Wibbley Wobbly, Timey Wimey
The laws of time – as revealed in Doctor Who – are distinctly confusing. You’d almost think the writers were making them up as they go along. 😀
That said, there are certain discernible rules.
First Rule (to distinguish it from Rule One). Time can be changed.
What this means is that the universe of Doctor Who (the Whoniverse) isn’t deterministic. Events are NOT fixed (unless they come under Rule Two). And since they aren’t fixed, they can be altered – especially by time-travellers.
And what this means for the Doctor is that he has a perfectly free choice about where and when he travels in time. Because events aren’t fixed, it’s possible for a time-traveller to visit a place when – in the original timeline – they weren’t originally present. However, because they weren’t there originally, anything they do will be an alteration of the timeline.
The Doctor: Time travel … is damage.
If they’re careful, however, the scars will heal and the universe’s timeline will revert back to a course that’s barely distinguishable from the original.
To someone who was able to observe from the outside, however, there’d be two different versions of events – one version that happened ‘before’ the time traveller visited, and one version that happened ‘after’. English isn’t terribly good with time travel tenses, so it might help to think of things as sequential rather than before and after in time. The ‘before’ happens first, the ‘after’ happens second. As we see with River and the Doctor, it’s entirely possible for one person’s ‘before’ to be the other person’s ‘after’.
Looking at a non-Moffat story – the Unicorn and the Wasp – the ‘before’ is the historical knowledge Donna and the Doctor have. Agatha Christie once went missing, and turned up ten days later in Harrogate with no idea what had happened.
That’s the original timeline.
The Doctor and Donna turn up and discover that a giant wasp was involved. At this point the timeline goes all wibbley, because while Agatha Christie was a very good writer, she isn’t someone who changes the course of human history. The Doctor and Donna, however, change events sufficiently that it becomes possible that Agatha Christie might die saving the world from the wasp. BUT they all manage to get events back on track – and the universe, despite the wobbly bit, looks much as before their intervention.
Had they not managed to save Agatha, the second line would still look very similar. There’d be a wobbly bit as the universe tackles the differences – but since people would probably pick up a Dorothy Sayers instead, the time-line will still recover.
Second Rule. Some events are fixed points.
Some events, often for reasons known only to the writer, are ‘fixed points’. In some cases it’s fairly obvious why something is ‘fixed’ – Pompeii had a very noticeable impact, Adelaide Brooks’ death inspired interstellar exploration. The Doctor’s ‘death’ (which turns out to be ‘the report of his death’) is something which impacts on Amy, Rory, and River, causes many of the events in Series 6, drastically impacts events with the Silence on Earth – well, you see the point. Take away the belief that the Doctor died, and what you get is something like the following diagram.
But why do you get the above diagram in the case of, say, Lake Silencio?
Once River changes events and doesn’t shoot the Doctor, Amy has no reason to believe the person in the spacesuit is dangerous. She’ll therefore not shoot at the little girl in the spacesuit. This might mean that little Melody is found and rescued by her parents before they even knew she’d been kidnapped. Which means Amy might well be rescued before she gives birth, which means Melody will never be in 1969 in the first place…
Even if they don’t manage to rescue Amy before Melody is kidnapped, they’ve still found Melody age 7, which means she never became Mels, which means Lets Kill Hitler never happened (no cries of ‘Thank God’, please), but more seriously, she may never regenerate into River either, which means that the Doctor may have died at the Library and never got to Lake Silencio in the first place. And there’ll be no River to be at Lake Silencio anyway.
Even if Melody spotted the Silence and decided to run for it, so that LKH and River happen on schedule, if she doesn’t shoot him, the Doctor is unlikely to be told he’s going to die, so won’t go on his farewell tour, so won’t meet Craig and Stormagedden and save them from the Cybermen. In addition, he won’t realise that he needs the Tessalector, because – after all – nobody present but the Doctor knew he was in the Tessalector. So they can’t tell his younger self – and if he isn’t actually shot, why would he need a Tessalector? So he won’t be at Lake Silencio in the Tessalector.
At this point the universe, struggling between all the possible alternatives, goes ‘stuff it. Some other bugger can sort this out. Churchill on a mammoth, pass the popcorn’; and stops the progression of time – thus preventing the infinite oscillation between alternatives.
Third rule: if you know your own future, it becomes a fixed point.
For the Doctor to have free will, he must remain largely unaware of his future. This is the one people are currently having problems with. Why, they cry, couldn’t the Doctor just tell Amy and Rory to book a sea passage to Europe and pick them up there?
Because he knew he didn’t, that’s why. 😀
Let’s look at a simpler example, before we go on to Angels in Manhattan. Suppose the Doctor has read in a book describing his future that he’s going to break his arm on Blackpool beach on November 23rd 2013. ‘Aha!’ he thinks, and makes a note to never go anywhere near Blackpool beach on November 23rd (generally a good plan).
Since he doesn’t visit Blackpool beach on November 23rd 2013, the book he read is never written. How can it be? The Doctor wasn’t there for anyone to write about.
This means that the Doctor has no idea he needs to avoid Blackpool beach on the 23rd. He therefore makes his visit, gets hit by a 20 foot wave whilst battling Zygons, and breaks his arm. Somebody sees him and writes a book about it.
The Doctor reads the book and decides not to go to Blackpool on the 23rd…
It looks a bit like this diagram
Okay, now back to Angels in Manhattan. Why is Rory getting trapped in and dying in New York a fixed point? So fixed that he couldn’t die anywhere or anywhen else?
Well, there could be other reasons; ones that haven’t yet been revealed. But what we do know is that one of the consequences of Rory getting trapped was that Amy left the Doctor to stay with Rory. This caused the Doctor to go and stay near his friends in Victorian London. This caused him to meet Victorian Clara, and start looking for Modern Clara. This eventually means he takes modern Clara to Trenzalore, where she leaps into his timeline.
Which we already know was a good thing, because if the Doctor had never met Modern Clara, Future Clara would never have existed and never crashed onto the Asylum. The Doctor would never have visited it, it would never have been destroyed, and he’d never have been wiped from the Dalek database.
Or, worse, he would have visited it – and without Clara, been killed. Or, even worse, the GI would have decided to take revenge without Clara to stop him.
Whatever. The Doctor may well have not worked out all the details, but I’m sure he learnt the zig-zag diagram at the Academy. Having learnt that Rory and Amy die in New York, he can’t go rescue them. If he does, their gravestone (and the book) will disappear. If there’s no gravestone/book, he has no idea where to start looking for Amy and Rory, so he can’t rescue them. Since he couldn’t rescue them, their gravestone will reappear…
Fourth Rule: changing your own timeline is dangerous.
Your past, like a known future, is a fixed point. The Doctor has crossed his own timeline; but only in certain circumstances. In the Three Doctors and the Five Doctors, it’s a special intervention by the Time Lords. What they were using to hold the time-line stable is unknown – but we later saw the Master convert the TARDIS into a machine capable of holding a paradox stable for over a year, so it’s clearly something they know how to do in emergencies.
In Time Crash it’s clear that Tennant’s Doctor remembers this happening from his first time round. There’s no paradox; Tennant and Davison’s Doctor met in Davison’s period – it’s just that we never saw it until Tennant’s time.
However, if Smith’s Doctor finds himself in his own timeline and changes his own past, he runs the risk of changing the events that led up to him entering his own time line, leading him straight back to the zig zag diagram of the Second Rule.
Final question: when can the Doctor change his own timeline?
- When he doesn’t know his own future. This isn’t a deterministic universe; he’s probably accidentally changed the non fixed parts of his future thousands of times.
- When he realises that the current timeline is NOT the one from his own path.
This is basically what happens in Fires of Pompeii. The contemporary timeline is one in which Mount Etna never erupts; the Doctor and Donna discover that they have to change it so the volcano does erupt. The fixed point was only created in the first place because they changed the time-line.
In order to know what the fixed point is meant to be, the Doctor and Donna must come from the future. The soothseers of Pompeii can only see what the timeline should be, not how it should be changed. Going back to the rules above: since they know the future, that future is, for them, fixed. The Doctor and Donna, however, know Pompeii as a fixed point in their past. The resolution to the contradiction is that the timeline will be/has been altered.
Similarly, if the Doctor’s timeline currently ends at the Smith Doctor, the Smith Doctor can’t change it (once he knows that – see the Third Rule). However, it would be possible for a time traveller who knows the future (either River or a future Doctor) to realise that – from their point of view – the Smith Doctor is not the final Doctor. Again, the resolution to the contradiction is that the timeline will be/has been altered.
But you will need the time traveller from the Doctor’s personal future for anyone to know that. 🙂