I. INTRODUCTION Some time ago, Witten showed that the Kaluza – Klein vacuum suffers from a non- pertubative instability due to the semi-classical nucleation of so-called bubbles of nothing . Once formed, these smooth “boundaries” of space expand and soon engulf the whole of spacetime [1]. Such instabilities may be cause for concern regarding the viability of certain higher dimensional spacetimes as acceptable vacua. It is therefore necessary to consider the existence of analogous decay processes for perturbatively stable compactifications. Flux compactifications [2] provide an elegant solution to the moduli problem in higher dimensional field theories [3–6] as well as string theory [7, 8]. By stabilizing the extra di- mensions with sufficiently high moduli masses, we can construct a model realistic enough to accommodate the low energy physics as well as a cosmological framework compatible with observations. These masses are induced by a flux potential, which depends on a discrete set of flux winding numbers. The diverse set of fluxes and associated winding numbers gives rise to the multitude of (meta)stable vacua known as the string landscape [9]. Although super- symmetric flux compactifications are known to be stable [10], the more phenomenologically interesting compactifications may enjoy/suffer from several instabilities, including decom- pactification [11–13] or more general transdimensional tunneling [13, 14], flux-transitions [12, 15–18] and, as we will demonstrate here, nucleation of bubbles of nothing. 1 The bubble of nothing geometry asymptotic to a given flux compactification is a gravitational instan- ton which represents both the decay mediator and subsequent classical evolution of the metastable spacetime. This is the case for Witten’s bubble of nothing in the minimal 5 d Kaluza – Klein (KK) model [1]. The outline of the paper is as follows. In section II we review the original bubble of nothing. In section III we discuss how these bubble solutions can be obtained as the space- times of de Sitter topological defects in a simple 5 d flux compactification, where the extra dimension is stabilized by the presence of a winding complex scalar field. In section IV we obtain numerical solutions describing these bubbles of nothing. We conclude in section V 1 Bubbles of nothing in flux compactifications have been recently discussed in [18] by matching different spacetime geometries across a codimension one brane. This is different from our present construction describing a geometry which is smooth everywhere, obviating the need to postulate the existence of domain walls. 1