Organiser: Fysikum, Stockholm University
Zoom: https://stockholmuniversity.zoom.us/j/69154692449
No registration required

Abstract:

The cosmological constant problem is one of the most puzzling problems in theoretical physics, challenging our understanding of the vacuum energy and how it gravitates. To paraphrase Wolfgang Pauli, the cosmological constant problem concerns the question, ‘Why is our universe larger than the distance to the moon?’. In this lecture, I review the calculations of the vacuum energy, the implications for the expansion of the universe, and the constraints from observations. I describe various versions of the problem, focussing on the most severe. I describe why the problem is not easily solved, and list conditions that successful solutions must satisfy. In view of this, I briefly outline classes of proposed solutions and assess their prospects.