Synchronicity (Blu-ray release 2016-5-10) not only has time travel, but another sci-fi concept as well.  Jim builds a time machine – one end of a worm hole – the experiment results in a Dahlia flower and the shadow of a man captured in video camera.  Then he meets a mysterious woman Abby, who has the exact same Dahlia.

I want to love this movie, but I don’t.  I’m fascinated by time travel, but not when the filmmakers deliberately withhold details that prevent a clear understanding of exactly what happened.  Time travel is already potentially confusing on screen, so Back To The Future II (1989), or the more recent Predestination (2014), do many things perfectly right to make it clear.  Besides the inherently interesting concepts of time travel and [the other sci-fi concept], there’s not much in the movie that is especially attractive.  There is no fun or tension to speak of.  Pacing is not good.  Repetition of some scenes and dialogues get tedious, even though they may actually be slightly different.

[SPOILER – Synchronicity movie explained]

This explanation is inspired by Piotr’s comments in this article.

Abby’s novel is the truth, and the multiple timelines we see are actually parallel universes with minor differences.

Let’s call Jim from the first timeline as Jim-A.  He travels through the wormhole to the second timeline, where Jim-B is known as Jim Prime in the movie.  Jim-A tries to make an early second jump before Jim-B does first jump, but this jump is not successful, because the left/right label is no longer there for Matty to perform the procedure correctly.  If this left/right label is erased by someone, this someone may be Jim-C: in another universe not shown in the movie, Jim-C successfully made the second jump to prevent Jim-A from making the second jump.

After failing to second jump, Jim-A travels to the far away hotel to prepare for death, but discovers the corpse of Jim-C, who successfully made the second jump so his remaining time of life was already used up.  He goes back to the Grand Hotel and witnesses Abby having sex with Klaus in order to get the MRD to allow Jim-B to jump, hopefully saving Jim-A.  Abby slips the book into Jim-B’s pocket, and goes back to the Grand Hotel but finds that Jim-A is already dead.

Jim-B (or yet another Jim from another timeline) reaches a different universe after jumping.  In this universe the parallel of Jim is known as John Bane instead.  Jim reads Abby’s book completely, and may have sabotaged the first experiment of John Bane and killed him.  Without John, Jim can now survive, and he goes to meet Abby in the bar.  Note that Abby has drawn a figure on a coaster that illustrates the multiple universes.