In the context of the weak gravity conjecture the notion of quasi-extremality for black holes and branes was recently defined as the property of having either vanishing horizon size or surface gravity. It was derived that such objects obey a no-force condition. In this short note I present a simplified derivation that is essentially present in the formalism of timelike reduction pioneered by Breitenlohner, Gibbons and Maison. This formalism also provides the natural definition of quasi-extremality for gravitational instantons (and wormholes) sourced by axion fluxes and strengthens the argument that macroscopic axion wormholes do not contribute in the path integral since they are self-repulsive in a Euclidean sense.

在弱引力猜想的背景下，黑洞和膜的准极值的概念最近被定义为具有消失视界大小或表面引力的特性。推导出这样的物体服从无力条件。在这篇简短的笔记中，我提出了一个简化的推导，它本质上存在于 Breitenlohner、Gibbons 和 Maison 开创的类时间缩减的形式主义中。这种形式主义还为由轴子通量产生的引力瞬时子（和虫洞）提供了准极值的自然定义，并加强了宏观轴子虫洞对路径积分没有贡献的论点，因为它们在欧几里德意义上是自斥的。