Chapter 1 Introduction As students begin their study of quantum physics they are usually bombarded with descriptions of experiments and theoretical innovations from the early part of the twentieth century that demonstrated and attempted to clarify the inadequacy of the physics at that time. We will describe only a few of the experiments and some of the oncepts that are particularly pertinent to the material to be presented in this book. We take some liberties with chronology to dramatize the detail 1.1 Early Experiments L.I. 1 The Photoelectric effect The photoelectric effect was discovered in 1887 by Gustav Ludwig Hertz while performing experiments directed toward confirming Maxwell,s theory of electro- magnetic waves. He observed that charged particles(electrons)were ejected from metal surfaces when the surface was illuminated by light. The electron flux was strongly dependent upon the wavelength of the light. Although Hertz did not follow up on his discovery, one of his students, Philipp Eduard Anton von Lenard, reported quantitative measurements of the effect in 1902. For this work Lenard received the Nobel Prize in 1905. The citation reads: for his work on cathode rays. " Subse- quently, in 1925, Hertz shared the Nobel Prize for a different body of work, a subject hat will be discussed later in this chapter The origin of the photoelectric effect remained a mystery until, in one of his three remarkable papers published in 1905, Albert Einstein, using Max Planck's treatment of blackbody spectra, explained the effect. Subsequently, in 1916, Robert Andrews Milliken performed detailed experiments that confirmed Einsteins explanation. Ein- stein received the Nobel Prize in 1921 for this work, although many think that his work on relativity also deserves a prize. The citation for Einstein's prize reads: " for his services to Theoretical Physics, and especially for his discovery of the law of he photoelectric effect Milliken was also awarded a Nobel Prize, his in 1923, the citation for which reads: "for his work on the elementary charge of electricity and on the photoelectric effect. C.E. Burkhardt, J.J. Leventhal, Foundations of Quantum Physics DOI: 10.1007/978-0-387-77652-1-L, O Springer Science+Business Media, LLC 2008Chapter 1 Introduction As students begin their study of quantum physics they are usually bombarded with descriptions of experiments and theoretical innovations from the early part of the twentieth century that demonstrated and attempted to clarify the inadequacy of the physics at that time. We will describe only a few of the experiments and some of the concepts that are particularly pertinent to the material to be presented in this book. We take some liberties with chronology to dramatize the details. 1.1 Early Experiments 1.1.1 The Photoelectric Effect The photoelectric effect was discovered in 1887 by Gustav Ludwig Hertz while performing experiments directed toward confirming Maxwell’s theory of electro￾magnetic waves. He observed that charged particles (electrons) were ejected from metal surfaces when the surface was illuminated by light. The electron flux was strongly dependent upon the wavelength of the light. Although Hertz did not follow up on his discovery, one of his students, Philipp Eduard Anton von Lenard, reported quantitative measurements of the effect in 1902. For this work Lenard received the Nobel Prize in 1905. The citation reads: “for his work on cathode rays.” Subse￾quently, in 1925, Hertz shared the Nobel Prize for a different body of work, a subject that will be discussed later in this chapter. The origin of the photoelectric effect remained a mystery until, in one of his three remarkable papers published in 1905, Albert Einstein, using Max Planck’s treatment of blackbody spectra, explained the effect. Subsequently, in 1916, Robert Andrews Milliken performed detailed experiments that confirmed Einstein’s explanation. Ein￾stein received the Nobel Prize in 1921 for this work, although many think that his work on relativity also deserves a prize. The citation for Einstein’s prize reads: “for his services to Theoretical Physics, and especially for his discovery of the law of the photoelectric effect.” Milliken was also awarded a Nobel Prize, his in 1923, the citation for which reads: “for his work on the elementary charge of electricity and on the photoelectric effect.” C.E. Burkhardt, J.J. Leventhal, Foundations of Quantum Physics, 1 DOI: 10.1007/978-0-387-77652-1 1, C Springer Science+Business Media, LLC 2008