After 10 regenerates, he happens upon Amy, a grad student working on her PhD in theoretical physics. Amy is interested in learning about 11 since he’s an alien from a future race that has made science theories at reality. 11 offers to take Amy around the universe and time, but she will only go if she can take her fiance Rory with her. They travel and have adventures, all the while being followed by some mysterious crack in time and space. Amy figures out that the cracks in time are being caused by ripples from the Time War. Where ever there is a crack, it makes either a different aspect of time or space leak or bleed through where it doesn’t belong. The Doctor now knows that he needs to go back to the Time War and figure out how to stop the ripples. Amy and Rory decide to stay on Earth for a time to figure out how to save the universe. The Doctor seeks out River Song, because her past is his future, for potential help. While River knows that she can’t give too much away (SPOILERS!) she tells him that the Time lock that was placed is starting to disintegrate, which is what is causing the cracks. In the meantime all he can do is try to find isolated cracks and fix them. 11 lands in Victorian England, where he meets Clara Oswald, who knows something is not right with the world, but can’t quite put her finger on it. It turns out that one of the cracks is making a race of ice and snow monsters come to earth, thus threatening it. Clara and 11 defeat the snow monsters by heat and the Doctor uses the vortex energy from the TARDIS to repair the crack. Clara is intrigued with the thought of traveling in time and space, so she decides to accompany the Doctor on his travels. Clara and 11 go find Amy and Rory on modern earth, where Amy has theorized that since the Doctor destroyed Gallifrey and sealed it in a time lock, the planet’s destruction is still happening, and is threatening the time lock and thereby the universe. 11 must figure out a way to end the Time War in a way that won’t ultimately lead to the destruction of the universe. Clara suggests that they could use TARDIS and Time Lord Technology to create a pocket universe and call all the past Doctors to it to help save not only Gallifrey but the universe. They create the pocket universe and use the TARDIS to bring past Doctors to it. This is done by using the energy emitted while they are rengenerating to temporarily pull them into this pocket universe. *also explains why they won’t remember this meeting, because it happened while they were in a state of flux*. While it works, there were a few glitches and some of his past incarnations seem to have aged while being pulled into the new universe. While they may look different, they still have the same intellect and personalities. They are met by a future doctor (John Hurt), who tells them that they need the power of 12 TARDISes to reset the time lock to just before the moment of destruction of Gallifrey. That would make a more secure lock, since the planet is stable and not in a moment of constant explosion. This worries some of the Doctors, especially 8,9, and 10 because that would mean that the Time Lords and the Daleks would still be a threat to the universe. After much discussion, they do decide to reset the time lock, knowing that the potential threat of the Time Lords and Daleks is a better situation than the one they are in now.