Ted Chiang, qui vient de recevoir le prix Nebula pour Le marchand et la porte de l’alchimiste (publié en français dans Fiction 7) est en interview sur le web.

Il revient justement sur cette nouvelle. Voici un (gros) extrait :

"You’ve talked about the influence of scientist Kip Thorne on the story. What was that influence precisely? Was it more to do with the science of the story, or with the ethical implications of that science?
Ted Chiang : Many years ago the physicist Kip Thorne was on a book tour in Seattle, and he gave a talk in which he described how you could—in theory—create a time machine without violating Einstein’s general relativity. Here’s the general idea: imagine you have one mouth of a wormhole in a laboratory on Earth, while the other mouth is mounted inside of a spaceship. Have the ship travel at near lightspeed to a location ten light-years away and then come back. To observers on Earth, it will take twenty years for the ship to return, but to astronauts on the ship, the trip will only take a year due to time dilation.
Here’s the cool part: if you’re in the laboratory on Earth looking through the wormhole mouth, you’ll see the spaceship crew experiencing the entire journey within a year. A year after the spaceship left, you’d see the crew disembarking back on Earth and receiving their ticker-tape parade, even though no one outside is going to throw that parade for another nineteen years. And if you then stepped into the laboratory’s wormhole mouth, you’d emerge from the spaceship’s wormhole mouth, and you could talk to the people who, nineteen years in your future, are welcoming back the astronauts. Those people could step through the spaceship’s wormhole mouth to visit your lab, and see their past.
Of course the next question is, can you change the past? Thorne examined a situation where you set up the mouths of a wormhole so that, if you fired a billiard ball into one mouth, the ball would exit out the other mouth a second earlier and knock itself out of the way before it could enter the first mouth. This is essentially a version of the grandfather paradox, but unlike the scenario of a person going back in time with a gun, this one is amenable to mathematical analysis. You can actually set up equations that describe this situation and solve them.
What Thorne found was, basically, that the billiard ball doesn’t knock itself out of the way. The ball exits the wormhole mouth at a slight angle so that it doesn’t hit itself head on; it only gives itself a glancing blow, so that the ball then enters the other wormhole mouth on a slightly different trajectory, which is why it exited at a slight angle. So, no paradoxes; you can’t change the past.
(See Thorne’s bookBlack Holes and Time Warps for more details.)
I thought this was all fascinating. Here was a version of time travel that actually made sense; it had limitations, but they followed naturally from the basic mechanism. Initially I considered writing a more traditional SF story about this, but any civilization that could realistically be able to manipulate wormholes would be so advanced as to be essentially unrecognizable to us. I could have set it in the near future, but that didn’t seem more plausible to me than setting it in the past; we’re not appreciably closer to real wormhole technology than medieval alchemists. Then it occurred to me that an “Arabian Nights” setting might be interesting, because the recursive nature of time travel fit with the convention of nested stories, and the idea of a fixed timeline seemed to mesh well with Islamic notions of destiny. "

Toute l'interview est ici