This public discussion meeting was held in conjunction with the annual meeting of the Euclid consortium, at University College, London. The title reflects the fact that this year marks the 100th anniversary of Einstein’s paper in which he first introduced the concept of a cosmological constant (actually published on on 8th February 1917). The discussion was led by Profs George Efstathiou (Cambridge) and Ofer Lahav (UCL).
Of particular interest was Ofer’s opening talk on the historical background to Einstein’s paper, and the fact that it Lambda was initially introduced to solve a boundary condition problem associated with Einstein’s formulation of GR, rather than to achieve a static universe, as is commonly assumed.
George’s talk explored some of the possible explanations for Lambda, and the reasons why it might have the currently observed value. The ensuing discussion covered a wide range of possibilities, including the contentious employment of the anthropic principle. George’s concluding remarks contained a plaintive exhortation for theoretical physicists and the cosmology community to come up with new theoretical models that could explain Lambda. In his view, unless there was a paradigm shift in our cosmological model, the astronomy community was doomed to measuring the properties of a mythical substance, Lambda, to ever greater degrees of precision.