Yeah. I've seen it a few times. It's got good writing, and a cool mathematics/quantum mechanics origin. They usually don't make movies with enough background story to make the superficial front end strong and thought provoking. This movie has a lot of neat ideas behind it. The tangent universe they base the story off of is based in retrocausation aka retrocausality. The theory is that when there's a break in time it forms an offshoot from the main timeline in the shape of a circle or ellipse that is separate from the main timeline. Like a coffee mug. So what happens in the movie is that there's an artifact that causes this break and a new timeline is formed in the loop. And the majority of the story is in this tangent universe and when the tangent universe finally intersects back with the main timeline, it's destroyed and everything is back to normal except one thing. The artifact is the effect that creates the cause. Instead of the natural cause and effect. It's backwards. This is a theory of quantum mechanics because cause and effect aren't defined in any way at the fundamental level.