Found: one time travel device

I was at school dropping of snack for the 4th grade today. They were doing their science lesson while I was there and I hung out for a few minutes to observe. The teacher does a KWL when they start a topic, which means what do we already Know, what we Want to learn and what we will Learn. So they were talking about space and someone said that space in infinite. Up goes WF's hand. The teacher called on him (and honestly, I know what kind of irrelevant answers he tends to give so I held my breath a little bit) and he says "some scientists believe that space is always expanding but eventually, it will get so big that it will come back in" His teacher says "Oh yeah, I think that is called negative matter. They can't see it but they can look for signs of it"

They move on down line and eventually another kid says that space has black holes. The teacher talks about how when he was a kid the question was are there black holes, now it is what happens to things that get sucked into black holes.

Boom, up goes my kid's hand again. I think "gah, what can he contribute to that discussion?", because you know that something about black holes triggered his thought. The teacher calls on him and he says "It's my opinion that things that get sucked into black holes go to a different time and place. A black hole is just a tunnel to somewhere else"

As I push my eyes back in my head, the teacher commented that lots of books have that theme and asked if anyone could think of one off the top of their head.

All I could think was "that's my little nerd!" LOL