论文标题
艾美奖给圣诞老人的信（以及答复）：瓦迪亚的几何和标量字段，带有空梯度
Emmy's letter to Santa Claus (and a reply): Vaidya geometries and scalar fields with null gradients
论文作者
论文摘要
艾美（Emmy）是一个神童，他写信给圣诞老人的信，要求一个vaidya解决方案，该解决方案由一个无数的标量领域带有无效的圣诞节。圣诞老人写了回信，解释了为什么不能构建这样的玩具，并提供了一个由标量场采购的精确平面波，其替换为浅色梯度。
Emmy, a child prodigy, writes a letter to Santa Claus asking for a Vaidya solution sourced by a massless scalar field with null gradient for Christmas. Santa writes back explaining why such a toy cannot be built and offers an exact plane wave sourced by a scalar field with lightlike gradient as a replacement.
