Tony is, at least, used to explaining things he finds normal and relevant to someone either from a less (Steve) or more (Thor) advanced society that doesn't quite get what he's mentioned and takes it in stride. Well- Mostly in stride.

"Nuclear what now?" That? That's new. That's- multiverse theory, everything here's a little weird and creepy, man eating things in the mist outside. Shit is relative. He shakes off his knee jerk panic (having tried to avert one in the past already) and just. Keeps on.

Freakouts later, solutions now. "Finding one? Unlikely. I can probably build one if we need."