SMuK 2023 – scientific programme
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GR: Fachverband Gravitation und Relativitätstheorie
GR 2: Cosmology I
GR 2.3: Talk
Monday, March 20, 2023, 17:10–17:30, ZEU/0255
Lightcone invariant observables in cosmology — Bhuvan Agrawal1, Markus Fröb2, and •William Lima2 — 1Mathematisch-Naturwissenschaftliche Fakultät, Universität zu Köln, Köln, Germany — 2Institut für Theoretisches Physik, Universität Leipzig, Leipzig, Germany
I will discuss a recent proposal by Brunetti et al. to construct gauge-invariant relational observables in gravity in the context of cosmological perturbation theory. I will report on new results showing how their method can be use to produce invariant observables adapted to measurements along the observer's past lightcone. These observables aim to model the experimental situation in cosmology, where virtually all experimental data is gathered via light-like signals. The lightcone observables are constructed using a field-dependent coordinate system, which I will take to be geodesic lightcone coordinates. As a concrete application, I will present a new computation of the correlator of an observable measuring the redshift produced by quantum-gravitational fluctuations on the de Sitter spacetime.