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Still as a graduate student, he published five important papers and turned his focus to the more general problem of uniting quantum mechanics (the laws governing the micro-world of elementary particles) and relativity (the laws governing the macro-world of planetary and universal gravitation). To this work Dirac brought his engineer’s ability to accept and use approximations when exact calculations were not possible and where exact measurements did not exist. This talent allowed Dirac to venture into new areas of analysis whose lack of exact measurements had stopped previous researchers. Dirac worked mostly in the world of advanced mathematics for these studies. He used the results of a number of lab studies conducted by other researchers to test and verify his equations and mathematical models. Through completion of his doctoral work and through the first five years of his work as a researcher at Cambridge, Dirac struggled to resolve the apparent incompatibility of these two major systems of thought and analysis. By 1929 Dirac had realized that his calculations required that several subatomic particles had to exist that had never been detected or thought of before. In order for the equations that he had developed and tested against lab results to work, an entire set of new particles had to exist. These new particles would mimic the mass and composition of the known particles, but would have the opposite electrical charge. Protons and neutrons were known. Dirac concluded that negatively charged particles of equivalent mass must also exist. The existence of this antiproton, or antimatter, was confirmed 25 years later. Similarly, Dirac concluded that if an electron existed, positively and neutrally charged particles of similar mass (positron and neutrino respectively) must also exist. The existence of positrons was confirmed two years later, in 1932. Neutrinos were positively identified in the mid-1970s, but their mass was not confirmed until work done by Japanese researchers in 1998. Dirac thus discovered the existence of antimatter and proved that the particles we can see, touch, and deal with represent only half of the kinds of particles that inhabit our universe. In so doing, Dirac moved science closer to an accurate view of the physical world. Fun Facts: When matter converts to energy, some residue is always left. Only part of the matter can be converted into energy. Not so with antimatter. When antimatter collides with matter, 100 percent of both matter and antimatter are converted into usable energy. A gram of antimatter would carry as much potential energy as 1,000 space shuttle external tanks carry.
More to Explore Daintith, John, et al., eds. Biographical Encyclopedia of Scientists, Second Edition, Volume 1. Philadelphia: Institute of Physics Publishing, 1994. Devine, Elizabeth, ed. The Annual Obituary, 1983. Chicago: St. James Press, 1990. Dirac, Paul. The General Theory of Relativity. New York: John Wiley & Sons, 1995. ———. The Principles of Quantum Mechanics. London: Cambridge University Press, 1998.
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