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Springer eBooks

Quantum Description of Microscopic and Macroscopic Systems: Old Problems and Recent Investigations

G. C. Ghirardi

Published Jan 1, 1988• 0 citations
Publisher
DOI
10.1007/978-94-009-2925-8_11

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Quantum Measurements.- Quantum mechanics of macroscopic systems and measurement processes.- The haunted measurement in quantum theory.- A quantum-statistical model of quantum measurement.- Potential and real states in quantum mechanics.- Wave function collapse in the ensemble interpretation.- Nonlinear models for quantum-mechanical measurements.- Meaning and measurability of nonlocal quantum states.- New Developments of Quantum Theory.- The mathematical expression of the uncertainty principle.- Quantization of Hamiltonian theories based on a probability operator.- Classical to quantum: A generalized phase transition.- Quantum description of microscopic and microscopic systems: Old problems and recent investigations.- Towards a process formalism in quantum physics.- A generalized Schroedinger formalism from a Hamiltonian flow in a higher dimensional space.- How the nonlinear phenomena impose the reinterpretation of quantum mechanics.- On the equivalence between the superposition principle and a global gauge invariance.- Meanings of Quantum Theory.- The 2-photon elementary quantum phenomenon and spacetime structure.- Causality as indentified with conditional probability and the quantal nonseparability.- Realism versus positivism: An attempt at reconcilement in the Einstein-Bohr debate.- Four-dimensional realism and waves carrying physical data codedly as keys to understandable models.- Testing interpretations of quantum mechanics.- On the relation between the recent new statistical prediction of quantum mechanics by Albert, Aharonov, and D'Amato, the EPR reasoning, and Bell's Inequality.- Beyond quantum theory: A realist psycho-biological interpretation of physical reality.- Locality, causality, quantum events, and all that.- The Einstein-Bohr debate: I. The background.- Contingency and lawfulness: Conditions for encounter.- Epr Paradox: Critical Examinations.- Towards a realist theory of measurement.- The tacit postulate on single events and the comparison of classical and quantum spin correlation experiments.- Weak realism for pairs of correlated systems.- Comments on EPR, locality and reality.- The EPR and the proposal of action at a distance.- The discription of separated systems and quantum mechanics and a possible explanation for the probabilities of quantum mehanics.- Against dualism: An observation concerning non-locality.- Bell's theorem: A note on locality.- EPR paradox considered as a criticism of the statevector reduction in the quantum mechanical description of correlated separated systems.- EPR and the strange nature of the quantum state or why I can live with EPR.- Why the EPR paradox has been resolved in favor of Einstein.- Probability and the way out of the great quantum muddle.- Where lies the mistake in the clauser and Home proof of Bell's theorem?.

Kluwer Academic Publishers eBooks•Jan 1, 1988•3 citations
Current interpretations of quantum mechanics suggest that the classical concepts of space and time are not applicable to microscopic systems. Salecker and Wigner have recently proved that these concepts have no operational meaning for microsystems. Therefore, space-time descriptions may be valid only for macroscopic systems. It is here suggested that space and time themselves arise from, but do not have analogs in, the properties of microscopic particles, in the same way that thermodynamic properties arise as a result of interactions among the many actually existing particles of the universe. Neither the particles nor the interactions need to be described in spatial-temporal terms. This macroscopic interpretation of space-time seems compatible with the known properties of the physical world, suggests a more direct interpretation of the statistical nature of microscopic events, and offers a new approach to some physical problems.
An explicit model allowing a unified description of microscopic and macroscopic systems is exhibited. First, a modified quantum dynamics for the description of macroscopic objects is constructed and it is shown that it forbids the occurrence of linear superpositions of states localized in far-away spatial regions and induces an evolution agreeing with classical mechanics. This dynamics also allows a description of the evolution in terms of trajectories. To set up a unified description of all physical phenomena, a modification of the dynamics, with respect to the standard Hamiltonian one, is then postulated also for microscopic systems. It is shown that one can consistently deduce from it the previously considered dynamics for the center of mass of macroscopic systems. Choosing in an appropriate way the parameters of the so-obtained model one can show that both the standard quantum theory for microscopic objects and the classical behavior for macroscopic objects can all be derived in a consistent way. In the case of a macroscopic system one can obtain, by means of appropriate approximations, a description of the evolution in terms of a phase-space density distribution obeying a Fokker-Planck diffusion equation. The model also provides the basis for a conceptually appealing description of quantum measurement.
Quantum Measurements.- Quantum mechanics of macroscopic systems and measurement processes.- The haunted measurement in quantum theory.- A quantum-statistical model of quantum measurement.- Potential and real states in quantum mechanics.- Wave function collapse in the ensemble interpretation.- Nonlinear models for quantum-mechanical measurements.- Meaning and measurability of nonlocal quantum states.- New Developments of Quantum Theory.- The mathematical expression of the uncertainty principle.- Quantization of Hamiltonian theories based on a probability operator.- Classical to quantum: A generalized phase transition.- Quantum description of microscopic and microscopic systems: Old problems and recent investigations.- Towards a process formalism in quantum physics.- A generalized Schroedinger formalism from a Hamiltonian flow in a higher dimensional space.- How the nonlinear phenomena impose the reinterpretation of quantum mechanics.- On the equivalence between the superposition principle and a global gauge invariance.- Meanings of Quantum Theory.- The 2-photon elementary quantum phenomenon and spacetime structure.- Causality as indentified with conditional probability and the quantal nonseparability.- Realism versus positivism: An attempt at reconcilement in the Einstein-Bohr debate.- Four-dimensional realism and waves carrying physical data codedly as keys to understandable models.- Testing interpretations of quantum mechanics.- On the relation between the recent new statistical prediction of quantum mechanics by Albert, Aharonov, and D'Amato, the EPR reasoning, and Bell's Inequality.- Beyond quantum theory: A realist psycho-biological interpretation of physical reality.- Locality, causality, quantum events, and all that.- The Einstein-Bohr debate: I. The background.- Contingency and lawfulness: Conditions for encounter.- Epr Paradox: Critical Examinations.- Towards a realist theory of measurement.- The tacit postulate on single events and the comparison of classical and quantum spin correlation experiments.- Weak realism for pairs of correlated systems.- Comments on EPR, locality and reality.- The EPR and the proposal of action at a distance.- The discription of separated systems and quantum mechanics and a possible explanation for the probabilities of quantum mehanics.- Against dualism: An observation concerning non-locality.- Bell's theorem: A note on locality.- EPR paradox considered as a criticism of the statevector reduction in the quantum mechanical description of correlated separated systems.- EPR and the strange nature of the quantum state or why I can live with EPR.- Why the EPR paradox has been resolved in favor of Einstein.- Probability and the way out of the great quantum muddle.- Where lies the mistake in the clauser and Home proof of Bell's theorem?.