Yousaf Butt questioned whether the Nobel committee had been premature in awarding the 2011 physics prize “for the discovery of the accelerating expansion of the universe” to Saul Perlmutter, Brian Schmidt, and Adam Riess on the basis of their work observing distant type Ia supernovae (PHYSICS TODAY, February 2012, page 10).
The decision was assuredly based on additional corroboration. Not only were subsequent corroborative supernovae Ia data published by other groups,1 but further evidence has accumulated.2 Studies of the cosmic microwave background and large-scale structure,3 baryon acoustic oscillations,4 and cosmochronology5 all support accelerated expansion and dark energy and have rendered the conclusion virtually unassailable, notwithstanding claims that the intrinsic motion of distant objects overlying the Hubble flow might cast doubt on the interpretation of the Perlmutter-Schmidt-Riess observations. The case for accelerated expansion in an Einstein-de Sitter-Lemaître “inflexional” universe has now been made irrefutably in numerous texts and in a continuing flood of papers dealing with dark energy, the cosmological constant, quintessence, and so on.
The discovery of the accelerated expansion of our universe’s spacetime has vindicated the presence of a cosmological constant in the field equations of general relativity and the consequent reawakening of interest in the role of antigravitational repulsive pressure in general-relativistic cosmological theory. It has also driven the examination of new vistas in astronomy and astrophysics. It has led to fresh insights into possible multiverses, extra dimensions of spacetime, and generalized aspects of particle physics, and it has brought a new scientific reality to the latest insights into cosmology.
The award of the 2011 Physics Nobel Prize in timely recognition of that fundamental progress and consolidation of our basic understanding of the cosmos is therefore well justified.
