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Germano Nardini (U Stavanger)01/06/2026, 14:30
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Abdolali Banihashemi (U Oslo)01/06/2026, 14:50
In this talk, I will discuss a model of extended quintessence in which a scalar field is non-minimally coupled to gravity, serving as a candidate for dark energy. I will present its properties at both the background and linear perturbation levels. While the non-minimal coupling is constructed to satisfy local tests of gravity without need to introduce screening mechanisms, the model exhibits...
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Yoann Launay (U Cambridge)01/06/2026, 15:10
Previous work on Stochastic Inflation in full General Relativity is extended to any dark energy model described by the Effective Field Theory of Dark Energy. The recipe to obtain the dynamics of a any such nonlinear and nonperturbative long-wavelength scalar-tensor theory, when dynamically sourced by classicalised fluctuations of the short modes, is explained, proved and illustrated with a few...
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Ofek Birnholtz (Bar-Ilan U)01/06/2026, 16:00
The worldwide LIGO-Virgo-KAGRA (LVK) network of gravitational-wave (GW) detectors continues to increase in sensitivity, thus increasing the quantity and quality of the detected GW signals from compact binary coalescences. These signals allow us to perform ever-more sensitive tests of general relativity (GR) in the dynamical and strong-field regime of gravity. We present the results of a suite...
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Sayantani Bera (Aix-Marseille U)01/06/2026, 16:20
The most debated crisis in cosmology today is, perhaps, the inconsistency of the estimated value of the current expansion rate of the Universe (known as the Hubble constant, H0) between different probes using high redshift and low redshift observations. Gravitational wave (GW) emitting sources, which are routinely observed nowadays through the ground-based LIGO-Virgo-KAGRA detector network,...
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Matteo Pegorin (U & INFN Padova)01/06/2026, 16:40
Next generation gravitational wave detectors, such as the Einstein Telescope and LISA, require an improvement of two orders of magnitude in waveform accuracy to control systematic effects. Therefore, completing the seventh post-Newtonian order (7PN) is critical for robust inference of cosmological parameters and tests of general relativity. This talk presents recent high order PN computations...
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Otto Kong (NCU Taiwan)02/06/2026, 14:30
The quantum dynamics of a particle, with or without spin, in curved spacetime is analyzed from the Heisenberg picture, hence with a focus on the observables. It is based on a covariant Hamiltonian formulation. For the spin-zero particle, quantum geodesic equations are obtained as differential equations governing the evolution of the position observables. The formulation is not compatible with...
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Gabriele Gionti (Vatican Observatory)02/06/2026, 14:50
A. D’Adda (2021) has shown that by assigning a length to each link and coordinates to each labelled vertex, one can define a non-Euclidean flat metric and a reference frame within each simplex that is invariant under GL(n,R). In this formulation, the metric tensor is a function of both the link lengths and the vertex coordinates. In this talk, we show that by performing an appropriate gauge...
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Mikolaj Myszkowski (U Southern Denmark)02/06/2026, 15:10
In a number of different approaches to quantum gravity, the effective number of spatial dimensions has been found to change with energy scale. Motivated by this phenomenon, we propose quantum systems in which the number of spatial dimensions is promoted to a dynamical quantum variable. This opens new avenues for constructing gravitational systems in which the very notion of dimensionality...
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Øyvind Christiansen (Czech Academy of Sciences)02/06/2026, 16:00
Recent cosmological data from DESI motivate modelling of extensions to the standard model that modifies late-time phenomenology, while maintaining concordance with early Universe, local laboratory and solar system experiments. One promising way to do so is to have additional cosmologically relevant degrees of freedom that are negligible until they are activated in underdensities of the...
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Lorenzo Giombi (U Helsinki)02/06/2026, 16:20
Using semi-analytical models, we investigate the power spectrum of gravitational waves generated by sound waves in the plasma during a first-order phase transition in new unexplored scenarios. (i) The phase transition is accompanied by a change of the equation of state from that of pure radiation. This modifies the shape of the gravitational wave power spectrum as a consequence of both sound...
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Lasse Gerblich (U Cambridge)02/06/2026, 16:40
Cosmic strings are one-dimensional topological defects, which are formed during symmetry-breaking phase transitions with a non-simply connected vacuum manifold. If they exist, they are expected to generate gravitational waves, which we might be able to detect with future gravitational wave observatories such as LISA or Einstein Telescope. In particular, local features on the strings, such as...
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Jessica Lopez-Sanchez (CEICO Prague)03/06/2026, 10:40
The observed diversity of small-scale structures suggests that dark matter may be multi-component. Ultra-faint dwarf spheroidal galaxies exhibit both cored and cuspy density profiles, which are difficult to reconcile if all dark matter components share purely adiabatic initial conditions. In this work, we investigate a scenario in which a subdominant dark matter component carries isocurvature...
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Panagiotis Giannadakis (King's College London)03/06/2026, 11:00
We investigate the effects of large scalar inhomogeneities during the kination epoch, a period in which the universe’s dynamics are dominated by the kinetic energy of a scalar field, by fully evolving the Einstein equations using numerical relativity. By tracking the non-linear growth of scalar perturbations with both sub-horizon and super-horizon initial wavelengths, we are able to compare...
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Alexander Oestreicher (U Southern Denmark)03/06/2026, 11:20
The current generation of telescopes will be able to detect the real-time change of cosmological observables, in particular the change in redshift and position of sources. This will provide direct dynamical insight into the evolution of the universe and its structures, including the first direct evidence of its accelerated expansion. To interpret these extremely precise measurements, it is...
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Hamed Barzegar (ENS de Lyon)03/06/2026, 11:40
In this talk, I provide a systematic classification and critical evaluation of warp-drive spacetimes within General Relativity (GR). Moving beyond the popular "creative" approach, I adopt a rigorous "agonistic" methodology to address the recent renaissance of claims regarding physically feasible, positive-energy warp drives. By applying a basic principle, which mandates mathematical...
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Eirik Svanes (U Stavanger)03/06/2026, 12:00
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