A mirror world consisting of matter which interacts with ordinary matter via gravity and weakly via other forces has been considered, inter alia, as a model for dark matter. A discrete symmetry under the interchange of fields means that both sectors experience the same forces. Separately it has been shown that it is possible to unify gravitation and electromagnetism by using a degenerate metric in five dimensions; in this theory there are two possible representations of charge, and there is a reflection symmetry between them which, along with a gauge-like invariance, achieves the unification. Here it is shown that mirror matter arises naturally out of the degenerate theory, and as a result a new means for measuring the Brans–Dicke constant is obtained.

由暗物质构成的镜像世界尤其被认为是暗物质的模型，该物质通过引力与普通物质相互作用，并通过其他力微弱地相互作用。场交换下的离散对称性意味着两个扇区承受相同的力。另外，已经表明通过使用五个维度上的简并度量可以统一重力和电磁。在该理论中，电荷有两种可能的表示形式，它们之间存在反射对称性，再加上像轨距一样的不变性，可以实现统一。在这里表明，镜面物质自然是由简并理论产生的，因此，获得了一种测量布朗斯-迪克常数的新方法。