* This is point one.
::This is a counter-argument to point one.
:::This is a counter-argument to the counter-argument above
* This is point two.
::Explanation of point two.
::Further discussion and query of point two.

... and so on. 

• This is a wibbly-wobbly, timey-wimey thing, of course. But how does the Doctor get out of the Pandorica in order to be able to tell Rory how to get him out of the Pandorica? If it's simply a case of somehow getting your future self to rescue your present self - well, this terrifying prison would appear to be about as effective as a chocolate teapot.

Well, to be fair, they never suspected he'd be out in order to free himself. And no one had a sonic screwdriver (which I'll admit was a bit anti-climactic; the ultimate prison foiled by a bit of sonic). Prisons are made to keep people from breaking out not breaking in.

Indeed, if the goal of the Pandorica was to trap the Doctor, it is a reasonable strategy to have it open up in the face of evidence that the Doctor is on the outside trying to get in.

Short answer: Rory let him out. Long answer: it's perfectly a consistent temporal cycle but presumably incredibly unlikely to arise spontaneously. Maybe the Doctor got lucky or it was a trick he could only employ because the universe was on its way out. Maybe the energy of the TARDIS explosion was keeping this part of the universe alive and the Doctor's connection to the TARDIS allowed him to play temporal tricks with the small corner of the universe that remained.

It does make one of those weird time paradoxes that always turn up in sci-fi. But I think the thing about it being a terrifying prison is fairly legitimate. It wouldn't be possible to rescue himself without: someone nearby on his side (Rory), a form of time travel (River's vortex manipulator) and either the power of the sonic screwdriver or (by my reasoning), the Doctors DNA which was carried in the screwdriver (as the Doctor suggests it was programmed only to open with his DNA on the outside of it). Plus, the 'alliance' that locked him in was expecting this to stop the cracks appearing. Thus they would've been able to guard it, and stop anything getting in or out.

It's the Preston/Logan Theory of Time Travel (aka Bill and Ted's). While he was trapped in the Pandorica he said "After I'm released from this, I'm going to go back in time and give Rory my screwdriver so that he can let me out!". And thus, it was.

Perhaps the "first time around", Rory was able to figure out some way to free the Doctor by himself - he would have had almost 2000 years to do so. Then once the Doctor was free, he could go back in time, speak to the earlier Rory, and save Amy.

It's a temporal paradox, where "events arising from means other than the normal flow of cause and effect" and effect precedes cause.

• When Rose made contact with her past self in Father's Day the Reapers appeared, why didn't they appear when Amy made contact with her past self?

The Reapers only appeared due to Pete Tyler surviving when he should have died, the amount of Rose's didn't matter.

It does matter because when Rose touched her younger self it made the Reapers stronger.

The two versions of Amy were now different people - the present Amy wouldn't have remembered going to the museum and seeing the Pandorica. It's like the Doctor said: they were all temporal anomalies; meaning Amelia Pond and Amy Pond are different people, so Amelia could be blasted into oblivion and yet older Amy would still exist.

Also, since the TARDIS is destroyed, this could also mean that time and space is destroyed. Since the Reapers exist outside time and space, they may have perished alongside everything else.

Everything occurs in a parallel universe, meaning the Reapers don't need to intervene.

The Reapers feed on damage to time. At this (subjective) point, the entire universe is being constantly destroyed at every single point in history simultaneously. The Reapers didn't emerge to feed on Amy's time-line crossing, because after 1,894 subjective years of this, the Reapers are possibly too metaphorically fat to move, let alone hunt.

Alternately, if at that point everything except the Earth had never existed, it may be that the Reapers never existed either.

Young Amy and older Amy live in different timelines, so it's probably similar to Mickey meeting Ricky from Pete's World.

Normally, the two touching Amelia's would have caused the Blinovitch Limitation Effect to come into play. (Remember that Rose never physically touched herself in Father's Day, at the insistence of the Doctor.) However, given the effect is time energy and space-time has all but collapsed, the residual energy would be incredibly low, maybe not even detectable. The Doctor had already noted time travel worked differently (the vortex manipulator, for one.) The temporal physics involved in the Blinovitch Limitation Effect may be different or completely ineffective.

This is false. The Doctor explicitly states in Father's Day that the presence of two copies of himself and Rose was what caused the weak spot in time that allowed the Reapers in when Rose saved her father.

You just answered your own point. The two copies of Rose caused a weak spot, only when Rose saved her father did they actually come down, because that was the anomaly. So, it was either the two copies allowed the reapers to notice/come into that time, but they only became a threat after Pete lived, or it was a combination of the two negative events that caused them to appear.

Reminder: In Father's Day, baby Rose was unexpectedly dumped into adult Rose's arms. Rose 'carrying herself' was quite a serious paradox, and this allowed the Reapers to appear inside the church. So I'm somewhat curious what you mean by: "Rose never physically touched herself"? That aside, this event didn't make the Reapers appear. They were already there, it only strengthened them. So to respond to the original question: The Reapers didn't appear because of multiple versions of Rose; there were other more significant factors at play. Furthermore there have been other instances of time-travellers interacting with past/future versions of themselves. And (afaik) this has never caused Reapers to appear.

• The two Eleventh Doctors are able to touch.

Different incarnations of the Doctor have touched before without the Blinovitch Limitation Effect coming into play. Perhaps it works differently for Time Lords.

See the counter-arguments to the above point as well.

The universe is very small at this point, so perhaps the Blinovitch Limitation Effect is much weaker.

• The Doctor is exterminated by the Stone Dalek, but he doesn't regenerate.

As we see in The Time of the Doctor that the Doctor had used up all his remaining regenerations thus he could not regenerate anymore.

Since the Dalek was not at full power, it's fire-power may not have been strong enough to kill him, just weaken him. Had it been at full power, he would have been disintegrated like the inferior Daleks in Victory of the Daleks. Plus, it's possible that he halted the regeneration process long enough for him to get into the Pandorica, possibly meaning that you can't regenerate inside it.

No it's like what happened to Amy, it kept him in the exact same condition and stopped him from regenerating.

To quote River Song: "The Doctor always lies." The Doctor didn't die, therefore he shouldn't regenerate.

Indeed. When the future Doctor says something to the present doctor, he then collapses. Then the present Doctor just pretends that the future one is dead. Go back and look at his reaction.

The Doctor was not "exterminated". He was shot by a severely weakened Dalek. Evidently the damage was not enough to kill him. And even if his injuries were severe enough to eventually cause his death, the Pandorica sustained him.

• What caused the cracks?

It would probably be the TARDIS. Possibly the cracks came from damaged time that gained from the TARDIS' repeating explosion, with itself repeating for many thousands of years, it may well have the cause of the cracks.

The TARDIS exploding - have you not been watching?

I would think the cracks came from the eye of harmony being released and tearing apart the universe.

Ok, re-correct that. Possibly the cracks came from damaged time that gained from the TARDIS nearly coming to exploding for two thousand years, it may well have been the cause of the cracks. The Eye of Harmony's an idea though (if it's still in the TARDIS somewhere).

The Doctor acknowledges that the destruction of the TARDIS should not have led to the destruction of the universe, but dismisses this as a "problem for another day". The outside force which drew the TARDIS to Amy's wedding day and spoke of "Silence" falling somehow contrived a set of (presumably highly abnormal) circumstances under which the explosion of the TARDIS would have that effect.

We later find out that the cracks are/were created by the Time Lords. So is this a plot hole?

The Crack were NOT created by the time lords, the left over cracks following big bang 2 are the weakest point in our universe and the time lords in their pocket universe were exploiting this weakness in order to come back.

• How is Rory alive again? Considering the timeline was restored and Rory was killed before he was erased.

When the Doctor leapt into the cracks, he and they were negated from time; therefore the timeline was reset so that Amy & Rory never met the Doctor, in other words the events of the entire series never happened until they remembered them happening. Because they never went to 2020, Rory never died there. QED.

Then how much else of series 5 is gone? Also if they remembered them happening and as you said, they then happened he should die there.

There are two phenomena at work here and they seem to have different effects on the story. The Doctor's reboot of the Universe rewrote time in the standard way, modifying history so things that once happened no longer did. Anything that came about as a result of the TARDIS explosion did not occur in the rebooted universe. So series 5 never happened. On the other hand, the crack seemed to have a much more minor effect on time. Things that were taken by the crack did not disappear from history, but seemed to disappear from the memories of history. Amy couldn't remember her parents, but she must have had parents or she wouldn't have been born. Luckily all our companions are time travellers now and therefore remember everything.

Without the crack the TARDIS crew would have left the Silurian base quicker, meaning Rory would not have been shot.

Was Rory always a Nestene or was he human then his conscience transferred to the Nestene duplicate (aka like the human cylons)?

The Pandorica rewrote every point in history based on the extrapolation from the atoms that had been sealed inside it when the Doctor was imprisoned. (He explains this when he introduces the concept of Big Bang 2.) This implies that only very minimal net changes to history occurred. Anything actually "changed" is not the direct result of the Pandorica having rewritten it that way, but rather the indirect result of history "filling in the gaps" where the restored history is now anomalous due to the absence of the cracks or the Doctor. For example, the Amy of June 25, 2010 was recreated by the Pandorica with the memory of having no parents because the Amy of June 25, 2010 had no parents. But the absence of the crack caused her parents to still exist; causing Amy, when she awoke on June 26, to be momentarily confused by the conflict between the parent-less state of her memories as written by the Pandorica and the "parentful" state of her memories necessitated by history.

This is kind of what's said above, but the events actually happened in Rory, Amy and the Doctor's timelines; just not in the perception of the normal world. In other words, the universe was 'rebooted' and Rory and Amy sent back to when they first left with the Doctor. The universe was parallel, including Amy's parents being back and Rory presumably not being Nestene, but the events that caused the universe to reboot in the first place still had to happen in order for that to be the case. Amy and Rory's true memories were repressed. But the Doctor made sure Amy had memory triggers enough for him to have had to exist. And Rory remembers the truth after seeing the Doctor ("How could we have forgotten the Doctor?"). It all happened, in their timelines, even if it may not technically happen in the new rewrite of the universe.

"Repressed" may not be the best word; it seems more like those memories were in something analogous to a state of quantum superposition, with two version of the memory both not-quite-existing (The version as created by the Pandorica, which included the Doctor, and the version necessitated by the Doctor-less history, without him). Amy's unusual nature allowed her to "choose" (in the same way she failed to do for Rory) for the Doctor-ful memories to become the "actual" ones.

There was sufficient information about him for the Pandorica to include him in the reboot.

• Since when has a Dalek cared for its own safety, like the Dalek in this episode?

Firstly, in The Daleks, when a frightened Dalek clearly says "Stay Away From Me!" When attacked by ordinary humans. More recently, in Dalek: "Have Pity!" "Why? You never did!" And countless other episodes since then when their eye-stalks were impaired, and so on. A Dalek will naturally have a sense of self-preservation if it wants to remain alive. In this case, by the voice it was the Supreme (an ego-inflated model) and its forcefield was down. So that it could no longer rely on that for a defence. Then, when its last defence - relying on the compassion of its enemy - was broken down, it like all bullies, was revealed to be a coward underneath its arrogance.

The Daleks in the Daleks were different in other ways to later Daleks. Other Daleks have only retreated because of logic not cowardice as they are meant to have no emotions other than hate, not ego. If the Dalek believes that River, being a companion of the Doctor, is disposed to show mercy, then begging for its life needs be nothing more than a strategy to achieve its desired goal.

However, baseless hatred is impossible. It has to be based on fear, or jealousy.

That's true only for beings who aren't sociopaths. The Daleks, by human standards, are sociopathic.

You are incorrect. Sociopaths and psychopaths are fully capable of feeling all emotions. What they lack is the concept of empathy, truly caring for others. If the Daleks did not fear for their own lives, why would they even have defences? Why would their biggest accomplishment be surviving the Doctor, if they didn't really want to survive? It's even mentioned in the show that the Daleks are afraid of the Doctor.

Daleks have never been shown to "not care for their own safety". Yes, Daleks have been willing to sacrifice themselves for their cause (the most extreme example probably being in Victory of the Daleks). But that is not really the same as "not caring".

• How does believing in someone make them exist if they were meant to be erased?

Because if you can remember something then it clearly existed or else you wouldn't be able to remember it.

Also, because it erased them from peoples' memories. So if you remember them they are no longer erased. That doesn't make much science fiction sense, but that's the explanation.

As I described further up (and despite how it's described) the crack doesn't seem to remove people from history it just seems to act as a perception filter, removing any record of people. So maybe all it takes is for one person to be certain you existed and you come back. Maybe Amy's better than normal at this (having lived next to the crack). Or maybe the Doctor's in so many people's memories that there's traces of him everywhere. Amy might have been the tipping point.

Additionally, remember that Moffat's big 'theme' here is fairytales or simply stories. Isn't the best way of 'keeping someone alive' to tell a story about them? Amy restoring the Doctor by telling the wedding guests about him as a character in a story is comparable to Martha (in TV: Last of the Time Lords) restoring the Doctor by getting people to have faith in him as a messiah-like saviour.

It's also possible (and more sciencey... well, for Doctor Who, anyway) that remembering somebody after they've been erased creates some sort of psychic connection that they can use to pull themselves back into the universe from the outside.

One way to look at it might be something akin to the observer effect in quantum mechanics. The Doctor, Rory, and Amy's Parents had all been erased. But the cause of this erasure also ceased to exist. And, thanks to the Pandorica restoring the prior state of the universe, many of the effects of their existences (various effects of the Doctor's intervention; the engagement ring; Amy herself, as her parents had been erased) still remain. This places those erased beings in a kind of ontological superposition, in a sense both having-existed and also not-having-existed. By remembering Rory, her parents, and the Doctor, Amy breaks the superposition, forcing their existence to be the "real" state of the universe. It's stated in the episode that Amy was unique in being able to do this because the crack in her bedroom wall changed her.

• How does a TARDIS exploding cause this? The TARDIS broke up in The Mind Robber and the Daleks were going to blow it up in Journey's End. Alright something could have been done differently here; but still, no explanation is given.

In neither of those instances (I believe) was the TARDIS in flight. Please correct me if I'm wrong, but in this one it was.

Like the Doctor, the TARDIS is a complicated anomaly in time: it exists at the beginning and the end of the universe, at the same time. The universe attempting to erase the TARDIS (that fought back using a time loop) may have been the cause behind this violent reaction. Then again, not even the Doctor knows what or why the TARDIS exploded, as stated in the final scene of The Big Bang.

Also the TARDIS blew up from the inside. I.e. allowing the spacial-temporal 'crack creating' powers to escape.

Yeah, not all explosions are created equal. A simple explosion could just destroy the TARDIS. But a chain reaction that fed off the Time Vortex could be an entirely different phenomenon.

That and it was being controlled by an external force, which could have magnified the force of the explosion.

The Doctor said that the explosion could be prevented by deactivating the engines. In the other two examples, exterior forces caused (or, in the case of Journey's End, almost caused) the destruction of an inactive TARDIS. Whereas in this one, the source was interior during flight. This proximity to the Heart of the TARDIS easily amplified the explosion.

Consider also that the Doctor's TARDIS is the only one in existence (excepting the possible survival of the Master who may possess a TARDIS. So this single TARDIS is channelling the entire power of the Time Vortex. The TARDIS is really at the centre of every created reality. So the destruction of the TARDIS would not, in itself, disrupt reality; but rather the vortex, channelled through the TARDIS. Kind of like a water pipe. If the pipe's valve is busted, the water will burst and flood. It may be that when Gallifrey was thriving, the vortex was balanced by many 'valves'.

And remember that the Master had to steal the Doctor's TARDIS in Series 3 so he can't have a TARDIS of his own. But remember in Time Crash (which is proven to be in canon), the Tenth Doctor exploded the TARDIS to save the universe and no cracks in time happened.

• How come the sonic screwdriver could open the Pandorica? I thought it had deadlocks.

The Pandorica is designed to stop beings getting into it, not out. It is basically like a door without a door knob on one side. The Doctor explains this early in the episode.

• Why would the Alliance turn to stone when erased from time?

The Doctor stated that this is because they were an "after image" - like the footprint of something that never existed.

They are "fossils", anomalous remnants resulting from the fact that the universe is collapsing. We may assume that, had the alliance been erased in a method other than by the destruction of the universe itself, the fossils would not have formed.

This is cracked. Why would they turn to stone?

As the universe is being destroyed, its not that unrealistic that the scientific laws that hold it together, are also going, so whose to say what would happen, if everything was destroyed.

• How come the Earth seems the same despite there being no stars? Without alien races this would have affected all history. This episode is over-elaborate and harder to understand then the Matrix films. Which person made it? They must be on drugs to keep trying to make everything bigger.

The Earth seemed pretty consistent with real-world Earth, and as far as I'm aware, we haven't had any contact with alien races. So how exactly should the Earth be different?

Uh huh, but we aren't talking about the real world here - in the Doctor Who universe. I believe the present day Earth got to its present day state through an awful lot of alien contact.

The course of events had changed as well, there were Egyptian penguins, Himalayan Pharaohs, and other things wrong with the timeline.

But still many alien races helped (by accident) to create the planet, life and humanity. The first life on an otherwise uninhabitable Earth billions of years ago was only created by the huge radiation given out by a Jagaroth ship exploding. The Fendahl manipulated the creation of humanity so that it could use it to take over etc. Also Earth wouldn't exist at all if not for the sun, as it was the gravitational pull of the sun that pulled the pieces together to form Earth.

The TARDIS, while burning up, is protecting the Earth, which is why it still exists. This could mean that it's holding the timeline of Earth together despite the inconsistencies. Although clearly it's doing a pretty shoddy job.

"Pretty shoddy job"? Okay, a few things:

1. The TARDIS' explosion was enough to keep the Earth and most of the humans on it existing for quite some time, considering.
2. Second, consider this: the Doctor has frequently mentioned the TARDIS is a living being. When it exploded, it was exploding at every moment from the beginning of time to the end. Even if Earth and thus everything left in the universe faded, it's possible the TARDIS would have just kept on exploding, unable to stop existing. I'm not sure if it's been confirmed if a TARDIS can feel pain, but if so...yeah. Feel bad yet?
3. It's possible that when the Doctor and Auton Rory arrived in the present-day of the "no stars" timeline, Amy was released from the Pandorica, and River being rescued from the TARDIS were all enough to shatter the "no star" Earth's fragile existence...literally.
4. Indeed, there were quite a lot of amusing and/or horrifying inconsistencies/changes on the Earth in the alternate universe, but those could be explained by the lack of stars/aliens. For example, if the "a meteor killed the dinosaurs" theory is true, no wonder there are dinosaurs in ice. As for penguins where there shouldn't be penguins, obviously the climate must be different.
5. Also, I believe at one point it is shown the moon is still there, so I suppose the TARDIS kept it existing, too. That's not too bad, eh?

And don't forget that the physical rocks that formed Earth collected around a Racnoss warship in The Runaway Bride.

For one, the earth is far from the same. But more importantly, the only sun we really need (from when the Doctor was locked in the Pandorica onwards) was the TARDIS.

Actually I think this was pretty decently explained:

1. First, I think the bit that most people struggle with is that they incorrectly try to apply Back to the Future time-travel rules to the behaviour of the cracks. Throughout the series, the cracks have been shown to remove people, but not perform massive rewrites to time. When people are removed, the major "rewrite" happens to memories. This is why artefacts of the people removed remain: (a) unknown faces in pictures, (b) wedding rings, (c and d) clerics removed but no substitutes appear, so there weren't enough to keep the Angels at bay but still the Angels didn't overwhelm the group in the "past", (e) peoples whose parents are removed still exist. (After young Amelia was eventually removed, even older Amy remained: because she was a distinct person and would have to be removed separately.)
2. The TARDIS explosion was a bit like an amplified crack. Stars were removed, and people's memories of them were removed. But they "left traces, little things we can't quite account for". (Yes the Doctor was talking about people, but still the same applies to the stars.) This is why the "star cults" existed. People didn't remember stars, but there was overwhelming evidence that they did exist. So much so that a 'non-believer' like Dawkins was a 'believer in stars'. Young Amelia however, was an exceptional person. She actually remembered the stars, which is why she painted them. All of this served to keep Earth's history on a generally similar path.
3. Finally, even if you really don't want to accept the above: many stories have placed emphasis on "fixed points in time". Some RTD era stories went so far as to make the point that you couldn't really change these even if you wanted to. They would find a way of pulling back in line. Any 1996 fixed-points (Amelia Pond almost certainly ranking up there) would find a way of happening; and would drag the rest of Earth's history along with it.

• How would married Rory remember Auton Rory's memories?

It is never explicitly stated how much Rory remembers, only that he remembers the Doctor.

Rory explicitly states "I was plastic". He absolutely remembers being an Auton.

Because he had been Auton Rory. The events of the episodes still happened in the personal timelines (or rather, the repressed memories) of Amy and Rory. So even though their lives were re-written, including Rory being non-Auton (and dying), they did still experience those events from before the 'rewrite'. As that's all it was: a change in the way the universe was, rather than a change in what actually happened.

Alternately, River stated that they would "Wake up where (they were) meant to be", so perhaps he's STILL an Auton but just suppressed the memory. Or even, he's normal-Rory but his memories are that of Auton-Rory, in that his MIND woke up where it was meant to be - his body.

In this episode, before the reboot, the Doctor says "The Nestenes took a memory print of her and got a bit more than they bargained for, like you. Not just your face, but your heart and your soul." Auton Rory wasn't just a dupicate with his memories, but was actually Rory with Rory's soul. So in this rebooted timeline, real Rory would remember being Auton Rory in the previous timeline, the same way Amy (and everyone else) would remember the previous timeline.

• Turn Left showed a dystopian alternate universe created because the Doctor never saved the world in Series 4. Shouldn't the world Amy wakes up in be similar, since the Doctor never existed?

Because the doctor's timeline was restored at the point she remembered him from her memories of the Doctor when she was a little girl. All the events that happened before meeting Amy in his timeline still happened as they had no reason to unravel if the Doctor existed again.

Due to the Universe being slowly destroyed, all the alien races that would have invaded Earth in the Doctor's absence never existed. And as all the stars are gone, with only the TARDIS explosion keeping the Earth warm, Earth is the only planet with life in the universe.

Yes but that only applies to the Earth where the TARDIS is a stand in for the Sun. Not the Earth which Amy wakes up to and gets married in.

Turn Left showed a universe which considered the possibility of: "What would happen if the Doctor died in Runaway Bride". In this story, the Doctor was removed by the cracks; and they've been shown to have a fundamentally behaviour. River says: "All memory of him will be purged". And that statement should probably be taken more literally than it's usually interpreted. Memory of him is removed, not the side-effects of his existence. And thus dystopia is avoided.

• Even if Rory was restored to existence, wouldn't he have still been killed by Restac?

He never traveled in the TARDIS as the Doctor never existed so he didn't go to 2020 to meet the Silurians. Plus it was the crack that distracted them long enough for Restac to shoot him.

• If the Cracks never existed, how did the Doctor stop the Weeping Angels?

The Weeping Angels never existed, as the only lifeforms in the universe were humans. The reason the Doctor goes back and sees himself running in the forest AWAY from the angels is because he remembers doing it - he is going back in his own timeline.

Um, okay, but what about after things are restored? Of course, for all we know, the Big Bang 2 restored the universe with some differences--maybe in the rebooted universe, Weeping Angels never existed? (Which is fine by me, considering how scary they are!)

If they still exist, the gravity of the Byzantium failed, and they all fell a considerable distance. They're stone, they would shatter.

More likely they definitely did exist but the entire crash of the Byzantium incident never occurred. Well I mean the Byzantium probably did crash but River and the Doctor never had an adventure surrounding it. River as a time traveller of course remembers it and puts it in her diary hence how she can reference it in Silence in the Library.

The reason the Angels went there in the first place was to feed on the energy of the crack, which they realised too late was going to 'eat' them instead. That's why they initially were swarming towards it, then ran away. With the cracks having never existed, the Angels are all still alive but never met the Doctor. This means the events of the two parter Weeping Angel story never happened, or rather happened then got rewritten. The reason the events are still remembered is that, according to the Doctor, time travellers see things in a different perspective so can remember times that have been rewritten.

I suppose one could consider that the cracks have the same effect on themselves as they did on people they removed. That is to say: when the cracks were removed, the side-effects of their former existence remained. However, the point is probably moot. Because since the reboot of the universe, one could say of the Angels: "They're baaaaacck!"

• If the Doctor never existed (after going into the cracks) surely the TARDIS couldn't be there at all? It was 'borrowed' by him from the Time Lords, so may have been destroyed previously in the Time War. I know that that never happened but surely he stepped in there before the Pandorica's light had restored everything from the TARDIS' explosion. By this logic surely the alliance could have just chucked the Doctor into a crack, as this would not only have stopped the TARDIS from being able to blow up, but also seal it as he is a complicated space-time event.

The whole reason of the Alliance was that they did not know the exact nature of the Cracks and assumed (mistakenly) that the Doctor was somehow responsible. Besides, how would they remember that throwing something into the Cracks would erase it from existence, since they wouldn't even remember throwing something into the Crack?

Firstly, after the Doctor went into the Crack, the TARDIS wasn't there. It only came back when Amy remembered it, since the logic of the universe (as stated somewhere above) states that if it is remembered instead of thought up, it must have existed. Secondly, the Pandorica's light was spread around history at every possible moment. So the process would have been instant. Thirdly, the Doctor's TARDIS would have been used by six other pilots and then decommissioned along with the other Type 40s (see The Deadly Assassin). Finally, you need to brush up on your logic, man.

The Alliance believed the Doctor caused the cracks. They thus may have thought that they would have caused a paradox which any time travelling race (e.g. the Daleks) knows is just as bad. Fathers Day is the best example of that.

• How was River Song at Amy's wedding? She presumably didn't time travel because the doctor still had her vortex manipulator.

River Song had been in June 26 2010 immediately prior to the destruction of the universe, so that was the state which was restored by the Pandorica when it recreated the universe.

But she had the vortex manipulator later on, didn't she? Please remember that time travel can go backwards as well as forwards, and River probably doesn't have as much concern for the integrity of the timeline as the Doctor.

I asked Steven Moffat on Twitter. Apparently she jumped through a stain glass window on to a space steam train and hijacked a camel. It sounds like something she would do.

• When Rory releases the Doctor from The Pandorica, the "light" clearly shines on a Dalek, and some other enemies in the alliance. Why didn't they come back to life - the Doctor and Rory were clearly there for long enough for something to awaken. Especially considering the time needed to fetch Amy's body.

The Dalek is resurrected after Amy is resurrected. Perhaps the restorative powers of the Pandorica were not active until triggered by young Amelia.

• Why didn't Auton Rory get erased as did the other Autons?

The Autons were erased because the Nestene consciousness and its home planet were erased. However, Auton Rory doesn't just owe his existence to the Nestene, but also to: Amy's memory of him, the Doctor's memory of him, and his own memories of being alive. So he would remain around unless those two were also erased.

• If the Daleks actually have living beings inside them and the light from the Pandorica just shone on the casing of the Dalek, how was the whole of the Dalek restored.

Guess their armors aren't completely restorative field ray proof.

• While the events of Series 5 actually happening for anyone other than the four principle time travellers involved is perhaps in doubt, is it safe to assume that everything else erased by the cracks was restored, since the Cracks themselves never existed and therefore could not have erased anything? I mean the sun was erased and restored, the Daleks and Cybermen, Sontarans, Clerics and Silurians were clearly restored as evidenced by episodes from Series 6. So it stands to reason that everything else, including events from episodes pre dating series 5 that were erased, were also restored. It cannot all hinge upon Amy's recollections of her travels with the Doctor since races such as the Sontarans were restored; but having never met them, Amy could not have any memory of them with which to restore their existence. This is, I admit, not so much a discontinuity but a need for clarification as there has been confusion.

Since there are no specific details on how the restoration works, what exactly is and isn't restored will certainly have some flexibility. I.e. producers will basically choose whatever suits them. ;) E.g. I'm sure it's convenient for the Cyber King attack in The Next Doctor to remain erased. As far as I can tell, the only restorations that hinged on Amy's memories were: her parents, the Doctor, and possibly a slight contributing factor to Rory's restoration.

• Why is the Doctor so willing to have himself erased in the new timeline? Surely he should think up some other solution? As by now he must realise that without him, every universe would be destroyed anyway. He has too much of an important place in the history of everything to not exist considering he saves the Earth everyday, the universe every month and the multi-verse every year, practically.

Yet this Doctor has also shown a bit more faith in humanity than the previous two (or, as compared to Tenth Doctor, more of an affectionate hope than a patronising infatuation). He probably honestly believed that humans could solve their own problems without him. Or, more likely, he hoped that someone would be able to remember him back into existence. Also recall that several of those invasions may have been directly or indirectly caused by the Doctor's presence on Earth - especially by the Master or other enemies who know that our planet has a soft spot in one of his hearts.

Still he is taking a big risk considering not all invasions are caused by him. E.g. Autons in Spearhead from Space, The Dalek Invasion of Earth, The Tenth Planet. If he wasn't around, the Daleks and Cybermen would still be causing chaos. Also remember Sutekh in Pyramids of Mars, when you saw what would happen if the 4th Doctor and Sarah Jane were not there. He is taking a big risk on just having someone remember him into existence. Also while he has become maybe more trusting in humanity surely he has not become so naive that he believes they will stand a chance against all of these monsters. Furthermore, he has caused so many important events in history, such as the fire of Rome; if he isn't there to cause that lord only knows what would happen. While the Doctor is always willing to die to save people being erased is different.

What do you mean "so willing to have himself erased"?! When he was rewinding in on his own timeline, he was doing his best to make sure Amy would remember him. By the final rewind, when he is in little Amelia's bedroom, while she is sleeping, he finally seems to give-up (a very well-done scene, BTW) in a sense. He even calls himself "silly old Doctor", self-deprecating himself for his hope that Amy would be able to save him. Still, he wasn't "willing". He probably thought about the dangers to the universe that would likely go unstopped by him. But, like mentioned above, he has more faith in humanity and in other living beings as a whole. Not to mention, the universe itself was almost completely gone! Even if the universe was filled with more evil without him, the Doctor still wanted to restore the existence of all the beings who had been "eaten" by the Cracks.

• How come River Song remembered the Doctor enough to give Amy her blue diary? If she remembered the Doctor, why did it also take Amy also to remember him back into existence?

It's entirely possible that, like a lot of the other events in the episode, River gave her the diary AFTER the Doctor's revival. I.e. the "Bill and Ted" solution - taking care of it at a point in her future. It is never established where River went with her vortex manipulator.

Same reason Amy was able to remember the Clerics in Flesh and Stone; they weren't part of her timeline.

River may have remembered fully, but it was Amy who had the gift to bring the Doctor back due having grown up with a crack in her bedroom. There's also the possibility that River didn't really remember, but had subconscious memories nagging her. So she followed her instincts.

• How come if there were two Stone Daleks only one came alive?

Because the light only shone on one of the Stone Daleks (from camera angels).

• If Amy's parents were erased by the Crack, how can she have existed.

Maybe she's a trace, like the ring, and Rory's face in a photograph.

Amy is an anomaly, or a complex space-time event.

No she's not, her parents were not erased from all history, they were simply taken from a moment after she was born, and she forgot them. Which means there is no paradox in her existing.

They were erased from being born per the crack's effect.

• Also if there were no stars, how is Amy even born. No stars would change history in so many ways. If there were nothing beyond the earth but darkness, then religion would dominate science. Indeed several religions where stars are significant would not exist and Amy would never ever be born. You can't say the TARDIS would hold this event in time, because nothing in the show says that. And its bad, "not thought out" writing if everyone else has to make up stuff that isn't there to make sense of the plot. Also why would it hold certain things like Amy being born but not others like what you see in the museum.

"Were all stars to disappear or die,

I should learn to look at an empty sky

And feel its total darkness sublime,

Though this might take me a little time." - W H Auden, The More Loving One

Life goes on, with or without the stars. Why would religion 'dominate science' without stars? Physics and biology and chemistry were still holding true on earth, just... No stars.

Time in the Doctor's universe is not linear or instant. Because Earth was at "the heart of the explosion" it's timeline remained intact to a degree. Also, the TARDIS may have acted like a Paradox Machine, holding the timeline together despite the inconsistencies.

I think you're forgetting that the TARDIS is exploding at every point in history. So the stars never existed, meaning that science would indeed be different. But religion (where did that idea of religious domination come from anyway?) would not be affected unless they were in some way dependant on the stars (for example, early Islamic nomads). Why would the deficit of stars affect Amy's birth anyway? Finally, yes we can say that the TARDIS holds that event; nothing in the program said otherwise. And it was fairly OK thought out writing, since based on what you've written, while they may have missed a few things, they didn't take into account mumbo-jumbo plot holes that aren't really plot holes anyway. I mean, what you have written doesn't even make any sense!

It does make sense. I am saying that without stars the history of the earth would be different. And why don't you think that no stars would change history in such a way that Amy wouldn't be born. Without stars or any planets lots of sciences would develop differently. And religion would dominate science as there were people who believed that there was nothing outside the earth. They would be proven right. Also there would be no space race, no science fiction even. Amy's parents would lead entirely different lives and most likely would not have met. Considering a person being born depends on two people having sex at the exact right time, it seems unlikely that in a world with such a huge change as no stars, that would happen again. Her ancestors probably wouldn't be born. Also smart arse, it is bad writing as there is nothing that says it's held it to be the same. That's you making it up. If you as a viewer have to make it up to explain away plot-holes like: why would earth exist with no aliens [Jagoroth], why would the same people be born in an entirely different world; (which are reasonable not mumbo jumbo), then that's bad writing. Also what you wrote doesn't make sense. As why would the TARDIS function like a paradox machine. The Master had to carefully construct the TARDIS to function as a paradox machine so why would it being blown to atoms do the same. By that logic when the doctor blew up the Daleks' spaceship it must have turned into a time destructor. And the timeline isn't meant to be exactly the same, as there are changes in the museum, remember. So, if no stars has meant to have changed the earth, why would it hold Amy being born but not those other changes. Again you can come up with theories but that's not what you see in the program. Also another reason religion would dominate science is that the stars going out was meant to have happened in ancient Rome, when people believed in the gods. Seeing all the stars going out they would probably think it was caused by the gods and it would be recorded. After that, religion would take a hold on humanity, as people would believe the stars were destroyed by the gods. And no one would be able to find the real reason. People would probably become more scared of the gods as if they thought the stars had been destroyed by them. Then they would be more likely to worship them. Also as some religions in Doctor Who were meant to have been caused by alien visitations, then these religions would never exist. So therefore more changes in the history of humanity. The slightest change in history is enough to cause someone not to exist; never mind religions that had a significant impact on the world, like ancient Egyptian religion and stars not existing, and as I said nothing in the programme says this has been held the same anyway.

OK, history wouldn't be that different: "I'm William the Conqueror, let's go invade England. Oh wait, no we can't go in a straight line in our boats, there's no stars!" No, I don't think so. In fact the only thing in that particular area of history that would be missing would be Hayley's Comet. Biology would be unaffected. Chemistry would be unaffected. Physics would be largely unaffected. The space race WOULD have happened because the Moon still existed. Hubble might not be up there, but that's going to make a massive change, isn't it? Religion doesn't even matter, because let's face it, the Jews spent 40 years wandering in a desert (see Exodus) and they probably would have got lost without stars to navigate by. Ergo, that religion goes, and as such so does Christianity. Islam suffers a similar fate. No sci-fi? Doesn't affect the plot. The Romans still invade. Then the Saxons, Vikings and Normans. Everything is pretty similar so far, isn't it? And yes, I am explaining away "plot holes" with (mainly) previously established things or common sense. As we had seen in Turn Left, humanity seemed fairly able to take care of itself (until 2007 anyway, but this is 1996). As we have found out in the real world. And when you say "the same people" we are talking about ONE person, ONE fixed point in space time. Nobody ever said she wasn't one of those points like the Bowie Base One event. I seem to remember the Doctor even implying that at some point. So that event would have been held, with or without an exploding TARDIS. And as it has been established, the stars NEVER ACTUALLY EXISTED. Therefore they won't be seen to go out. So religion would go out of the window. And finally, I need to point this out again, IT'S ONLY A STORY. Enjoy it, don't try (and fail) to ruin it for the rest of us.

The stars never "went out", as they never existed in the first place. In addition, the cracks hold the previous events in stasis, so that they still happened, you just can't remember a certain object. Also, you claim that the program is supposed to explain every single thing to us, not leave it up to us to figure out? That's total bull. Do they have to explain why people think the way they do? No, because we can figure out some stuff for ourselves. They put in problems and a solution, and if the solution doesn't fix all the problems, then maybe a side-effect of the solution did. If you're going to claim that we can only take for granted that what we saw, happened, then let's recount what happened with Rory: He must have just stopped existing for 2000 years, cause we never saw him, right? And Rory and Amy must not have gotten married at the end, either, because we didn't actually see the "I Do" scene. Well, we make assumptions. Just because we didn't view them doesn't mean they don't exist.

Those two previous explanations there deserves a round of applause.

Okay I am sorry I shouldn't have been so aggressive and rude. But still though I am not saying that everything has to be explained to us like obviously we don't have to see them getting married. But I think we do need explanations for certain things. Also the stars were meant to have existed as well. Amy was meant to believe in them meaning people had seen them at one point and seen them vanish. Plus my point is more that history on earth would have gone differently rather than just religion would dominate science. If several major religions like Christianity vanished, then our history would be different in many ways. Even if Amy is a fixed point then she could still go: The Doctor changed the events on Bowie Base one, plus every fixed point has been destroyed by the cracks. Plus does the moon exist if the sun is gone? Shouldn't the moon go too. Also this is a discontinuity section so we're supposed to point out plot-holes. You're not a real geek if you don't know that.

And we also explain them away. That's why we're geeks. Anyway, while Bowie Base One was changed, the course of events following it stayed the same. That's what I meant by fixed points - no matter what happens, she has to be in the right place at the right time to do the right thing. Even though the events on BB1 changed and two people survived (three if you count Adelaide committing suicide later), Adelaide still inspired her granddaughter. That's what I mean. So whatever happens previously, Amy Pond still happens.

The star cults remembered the stars so the science could be treated as religion in this world.

I still think the writers are going crazy with no stars. Why would the Time explosion only affect stars? By Star does it count the Morning Star? Isiah 14:12. Revelations idea perhaps at 6:13.

Um, it isn't the TARDIS explosion entirely that caused the stars to supernova. The Doctor mentioned a "total event collapse" in The Pandorica Opens. I don't think it's an actual science thing, but hey, it's the Doctor = techno-babble. Since "total event collapse" is mentioned specifically as the cause of the stars not existing, it's possible it's an event that can be caused by other means, not just a TARDIS exploding. The "time explosion" had multiple effects--the Cracks, doubling as a Sun for the Earth while also keeping the Earth existing for a while, and of course the "event collapse".

Amy Pond hadn't been born her parents had been erased. She was an anomaly so the change in history would have no effect on her, because her parents hadn't existed in the normal timeline anyway.

The thing to keep in mind here is that the eye of the storm was Amy's wedding in Leadworth in 2010 (or maybe a line leading from Stonehenge in 102 to Leadworth in 2011), not the start of time. So that's what you start with. All of history that still exists extends out in every direction from there, including back in time. So, things like Christianity, the science required to create smartphones, the formation of the English nation, etc., that are an integral part of Amy's existence, are still there in the past; as unchanged as possible given the non-existence of the stars. Other things that less directly impact on anything that's still surviving may have changed, or may just have only a fuzzy, shadowy hint of existence, or may not even exist at all. Space-time has become very small, and it's probably not symmetrical. Maybe it stretches out to include the 1066 Norman invasion, so you could still visit that in a time machine, but if you tried to go 20 miles away from there in 1066, or to China in the 1960s, or to Mars in the present day, you'd probably find no such location to land at.

• Why does Amy not seem concerned about enjoying her "new" parents. It just seems like she would want to take time to connect rather than running off in the TARDIS. Does she now have a "new" childhood with them or has their relationship just begun in Amy's mind? Her mom remembers the imaginary Doctor but does Amy now have ret-conned memories as well?

She and Rory seem to have all the memories they can possibly have. Amy of things before the Big Bang 2 brought back her parents and her adventures in time and space as well as her life with parents. (Note that the Series 5 premiere, The Eleventh Hour, did have Amy specifically mention her mother, something about apples, so they must have been "eaten" by the Cracks sometime after that). Rory remembers being Auton Rory and the adventures with the Doctor as well as the normal life without the Doctor.

• After the Doctor steps into the crack, Amy wakes up on her wedding day and there are the dolls of her and the Doctor that she made when she was little. She clearly remembered the Doctor when she was little for her to have made those dolls. So why didn't he come back then? Why did he only come back on her wedding day when she would have spoken about the Doctor to her psychiatrists that her mum sent her to?

Subconsciously, little Amelia remembered the Doctor, even if he never existed and they never truly met. Her memory of him was so clear that she was convinced he was real, which we know he is, so she ended up "needing psychiatric help", thus the psychiatrists. Here's the fun part: without the Doctor around, The Eleventh Hour never happened. Amy didn't have that adventure in 2008. The Doctor didn't arrive on the night before her wedding-day. Finally, during that wedding, seeing all those things that reminded her of the Doctor overwhelmed her and caused her to truly remember him.

• Doctor Song's timeline doesn't fully make sense with the stories we've seen. At the beginning of this story she is clearly in Stormcage. At the end she is clearly free. However in the early episodes as per the Doctors timeline (which is the only decent reference we have at the moment), she is back in Stormcage, but seems to suggest that she has already done the Pandorica. I can see two explanations:
• # For Doctor Song, there is something that happens off screen (at the moment) and she is recaptured and placed in Stormcage. The end of this episode to me suggests that the death she causes is to do with the Doctor (if not the Doctor himself). She said they will all return to the rightful places when the universe restarts. In the universe without the Doctor this is with her being free. Other evidence suggests missing (or future?) episodes, as she was better flying the TARDIS early in the Doctors timeline (no wushing sound).
• # For Doctor Song the Big Bang occurs after Flesh and Stone. Somehow in her past/Doctor's and Amy's future one of them dropped a spoiler which Doctor Song then used. Maybe this is part of a jail break by Doctor Song, to confuse the Doctor as to the order of their meeting and avoid him returning her to prison.

I would want to say 1 seems more likely, and that future episodes will have a Doctor Song between the two events, perhaps showing the Bishops catching her. However I wouldn't put it past Doctor Song to use time travel to confuse people as to when she really is from.

River has a clear chance to escape at the end of Time of the Angels and doesn't even attempt it. It may be that she is serious about atoning for her past crime, and simply returns to Stormcage of her own volition.

River is constantly breaking in and out of jail. That was just one of her "out" times.

When Amy 'dropped the spoiler' about the Byzantium, River may have figured out she needs to make a plan to get there. Using the vortex manipulator she obtained at the end of the story, she could have done whatever she needed to do to close that loop.

• Why were the Silurians wiped out of existence? They are from planet Earth which clearly survived the TARDIS exploding, even if it was for a short time.

The Doctor said "time is shrinking" to the point where the explosion happened in 102 AD. The Silurians were on Earth when humans were apes and before Earth had a moon, i.e. millions of years ago. This means that they would have been wiped as the past shrunk.

• A lot of this can be explained by the fact that the cracks erased time slowly. Step by step. But then, for a brief moment in this episode, the Doctor never existed. In other words, he didn't defeat the Cybermen in The Next Doctor and he didn't stop the Cybermen from taking over the world in Doomsday. And there a lot of other situations like this, for example: the fact that the Daleks weren't defeated in Journey's End. But in this situation, the absence of the Doctor could also have caused the Time War to have another ending (like the Daleks being __completely__ destroyed). But in the Cybermen-situation, how is it possible that in the world where the Doctor doesn't exist, Amy can have a regular wedding without a Cyberman standing in the room, or some other creature ruling the world?

1. I don't know that much about the classic Cybermen, as I have never really watched any classic Who. But in regards to the Cyberdyne Cybermen: if the Doctor never existed then he never went to Pete's world, and the Cybermen in that world never learnt about parallel universes, and therefore never bothered coming to the main Dr Who universe.
2. The universe never happened so every single thing went. So no time war, no Daleks, and the Parallel Cybermen couldn't come to our universe because it was never there in the 1st place. And the Time War never happened because all the Daleks never existed and the Time Lords never existed either.

See earlier response to question about a dystopian world similar to Turn Left.

• How could the Earth exist if it was created by the Racnos who acted as "the big rock" (The Runaway Bride). They never existed due to the explosion of the TARDIS and therefore the Earth should never have existed either.

See the various reasons above as to why Earth history wasn't totally different without the various alien interventions. Most likely, Earth was protected as the "eye of the storm". Or the TARDIS acted as a makeshift paradox machine, holding history together (albeit poorly), despite the inconsistencies.

Plus everyone and everything was a temporal anomaly, like young Amelia was erased but older Amy was still there. Same for the Earth.

• How is it possible to recreate the universe from the few atoms in the Pandorica?

1) The only atoms trapped in there would be air born ones (nitrogen, oxygen, carbon dioxide etc.) What happens to things made of all the other ones?

2) The scale is too large, the Doctors comment about re-cloning a being from a single cell doesn't even come close. Not even repopulating every planet in the galaxy does. There is no way that could work.

3) What about energy? That would go with the universe too.

In short, it's impossible that every sort of atom, and every arrangement of atom, could be found in the Pandorica. And that it could spread those few atoms wide enough, to use to copy across the entire universe.

1) How is a lead atom any better for recreating other lead atoms than a nitrogen atom. In fact, a nitrogen atom (or anything above hydrogen) encodes within it all of the quantum mechanical principles needed to generate all of the other elements. Not to mention that there are microscopic amounts of lead in the air anyway.

2) This one is a valid point; the Doctor's explanation smacks more of homeopathy than of any real science. But remember that he's explaining things for barely-scientifically-literate 21st century humans, not for Time Lord scientists, and 11 has been shown to be somewhat rubbish at such explanations. But there are many ways to answer this.

The simplest answer is this: The TARDIS explosion is in the causal future (as well as the causal past) of every event in history. If space-time is continuous (rather than discrete) and deterministic (rather than random), there are infinitesimal echoes of every event at the moment of the explosion. While it's impossible to _measure_ those echoes (damn that Heisenberg), it's not impossible for them to have effects. (This is exactly how quantum teleportation works.) The tiniest finite piece of continuous space-time holds an infinite (even uncountably infinite!) amount of information.

Many physicists believe that space-time is not continuous (in fact, Kaku argues that it must be discrete precisely because of this infinite-information property), which blows that explanation away. But (outside of loop quantum gravity and related hypotheses), the most common way of eliminating the continuum is T-duality (which falls naturally out of string/M theory). A universe at half the Planck length is identical to a universe at double the Planck length. So, while the information about a universe that's 10^75 Planck lengths across won't fit inside a single atom, it _will_ fit inside a speck of space-time that's 10^-75 Planck lengths across.

Many physicists also believe that random is actually present at all scales, which also blows away the first explanation. However, unless quantum mechanics is non-linear and chaotic (and most believe it isn't), that actually makes things easier. You don't need to _exactly_ recreate the universe, because any universe which is close enough for any observer is just as much "the same" as the old universe, as the old universe was the same as itself.

If I remember right, the holographic principle was obliquely mentioned at some point in the episode. There's enough information encoded on any surface to represent everything within the enclosed volume. Given a 10-dimensional hyper-surface and only 3 out of 9 dimensions worth of volume that actually matters, the problem gets a whole lot simpler.

Then there's Feynman's reflected-electron theory. A positron is identical to an electron travelling back in time. If space-time is (symmetrically) closed (and, thanks to the TARDIS explosion, it now is, even if it wasn't), all electrons and positrons in the universe are actually just a single electron that travels forward to the Big Crunch, turns around and travels as a positron back to the Big Bang, and so on, back and forth (sometimes bouncing off a photon only part of the way through), until it criss-crosses space-time a huge number of times. And the same goes for every other particle and its anti-particle; there's just one up quark and anti-up, one down quark and anti-down, and so on. In fact, once you toss various symmetries into the equation (e.g., a down quark can change into an up by emitting an electron and an anti-neutrino, so you don't need down quarks), you end up with at worst a couple dozen distinct particles in the universe, and possibly as few as 1.

3) It's possible that the universe actually has a total energy of 0 (adding together negative gravitational energy and positive mass energy), so the conservation principle isn't violated. More generally, "Big Bang 2" violates conservation of energy no more and no less than the universe itself does.

• The Dalek states, that as River is one of the Doctors friends she will show mercy. It's no wonder the Daleks always lose, if they believe that. I mean what gave them that idea? Not even the Doctor has ever shown mercy to them: he's cut of their power supply, blown up their city, turned their Doomsday weapon against them, frozen their army in ice, destroyed their embryos, blew up their planet, and destroyed their army six times.

Saying something and believing it are completely different. The Dalek could have been stalling for time, trying to trick her into 'not wanting to be a disappointment to the Doctor'.

• The River Song in The Time of Angels/Flesh and Stone had already experienced the events of The Pandorica Opens/The Big Bang. If she had, she must have come from after the universe was rebooted, which would be after the events of Series 5 itself had been unwritten from time. Yet here she is, in the pre-Pandorica timeline. How is this possible?

Only if all of series 5 was erased, and there's no reason to believe it was. The cracks and reboot didn't erase all of history. Otherwise, there wouldn't be much point to the reboot. They just erased a few things. The only ones we know about (based on Moffat's comments) are the public alien invasions of the 21st century (and the Cyberking in the 19th, and possibly the Zygons in the 20th). If the Doctor had asked River about, say, the events of Journey's End, it might have been just as gone for her as it was for Amy. Even if River was a time traveller "before" those events happened and therefore normally shouldn't have lost them. (Then again, "before" is a complicated thing to figure out here.)

• The Doctor says that being taken by the crack in time undoes everything in your history. When the doctor gets absorbed by the crack, shouldn't everything he has done get unwritten? So shouldn't the Daleks have been wiped out? Or if the Daleks were still all dead because of the Time War, the humans would still all be dead.

It is seen throughout the whole series that while the cracks 'undo the existence' of whatever they come into contact with, their lives and actions are all still present. The memory of them vanishes, but the universe seems to 'make up' for it. This entire "if this got erased from existence then that wouldn't happen" point is moot, as it is only their existence that is erased, not the effects of their previous existence.

He must've meant that not literally, more like what you've done stays the same, but absolutely noone remembers it was you who did it, so it's like you haven't done anything at all. Nothing gets unwritten, simply forgotten, and the other people's memories change.

• Okay, so Amy is capable of remembering things that had been erased, at least on a subconscious level, due to her long-term childhood exposure to a crack. I get that. But how can Amelia in the collapsed universe consciously remember stars? They were erased from existence just like, I don't know, the Daleks from The Stolen Earth, and "our" Amy couldn't remember them. In fact, that was a major red flag for the Doctor. So what's different about the collapsed-reality Amelia that enables her to remember the then-erased stars? Why is her memory not susceptible to erasure like "our" Amy's is, despite the two of them having essentially the same upbringing and childhood environment?

People naturally try to suppress bad memories anyway. So this could easily have been an additional factor: stars, her parents, the Doctor were all good memories. The Daleks were a bad memory.

• Another question about Amy's memory; if she can bring the Doctor and Rory and her parents back into existence simply by remembering them, then why didn't the clerics come back into existence in "Flesh And Stone" when Amy remembered them?

Possibly the level of connection wasn't strong enough. The clerics were just random people on a mission. Rory is the man she's going to marry. Her parents are, well, her parents. And The Doctor is the imaginary friend she's been obsessing about even in the rebooted timeline, ever since she was a child. Her mum even mentions taking her to a psychiatrist about the Doctor.

When remembering the clerics, she wasn't deliberately trying to remember them back into existence. However, by this stage the Doctor had told enough that she believed she would be able to bring him back.

• If the reboot meant the Doctor never existed, then how can anything that owes its existence to the Doctor exist? (Edited: please don't put spoilers to later episodes as discontinuities here.)

That's generally how the cracks operate. They remove something from existence, but they don't undo the effects of that thing's existence. That's why Rory's engagement ring was still there, why the Byzantium was still crashed, why Amy still existed and why River was still who she was.

• If the Doctor was erased from this universe (before Amy remembered him) wouldn't the world just end? I mean look at all the times he saved earth. If he never existed, he never would have saved the Earth all those times so how can earth have not been destroyed already? And also, if he never had existed he never would have stopped the Time War which would destroy the whole universe so how can the universe even exist?

It was explained that the universe reseals itself around the cracks.

• If all stars where to supernova, and the Sun does so as well, then the Earth and its Moon (as well as most of the Solar System would be vaporised. So after all stars go supernova, how would the Earth continue to exist without having been vaporised by the initial supernova? (This is one plot hole that has always bugged me.)

• How does the Doctor get the vortex manipulator in the first place? He seems to pick it up off the ground near the Pandorica, but we don't see River leaving it there. Did she double back to do it? And how did he know to look there for it?

• In Fathers Day, Rose saved Pete causing the Reapers to appear because, as The Doctor puts it, “there’s someone in the world who wasn’t before, the entire world is different because they’re alive”. In The Waters of Mars The Doctor saves Captain Adelaide Brooke, Yuri Karenski and Mia Bennett. Brooke kills herself at the end of that episode but Yuri and Mia both go on living their lives with no Reaper presence. Also in Father’s Day Rose holds herself as a baby, this causes the Reaper to appear inside the church, but other instances of the same thing such as The Big Bang Amy touches her younger self, or A Christmas Carol Kazran Sardick touches his younger self and in both instances, nothing.

Regarding Adelaide Brooke - I think the fixed point in time was the base's destruction (still happened) and _her_ own death, and other than that - things we're allowed to change a bit. So she still dies, and the base still goes boom.