Time travel happens all the time. Time is not set in stone. Because of relativity, objects at different relative speeds experience time differently, that's why GPS satellites don't work with ordinary clocks, they need to be adjusted accordingly.
We can travel to the future by approaching the speed of light, that makes our time go at different rates compare to other objects or beings. Light itself doesn't experience time, the moment something makes a photon and the moment that photon becomes something else (heat) are the same very moment from that photon's perspective.
Travelling back in time is another matter though. Perhaps it's theoretically possible when surpassing the speed of light? But that can't be done so I don't think travelling to the past is possible.
No troll is too much for me to handle. I rehabilitate trolls, I train people. I am the Troll Whisperer.
