Einstein regarded as one of the triumphs of his 1915 theory of gravity - the general theory of relativity - that it vindicated the action-reaction principle, while Newtonian mechanics as well as his 1905 special theory of relativity supposedly violated it. In this paper we examine why Einstein came to emphasise this position several years after the development of general relativity. Several key considerations are relevant to the story: the connection Einstein originally saw between Mach's analysis of inertia and both (...) the equivalence principle and the principle of general covariance, the waning of Mach's influence owing to de Sitter's 1917 results, and Einstein's detailed correspondence with Moritz Schlick in 1920. (shrink)
We argue that the Aharonov-Anandan-Vaidman model, by using the notion of so-called “protective measurements,” cannot claim to have dispensed with the ldcollapse of the wave function,” because it does not succeed in avoiding the quantum measurement problem. Its claim to be able to distinguish between two nonorthogonal states is also critically examined.
We review the present status of wave-particle duality of single-photon states in the context of some recent experiments. In particular, Bohr's complementarity principle is critically reexamined. It is explained in detail how this principle is confronted in these experiments and how a contradiction with the notion of “mutual exclusiveness” of classical wave and particle pictures emerges.
The nature of reality has been a long-debated issue among scientists and philosophers. In 1930, Rabindranath Tagore and Albert Einstein had a long conversation on the nature of reality. This conversation has been widely quoted and discussed by scientists, philosophers and scholars from the literary world. The important question that Tagore and Einstein discussed was whether the world is a unity dependent on humanity, or the world is a reality independent on the human factor. Einstein took the stand adopted by (...) Western philosophers and mathematicians, namely that reality is something independent of the mind and the human factor. Tagore, on the other hand, adopted the opposite view. Nevertheless, both Einstein and Tagore claimed to be realists despite the fundamental differences between their conceptions of reality. Where does the difference lie? Can it be harmonized at some deeper level? Can Wittgenstein, for example, be a bridge between the two views? This collection of essays explores these two fundamentally different conceptions of the nature of reality from the perspectives of theories of space-time, quantum theory, general philosophy of science, cognitive science and mathematics. (shrink)
"The nature of reality has been a long-debated issue among scientists and philosophers. Rabindranath Tagore met Albert Einstein at the latter's house in Kaputh, Germany on 14th July 1930 and had a long conversation on the nature of reality. This conversation has been widely quoted and discussed by scientists, philosophers and scholars from the literary world. The important question that Tagore and Einstein discussed was whether the world is a unity dependent on humanity, or the world is a reality independent (...) on the human factor. Einstein took the stand adopted that reality is something independent of the mind and the human factor. On the other hand, Tagore adopted the opposite view. Nevertheless, both Einstein and Tagore claimed to be realists--their conceptions of reality were obviously fundamentally different. Where does the difference lie? Can it be harmonized at some deeper level? Can Wittgenstein, for example, be a bridge between the two views? This volume consists of a selection of scholarly essays from the points of view of literature and philosophy and history and brings together for the first time a gamut of views on this important subject from scholars of eminence. It will be useful for scholars and researchers of philosophy, literature, history and political studies"--. (shrink)
In spite of its popularity, it has not been possible to vindicate the conventional wisdom that classical mechanics is a limiting case of quantum mechanics. The purpose of the present paper is to offer an alternative formulation of mechanics which provides a continuous transition between quantum and classical mechanics via environment-induced decoherence.
It is shown that below the threshold of pair creation, a consistent quantum mechanical interpretation of relativistic spin-0 and spin-1 particles (both massive and mussless) ispossible based an the Hamiltonian-Schrödinger form of the firstorder Kemmer equation together with a first-class constraint. The crucial element is the identification of a conserved four-vector current associated with the equation of motion, whose time component is proportional to the energy density which is constrainedto be positive definite for allsolutions. Consequently, the antiparticles must be interpreted (...) as positive-energy states traveling backward in time. This also makes it possible to define hermitian position operators with localized eigensolutions (δ-functions) as well as Bohmian trajectories for bosons. The exact theory is obtained by “second quantization” and is mathematically completely equivalent to conventional quantum field theory. The classical field emerges in the high mean number limit of coherent states of the exact theory. The formalism provides a new basis for computing tunneling times for photons and chaotic phenomena in optics. (shrink)
A number of papers on wave-particle duality has appeared since the two-prism experiment was performed by Mizobuchi and Ohtake, based on a suggestion by Ghose, Home, and Agarwal. Against this backdrop, the present paper provides further clarification of the key issues involved in the analysis of the two-prism experiment. In the process, we present an overview of wave-particle duality vis-a vis Bohr's complementarity principle.