"It might be from a whole other universe, if it's that fundamental a change."

Or science as a whole progresses a lot; there's nothing to really ground them in the types of worlds these memories are coming from.

Turtles and magic rituals...

Walter looks back up from the blueprints, eyeing Jim's face.

"When was the last time you slept?"

It's a subject change, sure, but it's also an important question - to him, at least.