translation.en: The reason why galaxy clusters can teach us about dark matter, the reason why galaxy clusters can teach us about the physics of the very small, is precisely because they are so very big.
translation.zh: 为什么星团可以 教我们暗物质的知识 为什么它们 可以教我们关于“极小”的物理 其原因就是因为它们太大了