Time Projection

Some fictional time travel involves not a vehicle that carries the traveler through time but a mechanism that sends him to another time and that might then retrieve him, e.g.:

Bring The Jubilee by Ward Moore; Midsummer Century by James Blish;
"The Little Monster" by Poul Anderson.

There are variations. Blish's example is mental projection only.

"'What we send is snapped back to here and now after thirty hours...'"
-Poul Anderson, "The Little Monster" IN Anderson, Past Times (New York, 1984), pp. 142-163 AT p. 145.

I think that Anderson means that the traveler spends thirty hours in the past, then returns to the temporal projector thirty hours after he had been projected from it but, of course, other scenarios are imaginable like returning to the exact "here and now" of departure.

I want to draw attention to one oddity of time projection, assuming that it is possible both to project and to retrieve:

instead of killing your enemy, you project him several hundreds or even thousands of years into the past which means that, other things being equal, he is now dead;

you project him into the remote past but, fifty years later, you retrieve him after he has been in the past for fifty years - assuming that he did survive for that long, of course;

you project him into the past but, fifty years later, you retrieve him from the moment when he arrived in the past;

fifty years later, you are undecided whether to leave him in the past, to retrieve him after he has been in the past for fifty years or to retrieve him from the moment when he arrived in the past.

In this last case, you know that, if you do not retrieve him, then he died a long time ago whereas, if you do retrieve him from the moment when he arrived in the past, then he did not die a long time ago. But you have not decided yet. It is as if he is on ice. But he is not. He is either dead in the past or he is not. But you do not know which yet. But you will decide. Even to do nothing is to decide.