http://arxiv.org/abs/2109.10336
Cosmological backreaction corresponds to the effect of inhomogeneities of structure on the global expansion of the Universe. The main question surrounding this phenomenon is whether or not it could explain the recent acceleration of the scale factor, also known as Dark Energy. One of the most important result on this subject is the Buchert-Ehlers theorem (Buchert \& Ehlers, 1997) stating that backreaction is exactly zero when calculated using Newton’s theory of gravitation, which may not be the case in general relativity. It is generally said that this result implies that backreaction is a purely relativistic effect. We will show that this is not necessarily the case, in the sense that this implication does not apply to a universe which is still well described by Newton’s theory on small scales but has a non-Euclidean topology. The theorem should therefore be generalised to account for such a scenario. In a heuristic calculation where we define a theory which is locally Newtonian but defined on a non-Euclidean topology, we show that backreaction is non-zero, meaning that it might be non-relativistic and might depend on the topology of our Universe. However, this theory is yet to be justified from a non-relativistic limit of general relativity.
Q. Vigneron
Wed, 22 Sep 21
25/57
Comments: Submitted to Classical and Quantum Gravity Letters
You must be logged in to post a comment.