Prof. Pedro G. Ferreira: "Can Cosmology Decide? The Problem of Dark Energy"

Is the universe's expansion truly accelerating because of a mysterious dark energy, or because our theory of gravity itself is incomplete?

For nearly three decades, cosmologists have built a remarkably successful picture of the universe around one deeply puzzling ingredient: a component accounting for roughly 70% of the universe's present-day energy budget, yet whose nature remains almost entirely unknown. Recent observations have only sharpened the mystery, with tantalising hints that dark energy may not be constant after all. Such findings open the door to new physics, including the possibility that gravity behaves differently on cosmological scales than Einstein's theory of General Relativity predicts.

In this colloquium, Prof. Pedro G. Ferreira will ask whether cosmology, as it stands today, can actually settle this question. Drawing on decades of work at the frontier of cosmology, he will guide us through the evidence, the tensions between different measurements, and what it would take to determine whether dark energy is really a "thing" or instead a sign that our understanding of gravity is incomplete. 

Questions about the limits of General Relativity lie at the heart of the research pursued at the Center of Gravity and connect directly to many of the fundamental questions we explore.

We're delighted that this talk will kick off the second season of the CoG Colloquia, following a hugely successful first season. We look forward to welcoming you, and invite you to join us for an apéro reception after the talk, a chance to continue the conversation.