Electron paramagnetic resonance, also called Electron spin resonance, used in Physical and Analytical Chemistry, Site-directed Spin Labeling, and Inorganic Chemistry
EPR paradox by Einstein, Podolsky and Rosen (Quantum Mechanics)
This disambiguation page lists articles associated with the same title. If an internal link led you here, you may wish to change the link to point directly to the intended article.
In quantum mechanics, the EPR paradox (Einstein-Podolsky-Rosen) is a thought experiment which challenged long-held ideas about the relation between, on the one hand the observed values of physical quantities and on the other, the values that can be accounted for by a physical theory.
The EPR paradox draws on a phenomenon predicted by quantum mechanics, known as quantum entanglement, to show that measurements performed on spatially separated parts of a quantum system can apparently have an instantaneous influence on one another.
In the many-worlds interpretation, a kind of locality is preserved, since the effects of irreversible operations such as measurement, arise from the relativization of a global state to a subsystem such as that of an observer.
The unreasonableness to which EPR allude in making "the reality [on the second system] depend upon the process of measurement carried out on the first system, which does not in any way disturb the second system" is just the unreasonableness that would be involved in renouncing locality itself.
EPR is about the interpretation of state vectors ("wave functions") and employs the standard state vector reduction formalism (von Neumann's "projection postulate").
To go back to the EPR dilemma between locality and completeness, it would appear from the Bell theorem that Einstein's strategy of maintaining locality, and thereby concluding that the quantum description is incomplete, may have fixed on the wrong horn.
Feeds |
Contact