论文标题
轻速记忆作为可观察到的柔软头发的本地记忆
Light speed memory as a local observable for soft hairs
论文作者
论文摘要
固定时空的爱因斯坦观察者是惯性观察者，它们使用光同步时钟。对于这样的观察者，光速是构造恒定的。但是，可以使用超级翻译将坐标从爱因斯坦更改为BMS坐标。从BMS观察者的角度来看，光速在整个时空和所有方向上都不是一个恒定的。因此，通常，为爱因斯坦观察者同步的时钟与BMS观察者没有同步，反之亦然。基于这个事实，我们提出了一个可观察到的局部观察，用于检测软发，这是此类观察者的光速变化。我们还研究了这种可观察到的重力记忆的关系，这是在重力波完全从中传递出来后，这是无穷大的测试颗粒位置的永久变化。结果表明，BMS时间坐标是重力波之后的物理时间，这是用于计算光速的合法时间。基于此论点，该分析预测了引力波后在渐近射线中传播的光速速度的永久变化。此外，可以通过比较其在观测值中的意义来解释这种变化与重力记忆的关系。
Einstein observers in flat space-time are inertial observers which use light to synchronize their clocks. For such observers, speed of light is a constant by construction. However, one can use super-translations to change coordinates from Einstein to BMS coordinates. From the point of view of BMS observers, speed of light is not a constant all over the space-time and in all directions. So in general, clocks which are synchronized for Einstein observers are not synchronized for BMS observers, and vice versa. Based on this fact, we propose a local observable for detecting the soft hairs, which is the variations in speed of light for such observers. We also investigate the relation of this observable to gravitational memory, which is a permanent change of position of test particles at infinity, after a gravitational wave passes completely from them. It is shown that the BMS time coordinate is the physical time after a gravitational wave, and it is the legitimate time to be used to calculate the light speed. Based on this argument, the analysis predicts a permanent change in the speed of light rays which propagate in asymptotics after a gravitational wave. Moreover, it is explained how this change is related to the gravitational memory by comparing their significance in observations.
