I am a Principal Researcher at the National Observatory of Athens/Greece. I have worked as a Postdoctoral Researcher in France, Taiwan, and Athens, and was a visiting Professor in France, Chile, USA, China and an Assistant Professor in Athens. My research interests are cosmology, relativity, theories of gravity, dark energy, Inflation, black holes, gravitational waves, and cosmological tensions. I have supervised more than 15 postdocs and Phd students, and I have performed more than ~1000 reviews for various journals, and more than ~20 international grant reviews. I have ~250 publications, with ~18000 citations, and h-index=77.