Por Francisco Lobo (Instituto de Astrofísica e Ciências do Espaço, FCUL).

The flaring-out condition at a wormhole's throat, which in general relativity violates the null energy condition, is a key feature in wormhole physics. This study explores modified gravity, where the matter at the throat satisfies the energy conditions, and we show that these non-trivial geometries are sustained by higher-order curvature effects acting as a gravitational fluid. These geometries may generate closed timelike curves, challenging causality. As causality is fundamental to physical theories, the potential for time travel and its paradoxes requires careful examination, which this presentation will explore in some detail.

Short bio: Francisco Lobo is a researcher at the Institute of Astrophysics and Space Sciences (IA) and Professor with Habilitation at the Department of Physics of the Faculty of Sciences of the University of Lisbon (FCUL). He is a member of the Euclid and LISA missions. He has published over 200 articles in high-impact international scientific journals, in the research areas of cosmology and gravitation.