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Home page of Donald McCartor
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The paper described below can be downloaded. The first half has the flavor of philosophy and should be readable by and interesting to everyone. An introductory course in quantum mechanics, and a bit of thinking, is enough for the rest of it. It has been published by the new physics journal Concepts of Physics in their first issue. Their web address is http://www.conceptsofphysics.net |
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Quantum Thought Experiments Can Define Nature It would be quite improper for thought experiments to matter to nature. They are a humble human device. Yet quantum mechanics very naturally frames thought experiments (as against bits of reality). They exemplify the informing powers of radiation. Though based on wave functions that have time symmetry, these fancied tableaus inevitably tell of irreversible behavior by nature. The paper sketches how John von Neumann’s measurement theory fits into this and retells N. David Mermin’s baseball story. A law both important and imperfect Perfect and imperfect ideas Thought experiments The probabilities of physics Measurement theory Typicalness, radiation, and inference Quantum measurement Quantum photography Imaginary experience Time reversal Defining the behavior that is typical of nature Von Neumann’s theory grounded on observation of radiation Basics Primitive observations The two division operations Four equations When instrumented observations do not interfere When observations are subsidiary to instrumented ones Conclusion |
37 pages in PDF, no figures, 220kB Download
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The paper below expands on one of the themes of the paper above by showing how many of the traditional assumptions of physics look in the light of it. |
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The Hourglass - Consequences of Pure Hamiltonian Radiation of a Radiating System Hourglass is the name given here to a formal isolated quantum system that can radiate. Starting from a time when it defines the system it represents clearly and no radiation is present, it is given straightforward Hamiltonian evolution. The question of what significance hourglasses have is raised, and this question is proposed to be more consequential than the measurement problem. Hourglasses Physics without true histories But histories are sometimes good Phlogiston and oxygen A closer look at quantum engineering Conclusion |
12 pages in PDF, no figures, 100kB Download
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