Speaker
Description
General Relativity (GR), together with Quantum Theory, is a cornerstone of modern physics. However, for nearly a century there have existed observational phenomena, "dark matter" and "dark energy", that cannot be explained within the framework of GR and our current understanding of particle physics. Attempts to detect dark matter particles have so far been unsuccessful, and explaining the nature of dark energy from the standpoint of quantum theory also remains challenging. A possible way forward is to modify or replace GR itself.
In this work, we develop one of the metric–affine modifications of GR, Symmetric Teleparallel Equivalent of General Relativity (STEGR). Unlike GR, in STEGR the only nontrivial geometric property of spacetime is non-metricity, which makes the covariant derivative of the metric nontrivial. Within our study, we reformulate the Einstein–Hilbert action, where curvature plays the key role, into the action of the symmetric teleparallel equivalent, and then modify it by introducing additional parameters of the theory. Using this formalism, we derive the equations of motion for cosmological perturbations in the Friedmann metric with conformal time. To obtain scalar perturbations, we employ the method of conformal transformations, which allows us to express the Einstein tensor for the Friedmann metric through quantities calculated for the perturbed Minkowski metric.
