标题： 时空泡沫与宇宙常数 显示英文标题

标题： Spacetime Foam and the Cosmological Constant

摘要： 在鞍点近似下，量子引力的欧几里得路径积分与热力学配分函数非常相似，其中宇宙学常数$\Lambda$起到温度的作用，“拓扑密度”起到有效态密度的作用。对于$\Lambda<0$，拓扑密度呈超指数增长，拓扑求和发散。在热力学中，这种发散可能表明存在一个最大温度。在量子引力中也可能如此：拓扑密度的快速上升可能会使有效的宇宙学常数趋于零。 显示英文摘要

摘要： In the saddle point approximation, the Euclidean path integral for quantum gravity closely resembles a thermodynamic partition function, with the cosmological constant $\Lambda$ playing the role of temperature and the ``density of topologies'' acting as an effective density of states. For $\Lambda<0$, the density of topologies grows superexponentially, and the sum over topologies diverges. In thermodynamics, such a divergence can signal the existence of a maximum temperature. The same may be true in quantum gravity: the effective cosmological constant may be driven to zero by a rapid rise in the density of topologies.