The discovery of subatomic particles

Author: Stephen Weinberg (USA)
Publisher:
Publish Date: 2006-06-01
Features: When the electric field does 1 joule of work on an object at a single location, this concept is important because electric potential can characterize the environmental features of charge motion without considering the numerical value of the charge itself. A battery can be seen as a device that generates a fixed electric potential difference (electric-potential difference) between its positive and negative terminals, or between the wires connecting the two terminals. For example, suppose a 1.5-volt flashlight battery causes 0.1 amperes of current to flow through the tungsten filament of a light bulb. Then, the amount of charge transferred from one terminal of the battery to the other per second is 0.1 coulombs. The battery does 1.5 joules of work per coulomb, so the power is 0.15 joules per second (i.e., 0.15 watts, where 1 watt = 1 joule per second). The concept of kinetic energy was introduced by the Dutch physicist Christian Huygens (1629–1695) in a book published posthumously in 1706. This concept played an important role in the development of mechanics in the 18th century; in the 19th century, its utility was greatly expanded because kinetic energy and potential energy were combined into a more general concept of energy. This broader understanding of energy is credited to one of the most outstanding figures in the history of science, Benjamin Thompson (1753–1814), an American who became Count Rumford of the Holy Roman Empire in 1792. Thompson is often described as "a loyal person, a traitor, a spy, a cryptographer, an opportunist, a lecher, a philanthropist, an extreme egoist, a lucky military commander, a military and technical advisor, an inventor, a plagiarist, a calorist, and the founder of the world's largest science popularization demonstration site—the Royal Institution." He was born in Woburn, Massachusetts, and fled to Britain in 1776, then to Germany. It was in Germany, while serving as a commander in the Bavarian army, that his research on cannons led him to doubt the prevailing views on the nature of heat at the time. It was commonly believed that heat was a weightless fluid called "caloric." However, Thompson discovered that mechanical work could continuously produce heat without limit when drilling holes in cannons, thus abandoning the caloric theory. He believed that heat was a form of motion, but he did not express his ideas precisely, nor did he elaborate on the equivalence between mechanical work and heat. P70-71