Professor of Physics at the Univ. of Conn., Dr. Ron Mallett shared his concept for a time machine, based on Einstein's two theories of relativity. Tests with atomic clocks have shown that speed and gravity can slow time down, said Mallett, who noted that if a person was near enough to a black hole for an hour or so, due to its massive gravity, a hundred years could have passed further away.
Gravity, which can be thought of as a "bending of space," can be manipulated locally, using a circulating light beam with a series of mirrors, that can swirl up empty space, he outlined. Such a device could be used for a time machine by twisting space into a loop that connects the future to the past, Mallett proposed.
Interestingly, he suggested the past a person travels to wouldn't be the one they came from, but that of a parallel universe in which they'd live in co-existence with their younger self. The traveler would not be able to return to their normal timeline, and from our point of view, they'd simply disappear from the world. Mallett also commented that we wouldn't begin to see time travelers until such a device came into use in our time frame.