Dr. Jorge A. Pullin

Louisiana State University
Rodolfo Gambini
University of the Republic, Montevideo, Uruguay
Relational Physics with Real Rods and Clocks and the Measurement Problem of Quantum Mechanics

As paradoxical as this may sound, the theory of quantum mechanics that describes the microscopic world is ordinarily formulated in terms of classical, macroscopic quantities. In particular, one assumes that one has access to arbitrarily accurate clocks and rulers. Such an assumption is clearly an idealization. This idealization becomes even more untenable in the context of theories of nature that include gravity. We show that relaxing such an idealization can help solve some of the conceptual problems of traditional quantum mechanics. These include the problem of how a classical world arises from the quantum theory and the problem of how to interpret the quantum theory and therefore to form a proper physical picture of reality.

When quantum mechanics is formulated in terms of relational notions, as is required by any theory of nature that includes gravity, it takes a different form than the usual one. In particular, there is a natural loss of coherence in quantum states when time and space are measured by realistic clocks and rods, which have quantum and other types of uncertainties in their measurements. We propose to investigate the impact of this loss of coherence on the fundamental problems of measurement in quantum theory. The aim is to show that the use of real clocks and measuring rods in quantum theory, combined with interactions with the environment, effectively eliminates most of the well known issues with the problem of measurement in quantum mechanics. It also opens a new perspective to be explored on interpretational issues of the quantum theory, since in view of the fundamental loss of coherence some interpretations of quantum mechanics immediately lose their compelling nature, whereas others arise as more natural.

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