Vacuums might be the key to time travel.
Amos Ori, a professor at Israel's Technion, has published a paper in Physical Review outlining a model of a theoretical time machine. Conceivably, these ideas could one day help humans travel back in time.
The concept revolves around controlling the curvature of space and time. Einstein's theory of relatively states that the space/time continuum can be flat, but it can also be curved by gravitational fields. Ori is investigating whether the laws of gravity will permit curving space and time in such a way as to make travel possible.
"The machine is spacetime itself," he stated in a prepared statement. "Today, if we were to create a time machine, an area with a warp like this in space that would enable time lines to close on themselves, it might enable future generations to return to visit our time.
"Such a journey requires a significant curvature of spacetime, in a very special form," he continued.
Other physicists have dismissed the idea of a time machine, nothing that such a machine would have to be made of a material with negative density. It is not clear if the material with negative density exists in any kind of quantities. In Ori's model, positive density material could travel back in time in a vacuum.
In layman's terms, that means that you wouldn't go back and forth through time to rescue women in pink dresses in a fancy chair like Rod Taylor in The Time Machine. You'd be in sort of a tube. But once you get there, you could square off against your nemesis in childhood form, like Popeye and Bluto do.
Ori, though, states that his model is only one step toward time travel, and it may never be possible.
Incidentally, Einstein planted a tree at the Technion (see photo) more than 50 years ago, and it is still thriving. And it never needs water. Hmmm.