Which arguably could be considered branches of their originating timeline, derivatives in and of themselves, given their presence within this environment. Any sort of deviation from the intended flow of time can be considered an alternate timeline. Though in theory, time is intended to be fluid; it flows in all directions -- seen and unseen -- and isn't meant to be contained to any singular points in history.

[ theoretical physics. it gives her a headache, but she understands it more than she ever wanted to. ]

Good guess, [ she compliments, taking the tricorder back and moving to return it to its holster. which isn't there, because she's in this godforsaken holodeck costume and not her uniform. ] That's one of it's primary functions, yes.

Which century would you say the available technology represents? [ she's a scientist, not a historian. ]