"Well, not necessarily for the train." Bulma waves a hand as if dismissing that - the train already travels through dimensions, it hardly needs to help to travel through time if it so wishes, so far as she can see.

"I'm saying I made one before, in my world. So I know how it works. Really... traveling through time isn't all that different, theoretically, than traveling through universes." She's bringing it down a little, here, just to make it simple to understand. Bulma is well aware by now that what she says is not always in layman's terms, and not everyone is a scientist who can understand it.

"Now, if Whis was here this might be a little easier to suss out, considering he does that sort of travel all the time, but since he isn't... I've been trying to work it out as best I can in my mind."