After the Scarlet Centurion waylays the Avengers on their way back from the 1940s, they find themselves in an alternative 1968 where the five original Avengers stayed together under the thumb of the Scarlet Centurion.

The story includes flashbacks and previously unknown explanations of the team’s previous trip to the ’40s in Avengers #56, and at the end of the story, Goliath uses Dr. Doom’s Time Platform to banish the Scarlet Centurion back to his time—and we think this is the only time travel that actually appears in the story (apart from the flashbacks). We don’t know what happens to the alternative 1968 (now known as Earth-689, but the traveling Avengers return to the universe that we all knew and loved in the 1960s (a.k.a. Earth-616), with their memory of the whole affair wiped by the Watcher.

Using Doc Doom’s time platform, the tag-3743 } Wasp sends Cap and the other three 1968 Avengers back to observe Bycky Barnes’s death at the hands of Baron Zemo.

Peter Norten and his wife Kathy already had a rocky marriage before heading up to Bruce Bunnish’s Colorado mansion for a ten-year reunion with Bruce and two other members of the Northwestern University B Team that Peter captained to a near-win at the North American Intercollegiate Team Chess Championship. But will Peter and Kathy’s marriage survive the trip, and just how did Bruce end up as the only member of the team to go on to success?

A physics guy invents a time machine that can go only backward and must always return the traveler to the exact same present from which he left.

Sure, others have pulled that 20th century actress forward to make modern films with spectacular failure, each attempt spawning a branch universe unconnected to the 21st century of time traveler Det Gruber, but none of the others took into account the psychological factors in the way that Det’s employers have done.

In 1949 Los Angeles, Detective Lee Kinlaw has writer/director Preston Sturges down in the morgue. The only problem is that Sturges is still alive and well in Hollywood.

Take a pair of time-hopping con artists looking for their next mark. Add a naïve and incredibly rich young scientist waiting to be fleeced. Stir together in the volatile political atmosphere of Roman-occupied Jerusalem at the time of the Crucifixion. The result: a wickedly entertaining blend of screwball comedy and biting social satire from one of science fiction’s most honored authors.

About five years after the first two Moment Universe stories, time traveling talent scount Det Gruber heads to 1942 in hopes of recruiting young, bitter Orson Welles to accompany him back to the future.

Imagine you’re a young boy in 1921 Cambridge when your equally young first love dies in a deep well. What would you do? Naturally, you’d vow to become a great scientist in an artsy movie so you could go back in time to alter the tragic event.

Apparently, people in early 20th-century Cambridge espouse many wise thoughts about time, parallel universes that encompass every possible combination of events again and again, and something about every decision every made creating a branch point. In the end, it's difficult to make a cohesive model of time from the plotline of Dimensions, but we tried our best to do so in our plot notes.

A twist on how meeting yourself for coffee interacts with how time travel works in your universe.

James takes his one-minute time machine to a park bench to try to pick up quantum physicist Rachel.

The gang up in the ITTDB Citadel showed this five-minute film to me on my first prime birthday of the 2010 decade.

Teenager Rachel is sent to the Pinewood facility because she remembers events that never happened and people who died but are still inviting her to dinner.

After Farway Gaius McCarthy fails his final examination at the Central Time Travelers Academy, he puts together a rogue time travel crew to swipe valuable artifacts from the past at moments when they won’t be missed. And it’s all roses until a mysterious girl sidetracks them on the Titanic and steers them into a multiverse of fading timelines.

As you might guess, we enjoyed Far and his friends, but the thing that sealed an Eloi Bronze Medal was the fact that when a particular timeline actually managed to branch (not an easy feat) and the traveler then jumped to the future, she found her another self—the her that was born on that timeline—waiting for her. Most branching timeline stories ignore this issue entirely.

Ryan Wasserman’s philosophical book is one of two books* that need to live on your nonfiction shelf. One by one and with complete reference to the past literature, he presents all the major paradoxes of time travel along with different models of time travel and arguments against time travel even being possible. Just get it and read it cover-to-cover. As a bonus, Professor Wasserman, who is on the Philosophy faculty at Western Washington State University, will cheerfully have discussions about time travel issues via e-mail with those of us up in the nearby ITTDB Citadel.

* The other, of course, is Paul J. Nahin’s Time Machines: Time Travel in Physics, Metaphysics and Science Fiction, Second Edition.

Alas, Sean Carroll doesn’t pull any punches in his realistic assessment of the kinds of time travel that are or may be possible under the laws of physics as we know them in our universe. Or, as Professor Carroll himself puts it: “. . . podcasting isn’t for the squeamish.” In my layman’s understand of his most excellent explication, time travel aficionados have two physical phenomena on which to hang their Hat Things:

1. Time Dilation: Under the laws of Einstein’s special relativity, a fast traveler who leaves the Earth, zooming around for a while at near light speed before returning, will experience less passage of time than those who stay in the more-or-less fixed reference frame of Earth. How cool is that? Yes, you can travel as far into the future as you like, so long as you have a means of zooming up to a high enough speed and returning. (And according to general relativity, time dilation also occurs inside a high gravitational field, although I didn’t notice a discussion of this sort of time dilation in the podcast.)
2. Closed Timelike Curves: The second hope for time travelers are certain distributions of matter that (according to Einstein’s equations of general relativity) result in directed paths through spacetime in which a traveler along the path is always moving forward through time—and yet completing a full circuit of the path returns the traveler to the starting point in both space and time. That’s the good news. The bad news is that such paths, called closed timelike curves, might only be possible in the presense of infinitely long rotating cylinders or other physical conditions that may be impossible to engineer.

Up in the ITTDB Citadel, many of us found ourselves in a disquieted state at this point in Professor Carroll’s podcast (roughly the two-hour mark). Some went to bed early in a kind of daze; others decided it was time for a long walk through the lonely ice paths that surround the Citdel. But for those with the fortitude to keep their ears glued to the pod, there was a great reward. Carroll had already waded through the swift, waist-high currents of causality, predeterminism, free will, the A Theory of Time, the B Theory of time, and more. But now he was ready to dive into deep, uncharted waters. Yes, now he was ready to leave known physics behind, to talk about branching time that went beyond the Everettian Many Worlds of Schrödinger’s equation, and to consider what kind of a world would be needed to allow stories such as Back to the Future and Looper to consistently hold together. With this in mind, he devices a four-pronged theory that concludes with what he calls Narrative Time. For me, narrative time shares some features with the time model of Asimov’s The End of Eternity (a model that we call Hypertime in our story-tagging system), but it goes far beyond that.

Suffice it to say that when all the Librarians up in the Citadel woke from their sleeps and returned from their treks, we had a celebration that was strident enough to raise Lazurus Long himself from the dead (if he is dead, that is).

On the 107th floor of the South Tower on 9/11, time travel tour guide Brad Eckelson meets Sitra Velasco, a woman who couldn’t possibly be there.

Despite having relativistic time dilation, actual time travel, and a nice treatment of various time travel tropes, the story of Buzz Lightyear (the movie character) who was the basis for Buzz Lightyear (the toy) fell far short of infinity in terms of plot and fun.

When Flynne Fisher’s ne’er-do-well brother lands a lucrative gig testing new VR tech, he drafts Flynne to do the heavy lifting, and she’s bowled over by the future world the VR has created—until she realizes it’s more than a sim.