Continuing Comparisons

Having just compared Robert Heinlein's and Poul Anderson's future histories and multiverses, let's look again at their time travel. Whereas Heinlein presents three ingenious statements of the circular causality paradox in futuristic sf settings, Anderson presents many more statements of the two time travel paradoxes, circular causality and causality violation, not only in futuristic but also in historical settings.

Anderson's The Corridors Of Time, There Will Be Time and The Dancer From Atlantis all contain that historical dimension that is absent from Heinlein's The Door Into Summer, "By His Bootstraps" and " -All You Zombies." (The Door Into Summer hints that Leonardo da Vinci was Leonard Vincent, Time Traveler, but does not dramatize this.) Anderson's Time Patrol series not only ranges throughout history but also presents a unique and subtle perspective on causality violation whereas Heinlein's works do not address that paradox.

Thus, Heinlein and Anderson resemble Newton and Einstein: the latter incorporates the former in a wider context.

The Best Of Times

I envisage a single collection of the very few very best works of time travel fiction, which I suggest are:

The Time Machine by HG Wells;
"A Stitch In Time" by John Wyndham;
"By His Bootstraps" by Robert Heinlein;
"The Sorrow Of Odin The Goth" by Poul Anderson.

These happen to comprise two British literary works and two American genre stories.

Wells implies but otherwise avoids the issue of causality paradoxes. The other three works are circular causality stories although the last is set in a causality violation scenario. The four works present a good balance of past, present and future -

Wells: nineteenth century to 702,601 AD, then the furthest future of Earth, and return;
Wyndham: time travel within a character's life time;
Heinlein: twentieth century to far future;
Anderson: twentieth century to the Dark Ages.

The Time Traveller interacts with Morlocks and Eloi. Anderson's Time Patrolman interacts with Goths and Huns. The Time Patrol's mass produced, streamlined, futuristic timecycles are conceptual descendants of the Time Traveller's elaborate nineteenth century contraption. The time traveller sits on, instead of being enclosed by, each of these vehicles. Both Wyndham and Heinlein instead envisage a machine that sends people through time instead of moving past- or future-wards, taking them with it.