Doctor Who: Quantum Immortality
As Amy Pond said, "Okay, kid. This is where it gets complicated."
There's a thought experiment in quantum physics birthed from the observation that inside an atom some particles appear to be moving in two different directions at once. Now, that seems impossible, and in a way it is. In another way, it's not. The theory of quantum suicide states that while the particles did in fact move in both directions, we end up in a universe where it only went in one. The other immediately creates a parallel universe where it went the other way.
Now extrapolate that to a human life. When you woke up this morning, you decided to hit the snooze button and were five minutes late getting on the road to work. A car that you would have otherwise missed had you left on time has now ended your life. You no longer exist in that universe.
When you woke up this morning, you didn't hit the snooze and you left on time. You never hit the car. You continue to exist in this and multiple other universes created from that decision. This act of dimensional creation constantly plays out until you have literally exhausted every single possibility of survival. In the end, you die in the last universe you could possibly be alive in. That's quantum immortality.
"The Rings of Akhaten" starts kind of slow, honestly. The meaning behind the leaf in Clara's book is revealed as a bit of happenstance that brought her parents together and that her father kept and passed on to Clara. Meanwhile, The Doctor tails Clara through her childhood, desperately trying to figure out how she is the same girl he met in "The Snowmen" and in "Asylum of the Daleks."
When dealing with new companions, there's a couple of episodes that are essential to their acclimation. You have the "Rose" episodes, where the companion first proves him or herself capable of saving The Doctor when he needs saving. Then you have the first date episodes, where they go someplace very amazing because let's face it, The Doctor is a showoff. It's not always in that order, and sometimes they're the same episode, as in "The Beast Below," but that's the general gist. "The Rings of Akhaten" is one of the combination episodes.
I think that we can safely put behind us fears that Doctor Who has gone from The Amy Show to The Clara Show. We do spend a lot of time with our new companion, but even when she's on screen, Jenna-Louise Coleman keeps the focus on the story. Her mystery takes a backseat to a mysterious little girl who as the repository of all her solar system's history is to be sacrificed to a massive parasite god.
What I find so amazingly fascinating about these last two episodes is how much The Doctor has changed. I swear they're putting Matt Smith in old age makeup, or perhaps he is just really that good of an actor. Regardless, his Doctor is actually regressing. No longer is he the bumbling clown that Smith borrowed so heavily from Patrick Troughton.