Theory:Doctor Who television discontinuity and plot holes/Amy's Choice


 * Copying from the Story Notes, TARDIS' "Build date: 1963." This implies that a) TARDISes are built (not grown for a very-very long time, like mentioned earlier) b) when the First Doctor stole it, it was just finished being "built", without leaving any sort of leeway for travelling with Susan beforehand and c) Gallifrey has the same year measuring system as the Earth does.


 * a) The heart of the TARDIS must be grown, then the mechanics are built around it.


 * b) It is perfectly believable that they stole it then returned to the same year. It is a time machine after all.


 * c) This is not a plot hole.


 * Not a plot hole, but still. We measure our years at the rate our planet goes around the Sun. Why would another planet oh so far away from us that is oh so much more advanced than we are, with a binary star system, use the same year measuring system as we do?


 * The TARDIS has a universal translator. Perhaps it does or can translate dates into comprehensible language; we wouldn't understand the calendar of an alien race so it translates it into the Gregorian calendar.


 * The Doctor has stated that there is not much difference between a Time Lord and a Human. He say's they're just a matter of "accidental" spatial geography. It's possible that certain mentality aspects appear in both the Time Lords and Humans, such as counting from 1 in integers.


 * Maybe the TARDIS just ended up with the date '1963' when it got locked into looking like a police box, as a form of disguise, and the writers picked the date as the date when Dr. Who first aired.


 * Who's to say that "1963" meant "1963 AD, Earth"? It could have meant "1963 in the third age of the Rassilon era", or something like that. There's no indication that it refers to the Gregorian calendar at all.


 * Perhaps this is not intended to be canon, and was just put there as an in-show easter egg.


 * In addition to all of the above very good points, this is reading far too much into something that could simply be a quirky thing the Doctor decided to put in there, and really was just glimpsed for an instant in what was a dream.


 * Forget the 1963 part for a while, what's more confusing is the part about the Shadow Proclamation. In The Stolen Earth they thought the Time Lords were nothing more than a myth, so how could they be in charge of authorising the use of a TARDIS?


 * At the time of The Stolen Earth, Time Lords were now a myth, since they'd all supposedly been lost in the war. Not everyone would know that the Doctor survived. They would not have been a myth at the time the TARDIS was built.


 * In addition to the above, this question is reading far too much into something that could simply be a quirky thing the Doctor decided to put in there, and really was just glimpsed for an instant in what was a dream.


 * This was a dream, granted, but seriously, a star that radiates cold? Since the Dream Lord is the Doctor, surely he would not dream of such a blatant violation against the laws of physics?


 * The Doctor said that he doesn't know everything, the universe is big, plus that the laws of physics in the parallel universes are different, so the Doctor could be in a parallel one?


 * It is quite likely that since the Dream Lord seems to be the opposite of the Doctor, he used his imagination and inverted it.


 * It is also implied that the Dream Lord designed the dream worlds to confuse his "victims", hence the impossible ice sun.


 * The Doctor may have realised by now that nothing is "impossible". He has said so many things are impossible, yet they still happen.


 * Also, a "Hot Ice" Planet has been discovered by scientists in the real world, making a star that burns cold more plausible: http://news.nationalgeographic.com/news/2007/05/070517-hot-planet.html


 * How could something burn cold and undergo fusion when its too cold to do anything. And it breaks the laws of thermodynamics.


 * This is wrong in all three respects.


 * You don't necessarily need heat for fusion to occur. At a high-enough density, fusion reactions will occur near absolute zero.


 * With fusion of large nuclei, each reaction will actually make the system colder instead of hotter. While this means you couldn't keep it up forever, the same is true for _any_ star, so there's nothing special in this case.


 * None of this violates the laws of thermodynamics in any way. The star would absorb heat from its environment instead of emitting it. (Yes, you can absorb heat from the stellar environment. For example, if you're below 2.725K, the CMBR would be a source of heat.)


 * While there's no violation of nuclear physics or thermodynamics, this would have to involve some astrophysics that we've never seen. (Then again, how could we see it? We can't even see the coolest regular stars.) Any star dense enough to meet the Lawson criterion for iron burning through gravity alone would already have collapsed into a neutron star or a black hole, unless there were some mechanism to prevent that. And, while weak S-capture would work fine, you'd need a source of neutrons from elsewhere.


 * During a supernova, you briefly get both of these--the core collapses toward a neutron star, and then it explodes and the shell is bombarded with neutrons. But setting up either one stably would require something abnormal.


 * If white holes exist, a star that captured a white hole could probably pull this off pretty easily.


 * Forget for a moment the sheer impossibility of the existence of a "cold star" Even if such a thing could exist, it would have absolutely no effect on the TARDIS, as the ambient temperature of space is only a few degrees above absolute zero. Even if a star could exist at freezing cold temperatures, it would not affect the temperature of space, as it is physically impossible to drop below absolute zero, and as the temperature of space remains unaffected, and so too would the TARDIS.
 * Read the above responses. It's a big universe, and we know comparatively very little about it. That being said, the Doctor ultimately does say that the cold star couldn't exist. Hence, why he concludes it's a dream.


 * A more blatant violation of physics that "people made of sleep and cities made of song"? As has been said, it's a big universe.


 * Another (yet equally unlikely) solution is bio-luminescence (Think fireflies or angler fish.) A bodily light source that produces zero heat. Remember that living star from episode 42? Say we mixed the two stars together. Now we have a living star that glows via bio-luminescence and is therefore a cold star.


 * Why is everyone saying it is the day before the birth of Amy's first child? Is there any on screen evidence other than the pains she has to suggest that?


 * While there is no on-screen evidence, it is heavily implied. Amy believes several times she is giving birth and the Doctor says to her that she could be giving birth right now.


 * The official synopsis for the episode on the BBC website states it takes place on the eve of the birth of her first child.


 * Surely the Doctor and Amy, don't have to take the fifty-fifty, risk they are going to die? After Rory 'died', all they have to do is wait to fall asleep again, and see if Rory is in the TARDIS. That would surely tell them the truth, as the Dream Lord said: if they died in a dream, they would wake up in reality. Why do they need to take the risk of death?


 * The Dream Lord said that they only had a few seconds left when they woke up after "dying". So even if they did fall asleep to see if Rory was there, they would have died in the TARDIS. (Even if it was a dream too.)


 * Amy is willing to take the risk because she refuses to believe that the world with Rory dead is the real one. And because as far as she's concerned being alive in that world would be no better than being dead. And the Doctor just can't bring himself to argue her out of that decision. (It's also possible that the Doctor suspects there's more to Amy's intuition than just grief, and is willing to trust that since they've got nothing else to go on. But that's not stated anywhere.)


 * Even if they woke up in the TARDIS to find Rory, could they be certain it wasn't another illusion created by the Dream Lord?


 * If Upper Leadworth was the reality, and TARDIS the dream, it would be perfectly possible that they could still dream of Rory being in the TARDIS, but it wouldn't be the real Rory, just their dream version of him. So even if they woke up in the TARDIS and Rory was still there, they'd have no way of being sure Rory didn't actually die.