energy, conservation of Principle of physics according to which the energy of interacting bodies or particles in a closed system remains constant, though it may take different forms (e.g., kinetic energy, potential energy, thermal energy, energy in an electric current, or energy stored in an electric field, in a magnetic field, or in chemical bonds [see bonding]). With the advent of relativity physics in 1905, mass was recognized as equiva¬ lent to energy. When accounting for a system of high-speed particles whose mass increases as a consequence of their speed, the laws of con¬ servation of energy and conservation of mass become one conservation law. See also Hermann von Helmholtz.
energy, equipartition of Law of statistical mechanics stating that, in a system in thermal equilibrium, on average, an equal amount of energy is associated with each independent energy state. It states specifically that a system of particles in equilibrium at absolute temperature T will have an average energy of VikT, where k is the Boltzmann constant, associated with each degree of freedom. For example, an atom of a gas has three degrees of freedom (its three position coordinates); therefore, it will have an average total energy of VikT.
Engelbart, Douglas (b. Jan. 30, 1925, near Portland, Ore., U.S.) U.S. computer scientist. He received a Ph.D. in electrical engineering from the University of California, Berkeley. In the 1960s he set up the Augmen¬ tation Research Center at the Stanford Research Institute in Utah. He invented hypertext, the multiwindow display, the mouse, and groupware. His demonstration of these capabilities in San Francisco in 1968 started the process of development that led to the Microsoft Windows operating system. Engelbart’s group at SRI was one of the original four members of the ARPANET, precursor of the Internet. After his retirement, he led the Bootstrap Institute, researching ways to support cooperative work by computers. In 1997 he received the Turing Award.
Engels Yeq-alsX, Friedrich (b. Nov. 28, 1820, Barmen, Rhine Prov¬ ince, Prussia—d. Aug. 5, 1895, London, Eng.) German socialist philoso¬ pher. Son of a factory owner, he eventually became a successful businessman himself, never allowing his criticism of capitalism to inter¬ fere with the profitable operations of his firm. As a young man, he devel¬ oped an interest in the philosophy of G.W.F. Hegel as expounded by the Young Hegelians, and he became persuaded that the logical consequence of Hegelianism and dialectic was communism. In 1844 he published The Condition of the Working Class in England. With Karl Marx, whom he met in Cologne, he formed a permanent partnership to promote the social¬ ist movement. After persuading the second Communist Congress to adopt their views, the two men were authorized to draft the Communist Mani¬ festo (1848). After Marx’s death (1883), Engels served as the foremost
© 2006 Encyclopaedia Britannica, Inc.
622 i engine ► English language
authority on Marx and Marxism. Aside from his own books, he completed volumes 2 and 3 of Das Kapital on the basis of Marx’s uncompleted manuscripts and rough notes.
engine Machine that can convert any of various forms of energy into mechanical power or motion. The steam engines developed during the Indus¬ trial Revolution to power stationary machinery were modified in the 19th century to propel locomotives and ships, and were joined later by steam turbines. Internal-combustion engines were developed by Nikoiaus Otto and Rudolf Diesel in the late 19th century. Gas turbines and rocket engines came into use in the later 20th century. See also diesel engine, gasoline ENGINE, JET ENGINE, ROCKET, and ROTARY ENGINE.
engineering Professional art of applying science to the optimum con¬ version of the resources of nature to the uses of humankind. Engineering is based principally on physics, chemistry, and mathematics and their extensions into materials science, solid and fluid mechanics, thermodynam¬ ics, transfer and rate processes, and systems analysis. A great body of spe¬ cial knowledge is associated with engineering; preparation for professional practice involves extensive training in the application of that knowledge. Engineers employ two types of natural resources, materials and energy. Materials acquire uses that reflect their properties: their strength, ease of fabrication, lightness, or durability; their ability to insu¬ late or conduct; and their chemical, electrical, or acoustical properties. Important sources of energy include fossil fuels (coal, petroleum, gas), wind, sunlight, falling water, and nuclear fission. See also aerospace engi¬ neering, CIVIL ENGINEERING, CHEMICAL ENGINEERING. GENETIC ENGINEERING, MECHANI¬ CAL ENGINEERING, MILITARY ENGINEERING.
engineering geology or geological engineering Scientific discipline concerned with the application of geologic knowledge to engi¬ neering problems such as reservoir design and location, determination of slope stability for construction purposes, and determination of earthquake, flood, or subsidence danger in areas considered for roads, pipelines, bridges, dams, or other engineering works.
England Southern part of the island of Great Britain, excluding Wales. Area: 50,351 sq mi (130,410 sq km). Population (2001): 49,138,831. It is the largest constituent unit of the United Kingdom of Great Britain and Northern Ireland. England is often erroneously considered synonymous with the island of Great Britain and even with the entire kingdom. Despite the political, economic, and cultural legacy that has perpetuated its name, however, England no longer officially exists as a country and enjoys no separate political status within the United Kingdom. It is a land of low hills and plateaus, with a 2,000-mi (3,200-km) coastline. A substantial upland, the Pennines, divides northern England; the Cheviot Hills define the Scottish border. In the southwest lie the Cotswold Hills and the pla¬ teau regions of Exmoor and Dartmoor; in the southeast lie the Downs and in the south the Salisbury Plain. English weather is diverse, with a gen¬ erally mild but erratic maritime climate. England is divided into eight geographic regions, often referred to as the standard regions of England; they do not serve any administrative function. The South East, centred on London, is an economically dominant area. It contains an extensive range of manufacturing and science-based industries and commercial endeav¬ ours. The West Midlands, in west-central England, is a diversified manu¬ facturing region that centres on Birmingham. The region also includes the Shakespeare country, centred on Stratford-upon-Avon. The East Mid¬ lands, in east-central England, is also a manufacturing region and con¬ tains some of England’s best farmland. East Anglia is the easternmost part of England. It is mainly an agricultural region, but high-technology indus¬ tries have developed there. Manchester and Liverpool are the chief indus¬ trial cities of the North West; the region has long been known for textile production, but that has rapidly given way to diversified manufacturing. The Humberside region lies to the east and is noted for textiles and steel¬ making, though its economy has become more diversified and there is extensive farmland. The North region extends north to the Scottish bor¬ der. It includes the celebrated Lake District and is a centre of engineering and pharmaceutical manufacture. The South West region, which includes Cornwall, has a growing tourist industry, and some areas are becoming industrialized. England is especially noted for its long and rich literary tradition, as well as for its architecture, painting, theatres, museums, and universities (see University of Oxford; University of Cambridge). It also played an integral role in rock music (see British Invasion).