Tracking Ideas

In HG Wells' The Time Machine, the Time Machine goes to the end of life on Earth and returns.

In Poul Anderson's "Flight to Forever," the time projector goes to the end of the universe and beyond.

In Anderson's Tau Zero, a time dilated spaceship goes to the end of the universe and beyond.

I used to track ideas through sf works by different authors but it does not follow that earlier works directly influenced later works. James Blish did not know of Edmond Hamilton's Cities In The Air when he wrote Cities In Flight and incorporated a reference to Jonathon Swift's flying island only when he remembered it. John Christopher wrote that his Tripods Trilogy unconsciously plagiarized Wells' The War Of The Worlds.

However, Anderson directly modeled his Psychotechnic History on Robert Heinlein's Future History and his Operation Chaos was directly inspired by Heinlein's Magic, Inc. Sf authors develop alternative implications of each other's ideas.