Gravitational waves as probes of new physics at the onset of multi messenger astronomy

Speaker: Dr. Antonino Marciano, Department of Physics, Fudan University

Abstract

Direct detection of gravitational waves was finally attained only two years ago, 100 years after Einstein formulated his theory of General Relativity. This latter constitutes the current theoretical framework of the Standard Cosmological Model, within which major advances in our understanding of the Universe were achieved over the last century, including the explanation of the structures’ formation (galaxies, cluster of galaxies etc…), of the features of the spectra of cosmic background radiation (light emitted 380,000 years after the Big Bang), and so on and so forth. Nonetheless, the same framework also inspired, through the prediction of Black Hole solutions, over half a century of theoretical disputes on the information loss paradox and on the possible violations of unitarity, which is one the pillars of quantum mechanics. The clash between the Newtonian theory of gravity
(and hence General Relativity) and data acquired through the years on the galaxies rotation curves and the visible amount of stars, required the introduction of the concept of Dark Matter, while the current accelerated phase of expansion of the Universe suggested the existence of Dark Energy, constituting over 70% of the energy density of the Universe. Within this vast and puzzling scenario, gravitational waves represent an amazing possibility to unveil new physics, and may contribute in a relevant way to solve at least some of these shortcomings.

The speaker will first review the steps toward this discovery, and comment on the relevance of the birth of multi-messenger astronomy for the understanding of fundamental physics. Then he will introduce gravitational waves in comparison with electromagnetic waves, showing similarities and differences between the two forms of radiation. Finally, he will show how gravitational waves can be relevant to distinguish models of early cosmology, and may shed light on new physical interactions, explaining dark matter and eventually dark energy.