Jun 4, 2022 05:33 PM
https://physicstoday.scitation.org/doi/f.../PT.3.5027
EXCERPTS: There are three types of quantum physicists: (1) those who think quantum mechanics is defaced by a so-called measurement problem; (2) those who think, as I do, that there is no measurement problem; and (3) those who think the issue is not worth serious thought. You can find the diverse views of 17 physicists and philosophers from the first two groups in chapter 7 of Maximilian Schlosshauer's Elegance and Enigma.
Most people in all three groups would agree on the following: Quantum mechanics describes a physical system entirely in terms of states. A state is a compendium of probabilities of all possible answers to all possible questions one can ask of the system. Quantum mechanics is inherently statistical. There is no deeper underlying theory that gives a fuller description.
The state assigned to a system can change in time in two ways. If no question is asked of the system, then its state evolves in time deterministically: continuously and according to fixed rules. If a question is asked of the system -- called making a measurement -- then when the question is answered, the state changes discontinuously into a state that depends both on the state just before the question was asked and on the particular answer the system gives to that question. The second process is called the collapse of the state. Collapse is generally abrupt, discontinuous, and stochastic.
[...] Many physicists in group 2 would add the following: There are no consequences of a quantum state assignment other than all the probabilities it gives rise to. While many (perhaps most) physicists view probabilities as objective features of the world, most probabilists and statisticians do not. As the celebrated probabilist Bruno de Finetti put it, "The abandonment of superstitious beliefs about the existence of Phlogiston, the Cosmic Ether, Absolute Space and Time, ...., or Fairies and Witches, was an essential step along the road to scientific thinking. Probability, too, if regarded as something endowed with some kind of objective existence, is no less a misleading misconception, an illusory attempt to exteriorize or materialize our actual probabilistic beliefs."
Isolated excerpts from Niels Bohr can support many diverse views. But a quarter century after publishing my concluding quotation, he wrote that "physics is to be regarded not so much as the study of something a priori given, but rather as the development of methods for ordering and surveying human experience." It's the same opinion, and it has the same ambiguity: Is "human experience" individual or collective?
Physicists who materialize their own probabilistic beliefs must also materialize quantum states, which are nothing more than catalogs of such beliefs. [...] That the quantum state of a system expresses only the belief of the particular physicist who assigns it to the system was emphasized by the theorists Carlton Caves, Christopher Fuchs, and Rüdiger Schack at the turn of the 21st century as being crucial to the interpretation of quantum mechanics.
[...] Such solutions [that alternatively contend that there is a problem] all take quantum states to be objective properties of the physical system they describe and not as catalogs of personal judgments about those physical systems made by each individual user of quantum mechanics.
Why does our understanding of scientific laws have to be impersonal? Science is a human activity. Its laws are formulated in human language. As empiricists, most scientists believe that their understanding of the world is based on their own personal experience. Why should I insist that my interpretation of science, which I use to make sense of the world that I experience, should never make any mention of me? The existence of a quantum measurement problem, either unsolved or with many incompatible solutions, is powerful evidence that the experience of the scientist does indeed play as important a role in understanding quantum theory as the experience of the statistician plays in understanding ordinary probability theory... (MORE - missing details)
EXCERPTS: There are three types of quantum physicists: (1) those who think quantum mechanics is defaced by a so-called measurement problem; (2) those who think, as I do, that there is no measurement problem; and (3) those who think the issue is not worth serious thought. You can find the diverse views of 17 physicists and philosophers from the first two groups in chapter 7 of Maximilian Schlosshauer's Elegance and Enigma.
Most people in all three groups would agree on the following: Quantum mechanics describes a physical system entirely in terms of states. A state is a compendium of probabilities of all possible answers to all possible questions one can ask of the system. Quantum mechanics is inherently statistical. There is no deeper underlying theory that gives a fuller description.
The state assigned to a system can change in time in two ways. If no question is asked of the system, then its state evolves in time deterministically: continuously and according to fixed rules. If a question is asked of the system -- called making a measurement -- then when the question is answered, the state changes discontinuously into a state that depends both on the state just before the question was asked and on the particular answer the system gives to that question. The second process is called the collapse of the state. Collapse is generally abrupt, discontinuous, and stochastic.
[...] Many physicists in group 2 would add the following: There are no consequences of a quantum state assignment other than all the probabilities it gives rise to. While many (perhaps most) physicists view probabilities as objective features of the world, most probabilists and statisticians do not. As the celebrated probabilist Bruno de Finetti put it, "The abandonment of superstitious beliefs about the existence of Phlogiston, the Cosmic Ether, Absolute Space and Time, ...., or Fairies and Witches, was an essential step along the road to scientific thinking. Probability, too, if regarded as something endowed with some kind of objective existence, is no less a misleading misconception, an illusory attempt to exteriorize or materialize our actual probabilistic beliefs."
Isolated excerpts from Niels Bohr can support many diverse views. But a quarter century after publishing my concluding quotation, he wrote that "physics is to be regarded not so much as the study of something a priori given, but rather as the development of methods for ordering and surveying human experience." It's the same opinion, and it has the same ambiguity: Is "human experience" individual or collective?
Physicists who materialize their own probabilistic beliefs must also materialize quantum states, which are nothing more than catalogs of such beliefs. [...] That the quantum state of a system expresses only the belief of the particular physicist who assigns it to the system was emphasized by the theorists Carlton Caves, Christopher Fuchs, and Rüdiger Schack at the turn of the 21st century as being crucial to the interpretation of quantum mechanics.
[...] Such solutions [that alternatively contend that there is a problem] all take quantum states to be objective properties of the physical system they describe and not as catalogs of personal judgments about those physical systems made by each individual user of quantum mechanics.
Why does our understanding of scientific laws have to be impersonal? Science is a human activity. Its laws are formulated in human language. As empiricists, most scientists believe that their understanding of the world is based on their own personal experience. Why should I insist that my interpretation of science, which I use to make sense of the world that I experience, should never make any mention of me? The existence of a quantum measurement problem, either unsolved or with many incompatible solutions, is powerful evidence that the experience of the scientist does indeed play as important a role in understanding quantum theory as the experience of the statistician plays in understanding ordinary probability theory... (MORE - missing details)