Brett makes an impatient gesture. "Shall we say hello to the new neighbors?"
"But…but…," you sputter, "time travel can't work this way. There are no time windows two days after we left." At Brett's puzzled look, you explain. "Nothing can arrive here two days later than we did. Believe me, I searched very thoroughly for any conceivable date this whole year." She looks dubious. You glance at your phone. "Besides, it's 10:42 a.m., not noon. What is going on?"
"What if this time machine started out from different geographical coordinates than ours?"
You shake your head. "Of course its precise latitude and longitude must have been different from the coordinates of our time machine. This RV couldn't have come from my parents' garage. Wouldn't even fit in it. But the dates and times when it departed from the present and arrived here have got to be identical to ours. That's the constraint imposed by the temporal equations. That's the whole reason why they're called 'time windows.'"
With a shrug, your friend says, "Maybe there's a fudge factor or a hidden window?"
"Can't be. The equations I derived can be solved only for a scant three time windows per year, no more." Nonetheless, you turn that notion over in your head. Could you have overlooked a fourth window? Or even more? You shake your head, recalling your diligent searches.
"Maybe the RV took off a year or three after us."
"Then it would get here a year or three later, as well," you reply. "The precise length of a temporal journey can't be altered willy-nilly." You think back on the readouts since your own trip began, knowing that you could have paid more attention to them, wondering what you overlooked or misinterpreted. The answers must lie inside that recreational vehicle. As you think it over…