Time travel could be one of the most important things the human race ever did, IF we did it. Up to this point in the human race, we have discovered how to manipulate, use, and interact with objects that are material and tangible. The keyword is tangible. Something we can feel or see, with physical properties.
Time is a peculiar subject. For it is something is part of us on a whim, or the most dire and serious matter. It may be the most important thing of our world. However, it is not tangible. It does not lie in our dimension and has not been proven to lie in any dimension. Some theories state the fourth dimension is time, but there is no hard evidence towards this.
If time is not composed of physical matter, we cannot interact with it in a way to manipulate it.
There IS however a different scheme. When consulted with stopping, rewinding, and skipping ahead of time, most think of using it. But they do not think of the molecules and atoms involved in this process. If one were to stop time, they would stop the progress of every single atom in existence. Why not try to do just that? Don't go about STOPPING time but instead freeze the aging, progress, and intention of every atom there is. Reversing the progress of all atoms to "rewind" time.
This produces a problem for traveling forward in time because the future has not happened. The atoms and every exchange between every entity would not have happened therefore one could not go about moving the progress forward at a split-second speed, while keeping their own existence free of the change in speed.
Theoretically, one could choose an outcome and move and manipulate all atoms to do his bidding. But this procedure would require too much information and instruction to be done with any machine we can think of now.
Suppose one were able to do this. Give instructions to molecules and atoms to carry out tasks in order to bring a desired outcome. If they were able to do this with certain atoms, but leave the rest of the world alone, age and progress would no longer correspond between the original world, and the section of the world that's been tampered with. The two would also need to never intersect or interact with each other, or the separate time speeds would conflict. This makes it so that if one were to use this theory of time travel or manipulation, they would need to use the entire world. For it is impossible to completely isolate one part of the world from the other.
The energy needed to do this would be astronomical. This is an abstract form of "time travel", but it may be the closest thing humans will come to. One thing is for sure, we are no where close to that point.