Is gravity caused by a curvature of space and time?
A common way to explain why gravity can appear to act instantaneously, yet still propagate with a delay, is the rubber sheet analogy. (See Figure 4.) A large mass sitting on a rubber sheet would make a large indentation, and that indentation would induce smaller nearby masses to role toward the indentation. This is an analogy for curved space-time, which is likewise supposed to be the cause of bodies accelerating toward large masses. The reasoning in the analogy further suggests that target bodies simply respond instantly to the local curvature of the underlying space-time medium (like the rubber sheet). Therefore, any delay associated with altering that local curvature would not produce aberration, and the target body would appear to respond instantaneously to the source unless the source suddenly changed its motion. The rubber sheet analogy is represented as a way of visualizing why bodies attract one another. However, in that regard, it is highly defective. A target body sitting on
