If our apparently four-dimensional spacetime is endowed with compact extra dimensions, our universe may not be entirely stable. It can decay, by the spontaneous nucleation of a “bubble of nothing”: a gravitational instanton that induces a catastrophic annihilation of spacetime. In this talk we discuss the connection between the bubble of nothing and an analogous Coleman-De Luccia (CDL) tunneling process, and use the CDL formalism to calculate the bubble nucleation rate for a de Sitter universe with a single extra dimension. Even in the interesting scenario where the size of the extra dimension is fixed by some stabilization mechanism, the formation of bubbles of nothing can still be relatively prompt.
