标题： 具有可变光速的宇宙学 显示英文标题

标题： Cosmologies with Varying Light-Speed

摘要： 我们分析了广义相对论的一个推广形式，该形式包含了真空光速的宇宙时间变化、由阿尔布雷希特和马久约提出的 $c,$ 和牛顿引力“常数” $G,$。 我们找到了弗里德曼宇宙的精确解，并确定了使平坦性和经典宇宙学常数问题得以解决所需的 $c$ 的变化率。 指出了这种方法在解决平坦性和经典宇宙学常数问题时可能存在的潜在问题。 提出了重新表述的方法，使得该理论在 $c$ 为常数时更接近一个可变 $G$ 理论的理想极限，并讨论了它与电子电荷可变且 $c$ 为常数的理论之间的关系。 显示英文摘要

摘要： We analyse a generalisation of general relativity that incorporates a cosmic time-variation of the velocity of light in vacuum, $c,$ and the Newtonian gravitation 'constant', $G,$ proposed by Albrecht and Maguejo. We find exact solutions for Friedmann universes and determine the rate of variation of $c$ required to solve the flatness and classical cosmological constant problems. Potential problems with this approach to the resolution of the flatness and classical cosmological constant problems are highlighted. Reformulations are suggested which give the theory a more desirable limit as a theory of varying $G$ in the limit of constant $c$ and its relationship to theories with varying electron charge and constant $c$ are discussed.