Since 2015’s celebrated first detection of gravitational waves from merging black holes, detectors have measured waves from nearly a hundred different events. Many current detectors are being upgraded, improving their sensitivity and broadening their sensitive wave bands; future detectors are planned which will likewise have wider bands and deeper sensitivity. These future instruments will be...

We will present results regarding the instability of extremal black holes. We will show how these results can be used to derive observational signatures for extremal black holes.

Working within the space of smooth solutions of GR and tuning to the threshold of black hole formation, we arrive at extreme spacetimes which are generally expected to contain naked singularities. In the spherical setting such configurations have been accurately studied by numerical work for three decades. This resulted in a beautiful understanding of the threshold of collapse through a...

LISA (Laser Interferometer Space Antenna) is the future large mission by the European Space Agency aimed at observing the Universe with gravitational waves. It was approved in 2017 following the success of the technological demonstrator LISAPathfinder and the detection of gravitational waves by ground-based observatories LIGO-Virgo. LISA has nearly completed its detailed definition phase...

I will discuss some explicit solutions of higher order scalar tensor theories. We will start by reviewing classical GR solutions and some of their key properties such as integrability of geodesics in Kerr spacetime. We will then construct stealth solutions, i.e. solutions that are still Einstein metrics but with a non trivial scalar field. We will construct solutions which are distinct from...

I will review recently proposed probes of gravity and dark matter based on the oscillations of stars. In this regard, I explain how current and future solar/stellar oscillations can place tight constraints on the properties of dark energy and dark matter.

We consider some cosmological models where soft future singularities arise and discuss how the crossing of these singularities can change the properties of matter fields. We also compare different approaches to the possibility of the crossing of the singularities of the Big Bang – Big Crunch type. We discuss what happens with the singularities in quantum cosmology and study what happens with...