4. Science & Technological Advancement

Historical Narrative.
Advances in the field of physics have had a greater impact on 20th century history than advances in any other science. Discoveries in this field have given us an awesome new source of power - nuclear energy.
Atomic Energy
In the late 19th century, physicists made discoveries that led them to question established ideas about physical reality. Prior to these discoveries, they had thought that atoms, the so-called building blocks of matter, were tiny, solid balls. Marie and Pierrre Curie provided the first contradiction to this idea. In 1899, when they discovered the new element radium, they observed that its atoms do not have a constant atomic weight. (This is the average mass of an atom of an element.) The atoms constantly give off tiny particles of matter called electrons and protons.
The German physicist Max Planck (1858-1947) took up the study of subatomic energy. He discovered in 1900 that an atom releases its particles in uneven spirts, which he called "quanta." His ideas are called the quantum theory. Quantum mechanics is part of this theory. Planck's studies of subatomic energy suggested that there is no sharp division between matter and energy.
Albert Einstein (1879-1955) did more than anyone else to challenge traditional ideas about physical reality. He is considered to be one of the greatest scientists ever. Einstein was driven out of Germany in 1933 by the Nazi government. The rest of his life was spent in the United States.
Einstein's theory of relativity corrected Newtonian concepts of time and space. Newton had believed the concepts to be constant. In a universe where space and time are constant, speed and distance can be measured. Einstein pointed out that space and time are not constant. Because everything is in motion, there is no fixed point from which to measure it.
To illustrate his ideas, Einstein gave various everyday examples involving trains and elevators. Suppose that a person walked from the center of a moving train to the front of it. The distance that the person travels and the speed of his or her motion will be different if measure from inside the train that if measured from a point outside it. This meas that measurements of speed and distance are relative to the frame of reference from which they are measured. The speed of light is an exception to this theory, however. No matter from which frame of reference it is measure, the speed of light is constant.
Einstein also disproved the belief that atoms are tiny balls of matter that cannot be reduced into other forms. He stated that matter and energy are basically the same thing. His equation E = mc2 expressed the fact that a tiny particle of matter is capable of releasing vast amounts of energy. This equation, by unlocking the potential energy of the atom, was the first major step in the development of atomic and nuclear weapons.
A New Zealand physicist, Ernest Rutherford (1871-1937), described the structure of an atom in 1911. As though they were planets in a tiny solar system, units of electrical energy, called protons, orbit around a central particle, called the nucleus. In 1917, Rutherford split the atom by artificial means, an achievement that made the development of atomic weapons and nulear power plants a pratical reality.
The work Lise Meitner (1878-1968) of Germany and Sweden also contributed to current uses of nuclear power. In 1939, she and her colleague Otto Frisch (of Austria) identified nuclear fission - the process by which a heavy nucleus combines with another particle and then divides into two other, lighter nuclei. They also realized that because this process would occur in a chain reaction, the energy it released would be enormous.
Nuclear Fission.
World War II increased efforts to produce the superweapons promised by the process of nuclear fission. Danish physicist Niels Bohr was working on a theory of nuclear fission when the Germans invaded Denmark in 1940. Learning that the Germans planned to force him to produce an atomic bomb for their war effort, he escaped to the United States in 1943. Bohr joing British and American scientists working on the atomic bomb project at Los Alamos, New Mexico.
The Bomb.
The project to develop the atomic bomb was called the Manhattan Project to keep it a secret. Among the other physicists who contributed to the development of the atomic bomb were Enrico Fermi, J. Robert Oppenheimer, and Edward Teller. Fermi's experiments with nuclear fission had resulted in the firstsustained nuclear reaction in 1942. Oppenheimer was director of the weapons laboratory that produced the bombs in 1945. Teller later used his experience on the Manhattan Project to formulate theories that led to the production of the much more powerful thermonuclear, hydrogen, bomb. Oppenheimer and Teller disagreed about the future of nuclear weapons. When Oppenheimer opposed further development, Teller publicly criticized his judgment. Many scientists of the time felt that Teller's criticism heightened suspicions of Oppenheimer's loyalty to the United States and hurt his career.
Source:  Brun, H., Forman, L., and Brodsky, H. Global History and Geography: The Growth of Civilizations. New York: Amsco School Publications Inc. 559-561.
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