The comunicator: "Restore. To restore messages, press "rewind" now. "
"Instructions for building a Tipler cylinder, press 9."
They assemble an enormous cylinder of infinite length with the total mass of about ten Suns. It is so dense, that it turns into an elongated black hole. They make it rotate at an unimaginably fast rate, a few billion times every minute. The cylinder drags space-time along with it. They hop on a spacecraft and follow the spiral course of the cylinder. That takes them back in time. Time folds upon itself, and Shaklyn 2 finds theirself in a closed timelike curve. It’s a loop, in which their traveling into the past has always been a part of that past. So s/he will not create any time paradoxes.
30 minutes after Shaklyn 2's arrival Shaklyn 1 will leave.
"Sorry I'm late."
"Glad I caught you."
"Well, I have been under a lot of stress lately."
"What are you doing here?"
"I want to help."
Two forty-five p.m.