Corrected entry: When Cooper is in the 5th dimension, he only "sees" Murph's room so he uses the books and the watch to communicate with her, but she takes the watch off the house and takes it to the lab in NASA and the watch is still "shaking" in Morse outside the room and the house, where Cooper can't manipulate gravity.
Phixius
26th May 2015
Correction: Cooper is not *only* manipulating gravity, he's effectively reprogramming the laws of physics. He permanently affected the watch so that the second hand only ever ticked out his coded message, no matter where it is taken.
Phixius ★