The cloth sheet example with heavy object in the center making other objects come towards it never made sense to me. This example would never work in zero grav

The cloth sheet example with heavy object in the center making other objects come towards it never made sense to me. This example would never work in zero gravity. Someone gave this sponge visual on stackexchange I think and since then it made so much sense. Also, this makes time travel totally senseless. You can not travel back in time without reversing all input you ever received from external factors. Only thing we can probably do is stop or slow down time for something.