Relative locality is a proposed physical phenomenon that different observers would disagree on whether two space-time events are coincident. This is in contrast to special relativity and general relativity in which different observers may disagree on whether two distant events occur at the same time but if an observer infers that two events are at the same spacetime position then all observers will agree.
When a light signal exchange procedure is used to infer spacetime coordinates of distant events from the travel time of photons, information about the photon's energy is discarded with the assumption that the frequency of light doesn't matter. It is also usually assumed that distant observers construct the same spacetime. This assumption of absolute locality implies that momentum space is flat. However research into quantum gravity has indicated that momentum space might be curved which would imply relative locality. To regain an absolute arena for invariance one would combine spacetime and momentum space into a phase space.
- Principle of relative locality, Giovanni Amelino-Camelia, Laurent Freidel, Jerzy Kowalski-Glikman, Lee Smolin, 5 Jan 2011, Phys. Rev. D 84, 084010 (2011), doi:10.1103/PhysRevD.84.084010, arXiv:1101.0931
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- Relative locality: A deepening of the relativity principle, Giovanni Amelino-Camelia, Laurent Freidel, Jerzy Kowalski-Glikman, Lee Smolin, International Journal of Modern Physics D, Vol. 20, No. 14 (2011) 2867–2873, World Scientific Publishing Company, doi:10.1142/S0218271811020743, arXiv:1106.0313
- Beyond space-time: Welcome to phase space, New Scientist, 8 August 2011, issue 2824
- Meaning and job of the phase spaces, The Reference Frame, 7 January 2011