Gott Shell
In essence, a Gott shell is a huge concentration of mass. The shell's sheer density creates a gravitational field that slows down the clock for anyone enclosed within it. Outside, time rolls along at its familiar pace, but inside, it creeps. Thus the Gott shell is useful for travel into the future only. If you're planning a jaunt to the past using a Gott loop, you might want to bring along a Gott shell for the return trip. What to do, step by step:
?Salvage scrap planetary matter to assemble a mass equal to or greater than Jupiter's.
?Working slowly so as not to produce sudden gravitational disturbances, assemble the matter around yourself in a sphere. For your comfort - and to avoid inadvertently creating a black hole later in the process - be sure to leave a cavity larger than 18 feet in diameter at the center.
?Stock the cockpit with lots of food, drink, diversions, and back issues of Wired. Your journey might take a while.
?Using a high-powered energy source, compress the shell. The greater the compression, the faster you'll be transported - up to five times the pace of ordinary time for a Jupiter-sized mass, faster for a larger ball of matter.
?After waiting the desired interval - several decades works best - slowly decompress the shell and emerge. You'll find yourself in the same place but in a distant epoch. Welcome to the future.