Re: anti-particles "moving backwards in time" ?
"Time reversing Big Bang-Big Crunch scenarios do exist. I think yours has the added disadvantage that all matter has to be converted into antimatter."
That's the bit I'm not sure about. If we could somehow view this hypothetical universe, would we see it like a movie being run backwards? (ignoring the fact that photons would presumably be absorbed where in our universe they would normally be emitted, so we wouldn't see anything) So from our point of view we would see matter falling out of black holes and coalescing into suns? I can't get my head round the concept that a universe formed in a Big Bang that then proceeds backwards in time, hasn't emerged from a played-backwards collapse.
This is the trouble with reading sci-fi but not understanding cosmology.