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 build (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.


 * Also this was a dream, so we shouldn't trust anythig we see.


 * 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.


 * 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 effect 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


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


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