Vacuümdecay

Vacuümdecay, also written as vacuum decay, is the hypothetical transition of a metastable vacuum state to a lower-energy true vacuum in quantum field theory. In such scenarios, a field may reside in a local minimum of its potential—a false vacuum—while a deeper minimum exists at higher field values. If a false vacuum is metastable, quantum tunneling or thermal fluctuations can nucleate bubbles of true vacuum, which can grow and convert neighbouring regions of space to the new vacuum state.

The decay process is described using semiclassical methods that rely on instanton solutions, often referred to as bounce solutions. In curved spacetime, gravity can influence the decay via the Coleman-De Luccia mechanism. The decay rate per unit volume is typically exponentially suppressed by the Euclidean action of the bounce, making the spontaneous occurrence extremely rare under many conditions. Once a true-vacuum bubble forms, its interior may have different physical constants and laws, and the bubble wall propagates at relativistic speeds, erasing the false vacuum inside as it expands.

In the Standard Model of particle physics, discussions of vacuum stability focus on the Higgs potential. With current measurements of the Higgs boson and top quark masses, the electroweak vacuum could be metastable, though estimates suggest the Universe’s lifetime far exceeds its current age, and there is no empirical evidence of an imminent decay. Many models beyond the Standard Model or different high-field behavior of the Higgs potential can alter stability conclusions.

Vacuümdecay remains a theoretical construct with profound implications for cosmology and fundamental physics, illustrating how the global structure of a field’s potential can influence the fate of the universe. See also: false vacuum, Coleman-De Luccia, Higgs field.