Headscratchers / Doctor Who S36 E6 "Extremis"

• So, it's revealed that Nardole is with the Doctor because he promised River Song he'd look after him. So far, so good. When he catches up with the Doctor on the executioners' planet, it's implied that the Doctor didn't actually take Nardole with him when he left Darillium, and that River sent him after the Doctor. Here's where the problem fits in: when Nardole catches up with the Doctor on the executioners' planet, he has River's diary. In "Forest of the Dead", what should have been the last chronological appearance of the diary before this episode, the Doctor is seen leaving it in the Library. Now, while River mentions at the end of "The Husbands of River Song" that there are legends stating that Darillium will be her and the Doctor's last night, and that her next meeting with the Doctor will be the day she dies, there's no way that the Doctor would actually explicitly confirm this and tell her where she dies. River, therefore, wouldn't have been able to tell Nardole where to go to retrieve her diary. So how does he have it, since given his promise to River he seems to have gone directly in search of the Doctor?
  • Twelve is prone to being a little absent minded. He may have let something slip or River may have calculated a Batman Gambit to exploit Stable Time Loop based on what she knows of her sweetie, sending her manservant to "kindly" retrieve her diary and read the orders she left on the last page after Ten left. It's not like The Doctor would go back to the Library to check. And given that Nardole is a living head on a cyborg body, he wouldn't have made an appealing meal to anything that might have been left.
  • Word of God is that River told Nardole to go pick up her diary at the Library before going after the Doctor. Presumably she didn't know exactly what would happen, but she knew she was going to the Library and that Darilium was rumored to be their last meeting before she died, so she told Nardole, "If I don't come back, find my diary and...."
  • Virtual River in the Library may have sent Nardole a message about where it was. With Cal no longer delusional and her friend, she could easily e-mail someone in the real world, just as the virtual Doctor does at the end of this episode.

• Why would the creators of the Extremis simulation build it so that email can be sent outside? Presumably they would want to make it into an entirely closed system with no connections to any networks, so the simulated Doctor's email should never have reached the real Doctor.
  • The doctor did mention that they did too good of a job, and that the sunglasses were psychically linked to him. I don't think a regular email could have gone out but a message to himself based on brainwaves more then wi-fi might be able to without any problems.
  • But the simulated Doctor's brainwaves are still part of the computer simulation, so they'd be just 0s and 1s, and wouldn't correspond with the brainwaves of the real Doctor, a biological being.
  • I assume the properties of the simulated sonic sunglasses allows them to hijack a portion of the code and 'break free' of the closed system. Sort of like a virus turning your computer into a zombie to send spam e-mails. So essentially, the Monks were 'too good' in that they created part of the software that could hijack itself.
  • The simulation is more like a holodeck than a traditional computer, as demonstrated by people from the simulation visiting the white room with the hologram projectors. So just picture a holodeck character using a simulated commbadge to contact someone outside the holodeck.
  • The following episode shows that it's not like a holodeck, as we see the computer room where the simulation is run.
  • The simulation won't do the Monks any good if they can't observe it, so it can't have been built as an entirely closed system. What the virtual-Doctor probably did was hijack whatever output mechanism the real-world Monks used to monitor developments within the simulated universe, then used the Monks' own covert links into the email network to send the message on from there.

• The Extremis simulation is supposed to precisely simulate the entire history of the Earth. However, as we know, throughout the millennia Earth has been visited by many aliens, the Doctor included. But to perfectly simulate the aliens too, you would need to know who they have met during the course of their lives, what other planets they have been on, et cetera et cetera... So ultimately Extremis would have to simulate the entire universe. What computer has so much processing power? And if the creators of Extremis are somehow so advanced they can create such a miraculously complex simulation, why would they even need to conquer a backwater planet like Earth?
  • Judging by their behaviour and the synopsis' for the next two episodes, I'd say it's fair to assume the Prophets of Truth want something more than simple conquest. Their name implies some degree of fanaticism, so their motives may prove to be very different from what we're expecting.
  • Perhaps they only simulated recent history, rather than all of Earth's history? The Doctor theorized that it was all of it, but did the Prophets claim to have done so?
  • How can simulate just recent history without knowing what's happened before? You can't just start from a point zero, because people have memories of earlier events, so they'd have to know what those events were; their behaviour is shaped by how their parents raised them, so the simulation would have to know what their parent's were like, and their parents' parents, etc. So they'd still need to know all of history. And many of the alien visits happened in recent history, so they'd still have to know what motivated those aliens, which planets they had visited before, etc. So there really isn't a way to create a perfect replica of Earth without including all of its history, and the entire universe.
  • Presumably, they'd have to start by taking a complete scan of the entire world at some point in time. This would include everyone's memories and personalities as they stood at that point in time (which would be the product of the above factors you mentioned such as their parents' parents). The aliens wouldn't need to know all of history, just the world that existed at that point in time. It is possible to stop an actual simulation and resume it later because it isn't necessarily dependent on its full history, just the state (all information about the current structure) of the simulation at that point in time to continue from. Similarly, they just need to know the full state of the world. If the simulation were perfect, it could then play out the same way as the real world until something external impacted the real world. So it would be possible for them to do that, but then anywhere the aliens wanted the simulation different from human history (which would presumably have to include the whole history of Extremis since that wouldn't have existed in a copy of the real world) they'd have to effectively add this in and alter everyone's memories to suit.
  • Possibly their simulation's "starting point" would be shortly after the Silence were ousted from power, as computers can't retain full information about those guys for long. Modeling the Earth when Silents were still in charge wouldn't be accurate enough.

• How does the random number generation the aliens use work? People don't seem to be following a long complex sequence of random numbers like a normal computer (which wouldn't be synchronised like this). Are they just generating pseudo-random numbers based on the time? Or is there supposed to be one global “random number generating function” which everyone calls on at once whenever they want to think of a random number (and which again returns the same value at a point in time)?
  • For that matter, how does the Veritas' list of numbers work? Presumably the numbers in the Veritas are fixed at whatever numbers the writers put down, and yet somehow everyone who reads it and tries the test ends up coming up with the same list. That doesn't fit with the idea of the number changing over time.
    • If you think about the book as being immutable, yeah, it doesn't make sense. But since the world is a simulation, maybe the text exploits it somehow, making the numbers appear dynamically as they're read? It's a complicated solution, and very hard to believe in (specially since the Doctor listened to a copy of the book passing through text-to-speech software, rather than the original), but the only alternative is that the writers simply messed up..
  • Presumably the simulation has a really bad random number generator, which runs on a time-based seed for everyone at once. So, if two people "call" a random number at the same time, they get the same result. How the simulation even works with a crappy RNG like that is e headscratcher all on its own.
  • My guess is that it's seeded with time, and nothing else (Bill and Nardole are given the challenge at the same time, and if the remainind CERN people run the sequence in their heads as well, they received the same seed). Any RNG output is ultimately deterministic, no matter how good it is. For a good random number generator, you're not supposed to be able to compute the internal state from the output, but any RNG will produce the same sequence given the same seed. The question is why would they only seed it with time? All they had to do was seed it with some unique identifier (or the hash thereof) along with time, and they would be in the clear.
  • You're all missing the larger picture: the Monks wanted the sim-Doctor to catch on to their presence, because testing out what he'd do to oppose them is the whole point of running simulations in the first place. The non-random "random" numbers pre-programmed into every sim-person's "guess a number" subroutine, the existence of the Veritas itself, the Pope asking Twelve for help: all of them are ploys intended to rouse the Doctor's suspicions, so they can anticipate what the real Doctor will do when he similarly sets out to stop them.

• Why on Earth did the Doctor take the Vault to, well, Earth to watch over it? Whether Missy escapes, is freed, or the 1,000 years go by without her leaving, she would eventually be released on the planet she's tried to conquer countless times! Why not go back to Gallifrey, where he'll have backup? Or a lonely asteroid or planet where she can't make trouble? Surely he has enough books in the TARDIS library to sit a spell for a millennium.
  • This is the Doctor we're talking about. He has an extremely hard time sitting still at the best of times so if he's going to be (mostly) stuck in one place for 1000 years, of course he'll pick someplace he likes. Also, could you sit alone on an asteroid for a 1000 years, even with a huge "mansion" full of books and swimming pools and such? Probably not. You'd want to be around people.
    • Gallifrey is still an option, though. The Time Lords might appreciate that he's got one of their worst criminals in hand. Alternatively, why not find some other long-lived people to befriend to provide some TARDIS-mates besides Nardole? Or do what he'd said he was doing back in "Hell Bent" and find some way to track down Clara Oswald, who's got plenty of wiggle room?
    • Appreciate that he's currently at the moment stopping one of their worst criminals from causing trouble, yes. Appreciate that he hasn't executed said worst criminal, maybe not so much.
  • This isn't the first time The Doctor's had to stay in one place for centuries. The Eighth Doctor once spent 600 years on an aquatic world populated by jellyfish people. Eleven defended the town of Christmas for so long that he wound up dying of old age! The Doctor is capable of waiting out long periods of time on a single world if the need arises.
    • Waiting for long periods on one planet, yes. Waiting for long periods in one place alone? Been there, done that, hated it.

• Why does the Doctor spare Missy when he'll never have a better chance to rid the universe of her for good? As he told the head of the alien executioners, he's listed as a cause of death for countless enemies. What's one more, especially when he was ready to finish her off in "Death in Heaven"? When the universe will cheer what he's done, isn't the truly moral choice to slay her rather than try to be the Doctor with his high ideals and reluctance to kill enemies that can be reasoned with/capable of goodness?
  • Perhaps it is the moral choice, but many people would struggle killing someone they care about even if they might believe it's the right thing to do. Plus the Doctor IS the Doctor, with his high ideals and all. Whether they're right in this case or not, whether he may have been prepared to kill her previously or not, being unwilling to go through with it in the end is consistent with the character who has been merciful more often than not. Besides, the Master/Missy for all his/her evil traits has still been the longest lasting association with anyone he has had in his life. On some level, the Doctor would prefer to believe that he has a right to save Missy rather than deciding that he has to kill her and by extension face the idea that when his current companion is gone, as inevitably they will be in a year or two or three (nothing really, to a man who had lived for hundreds) he'll be alone again and the one person who was always there won't be anymore.
  • There is a difference between killing someone in the heat of battle (which the Doctor does a fair bit) and executing someone (which the Doctor has rarely if ever done). The former is an act that cannot be avoided if the enemy refuses to back down, the latter is a choice made with other options on the table. This naturally depends on one's feelings about the death penalty but Doctor Who has been fairly consistently anti on that score (not surprising for a British show). While it does bring up the counter arguments this season's arc with Missy generally concludes that the more moral thing to do is to give someone the chance for redemption at the risk of them not taking it rather than killing them and removing that chance. After all Missy did in fact have a Heel–Face Turn by the end.
  • A lot of people disagree with the death penalty. Very few of them think that a better option is to spring a serial killer from Death Row and attempt to personally make sure they don't kill anyone else. The episode tries to present the Doctor's actions as "goodness" but they actually come across as the worse of two evils. By saving the Master from an execution that appears to be both legal and justified, the Doctor is effectively to blame for every death he/she will inevitably go on to cause. Including, as it turns out, committing genocide against the Time Lords.
  • Because he loves her, duh.
• If the Doctor didn't want to follow the sentence the executioners laid out and kill Missy, why does he still faithfully follow the part of the sentence that Missy should be locked up for 1,000 years, and he should personally guard the Vault for that whole time? The previous episodes made it seem like the promise the Doctor had made held some deep personal significance to him, but here we find out it was just a loophole he abused. Isn't his number one rule "The Doctor lies"?
  • Apparently the issue is with the oath he made. For some reason, he's unwilling to flat out break it, even if he still fidgets around it. The oath never mentioned carrying out the execution, only guarding the body in the vault, so that's all that he feels really compelled to do. Maybe if/when he eventually breaks the oath by freeing Missy, we'll see some consequences for the oathbreaking.
  • Someone has to guard the Vault to make sure one of the most dangerous criminals in the universe doesn't escape. He and the executioners know that there aren't other Time Lords roaming the universe who might take on the job, and 1,000 years is a long time for anyone. Since Missy is so dangerous, the Doctor knows that he has to accept responsibility for letting her live. Moreover, even if he had killed her, he would have had to guard the Vault as well in case she came back from the dead (again, who else would do it?).
  • There IS a deep personal significance and reason for him to keep the oath, alongside the possibility he'll be in deathly trouble if he breaks it — his friend is in there. She may be dangerous, but she's also bored, lonely, etc. The Twelfth Doctor's known what it is to be absolutely alone in the universe for a very long time, and he wouldn't want anyone else to suffer the same fate.
    • Even more important - when the Doctor is bored, he does some... strange... things. Imagine what Missy could do if she really got bored?!
  • Why would he keep the oath? No, the question is why wouldn't he? Missy used to be his best friend when they were kids and even now is a Friendly Enemy. The Vault enables him to nullify the "enemy" part of that. He can share meals and stories with his longest known friend without worrying (well, there's less worry about usual) about her causing trouble. It's basically what he planned to do at the end of "Last of the Time Lords" before Lucy intervened.

• Shouldn't the fact that when you think of a number and it's the same as everyone else's choice be a heavily documented phenomenon instead of breaking apart everyone's reality?
  • Depends at what point the simulation was actually started and what of "history" is just fake.

• When the simulated Doctor sends the real version of himself an email of the Monk's simulation, it doesn't make sense. Wouldn't the simulated Doctor just receive an email to himself around 5 to 10 seconds after he pressed "send"? His words should mean nothing to the Monks then.
  • We don't really know how much time has elapsed between when the Doctor read the Veritas and when Bill got to the White House. He could have been spending that time analysing the monks' computer system and networks and figuring out a way to send an email to the real world from inside of it.
  • How many times in sci-fi, or even in Doctor Who specifically, have we seen an intelligent computer program go rogue, and start manipulating interlinked technology it was never meant to be able to access, behind its unsuspecting creators' backs? There's nothing strange or unprecedented about what the sim-Doctor is doing, only that it's a good guy A.I. subprogram that's doing it instead of a villainous one.

• In "The Return of Doctor Mysterio", Nardole indicated that the Doctor reassembled him and brought him along to assuage his loneliness after River died. In this episode it's shown that Nardole tracked the Doctor down on River's last orders, looking as though he had already gotten a new body. I can't really think of a scenario where both of these explanations can be true.
  • Nardole tracked him down to the execution planet on River's orders. He was already travelling with him but the Doctor did not invite him there. Makes sense to me.
  • Could be that the body Nardole is using in the flashback is another robot, just one that can pass for an ordinary Human Alien. Ramone may have kept Hydroflax's. Eventually the Doctor rebuilds an organic body for Nardole because that's what Nardole wants.
  • Most likely the Doctor built Nardole a new body during their stay on Darillium. When River dies, he brought Nardole along on his travels, including "Doctor Mysterio". Then at some point, the Doctor was summoned to execute Missy, and he left Nardole behind. Nardole made his own way to the Library, then or previously, to retrieve the diary, and came to the execution planet separately to confront the Doctor before he could carry out the execution.

• Why did the Doctor even come to the execution planet in the first place? Did he know he was coming to execute Missy? Did they capture him, or fake him out like the writers faked us out that he might be the one being executed? Was it a mysterious invitation only hinting at its purpose, a mystery to lure the Doctor in? Why on earth did they think the Doctor would be willing to carry out the execution at all?
  • The Doctor spends long enough on Darillium that it was probably known that he could be contacted on that planet, and he may have remained there to grieve for a while after River left to explore the Library. Alternately, Karabraxos may have passed the TARDIS's phone number on to others. As for why they thought he'd do it, the Doctor's long-standing feud with the Master is well-known throughout the universe; the Doctor and the Master having grown up as best friends is not.

• If Gallifrey is out of the Time Lock at this point, why did they have to summon the Doctor (known friend of the Master) rather than importing an executioner from Gallifrey?

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