Pseudostable bubbles

The evolution of spherically symmetric unstable scalar field configurations ("bubbles") is examined for both symmetric and asymmetric double-well potentials. Bubbles with initial static energies $E_0\lesssim E_{\mathrm{crit}}$, where $E_{\mathrm{crit}}$ is some critical value, shrink in a time scale determined by their linear dimension or "radius." Bubbles with $E_0\gtrsim E_{\mathrm{crit}}$ evolve into time-dependent, localized configurations which are very long-lived compared to characteristic time scales in the models examined. The stability of these configurations is investigated and possible applications are briefly discussed.