More Time Travel Paradoxes

For John Macnab covers see here.

A particle appears and divides. One of the new particles mutually annihilates with an already existent particle. Was there creation and annihilation or did a single particle briefly reverse its arrow of time?

Discussion of time travel paradoxes is endless. Poul Anderson's "The Barrier Moment" assumes a single continuous timeline with neither causality violation nor any uncaused events - except maybe that earliest moment.

Once, the scientists try the experiment of not sending into the past the cage of mice that has already appeared beside itself in the laboratory - until someone does absent-mindedly send it. Suppose that they had decided to be stringent and consistent about not sending back cages that had appeared? In that case, cages would stop appearing.

In Anderson's There Will Be Time, Jack Havig demonstrates time travel by standing beside himself for thirty seconds. If Jack were the kind of guy who, having seen his slightly older self standing beside him for thirty seconds, would then refuse to travel thirty seconds into the past, then the slightly older Jack would not have appeared in the first place. If Jack were the kind of guy who would decide to travel thirty seconds into the past even though a slightly older Jack had not appeared thirty seconds previously, then something - we do not know what - would happen to prevent him. This is where the logic of this scenario starts to get shaky.