https://doi.org/10.1140/epjc/s10052-025-13888-6
Regular Article - Theoretical Physics
Non-geodesic timelike observers and the ultralocal limit
1
Department of Physics and Astronomy, Bishop’s University, 2600 College Street, J1M 1Z7, Sherbrooke, QC, Canada
2
Department of Physics, McGill University, 3600 rue University, H3A 2T8, Montreal, QC, Canada
Received:
12
August
2024
Accepted:
2
February
2025
Published online:
12
February
2025
The ultralocal limit along timelike geodesics, in which any geometry reduces to Bianchi I, does not extend to non-geodesic timelike observers. Exceptions are discussed, including particles with variable mass, test particles in Einstein frame scalar-tensor gravity, and self-interacting dark matter.
© The Author(s) 2025
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