We study the problem of the instability of inhomogeneous radiation universes in quadratic Lagrangian theories of gravity written as a system of evolution equations with constraints. We construct formal series expansions and show that the resulting solutions have a smaller number of arbitrary functions than that required in a general solution. These results continue to hold for more general polynomial extensions of general relativity.

中文翻译：

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修正重力的辐射不稳定性

我们研究了二次拉格朗日引力理论中非均匀辐射宇宙的不稳定性问题，该理论被写成具有约束的演化方程系统。我们构造了形式级数展开式，并表明所得解决方案的任意函数数量少于一般解决方案所需的数量。这些结果继续适用于广义相对论的更一般的多项式扩展。