While everything in this article is factually correct, it maybe gives a different impression than it should. Time dilation is of course a long held tenet of special and general relativity. Can we call that time travel into the future? I'm not really sure. In a way I guess it is (how is it practically different from placing yourself into a separate bubble of spacetime?). Of course, actually achieving this in a practical sense is pretty much impossible considering the energies involved.

As for time travel into the past... pretty much no. That would have a bunch of really disturbing consequences, including traveling faster than the speed of light and violating the second law of thermodynamics.

Of course, this just a former physics minor on stupid macro affects. When you get down to the quantum particle level the game probably changes considerably.

Maybe it's my scifi/fiction writing past but I've always thought that time travel is a possibility someday.

Perhaps it's that the universe/laws of physics prevents physical, solid matter from moving through time. In the far future we may discover a way to send pure energy - aka our pure consciousness - through time, allowing one to witness history as a sort of ghost (sort of time travel telepresence). This would prevent someone from affecting the timeline because no direct interaction would be possible as well.

No. The past and future do not exist except as ideas. The only time is 'now'.