Time travel is possible and has been utilised already by the Plejaren and the Timarians. Billy has also travelled through time, for instance, he has been to the past and observed dinosaurs and an Earth with two moons, conversed with a man of Middle Ages France named Jechieli and has even spoken to Jmmanuel. Billy has also travelled into the future and observed a devastating earthquake in the vicinity of San Francisco, California, USA and during which time there were also cars visible that had windshields extending quite far back, a type of car that has only just recently been prototyped. The Plejaren and Billy can also look into the future using both spiritual and technical methods.
Regarding encountering oneself during time-travel
From the FIGU Forum:
What happens when two persons with the same spirit form get together in a time trip, like Billy and Jmmanuel? Billy can tell his first hand experience, I hope.
ANSWER: It is not the "same" spirit form, even if it is of the same lineage. One spirit form is less developed/evolved than the other, and there are two entirely different personalities present.
The same is true even when a person visits oneself in the actual life (through time travel).
The best way to make this understandable is when a person of, say, 50 years looks at an old photograph when he or she was 10 years old. The child was a different personality than at the age of 50! You will be aware of this if/when you look at a photograph!