"If you need a door, then time isn't your answer," David told him, shaking his head. "You need transdimensional portals, which is a whole other kind of math. Not many people know how to work it. Hell, even I'm barely an amateur at it, and I'm very good at what I do. The two aren't the same."

And it hurts him to say that.

"I know, I want to get the people I love home too."