h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

I've been pondering the love that several of us in other conversations have expressed for The Aztecs. One of my favourite reasons is the (unspecified though clearly explained) reference to the Blinovitch Limitation Effect. The Doctor explains to Barbara that she can't change history (by which he means her own history) - not one metaphorical dot or comma. Her actions merely caused the time-line of her planet to continue as it had done right to 1963 when she departed from it. History could have taken no other course with or without her visit. It was a shame that the historicals later departed from this.

On a tangent, it is known that during the Munich Putsch of 1923 a man with his arm linked to Hitler's was shot dead. One might speculate that someone from the future had come back to try to eliminate him from history, and missed - preventing the assassin from having another go and leaving his/her own history intact. That person's future history had to go ahead without the time-line entering paradox and so the assassination had to fail.

There is another, much more surprising reason why the Doctor says that Barbara can't change one line of history... self preservation.

The Doctor wished to observe the universe but was forbidden from doing so. If he changed history, he knew that the ripples through time would lead the Time Lords back to him and he'd be captured and returned for trial on Gallifrey. So when he tells Barbara off, it is purely to save his own skin (remember in the first series the Doctor was a much more selfish character anyway, so this isn't as out of character as might appear).

Of course, later, in Pyramids of Mars, we see the Doctor giving Sarah Jane a practical example of why sometimes they physically cannot change history - or assume that by not stopping someone else from doing it that everything will work out alright. It's a very fraught path one walks along when becoming a traveller in time...

A very good point well made. But we know from later stories that all TARDISes are powered from Gallifrey - so the Time Lords knew where he was all along. He was their unwitting agent until he had no choice but to call them in having ended the War Games; and the Celestial Intervention Agency (named in The Deadly Assassin) had been better off allowing him to think he was on the run. Oh, they're a conniving lot...

Odd, isn't it, that his punishment for interfering in the affairs of other planets was to be posted to a planet that was in immediate need of continual intervention?

Is there not an inconsistency? In almost every episode they *are* changing history - or restoring it - "putting right right what once went wrong" as the intro to Quantum Leap used to say... Their very presence is inevitably changing something.

Inevitability in intervention? Asimov's "The End of Eternity" comes to mind.

A speculative example based on fact: during the Munich putsch in 1923 one of the marchers whose arm was linked to Hitler's was shot dead. A well-thinking sniper from the future, perhaps, who mis-aimed and caused history to happen exactly as it did? Day of the Daleks is very good on this theme (which makes up for the presence of Daleks who are pretty much superfluous to the plot. A human dictatorship would have made for a first-class story rather than an upper-second).

That's not actually what they're doing. The whole point of the Doctor's journeys is that he know established history and fights to preserve it. The antagonists are the ones who change things for their own benefit regardless of consequence.

For the sake of drama there has to be a level of insecurity - there'd be no point to the first Dalek story if the Dctor already knew what the Daleks were, though they get around that in stories such as The Tenth Planet and The Time Warrior in that the Doctor knows the races involved but doesn't know how the big picture affects the smaller events. We all know that Kennedy was shot on 22 November 1963, but we don't know how that news affected a military station in Nevada or a medical operation in Arkansas.

Doctor Who occasionally delves into the bigger picture to show how certain historical events might have happened - the Great Fire of London being kickstarted by a Terileptil soliton gas machine for example. But generally it looks at the smaller stories - the transportation of a new bride for Kublai Khan that just happens to take place alongside the last leg of Marco Polo's great journey. Even there, it's important that the travellers observe, possibly interact, but don't actively set out to change time. Barbara tries this in The Aztecs - as this thread began with - and she failed. Even if the travellers set out to change time, Time won't let them...

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Which reminds me of the 1979 film 'Time After Time' with Malcolm McDowell, in which hem as H G Wells, and Mary Steenburgen as a character whose name I forget, try to save people from Jack the Ripper who used Wells' time machine to go to San Franscisco in when else, 1979... They fail miserably - what's done is done! What a downer, and yet, how interesting!

"Time may change me - but I can't change time." - David Bowie

This really has me thinking about the quantum butterfly for some reason. May have something to do with that big picture talk earlier...