Futility Closet posted a thought experiment the other day, which I have a problem with. Go read it now – it’s short. No worries, I will still be here when you get back.
Done? Great. So, I don’t think the preconditions to this experiment are logically possible. This is not a stable time loop; a successive line of descendents are individually going back, not the same two people. This means the past should have “filled up” with these men – each time one goes back, he meets all the others who already did, and therefore Jocasta would not have found just one deep freeze, but a possibly infinite number of them.
An alternative interpretation is that this assumes the parallel universe theory of time travel (IE, there are infinite parallel universes, and traveling into the past necessarily “jumps” you to another universe, neatly avoiding paradoxes since you cannot now change your own past). In this interpretation, though, Jocasta never meets her own offspring – the man she marries is a parallel Jocasta’s son, not her own.
Thus the thought experiment is invalidated, and the ultimate problem is prevented from occurring and therefore unanswerable.