标题： 低频宇宙引力辐射的经典反作用 显示英文标题

标题： Classical back reaction of low-frequency cosmic gravitational radiation

摘要： 我们在Brill-Hartle类型的近似下，研究了线性引力波的叠加对平均引力场的反作用，直到波幅的二阶。 背景场被取为爱因斯坦-德西特几何。 为了遵循暴胀情景，允许波长超过临时的哈勃距离。 如同光学相干理论中一样，波幅被视为随机变量，形成一个均匀且各向同性的随机过程，具有背景度规的对称性。 随机波的有效应力-能量张量通过关联函数计算，涵盖了亚视界和超视界模式，后者在许多情况下对能量密度和压强产生负贡献。 我们讨论了包括纯引力辐射宇宙在内的二阶方程的解。 显示英文摘要

摘要： We study in a Brill-Hartle type of approximation the back reaction of a superposition of linear gravitational waves on the mean gravitational field up to second order in the wave amplitudes. The background field is taken as an Einstein-deSitter geometry. In order to follow inflationary scenarios, the wavelengths are allowed to exceed the temporary Hubble distance. As in optical coherence theory, the wave amplitudes are considered as random variables, which form a homogeneous and isotropic stochastic process, sharing the symmetries of the background metric. The effective stress-energy tensor for the random waves is calculated in terms of correlation functions and covers subhorizon as well as superhorizon modes, the latter give in many cases negative contributions to energy density and pressure. We discuss solutions of the second-order equations including pure gravitational radiation universes.