As science fiction concepts go, time travel is one of the most captivating. It's hard not to wonder what it would be like to zip back into history to witness a Roman battle in action. It's perhaps even more intriguing to ponder what our world would look like if you could instantly peek 1,000 years into the future.
As it turns out, time travel might not be fiction. It may be that we just haven't quite figured out how to make it work for us.
One possibility is wormholes, which are bridges of a sort that could help people move through time and space. If you could breach an opening into a wormhole, you could theoretically enter it and then wind up on the other side of the galaxy in a different place and time.
We could try traveling at the speed of light, at which point your world slows down greatly compared to the one you leave behind. Our current science says that nothing can move as fast as light, though, and even if we could, it might tear our bodies apart.
Maybe we could orbit massive black holes, which have such incredible gravitation pull that they actually slow down time. Hang out by a black hole and your experience of time would be roughly halved compared to life on Earth. If you returned 10 years later by your perception, your family would have aged 20 years in that time.
Or perhaps we could use cosmic strings, the so-called cracks in the universe, to navigate time. These strings (which are also sometimes loops) have so much mass that they may actually cause the space-time around them to fluctuate.
Manipulating any of these scenarios might grant us the power to finally realize time travel. Even we can figure out the science, though, there are numerous paradoxes that might make time travel unfeasible or downright dangerous. So for now, traveling in time is still simply the stuff of books and movies.