black holes and worm holes have always (as far as i know) been the real life theories to quote unquote "time travel"
from what i've read and watched, black holes can make time slow down for those it affects, while time remains the same for those it doesn't. if you were able to live through the entrance and exit of a black hole, (provided you didnt end up in some other possible universe or weren't stretched to oblivion) and where able to travel back to earth, what would have seemed like a couple hours in the black hole to you could have really been 10-50+ years on earth
worm holes i believe are the theory for traveling BACK in time. if i remember correctly the physical example of wormholes is taking a sheet of paper(which represents space time), taking that sheet of paper and bending it in half, and then poking a hole through said paper, so that you've essentially poked a hole through one side of the universe to the other. apparently they're able to bend and poke holes through space time is what im getting at. i want to say their formation is caused by black holes, but i honestly dont know how they're formed. i think black holes energy eventually evaporates and they inevitably explode