Why doesn The Doctor just go back and fix things he got wrong?
SA) Because everything could go Pear Shaped. LA) It’s been long established in Doctor Who that traveling into your own time line is against the laws of time. It was never really explained why in the old series, but in the new series it has clearly been demonstrated in Fathers Day. The presence of the same person more than once in close proximity can cause a weakness in the fabric of time, then altering the course of events while there is a weakness can cause a rift. In Fathers Day the presence of 2 Doctors and 3 Roses and the saving of her Father, who should have died, caused a rift that allowed the Reapers to get it. This weakness being caused by the multiple persons also explains why when The Doctor meddles with events normally, when there’s only one of him, he doesn’t cause a rift. It was also pointed out in this episode that Time Lords were able to prevent things like this happening, so presumably when they detected a weakness, they could shore it up.
SA) Because everything could go Pear Shaped. LA) It’s been long established in Doctor Who that traveling into your own time line is against the laws of time. It was never really explained why in the old series, but in the new series it has clearly been demonstrated in Fathers Day. The presence of the same person more than once in close proximity can cause a weakness in the fabric of time, then altering the course of events while there is a weakness can cause a rift. In Fathers Day the presence of 2 Doctors and 3 Roses and the saving of her Father, who should have died, caused a rift that allowed the Reapers to get it. This weakness being caused by the multiple persons also explains why when The Doctor meddles with events normally, when there’s only one of him, he doesn’t cause a rift. It was also pointed out in this episode that Time Lords were able to prevent things like this happening, so presumably when they detected a weakness, they could shore it up. Which explains how with their
