Why does Herdeg appear in the abandoned ruins of his own house?
Our first reaction is that this makes sense. He was in his own house, and the universe changed around him. However, this is inconsistent with all of our other trips. Dave and Jimmy appeared where the town had been (in Nevada, nowhere near Philadelphia), and so did the mast from the Eldridge; the ship itself, and the town, remained in the vortex until released to their originating points at its (temporallly shifted) ends. Jimmy's return trip puts him at the vortex opening in the past. The bomber makes sense, because American Mailer was attempting to teleport it and succeeded in doing so, but failed to prevent the temporal shift; and we can perhaps accept that the German Mailer time machine is able to target its arrival point spatially as well as temporally. However, when Dave moves from the original universe to the altered universe, he is in California, nowhere near any vortex point of which we are aware.
He is also in a room that cannot exist. We might accept that the house was built before (or, less likely, during) the war, and thus that the room itself would be there; but would it contain the furniture which Dave and Allison, who now never met so never lived here, undoubtedly obtained for their son Benjamin, now never born? Perhaps they rented it furnished--against all odds, with the same furnishings--but would not the furniture have been moved to accommodate the preferences of a young boy? Not only should Dave not be here, "here" should not exist as it does.
Obviously, though, the point is supposed to be that Herdeg remains who he is and where he is, and the universe changes around him. However, the changing of the "universe" seems to be somewhat selective; that is, the part which does not change extends beyond Dave Herdeg to include his acoutrements. He is wearing a baseball cap with a label that says it is made in the United States in 1993, and carries modern identification such as a drivers license, and perhaps most telling a photo of his son Ben. Sure, we can invent possible explanations--some kind of field immediately surrounding him, such that everything on his person must go with him--but these are all inconsistent with everything we already know about this event. We are ultimately faced with the problem that this is the wrong David Herdeg. He cannot exist in this universe, and the fact that the other universe has been erased means either:
- he traveled here as a twenty-five year old from 1943 when German Mailer opened a gate (and so would have arrived where that experiment occurred), or
- he ceased ever to have left the vortex at any time, or
- when the history was written that prevented Longstreet's experiment with the town, the vortex never happened and Dave returned to 1943 with Jimmy, or
- when American Mailer's experiment went wrong, Dave was swept into the trip and delivered to a point several thousand feet above Weisbaden, Germany, in 1943.
No logical consideration of the event puts him in that house. As the Maine farmer replied when a traveler asked for directions to Alaska, "You can't get there from here." Or rather, we cannot get here from there.
The story, though, insists that somehow Dave is still connected to hyperspace, such that whenever anyone tampers with hyperspace technology he feels it, and so that when American Mailer using hyperspace time travel destroys all of the history in which Dave travels to 1984 and creates a new history through 1993, Dave pops back into hyperspace just long enough to arrive in the new history. It makes no real sense, but there it is.