Economics Dictionary of ArgumentsHome![]() | |||
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Quantum mechanics: is a partial discipline of physics, dealing with processes at the level of elementary particles. Here, principles which cannot be observed at the level of everyday objects are valid. The special forces and interactions that prevail within the quantum world are not to be found on the macro level. See also superposition, entanglement, uncertainty principle._____________Annotation: The above characterizations of concepts are neither definitions nor exhausting presentations of problems related to them. Instead, they are intended to give a short introduction to the contributions below. – Lexicon of Arguments. | |||
Author | Concept | Summary/Quotes | Sources |
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John D. Barrow on Quantum Mechanics - Dictionary of Arguments
I 233 Quantum mechanics/QM/Atom/Uniformity/Equality/Barrow: the quantization of energy is the reason why hydrogen atoms are identical. >Energy, >Symmetries. I 235 Measurement Problem/QM/Barrow: it is about whether the quantum theory describes everything that happens in nature, including the measurement process, or not. >Measurement problem. I 237 EPR/Barrow: Paradox: we cannot predict which the two photons will move clockwise in the decay - but if we were to go to the other end of the universe, we would know instantly because of quantum mechanics that the other photon rotates in the other direction, without having measured it. - I.e. the unmeasured momentum must match reality. - It must be real, because it is predictable. Knowledge without measurement, i.e. independent of observation. >Observation, >Observation independence. Paradox: the second photon must know the direction of the other. Proof: Alain Aspect experiment, 1982. I 240 Barrow: in fact, no information is transmitted - VsEPR: simultaneity is a concept that depends on the observer. - E.g. three observers could be in motion relative to each other and to the experiment - one would see that the measurements of the spins are conducted simultaneously, while the others would first observe one or the other. I 238f John Bell/QM/Non-Locality/Barrow: (1960s): John Bell showed that every theory that describes EPR phenomena needs to have a non-local description if a simple arithmetic condition is satisfied. >Non-locality. Bell Test/Uncertainty: Uncertainty is not about the coarseness of the observer - this would be a local explanation. Bell: Each correct view of nature must be non-local. I 242 Copenhagen Interpretation/Bohr: In the traditional sense, no deeper reality can be discovered, but only a description of it. - It is useless to say that the measurement somehow changed a deeper reality. I 245 While the wave function is deterministic, linear, continuous and local, and does not know any determinate time direction, the measuring process is almost random, non-linear, discontinuous, non-local and non-reversible. >Wave function, >Measurements, >Time arrow, >Time, >Time reversal. SchrödingerVsBohr: Schrödinger's cat: is in a mixture of dead and alive, as long as we do not look. I 247 Wheeler: Problem: all astronomical measurements are made with radiation. - So according to Bohr's Copenhagen interpretation, they would only be made alive by measuring. I 253ff Copenhagen Interpretation/Many-Worlds Interpretation/MWI/Aspect/Experiment/Barrow: the assumption of non-locality was experimentally confirmed by Aspect. >Many-Worlds Theory, >Copenhagen Interpretation. Barrow: The Copenhagen and the many-worlds interpretation appear to be completely incompatible, but there is the unanimous opinion that they are experimentally indistinguishable._____________Explanation of symbols: Roman numerals indicate the source, arabic numerals indicate the page number. The corresponding books are indicated on the right hand side. ((s)…): Comment by the sender of the contribution. Translations: Dictionary of Arguments The note [Concept/Author], [Author1]Vs[Author2] or [Author]Vs[term] resp. "problem:"/"solution:", "old:"/"new:" and "thesis:" is an addition from the Dictionary of Arguments. If a German edition is specified, the page numbers refer to this edition. |
B I John D. Barrow Warum die Welt mathematisch ist Frankfurt/M. 1996 B II John D. Barrow The World Within the World, Oxford/New York 1988 German Edition: Die Natur der Natur: Wissen an den Grenzen von Raum und Zeit Heidelberg 1993 B III John D. Barrow Impossibility. The Limits of Science and the Science of Limits, Oxford/New York 1998 German Edition: Die Entdeckung des Unmöglichen. Forschung an den Grenzen des Wissens Heidelberg 2001 |