Reserved for my role plays and fiction in general. The only one I have at the moment that plays around with multiple timelines is Legend of Renalta 2, as a mystery of the universe. A bunch of mages attempted to understand how time worked, so they attempted to create doorways through time. Upon opening a doorway in a swamp, they realized that the doorway led to a conceptual infinity of other timelines. Before those mages could turn back, they were ripped through countless thousands of timelines and ended up popping out of the swamp in disfigured, disheveled heaps of body parts, each at a different, random age. So a person could have the arm of a five year old but the liver of a forty year old. Needless to say, they all died within days.
As a result, those swamps became an unstable point in time that vomits out stuff from the past, present, and future, from other timelines. It is impossible to control and highly dangerous to tread there. One of the new player characters, made by
@Jorick came from an apocalyptic timeline where demons swarmed the world. Dinosaurs sometimes also spew out of those holes in time.
Basically, the point of it is to show that while magic has unlimited capabilities, those who wield it do not. You can open a gateway to time itself, but the human mind is incapable of processing what infinity truly is as a concept, and as a result, you invariably lose control.
Time & alternate dimensions can be interesting to explore in fiction, but we're not at a technological point in real life to know whether such a thing is possible or not in any sort of concrete fashion. Leave alone daydreams.
EDIT
Also, science is the epitome of childish curiosity and imagination. It's all about searching this universe of infinite possibility. Scientists are children who learned how to think critically.