Zenith Grant Awardee
Dr. Jorge A. Pullin
Louisiana State University
Co-Investigators
Rodolfo Gambini, University of the Republic, Montevideo, Uruguay
Project Title
Relational Physics with Real Rods and Clocks and the Measurement Problem of Quantum Mechanics
Project Summary
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.
Technical Abstract
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.
QSpace Latest
PressRelease: Precision experiment puts pressure on quantum collapse theories
Quantum mechanics, the theory governing the microscopic world, is famously counterintuitive. A particle can exist in a superposition of multiple states, such as different positions, until a measurement is performed. At that point, the wavefunction describing that particle appears to ‘collapse’ to a single outcome. This puzzle lies at the heart of the measurement problem, famously illustrated by Schrödinger’s cat, suspended between life and death until observed. The XENONnT detector, which was designed to be sensitive to rare physics events, has tightened constraints on one family of possible solutions to the measurement problem, known as ‘collapse theories.’ The work, which was partially funded by FQxI, was reported in Physical Review Letters in March 2026. Image credit: XENON Collaboration.