Why is Rose Tyler back in Doctor Who episode 1 series 4?

The realistic reason Rose is back is probably because Martha was a slight disappointment to many fans as far as companions go (and who can blame her, Rose, being in love and seemingly of the same mindset as the Doctor, was a tough act to follow) As far as the series setting goes, I think she realized that the alternative Torchwood has been messing with the rift, which, if you follow the Torchwood series, is completely obvious since most, if not all, of their phenomena is due to the rift and in the finale of season one, they opened it again. Rose couldn't stay gone for long, the Doctor never got to finish telling her he loved her...and, as they say, love knows no boundaries. For confirmed answers, we'll all just have to continue watching the series with baited breath. She is confirmed to appear in at least three episodes this season and is supposedly signed to be in the specials of 2009 as well... _________ If you really want to know, review this episode that has already been shown: http://en.wikipedia.org/wiki/Partners_in_Crime_%28Doctor_Who%29 Also see this link: http://en.wikipedia.org/wiki/Rose_Tyler ... the links to future episodes are here, and will be updated as they are shown in England (before they make it to the US).... she should be in at least two more episodes. Short answer... she'd probably back because she is a very popular character, but the show's creator says this return was planned from the beginning, and there are unresolved issues in the storyline. Stay tuned though for more information... you know I will be glued to the screen until we find out. :)