# Free-falling in Quantum Spacetime

### APA

Parikh, M. (2024). Free-falling in Quantum Spacetime. Perimeter Institute. https://pirsa.org/24030103

### MLA

Parikh, Maulik. Free-falling in Quantum Spacetime. Perimeter Institute, Mar. 07, 2024, https://pirsa.org/24030103

### BibTex

@misc{ pirsa_PIRSA:24030103, doi = {10.48660/24030103}, url = {https://pirsa.org/24030103}, author = {Parikh, Maulik}, keywords = {Quantum Gravity}, language = {en}, title = {Free-falling in Quantum Spacetime}, publisher = {Perimeter Institute}, year = {2024}, month = {mar}, note = {PIRSA:24030103 see, \url{https://pirsa.org}} }

Maulik Parikh Arizona State University

## Abstract

When the spacetime metric is regarded as a quantum field, the classical trajectories of freely falling objects are subject to random fluctuations, or “noise”. This fundamental noise might even be observable at gravitational wave detectors: if detected, it would provide experimental evidence for the quantization of gravity. The effect of the quantum-gravitational noise is to turn the classical geodesic deviation equation into a stochastic, Langevin-like equation. Moreover, when these results are extended to congruences of geodesics, the quantum fluctuations of spacetime give rise to an additional term in the Raychaudhuri equation with the same sign as the other terms.

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