotates on its axis and revolves around the Sun. He also believed that the stars are at different distances from the Earth and might be orbited by habitable planets, and that the planets were kept in their orbits by magnetic attraction.
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