I studied Physics and I always disliked the logical implications that occur in SF with Time Travel Elements. It also collides with my basic believe that the Future is fluid and that we as individuals and as society have an influence on the future due to our actions. If time travel into the Future would be possible then everything is already decided and fixed. If time travel in the past would be possible then any action taken in the past would affect the
Future. Even as simple as eating and breathing or going to the bathroom.
Therefore Time Travel in the GC Universe is not possible (A time traveler into the back would create a new Parallel Universe and a Time Traveler into the future would end up in a Parallel Universe where time has advanced further than his own.) Creating a Causality Loop
These are Universal Rules set into place by the One Behind it all.
Time travel is the concept of moving between different points in time in a manner analogous to moving between different points in space. Time travel could hypothetically involve moving backward in time to a moment earlier than the starting point, or forward to the future of that point without the need for the traveler to experience the intervening period (at least not at the normal rate). Any technological device – whether fictional or hypothetical – that would be used to achieve time travel is commonly known as a time machine.
Although time travel has been a common plot device in science fiction since the late 19th century and the theories of special and general relativity allow methods for forms of one-way travel into the future via time dilation, it is currently unknown whether the laws of physics would allow time travel into the past. Such backward time travel would have the potential to introduce paradoxes related to causality, and a variety of hypotheses have been proposed to resolve them, as discussed in the sections Paradoxes and Rules of time travel below.