Board Thread:The Reference Desk/@comment-82.20.113.152-20130213135009/@comment-7302713-20130405182741

However you want to number the universe's it doesn't really matter. My only point was that it isn't like there's a universe with things missing (like Amy's parents) and a universe where everything missing has been restored. It's not quite that simple, because there are all these things that we've seen happen that never happened because of the cracks in time. However you count things the whole cracks in time/big bang storyline erased things. Things that we saw happen never happened. Since there was a new cast we don't know how this affected anyone other than the Doctor who remembers because it's part of his personal history. For all we know this means that the companions of this period don't remember this stuff happening.

Basically, it's complicated.