Abstract Following the path by which humanity learned quantum mechanics can lead to an improved understanding of the theory and the origins of its perceived limitations. Our goal is to retrace the development by investigating primary sources, including original published papers and letters, with attention to their timing and influence. Quantum mechanics began in 1900 with the introduction of Planck’s constant, which lead to the “old” quantum theory and Bohr’s model of the atom. With the introduction of matter waves in 1924, a second more intense period began. By 1928 the complete fundamental structure of quantum mechanics was established with the introduction of the Schrödinger equation, the proof of its equivalence to Heisenberg’s matrix mechanics, and the introduction of the relativistic Dirac equation. The theory retains the same essential form today, fueling the technological revolution that began in the last century. We culminate with an introduction to quantum information and computing. This completely new physical scientific paradigm was developed largely in Germany during a period of enormous social, economic, and political upheaval—in a hostile intellectual environment—that parallels the overturning of classical physics. It is striking that all the problems debated today were immediately recognized by the founders of the theory and instructive to see how they dealt with the various issues. We emphasize the centrality of the often neglected second quantization form of the theory for questions of interpretation and give a detailed examination of von Neumann’s widely misunderstood hidden variable theorem.
Abstract Following the path by which humanity learned quantum mechanics can lead to an improved understanding of the theory and the origins of its perceived limitations. Our goal is to retrace the development by investigating primary sources, including original published papers and letters, with attention to their timing and influence. Quantum mechanics began in 1900 with the introduction of Planck’s constant, which lead to the “old” quantum theory and Bohr’s model of the atom. With the introduction of matter waves in 1924, a second more intense period began. By 1928 the complete fundamental structure of quantum mechanics was established with the introduction of the Schrödinger equation, the proof of its equivalence to Heisenberg’s matrix mechanics, and the introduction of the relativistic Dirac equation. The theory retains the same essential form today, fueling the technological revolution that began in the last century. We culminate with an introduction to quantum information and computing. This completely new physical scientific paradigm was developed largely in Germany during a period of enormous social, economic, and political upheaval—in a hostile intellectual environment—that parallels the overturning of classical physics. It is striking that all the problems debated today were immediately recognized by the founders of the theory and instructive to see how they dealt with the various issues. We emphasize the centrality of the often neglected second quantization form of the theory for questions of interpretation and give a detailed examination of von Neumann’s widely misunderstood hidden variable theorem.
Science has developed through a variety of investigations more or less over the time scale of human existence. On this scale, quantum mechanics is an extremely young field, existing essentially for only just over a century. Even our understanding of classical mechanics has existed for a comparatively long period—roughly having been formalized with Newton's equations published in his Principia Mathematica , in April 1686 (1687). Up until the very end of the nineteenth century, mechanics in the form of Newton's laws were comfortable, being understood and accepted by all who dealt with the motion of reasonable bodies. With the turn of the new century, however, mechanics would be shaken to its roots. The change began already on December 14, 1900, when Planck (1900) presented his new theory of black-body radiation to the German Physical Society, and this change would affect mechanics in physically small structures (and lead to quantum mechanics). Mechanics of large bodies would similarly be changed in 1905 with the arrival of Albert Einstein's (1905a) relativity theory. In this book, we will deal with only the first of these two great breakthroughs.
2025 is the year UNESCO selected to celebrate 100 years of this novel science, quantum mechanics, based on Heisenberg’s “uncertainty principle” discovery. However, quantum mechanics began with the discovery of quantum packets of energy emission formulated by the German physicist Max Planck, and it incorporated additional discoveries and principles from Albert Einstein, Niels Bohr, Heisenberg, Pauli, de Broglie, and many others in the early 1900s. Since then, many advancements and breakthroughs have been made. Such scientific contributions have influenced the culture and technology of humanity from the 20th century onwards, with the first quantum revolutions bringing innovations in technology and engineering, including the omnipresent light amplification by stimulated emission of radiation (Laser), magnetic resonance imaging (MRI), microprocessor manufacturing and design for computers and nuclear energy. Thus, at the beginning of the Second Quantum Revolution in the 21st century, amid a new wave of novel quantum technologies promising to create the 5th Industrial Revolution and transform humanity, a brief history of these marvellous sciences is condensed, connecting the wonders of the new quantum technogenesis that is being forged, linking its past with classical mechanics and also with novel relativistic mechanics. Understanding these developments highlights the significance of quantum technologies shaping our future and what lies ahead for us. This article explores technologies that are presently under research and development (R&D) in the quantum physics realm, including quantum computing, quantum cryptography, quantum sensing and metrology, and quantum simulation. It also discusses emerging careers in the quantum field and the unresolved mysteries that continue to challenge scientists. The discussion follows the ancient griot tradition of storytelling, a method that the distinguished physicist, great professor, and Nobel laureate Richard Feynman encouraged us to use to explain complex scientific ideas.
Quantum physics, emerging from the intellectual crisis of classical mechanics at the dawn of the twentieth century, has over the course of twelve decades established itself as the most foundationally disruptive, experimentally verified, and technologically generative scientific framework in the history of human inquiry. This article presents a synthetic, balanced account of quantum physics across three temporal dimensions — its historical origins and theoretical maturation, its present theoretical frontiers and technological applications, and its future prospects across computing, communication, sensing, and the search for a unified theory of physical reality. Drawing upon foundational primary literature, historiographical scholarship, experimental physics, and contemporary quantum technology research, the article traces the discipline's evolution from Planck's quantum hypothesis of 1900 through the quantum mechanical revolution of the 1920s, the development of quantum field theory and the Standard Model, and the emergence of a second quantum revolution deliberately harnessing entanglement and superposition as technological resources. The analysis identifies three domains of outstanding significance for quantum physics in the present century: the unresolved interpretational and foundational questions surrounding the measurement problem and the nature of quantum reality; the technological race toward fault-tolerant quantum computing and global quantum communication networks; and the deep theoretical challenge of reconciling quantum mechanics with general relativity in a unified framework capable of describing physical reality at all scales. The article concludes that quantum physics remains an unfinished revolution whose most consequential theoretical discoveries and technological applications may lie not behind but ahead of us, and that understanding its past, present, and future is essential for any serious engagement with the scientific and technological landscape of the twenty-first century.
This invaluable book takes the reader from Planck's discovery of the quantum in 1900 to the most recent interpretations and applications of nonrelativistic quantum mechanics. The introduction of the quantum idea leads off the prehistory of quantum mechanics, featuring Planck, Einstein, Bohr, Compton, and de Broglie's immortal contributions. Their original discovery papers are featured with explanatory notes and developments in Part 1. The invention of matrix mechanics and quantum mechanics by Heisenberg, Born, Jordan, Dirac, and Schrödinger is presented next, in Part 2. Following that, in Part 3, are the Einstein–Bohr debates on the interpretation of quantum mechanics culminating in Bell's inequality and Aspect's experiment demonstrating the actuality of the long range quantum correlations to which Einstein, Podolsky, and Rosen took great exception. Resolutions of quantum paradoxes and the current state of such debates are summarized. Part 4 presents a selection of the most dramatic modern developments, both theoretical and experimental. These include Feynman path integrals, the modern interpretation based on decoherence, quantum optics experiments leading to teleportation, DeWitt's wave function of the universe, and a brief introduction to the end-of-the-millennium prospects of quantum computation. A concluding chapter presents the authors' conjectures for the next 100 years of the quantum. This book is ideally suited to anyone with a junior level background in modern physics and quantum mechanics, and a cultural interest in the original sources of the greatest ideas of the greatest founders of this subject as derived from their first discovery papers. These papers have led, in giant strides across the whole of the twentieth century, to the revolutionary experimental advances of the last decade. The book makes accessible - physically and intellectually - both the deepest roots and the highest branches of nonrelativistic quantum physics
Quantum mechanics deals with the behaviour of matter and light on the atomic and subatomic scale. It attempts to describe and account for the properties of molecules and atoms and their constituents--electrons, protons, neutrons, and other more esoteric particles such as quarks and gluons. Its concepts frequently conflict with common-sense notions derived from observations of the everyday world. Quantum mechanics has attracted some of the ablest scientists of the 20th century, and they have erected what is perhaps the finest intellectual edifice of the period. Quantum mechanics is concerned with phenomena that are so small-scale that they cannot be described in classical terms. The history of quantum mechanics may be divided into three main periods. The first began with Planck's theory of black-body radiation in 1900; it may be described as the period in which the validity of Planck's constant was demonstrated but its real meaning was not fully understood. The second period began with the quantum theory of atomic structure and spectra proposed by Niels Bohr in 1913. True quantum mechanics appeared in 1926, reaching fruition nearly simultaneously in a variety of forms--namely, the matrix theory of Max Born and Werner Heisenberg, the wave mechanics of Louis V. de Broglie and Erwin Schrodinger, and the transformation theory of P.A.M. Dirac and Pascual Jordan.
Quantum mechanics is one of the great success stories of modern physics, making sense of the very small just as Einstein's theory of relativity made sense of the very large. But, for most students, the ideas that make quantum mechanics powerful can be confusing and counterintuitive. This volume in the Greenwood Guides to Great Ideas in Science series provides a history of quantum mechanics from the early breakthroughs of Planck and Einstein, at the beginning of the 20th century, to the present frontiers of quantum computing and quantum gravity. The approach is entirely non-technical, and is aimed at the general reader who may not have much mathematical background but who has a strong curiosity about some of the most important developments in modern science. Quantum Mechanics: A Historical Perspectivetraces the history of this powerful theory, including: ; The early discoveries by Max Planck and Albert Einstein regarding the quantization of radiation ; The early quantum theory, including Neils Bohr's theory of the atom ; The birth of modern quantum mechanics through the work of Heisenberg, Schrodinger, Born, Dirac and others ; Applications of quantum mechanics in chemistry, nuclear physics, electronics, and many other areas ; Recent work in quantum computation and quantum information theory The book emphasizes the fact that despite the great success of quantum mechanics, many exciting intellectual frontiers remain open for further researchers to explore. It includes a glossary, a timeline, and a bibliography of accessible resources for further research.