From its very beginning, Quantum Theory developed contrary to the intentions of its creators. For Max Planck it marks the failure of a long-term research program, in which he tried to understand the 2nd law of thermodynamics deterministically in terms of mechanics and electrodynamics. For Albert Einstein it meant a refutation of his scientific credo. I describe parts of the early stages of this most remarkable development, up to Einstein's light-quantum hypotheis and its unfavourable reception by most other physicists.
From its very beginning, Quantum Theory developed contrary to the intentions of its creators. For Max Planck it marks the failure of a long-term research program, in which he tried to understand the 2nd law of thermodynamics deterministically in terms of mechanics and electrodynamics. For Albert Einstein it meant a refutation of his scientific credo. I describe parts of the early stages of this most remarkable development, up to Einstein's light-quantum hypotheis and its unfavourable reception by most other physicists.
This is an account of Einstein's work and thoughts on the quantum theory. The following topics will be discussed: The light-quantum hypothesis and its gradual evolution into the photon concept. Early history of the photoelectric effect. The theoretical and experimental reasons why the resistance to the photon was stronger and more protracted than for any other particle proposed to date. Einstein's position regarding the Bohr-Kramers-Slater suggestion, the last bastion of resistance to the photon. Einstein's analysis of fluctuations around thermal equilibrium and his proposal of a duality between particles and waves, in 1909 for electromagnetic radiation (the first time this duality was ever stated) and in January 1925 for matter (prior to quantum mechanics and for reasons independent of those given earlier by de Broglie). His demonstration that long-known specific heat anomalies are quantum effects. His role in the evolution of the third law of thermodynamics. His new derivation of Planck's law in 1917 which also marks the beginning of his concern with the failure of classical causality. His role as one of the founders of quantum statistics and his discovery of the first example of a phase transition derived by using purely statistical methods. His position as a critic of quantum mechanics. Initial doubts on the consistency of quantum mechanics (1926-1930). His view maintained from 1930 until the end of his life: quantum mechanics is logically consistent and quite successful but it is incomplete. His attitude toward success. His criterion of objective reality. Differences in the roles relativity and quantum theory played in Einstein's life. His vision regarding quantum theory in the context of a unified field theory. His last autobiographical sketch, written a few months before his death, concluding with a statement about the quantum theory, a subject to which (by his own account) he had given more thought than even to general relativity.
In 1905 Einstein wrote five history-making papers (on the particle nature of light, Brownian motion, special relativity, energy and inertia, and on molecular dimensions). He was 26, married to Mileva Mari, with one-year-old child Hans Albert, and employed as Technical Expert (third class) by the Bern Patent Office. His relativity theory captured the public imagination, but his quantum ideas were even more revolutionary. His light quantum (now the ‘photon’) was rejected by Planck, who is often thought of as the originator of the concept, and by Millikan, whose 1916 photoelectric data agreed beautifully with Einstein’s predictions (‘a bold, not to say reckless, hypothesis of an electromagnetic light corpuscle ... which flies in the face of thoroughly established facts of interference’). Compton’s 1923 paper on the scattering of X-rays and gamma rays uses the light quantum idea, but makes no mention of Einstein. There followed more than 20 papers on various aspects of quantum theory, substantial enough to make Einstein one of the founders of quantum mechanics, possibly the founder. This paper traces the beginnings of quantum mechanics, giving an outline of Einstein’s contributions. It begins with a sketch of his early life.
The beginning of the 20th century is marked by tremendous new scientific developments and specifically by the birth of quantum mechanics. It starts with Max Planck and Max Einstein, who introduce and apply the concept of quanta to characterize the energy of light. Quantum computers can considerably decrease the time it takes to complete calculations and solve extremely complex problems. Until the 18th century, very little is understood about light. According to the philosophers Euclid and Plato, light is produced by our eyes. Light is clearly capable of traveling through an interstellar void, while a wave needs a medium for material propagation to exist. However, because of Isaac Newton’s reputation, the corpuscular theory persists until the 19th century. When light is beamed on the top layer, it frees and pushes an electron that moves towards the bottom layer, creating a current. This current is then used to power engines for electric cars.
Abstract The events that led to the formulation of the laws of quantum mechanics are presented. Quantum revolution took place in two phases. In the first phase, three important developments took place. Max Planck explained the radiation emitted by heated objects via a quantum postulate, Albert Einstein explained the emission of electrons when light shines on metals by treating light as consisting of photons, and Niels Bohr developed a model for the hydrogen atom by invoking a quantum postulate. In the second phase, Heisenberg and Schrödinger formulated the laws of quantum mechanics that could not only explain all the known phenomena but predict many others.
Along with the exciting experiments that changed the face of physics in the twentieth century, work proceeded feverishly on the theoretical side to rebuild the conceptual world that had been severely shaken. Sometimes the theorists lagged behind the experimentalists, and certain experimental results waited for several years to be explained. And sometimes experiment lagged behind theory, and a new theoretical model waited for years to be verified experimentally. Two great theories left their mark on physics in this century: the theory of relativity, and quantum mechanics. In this chapter we shall briefly review the main ideas of these theories which are vital for the understanding of the atomic world. The theory of relativity The theory of relativity was formulated by the great physicist Albert Einstein. The first part of it (and the important one for us) — the special theory of relativity — was published in 1905, and sprang from the need to explain a puzzling question that exercised the physicists of the nineteenth century: why was it impossible to alter the speed of light, which remained constant (299 792.5 kilometres per second) even when the detector was moving relative to the source of light? In contrast to other physicists, Einstein did not try to explain this phenomenon.
Planck's introduction of the quantum of action in 1900 was followed by 25 years of trial and error in quest of the understanding of the quantum world; different ideas and directions had to be pursued until the path leading to the elementary quantum theory was discovered. Radical changes away from traditional perceptions about natural phenomena were necessary, the entire system of basic concepts in classical physics had to be abandoned and replaced by a new mode of thought. Continuity and determinism of classical laws were no longer applicable on the quantum scale, where dynamical behaviour proceeds by discontinuous and statistical quantum transitions. Albert Einstein laid the essential foundations for the new concept; Max Born made the decisive step further leading to the breakthrough in 1925. The development of the ideas, which eventually resulted in the elementary quantum theory in 1925/26, will be described, relying on original publications and letters written during that period in time by the major contributors. The fundamental laws of Quantum Theory derived by Max Born and Pascual Jordan may mathematically be represented in many different ways, and particular emphasis is given to the distinction between physical content and mathematical representation.