The universe is expanding at an ever-increasing rate. Theoretical nuclear and particle physics is trying to explain this in terms of the energy of quantum processes in empty space. The problem is that hitherto all potential sources of this so-called vacuum energy give values that far exceed the cosmological constant, an estimate of the universe's energy density based on its observed expansion rate. This has been described as the worst physics prediction ever made. I will explain how, owing to the remarkable property of quark and gluon confinement, the quark condensate is entirely contained within the pions, protons and other hadrons that constitute the spectrum of particles produced by the strong-interaction. Thus, contrary to conventional belief, there are no space-time-independent condensates permeating the universe. From this new theoretical perspective, quarks and gluons cannot flutter in and out of existence unless they are inside hadrons. As a result, the vacuum that fills spacetime is much calmer. This paradigmatic shift has a huge impact on the cosmological constant paradox: it reduces the mismatch between theory and observation by a factor of 10⁴⁵!

Argonne Physics Division Colloquium Schedule