Okay, so The Big Bang was a fantastic and clever and silly Doctor Who series finale, but also rather difficult to understand in some places.

So here’s a quick run down on what I think happened. Most of this is drawn from comments in the show, but you have to go beyond the Pandorica: The Eleventh Hour and Flesh and Stone are also needed to understand everything that happened. Being fair, I’m pretty sure of about 60% of this, less sure of 30% and there’s 10% that’s guesswork (particularly regarding the fate of Auton Rory).
 
How did the Doctor get out of the Pandorica?

Rory let him out. Simple as that!
 
Alright, not actually that simple. Rory could only do that as the Doctor, who had already been let out of the box by Rory, came and told Rory to let him out.

This has made some people very uncomfortable as they feel that the Doctor must have got himself out some other way then come back to get Rory to do it. Sad to say, they are wrong. While it may not be pleasant, and some may see it as cheating, there is no reason that this can’t happen within the rules as established in the DW universe. If you have a time machine you can go back in time and save yourself, so allowing yourself to go back in time. In Star Trek they call it a Predestination Paradox and a big, fat paradox it is, but that doesn’t stop it being allowed.
 
We have plenty of other examples of it happening in DW, they are just less obvious. Time Crash is one – the Tenth Doctor saves the TARDIS because, when he was the Fifth, he saw the Tenth do it. Blink is another – the only reason the Doctor knows what to say to Sally on the DVD is because he has a transcript written by someone who watched him on the DVD. Even in the old series, Day of the Daleks is built on this sort of paradox.

But Day also shows its weakness – one change and the whole timeline goes up in smoke. Essentially the Doctor is crossing his own time-stream and this is deeply frowned upon because of the trouble it can cause if it doesn’t work – look what happened in Father’s Day!

But, by this point, the universe has collapsed and they are all doomed. In this circumstance it’s understandable that the Doctor throws the rulebook away: he knows that if he screws this one up, then it can't really get any worse than, er, the universe having been destroyed.
 
More generally, after the loss of the Time Lords, the rules of time seem to be rather less well enforced than they were. As Waters of Mars makes clear, they are not physical but legal constructs, designed to stop people playing silly buggers with the time-stream. And that episode shows that the rules can be broken, but doing so tends to have serious consequences.
 
How come the Pandorica was so easy to open?

That’s the thing about prisons: you have to be able to open them from the outside to put someone in. They only need to be secure from the inside. The Doctor chose not to open it in The Pandorica Opens because he wasn’t certain what was inside, not because he couldn’t open it at all.
 
Why was the Vortex Manipulator so good at time travel if it’s meant to be crap?

The Doctor kindly explains this in a throwaway line. The universe is now much smaller, taking up essentially only the Earth-Moon area, so time and space travel is much, much less complex.

Why did River run into a wall when she tried to leave the TARDIS?

A good question. As the TARDIS is beginning to explode, the Doctor tells River that if she leaves the engines will stop. The implication is, therefore, that the wall is put there by whoever is controlling the TARDIS to stop that happening. One for next season.
 
Why did the Dalek not kill the Doctor?

When the Doctor shuts the roof hatch he says the Dalek will need four and half minutes to charge to lethal capacity. The conversation then runs seamlessly until the Doctor is shot roughly a minute and half later. Hence the Dalek was not at lethal capacity.
 
Why did big Amy not explode when she touched little Amy (like the Sonic did)?

For those who don’t know, this refers back to Father’s Day (and even further back to Mawdryn Undead). Essentially the idea is that if a single item at two points in its timeline touches, a lot of energy is released.

In the case of Amy, big Amy and little Amy are not the same object. Big Amy is from the universe with stars and little Amy is from the one without. At no point in little Amy’s timeline will she become big Amy, hence no discharge.
 
An equally valid question is why this doesn’t happen to the Doctor when he hugs himself. He really is the same person in both.

The short answer is that this never happens to the Doctor. The Doctor has touched other versions of himself in all the multi-Doctor stories and has never exploded. Time Lords seem to be immune.
 
Why did Amy and Rory not remember the Daleks?

Some people seem to think Amy has forgotten the Daleks because she was near a crack as a child, so Rory should still remember them. This is not the case. Flesh and Stone pretty-much states that the Daleks from The Stolen Earth (and the Cybermen from The Next Doctor) are eaten by a crack and so removed from time. Hence nobody remembers them – resetting Russell T Davies’ decision to have the people of Earth know about aliens (and perhaps retconning every continuity error ever).
 
Hang on, if people don’t remember the Daleks, what did people think happened during The Stolen Earth?

This is difficult to say and, to be honest, I’m not certain myself. Once you remove the memory of the Dalek invasion fleet, the whole experience from the stealing of Earth to its later return is unlikely to make much sense to people.

The obvious defence mechanism is that the mind skips the whole experience so nobody remembers any of it. A few unexplained heart attacks and the deaths are dealt with as well. By making time-travellers immune from the effect, Sarah-Jane and Jack can even continue to remember it all. This is similar to people forgetting the Yeti on the underground (The Web of Fear) or the Cyberman invasion (The Invasion) – in the DW universe it’s amazing what people can convince themselves of!
 
How did these cracks work anyway?

Excellent question and, after The Big Bang, we have enough information to answer it.

The cracks were caused by the TARDIS exploding which, it being a space/time machine, took place at all moments in space and time. From what we were shown, as the Doctor/TARDIS’ personal timeline got closer to the event, the cracks became more numerous and more dangerous (they were wider each time).

Being near a crack is dangerous because sometimes (although not always) light from the crack can erase someone from history. The important point here, and this was consistent throughout, is that erasure from history does not mean that actions already taken by the erased individual disappear. They still stand. This was made clear by Father Octavian still being dead and, most importantly, Amy still existing when her parents didn’t.
 
How this sits with “time can be re-written” is a sticky point. This whole thing becomes easier if erasure is just that – total erasure of all actions taken from the timeline. But it can’t be because, if that was the case, Amy couldn’t exist and the Doctor, Amy and River would all have reverted back to where they started once the Angels were removed in Flesh and Stone. One for Mr Moffat should anyone interview him soon.
 
From what we saw, an erased individual has no future from the point they are absorbed by the crack – hence future Rory disappears in Cold Blood. The effect on the past of the individual is that they cease to be remembered, something like a perception filter. Some objects from their life still exist (like the engagement ring) and individuals find themselves unaccountably confused by the gap but, essentially, the universe papers over the cracks and carries on regardless. Thus the Daleks still invaded Earth and the Cyberking still walked over London, but nobody remembers it happening.
 
The cracks don’t always do this. As Lady Calvierri pointed out in Vampires of Venice, through some cracks they saw other worlds. It seems that cracks can link places (like Amy’s bedroom and the Atraxi prison) or eat people. Presumably which effect occurs when is pretty much random.
 
Why were Amy’s memories important?

Amy was special because of her long-term proximity to a crack. As the Doctor said, the universe had been pouring out of the crack, filling her subconscious (“dreams”) with information about the universe – past, present and future. This made her memories unusually powerful and accurate (or at least her subconscious ones). Essentially it turned her head into a reality store. When she remembered something, she remembered its essence as well as its form.

Hence, when the Alliance take a scan of her memories and create a replica Rory, instead of being like an ordinary person’s memory of him (i.e. only the things known to them), he is a complete simulacrum of Rory including his own memories right up to the moment he died.

The young Amy demonstrates this too when she remembers stars in the dying universe.
 
It is this function of Amy’s memory that allows her to bring her parents back. And this is a vital point, because it shows that Big Bang Two did not undo the effect of the cracks. If it had, Amy would not have needed to do anything, her parents would have just popped back into existence on their own. Instead the Doctor had to tell her to specifically remember them. They (and by implication Rory) are returned only because she brought them back from her memories when the universe was reset. Everything else that had been eaten by the cracks remains eaten.
 
So the Angels aren’t back?

Correct. The Angels stay eaten as Amy didn’t bring them back through her memory.
 
Then what happened to the cracks? Didn’t they shut?

Yes and no. We saw, as the Doctor moved towards the explosion in his own timeline, the cracks got bigger. Conversely, as the Doctor goes back over his timeline as he is erased, the cracks shut, but that didn’t stop them existing for a time. The moment they close does not seem to be identical to the moment they open.
 
In addition, the presence of the jacketed Doctor in the original Flesh and Stone shows that the post-Pandorica and pre-Pandorica universes are identical. The explosion and its cure are therefore pre-destined – they always happen.

Thus, in the timeline (as there is only one) the cracks open, eat people, and shut again, but the universe is not destroyed as the explosion is countered the moment it happens. This also allows River to encounter a crack in her, subjective, future (Flesh and Stone), during which she remembers the events of The Pandorica Opens.
 
So did any of the series happen?

Absolutely! All of it happened. Once the cracks are closed, it’s like the Doctor has been erased: all of his actions stand but nobody remembers them. So Amy left with him, Rory was killed etc. Everyone (except seemingly River) has forgotten these events until Amy brings back the Doctor.
 
Why was the Doctor erased?

He flew into the explosion, which had reality erasing effects. Essentially it was like throwing oneself into one of the cracks (given that the explosion was at the centre of them). His timeline unwound in much the same way Rory’s did – however in the Doctor’s case he seemed to be able to get on and off the rewind and, incredibly, interact with Amy.

Why he would be able to do this is anyone’s guess. It could be a simple as, as a Time Lord, he can control his time stream to an unparalleled extent. This is certainly implied by his decision to skip the rest of the rewind.

But there are two important points. Firstly he is always near a crack. My presumption is that, as he rewinds, he is stepping through these cracks into reality. This would explain why he needs to be on the other side before they can close properly. Secondly, only Amy can hear him and, each time, he appears near her. Again why this would be the case is not clear, but it might be because he is (in forwards time) already in Amy’s memory so she is anchoring him to the timeline.
 
What about the Pandorica?

By flying into the explosion, the Pandorica, like the Doctor, is erased. Events involving the Pandorica are gone from people’s memory, seemingly leaving enough residue in the timeline for the Pandorica to become a fairy-tale.
 
In addition, the events in the dying universe get removed completely (we see this timeline unravel) as the explosion is countered at the instant it occurs. Hence that whole part of the timeline just melts away and the 26th June 2010 carries on from where it left off (with the addition of Amy’s parents and Rory). This is similar to Day of the Daleks when the timeline unravels back to the event where the pre-destination started (the peace conference).
 
Why were the Doctor, Amy, River and Rory still alive in the dying universe?

Amy actually asks the Doctor this and his answer is characteristically unhelpful. In the case of the Doctor, he was in the Pandorica and so seems to have been protected from the erasure. The same is true for River who was kept safe in a timeloop by the TARDIS.

Amy and Rory are rather more difficult. One option is that, since Amy’s enhanced memory can bring people back from erasure, her memories of herself can counter her own removal from history. Similarly, since Rory is created from her memory, he may get the same protection.
 
A more interesting point is what this all looks like from the point of view of the Alliance. Once they seal the Doctor in the Pandorica, the universe then ends and is instantly re-instated – without the Pandorica, the Doctor, Amy or Rory. For them, they all just disappear. I imagine a long and slightly fraught conversation then occurs.

Given that they’ve all time travelled to get to the second century (a lift with the Daleks perhaps?), they are presumably immune from the erasure of the Doctor and the Pandorica, so they still know why they are there.

One of two things could then happen. Either they conclude that the Doctor has tricked them and set about hunting him again. Or, more likely, they conclude that the explosion has been averted and they can all go home.
 
Where did the burn marks on Amy’s lawn come from?

It seems to have been from the Nestenes, since they took the memory scan of Amy. Unfortunately that would mean the memory scan was taken when Amy wasn’t there, as she had already left with the Doctor earlier that night (although she returns briefly in Flesh and Stone so it may have been then). Equally they could have taken a psychic imprint of Amy’s mind left in her house so she needn’t have actually been present.
 
The real question is why they would pick up the memory of Rory’s death, which hadn’t happened yet. Everything else (the Romans, the Box, even Roman Rory) is already present. In fact it may not matter. As we said above, the crack was pouring information from all across time into Amy’s head so her unconscious memory of Rory may have included his death even before it happened.
 
On a side note, in the photograph Roman Rory appears to have been at a fancy dress party (Amy is dressed as a police woman) and this seems to have given the Alliance the idea of putting him with the Romans in the first place as an extra distraction for the Doctor and Amy.
 
So is Rory still an Auton?

No. Or at least, I think no.
 
The reason I think this is as follows. As we said above, after the Doctor’s erasure his actions must still stand (even if nobody remembers them). If they didn’t, the whole of reality would have been different from the dawn of time onwards, which is not what is shown.

So, original Rory is still dead, even if nobody remembers him dying.

This has to be the case because, if Rory at the wedding were the original, he would spontaneously disappear when the Doctor’s history returns.
 
So, Wedding Rory could then be assumed to be Auton Rory returned from the dying universe. But if the Doctor had stayed erased, Amy and Rory’s marriage would have become increasingly difficult when it was discovered he was a practically-immortal plastic robot. Somehow that just doesn’t seem right.

Logically therefore, Auton Rory doesn’t exist in the new timeline. He disappears into the dying universe in Roman Britain and never comes out – he’s essentially erased as, when the timelines reset, there’s nowhere he can sensibly exist. If my theory about why he survived in the first place is correct, one could suggest that once Amy leaves that universe, her memory is no longer there to prevent Rory from being wiped.
 
And if anyone can come up with a better explanation of what happened to Auton Rory I'll gladly hear it!
 
Then where does the Rory that Amy marries come from?

Assuming that the above is true, it appears that when the universe reset, Amy brought Rory back through her memory in the same way she brought back her parents. Thus Rory can die in Cold Blood, be eaten by a crack and be alive at the end of The Big Bang. Once the Doctor returns, Rory’s memories of his past return.

You can see this happen – he has no idea what Amy is talking about until the TARDIS appears then he suddenly gets it all back. You can actually hear him in the background remembering the Doctor being the stripper at his Stag Night and being an Auton (“I was plastic”). He remembers both events because Amy considers Auton Rory to be a continuation of real Rory, so both sets of memories will be present in the version she creates.
 
So how did Amy bring the Doctor back?

Same way as she did with her parents and Rory. The Doctor tucked a copy of himself (and the TARDIS) into her childhood memories using the ‘Something borrowed…’ rhyme as a trigger. He knew she would marry Rory once the timeline reset and so hoped the rhyme would jog her memory.

We saw in The Eleventh Hour that Amy responds to the Doctor when unconscious, so it’s not like he didn’t know if she could hear him. Interestingly, given that the TARDIS still explodes (even if nobody remembers it happening) she must have remembered that into existence too.
 
How this astonishingly risky strategy works is questionable. The Doctor seems to believe that his adventures with Amy are never going to happen now. On some level he’s right – he won’t remember them and neither will she (or anyone else) so, by some definitions, they didn’t happen.

He then hinges his own survival on the assumption that Amy will still remember these non-existent events. In essence, she has two divergent sets of memories, one subconscious (her life with him) and one not (her life with her parents). That she is confused is evident in her reaction to the appearance of her parents as adults in 2010, despite the fact that the Doctor told 7-year-old Amy that 'tomorrow, when you wake up, you'll have your parents again'. This implies that, until he's reinstated, there is a fundamental instability in the timeline - both sets of events may have happened, and Amy has access to both sets of memories.
 
Why did River still remember the Doctor?

Damn fine question. This may be to do with the nature of who River is. Alternatively, we saw in Flesh and Stone that being a time traveller means that the cracks don’t always affect you. Hence the Doctor’s erasure may not have affected her.

Another possible explanation is that River made the effort not to forget, because she knew it was likely to happen. We saw Amy fail to do this in Cold Blood, but the Doctor stated that it was possible to maintain the memory through mental effort.
 
An equally good question is how she got to Amy’s wedding. We don’t know where time put her after the re-boot so it’s difficult to be sure, but the implication is that she and Amy (the only two survivors of the dead universe timeline) both ended up at that date because it was the centre of the explosion so that’s when time reset itself. Certainly Amy’s reaction to seeing her parents when she wakes strongly implies that, although history has been changed, the wedding day is actually Amy’s first day in the reset timeline.
 
For further evidence, it’s worth noting that, when River sees the Doctor at the wedding, he gives her back the Vortex Manipulator, implying that it is straight after the earlier events for both of them.

Phew.

So there you are. It’s mind-bending and mostly constructed from extrapolation and inference but it does make sense. You are of course free to disagree with any or all of it but, notwithstanding The Moff telling us what really happened, I’ll stick with this for the moment!
 
Our review of The Big Bang is here