Word: electronic
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Dates: during 1970-1979
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DIED. Samuel A. Goudsmit, 76, Dutch-born atomic physicist and amateur Egyptologist; of a heart attack; in Reno. In 1925, while enrolled in the University of Leiden, Goudsmit and Fellow Student George E. Uhlenbeck determined that an electron spins as it orbits the nucleus of an atom, a discovery that helped explain how atoms have magnetic properties. Two years later, he emigrated to the U.S., and during World War II served on a secret European mission to investigate German progress toward the atomic bomb...
...that Astronomer Maarten Schmidt discovered the nature of quasars, perhaps the most distant objects in the universe, that Theoretical Physicist Murray Gell-Mann described the way in which more than 100 subatomic particles are related, and that Physicist Carl D. Anderson discovered the positron, a fundamental particle with an electron's mass but a positive charge. The first successful U.S. orbiting satellite, Explorer I, was launched by the school's acclaimed Jet Propulsion Laboratory, which developed the principles that make jet flight possible...
...make transistors and chips, scientists "dope" a semiconducting material ike silicon with impurities, creating regions that have either an excess or a deiciency of electrons-and thus are negatively (n zones) or positively (p zones) charged. If two n zones, say, are separated by a p zone, they act like an electronic switch, or transistor; a small voltage in the p zone controls fluctuations in the current flowing between the n zones. But every time an excess electron is released in the n zone to join the current flow, it leaves behind a positively charged spot. Because opposite charges attract...
...create what in effect is an electron freeway without these obstructing potholes, Bell Physicist Raymond Dingle and his colleagues built a semiconductor made of extremely thin, alternate layers of aluminum gallium arsenide (which they doped) and gallium arsenide (which they left pure). They reasoned that any electrons donated by the impurity would tend to migrate to the adjoining undoped gallium arsenide layer because of their tendency to seek what physicists call a lower energy state. Explains the Australian-born Dingle: "It's rather like the inclination of water to flow downhill." The new design worked. Isolated from the obstructing...
Where will it all end? Circuits in some densely packed chips are already so close that there is sometimes electron leakage between conductors-interfering with the proper working of the chip. Is technology fast reaching the limit of miniaturization? Computer scientists think not. They point to the stupendous amounts of data contained, for example, in a DNA molecule-or in one-celled animals and plants that are visible only under a microscope. Says M.I.T.'s Michael Dertouzos...