> Assuming they can drag around the big mass from one position to the other in a short amount of time, shouldn't the people at the remote facility be able to de

> Assuming they can drag around the big mass from one position to the other in a short amount of time, shouldn't the people at the remote facility be able to detect where the big mass is long before light could reveal its position? No, the remote facility won't notice the thing moved until the gravity wave hits and that only moves at the speed of light. If it's a light year away, it'll take a year before the remote facility notices the shift.