Speaker
Description
Dark Energy is the term given to the dominant energy density in the universe today which appears to be causing it to accelerate. A key question then is what is responsible for the dark energy? There are three favoured candidates: a cosmological constant which has a fixed constant energy density, a quintessence field which has an energy density which varies with time or a modification of Einstein's General Theory of Relativity, where the presence of extra curvature terms could lead to the observed acceleration. We will discuss these options, and their problems (they all have some!), and comment on the recent tentative evidence emerging from the DESI collaboration of dynamical dark energy - exciting but not as you would expect from quintessence!