Considering the Practicalities of Time Travel

Introduction:

Click on the image to expand

The act of traveling either back or prematurely forward in time has often been a popular concept in science fiction narratives, whether in the plots of motion pictures or books. The very idea of exploring  "what could have been" or "what could be" is something that has always fascinated humanity, regardless of the cultural backdrop. It is therefore no wonder time travel has become perhaps the most well-known hypothetical scenario of either revisiting time or "skipping" time on Earth to another time frame.

The concept has literally given story writers and movie producers plenty of material to work with; such science fiction motion pictures like Star Trek, Super Man, Back to the Future, The Twelve Monkeys, and the like come to mind. Why not? There is almost no limit to what can be imagined, as a theme around time travel, whether it has to do with visiting new worlds in our universe, someone accidentally waking up in very different time from his/her own, or someone yearning to change a situation to his/her advantage in their present time, with the aid of changing the course of history by altering some event or another, and the list can just go on.

In all seriousness though, just how practical is the concept of managing the course of history with the manipulation of time?