Luis Alvarez Biography

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World of Scientific Discovery on Luis Alvarez

Alvarez was born in San Francisco, California, on June 13, 1911, the son of a physician at the University of California. When the senior Alvarez took a position at the Mayo Clinic, the family moved to Minnesota, where young Luis was educated. In 1928, he entered the University of Chicago, where he eventually earned his bachelor of science (1932), master of science (1934), and doctoral (1936) degrees. After receiving his doctorate, Alvarez accepted a teaching position at the University of California at Berkeley. He became full professor there in 1945 and spent a total of 42 years in various positions at the institution.

Alvarez's accomplishments cover an impressive variety of topics. During World War II, for example, he developed a narrow-beam form of radar that can be used to help land a plane in foggy weather. He also invented a method for using radar in the aerial bombing of targets. In addition, he worked on atomic weapons development as a part of the Manhattan Project.

The 1968 Nobel Prize for physics that Alvarez received was awarded for his research on elementary particles and for his development of technology used in that research. Alvarez chose to use the bubble chamber invented by Donald Glaser in 1952 as his primary research tool in studying particle reactions. He found ways to improve and enlarge the bubble chamber until he eventually produced one that was nearly 72 inches (2 m) in diameter. In addition, Alvarez developed ancillary systems that allowed the detailed analysis of events recorded in the bubble chamber.

As a result of this vastly improved technology, Alvarez and his co-workers were able to discover a number of new resonances in their research. A resonance is a particle-like state that is formed when two high-energy particles collide with each other. A resonance tends to decay very quickly, often in a time span of no more than 10^-22 seconds. The discovery of about 100 resonances, many of which Alvarez was involved with, eventually led to the necessity for a scheme of organizing these particles, a need that was later fulfilled by the Murray Gell-Mann and Yuval Ne'eman theories of the eightfold way.

Other discoveries in which Alvarez was involved include the recognition of the "east-west" effect in cosmic ray s, the existence and radioactivity of tritium, K-electron capture in radioactive materials, and the discovery of a number of radioactive isotopes. In 1980, Alvarez and his son made an unexpected discovery of great geological significance. The Alvarezes observed that a layer of sedimentary rock in Italy contained an unusually high concentration of the element iridium. The date assigned to the layer was about 65 millions years B.P. (before the present).

The father-and-son team hypothesized that the iridium layer was evidence that a large asteroid had collided with the Earth about 65 million years B. P. They suggested that dust produced by this collision traveled to the stratosphere, blocking out solar radiation for as long as three years. Loss of sunlight resulted in the widespread death of plant life on Earth, they suggested, a situation that also resulted in the extinction of much animal life, including the dinosaurs.

Many scientists were dubious about this theory when it was first proposed. However, by the time of the senior Alvarez's death in Berkeley on September 1, 1988, additional evidence had been obtained to provide strong support for the idea, which is now referred to as the Cretaceous catastrophe.