Classical World Arising out of Quantum Physics under the Restrictionof Coarse-Grained Measurements

Author(s): J. Kofler, Č. Brukner

Journal: Physical Review Letters

Volume: 99

Page(s): 180403

Year: 2007

DOI Number: --


Conceptually different from the decoherence program, we present a novel theoretical approach to macroscopic realism and classical physics within quantum theory. It focuses on the limits of observability of quantum effects of macroscopic objects, i.e., on the required precision of our measurement apparatuses such that quantum phenomena can still be observed. First, we demonstrate that for unrestricted measurement accuracy, no classical description is possible for arbitrarily large systems. Then we show for a certain time evolution that under coarse-grained measurements, not only macrorealism but even

classical Newtonian laws emerge out of the Schro¨dinger equation and the projection postulate.

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