It is not unreasonable to think there might be some kind of gap. In my world you may travel between planes of existence if you know how to shift or you find a gateway.

And those of us from the train mostly [because McBurn] agreed to go investigate the coordinates our group received once things were stabilized. There were wefts in space, drawing worlds in. Something like that...

Hm. Wefts. Maybe there was a very thin barrier separating us even when they were here, which might explain the limited tangibility.