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.