In the physical world, any quantity exhibiting variation in time or variation in space (such as an image) is potentially a signal that might provide information on the status of a physical system, or convey a message between observers, among other possibilities.
” 在现实世界中，任何随时间或者空间变化的量（如影像）都是潜在的信号，它们可能会提供一个物理系统的状态信息，或在不同观察者之间传达消息等。