Physcial time travel: not possible
For one thing because time is not physical. It's just a unit of measure. And the one little phrase that so many seemingly intelligent people gloss over in conversations such as these, the amount of energy necessary would approach infinity. Same thing as traveling at the speed of light. Apparently, some people don't get what infinite means. As the subject for movies that we all agree are just ways to waste some time, it's fine. As a subject for serious study? Come on, guys. You've already answered the question. Why keep asking it?
The pints all I need to travel to any space-time continuum I desire.