I agree that you do make a point.  There is really no way for us to know what is to come.  Sometimes we think we are looking at a square, but it really is a cube and we are just unable to look beyond are current perspective for whatever reason.<p>I would say one obstacle that stands in the way of &quot;spying&quot; on objects moving on the Earth&#x27;s surface is that the gravitational wave energy emitted by accelerating objects on Earth would be &quot;too small&quot; for current detectors.  Not to mention that there would be the issue of how to filter gravitational wave noise, and&#x2F;or isolate frequencies.  However, if it possible to build an amplifier or filter to resolve these issues, that remains to be seen - or maybe somebody else could chime in.<p>edit: typos, clarity