Yes, time travel is fantasy. But it's a fun fantasy to think about.
I know where that sample sentence came from -- a classic Sci-fi short story called "A Sound of Thunder"
A thrill seeking hunter went back to prehistoric times to hunt dinosaurs, and accidentally stepped on a butterfly. He irrevocably changed history when he got back. In fact, now I want to re-read it.
Here's the story in PDF:
I heard a guest on talk radio recently saying that he thinks time travel is possible, and, if it is in fact possible, that could explain how we would get the multiverse, because, he said, when the guy who stepped on the butterfly (for example) got back to the present (from which he had traveled back in time) and found the universe all different, the universe that he had first come from would not have ceased to exist but rather it would have continued to exist as an alternative universe, different from the universe the man sensed upon his return, but existing as it were in a parallel reality which the man did not know how to observe. This doesn't mean he was unable to observe it, but that to do so he would require certain specific knowledge to do so, and the description of that knowledge is an entirely new theme to develop and describe. Since it may entail activities and procedures that are entirely unfamiliar to us, we might not have vocabulary to adequately and accurately describe it such that a reader may be able to go out and replicate the process. He used the example of the mysterious man in Florida who built the Coral Castle, but he died and left no notes describing his procedure, nor did he take on any apprentice, so as to teach his skills to someone else who might survive him. He also used the example of an automobile mechanic going back in time with a car to an ancient culture where he would then attempt to describe to the people he met how to do repair work on the car or to partially disassemble it in order to show them how it works. They would probably end up killing him, accusing him of witchcraft or some such thing.