Time travel, has been a popular sci fi topic from HG Wells "The Time Machine" written in 1895 up to right up to the DeLorean time machine of Dr. Emmett Brown and Marty McFly from 1985s Back to the Future.
As we advance through the chronological illusion of time on a societal basis we are learning that time travel may not be a fantasy at all, but could actually be possible and may have already been perpetrated. In fact you can leave out the "May Have" fragment of the last sentence because we already have a time machine, it just needs to be tweaked a tad ... okay ... a few tads more than a tad. And it is not a super secretive cloak and dagger Government conspiracy. It's right in our face for those who wish to delve into the topic.
The theory of special relativity postulates that time is relative largely depending on the speed you are traveling. The faster you move through space, the slower you move through time.
Astronauts, Cosmonauts, Little Green men and Gray Aliens are moving through space much faster than the people on Earth. This means that space travelers, free of the Earths Gravitational pull travel through time at a barely discernable slower rate than those of us on the Earths surface.
Cosmonaut Gennady Padalka holds the record for the longest stay in space at 879 days. When he returned to the Earth, he was 1/44th of a second behind the rest of Humanity on our endless trek through time. While 1/44th of a second isn't a whole hell of a lot there are other technologies right here on Earth, in our time that move matter through space incredibly faster than space travelers go back in time.
The Hadron Collider blasts protons at speeds approaching the speed of light. The protons propelled by the collider therefore traverse time nearly 7,000 times slower than the Human Observers. Basically, these protons are being sent 'back to the future'.
Here's where the tweaking part comes in. Allthough science can send Astronauts and subatomic particles to the future by nanoseconds, fractions of seconds and in rare instances whole seconds there is still a colossal chasm between where we are now and where we want to be in order to catch up with Marty McFly.
A major obstacle would be making a vessel capable of reaching near light speed, or warp factor five as kirk would say. The fastest object humanity has built, that we know of, is not a Delorean but the Parker Solar Probe which is capable of reaching .00067 % of the speed of light.
Another Theroretical Time device is on the drawing board by Professor Ron Mallett who has drawn up plans for an actual time machine.