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  • Open Access

Geodesics in quantum gravity

Benjamin Koch1,2,3,*, Ali Riahinia1,2,†, and Angel Rincon4,‡

  • *Contact author: benjamin.koch@tuwien.ac.at
  • †Contact author: ali.riahinia@tuwien.ac.at
  • ‡Contact author: angel.rincon@physics.slu.cz
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Phys. Rev. D 112, 084056 – Published 22 October, 2025

DOI: https://doi.org/10.1103/w1sd-v69d

Abstract

We investigate the motion of test particles in quantum-gravitational backgrounds by introducing the concept of q–desics, quantum-corrected analogs of classical geodesics. Unlike standard approaches that rely solely on the expectation value of the spacetime metric, our formulation is based on the expectation value of quantum operators, such as the affine connection operator. This allows us to capture richer geometric information. We derive the q–desic equation using both Lagrangian and Hamiltonian methods and apply it to spherically symmetric static backgrounds obtained from canonical quantum gravity. Exemplary results include lightlike radial motion and circular motion with quantum gravitational corrections far above the Planck scale. This framework provides a refined description of motion in quantum spacetimes and opens new directions for probing the interface between quantum gravity and classical general relativity.

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Phys. Rev. D 112, 084056– Published 22 October, 2025
  • Received 7 July 2025
  • Accepted 27 September 2025
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