BiBi did not answer the question that Elon asked about which books motivated him the most in his life. My list includes Heinlein Stranger in a Strange Land, about interplanetary travel, the series "Fringe" about multiple universes and travel between them. And most anything about time travel, especially if there are dogs in the story.
Is string theory is correct? Do parallel universes exist? There is no time? It's relative to the string and universe we happen to "be" in at a given moment, or as I like to consider it: what I attend to is when I am. The same "I am" exists in all time. Here/now in a body, then in mind, in future as the future embodiment of the I am of now. I travel with my attention, my consciousness follows my attention.
Changing the past might be like the Japanese seamstress weaving a patch into a garment with a hole, strand by strand. A string, a strand, a bit of code, a byte or a few bits. It boils down to perhaps binary. The one who "really works at it" develops new code. Placing it in the opportune place and time can provide opportunities to coalesce like minded individuals who would not otherwise reach a critical mass necessary to make a lasting change.
A ripple, in time. -- Aviva in Akko