How traveling back in time could really, physically be possible

If we want to scale that up, however, to allow something like a human being through, that’s going to take some work. While every known particle in our Universe has positive energy and either positive or zero mass, it’s eminently possible to have negative mass/energy particles in the framework of General Relativity. Sure, we haven’t discovered any yet, but according to all the rules of theoretical physics, there’s nothing forbidding it.

If this negative mass/energy matter exists, then creating both a supermassive black hole and the negative mass/energy counterpart to it, while then connecting them, should allow for a traversible wormhole. No matter how far apart you took these two connected objects from one another, if they had enough mass/energy — of both the positive and negative kind — this instantaneous connection would remain. All of that is great for instantaneous travel through space. But what about time? Here’s where the laws of special relativity come in.