标题： 光速变化能否解决宇宙学问题？ 显示英文标题

标题： Does a varying speed of light solve the cosmological problems?

摘要： 我们提出了一种广义相对论的新推广形式，它同时包含了真空光速（c）和引力常数（G）的变化，并且具有协变性和洛伦兹不变性。 我们求解了关于弗里德曼宇宙的广义爱因斯坦方程，并表明对于满足强能量条件的理论，c 和 G 的任意时间变化都不会解决平坦性、视界或$\Lambda$问题。 为了实现这一点，需要构建一种理论，在任何时间、长度和能量单位的选择下都不退化为标准理论。这可以通过打破一些不变性原理（如协变性和洛伦兹不变性）来实现。 显示英文摘要

摘要： We propose a new generalisation of general relativity which incorporates a variation in both the speed of light in vacuum (c) and the gravitational constant (G) and which is both covariant and Lorentz invariant. We solve the generalised Einstein equations for Friedmann universes and show that arbitrary time-variations of c and G never lead to a solution to the flatness, horizon or $\Lambda$ problems for a theory satisfying the strong energy condition. In order to do so, one needs to construct a theory which does not reduce to the standard one for any choice of time, length and energy units. This can be achieved by breaking a number of invariance principles such as covariance and Lorentz invariance.