%0 Generic
%A Pauly, Martin
%C Heidelberg
%D 2021
%F heidok:30644
%R 10.11588/heidok.00030644
%T The Imprint of Spacetime: from Networks to Particle Physics and Cosmology
%U https://archiv.ub.uni-heidelberg.de/volltextserver/30644/
%X We study the link between spacetime and properties of physical systems in two settings.  First, we demonstrate how the embedding geometry constrains real-world networks, such as e.g. road networks or biological neural networks, by studying diffusion processes on such networks. Surprisingly, we find a resemblance between a class of nodes in some real-world networks and networks inspired by models of the fundamental structure of spacetime.  Second, we introduce asymptotically safe quantum gravity, a theory of quantum spacetime. Asymptotically safe quantum gravity could constrain models that aim at explaining three cosmological observations: the accelerating expansion of the universe today, a period of accelerated expansion in the early universe, and dark matter.  We strengthen indications that asymptotic safety quantum gravity flattens scalar potentials and explore consequences for said cosmological models. We find that for asymptotically safe models of the early universe it is challenging to reproduce the amplitude of spacetime fluctuations observed from this epoch.   Asymptotically safe quantum gravity could enhance predictivity in dark matter models: we find indications that an asymptotically safe extension of the Standard model by a dark scalar and a dark fermion could feature a single free parameter in the dark sector and might yield the observed amount of dark matter. The same model could also alter the Higgs boson mass predicted in asymptotic safety such that it matches present observations.  In addition, asymptotically safe quantum gravity could constrain whole classes of Standard Model extensions. We find indications that asymptotic safety might not permit a large class of models featuring a global discrete symmetry.