Time Travel in Doctor Who

In typing up the article 'Time - Who's Worried' (see previous article) I felt it was necessary to redress several questions and issues I have raised and clarify the point I criticised about The Trial of a Time Lord.

The first issue is to work out what exactly is time, secondly how it might be affected by the time-traveller. I see the fundamental nature of time as lying in causation - that every event has a preceding cause and that given the preceding events that lead up to an action in was inevitable that the action happened. Causation, although not a provable law, is one of the fundamental axioms of the universe and its operating systems. The idea that every event must have a cause is something so basic and logical that it can't be argued with. The main problem in citing causation is that the universe must then exist upon a teleological assumption - that the First Cause of the Universe or Event One could not have had a cause and must have come from nothing. Naturally Doctor Who has an answer to this by citing time paradox but more on that later.

The metaphor that is most commonly used for time is that of a river. I prefer that of a Cat's Cradle where everything happens with rigid mechanical precision and events have a momentum. One can see the momentum of events in terms of psychological makeup - the various experiences of a person's childhood that go on to make them the person they are and in essence build the personality that helps make the choices for events they will make in later life. Some events, accidents, traumas, have greater momentum than others in the extent that they are able to influence. Each event in turn sparks off a whole range of events, big and small, in everything else. The correct metaphor for time then should probably be the probability wave of quantum physics. Indeed in light of the Master's lecture on the nature of granular time in The Time Monster this is an idea which could well be taken literally instead of metaphorically.

Now time travel throws a spanner in the works of causality and as a result it is possible to have an event which happens before its cause - an apparent impossibility. This is why science tends to agree that time travel is impossible (at least travel back in time, relativity will allow a limited one way forward trip through time). For example if I were to throw a banana skin back in time five minutes and trip somebody up that would mean that the event - their tripping up - would have a cause that exists five minutes in their future - namely me. But let us say they were so incensed by this act they decided to immediately come and punch me on the nose. I might then reconsider my actions and decide not to send the banana back through time in another few minutes and as a result the other person would not trip up. But then if the person was not so incensed by my actions how could he come and bop me and cause me to stop which means I must have sent the banana after all which means that he will come and bop me which will cause me not to send the banana ad infinitum.

I don't necessarily see time travel as an impossibility, although a distinct improbability. And I don't see that the nature of paradox necessarily precludes all reverse time travel, although it could be argued that all reverse time travel includes the inherent potential for paradox. If we are to discuss time travel we must create a dialectic that precludes such paradoxes and other accidental problems such as being able to prevent one's own birth. While on the subject of paradoxes Doctor Who has several - Day of the Daleks where the attempts of the rebels to alter their own future end up creating it in the first place; Battlefield where the Doctor's future incarnation is able to pop back and get his younger present self out of a tricky situation in order that he, the future Doctor, may survive to return; and Terminus and Slipback where various events cause the Big Bang which of course gave birth to the universe and the people that would go on to cause the Big Bang.

I have broken time travel down into three different possibilities, giving examples of such in action:

1 - Causal Split

That the time traveller returns changes an event - a new causal chain of events - or timestream - follow which supersede the primary timestream or allow the existence of two parallel timestreams. In essence one is able to change history.

Examples include: not that many Doctor Who episodes - Inferno, Battlefield, Day of the Daleks. Better examples may be found in the vast range of alternate history stories available in science fiction. Personal recommendations: The Man in the High Castle by Philip K.Dick (where Germany wins World War II), Bring the Jubilee by Ward Moore (where the South wins the American Civil War), Pavane by Keith Roberts (where Queen Elizabeth I is assassinated), The Iron Dream by Norman Spinrad (where Adolf Hitler comes to the US and becomes a science-fiction writer), Harry Harrison's West of Eden and sequels (where the dinosaurs never died off and instead evolved into intelligent creatures), Asimov's The End of Eternity, Fritz Leiber's The Big Time, L. Sprague de Camp's Lest Darkness Fall and the world of H. Beam Piper contain various parties altering the timestream for their own individual ends. Media examples include the 1963 film It Happened Here (Nazi England) and Mr Goodall's aforementioned Back to the Future Part II.

2 - Elastic Causality

That time travel happens but the timestream is sufficiently elastic to allow changes but time will adjust to protect the shape of the one and only primary time-line. You may be able to influence the timeline but it will manipulate events to place itself back on track. A good discussion on these possibilities are discussed in John Varley's Millennium, recently filmed. I am unable to find any good Doctor Who examples.

3 - Rigid Unvariant Time

That time has always happened the way it has and that to change it is impossible. One may find that actually travelling back is not possible or that if one were to do so and try to change events attempts would fail as any attempt to change time is not the way things have happened. For example if I were to try and kill my parents I would inevitably fail as obviously I am alive and couldn't do so, hence the gun would fail or maybe they would recover from the shots or whatever. The prologue in the novelisation of The Crusade contains a discussion along the lines of this issue.

The trouble is that Doctor Who tries to use every single one of these apparently contradictory theories. It allows the possibility of both the establishment of alternate time-lines (Inferno, Battlefield) yet also time-changes that supersede others (the possibility of Sutekh's destroying the world in Pyramids of Mars or the ability to rectify futures in Day and Genesis of the Daleks). Elastic causality is permitted every time the Doctor and companions visit their own past, time recovers from the changes that such actions as their teaching cavemen fire in An Unearthly Child or the killing of El Akir in The Crusade would have had. The fourth example must also be at work - time must at intervals be driving the Doctor to do various things so that he had no choice to do otherwise. In creating the universe in Slipback the Doctor would have had no choice but to do what he did, similarly the Master's sinking of Atlantis as history shows that Atlantis is no longer standing and we do have a universe in existence. This gets tricky as this means the Doctor and Master are running on a 100% probability wave forms, there is no uncertainty in their lives. At this point it would be useful to introduce the concept of Free Will.

Free Will argues that some actions are caused - a rock rolling down a mountain has no real choice as to whether is wishes to roll down the mountain and nobody but the most lunatic pantheist would try and argue otherwise - but in most cases we have the choice over which actions we conduct. This argument is most usually used in attributing morality to situations - when someone throws up over your living room floor you will blame them if they were drunk at the time (a situation where they had a choice) but probably not if they were ill (a situation over which they have no choice). My argument against Free Will is that a majority of people only make conscious decisions and mostly operate on in-built programming the rest of the time. But I also question - what facility is it that people use in making choices? Choice is not the great ontological facility of philosophical reasoning - it is not a function that exists in itself - but merely a function of thought process - our choices are always based on the experiences we have had. Does this not sound like causality? Should not Free Will then be an illusion? So it should be argued that when someone throws up on your living room floor you shouldn't blame them as they only made the choice to get drunk as well out of inherent social conditioning. Either instill better social conditioning or surrender to your own which of course will be telling you to get mad.

How does Free Will relate to time-travel? It means that if it exists, causality is no longer such a rigid principle. To every action there is the possibility that it did not happen and spreading from that a chain of other did/didn't possibilities. Mr Goodall uses the Free Will argument in favour of the view that the Doctor could not possibly know his fate. I agree that if we accept that the Doctor has infinite choices for every action and that for every action it sparks off its own series of events to which somebody will have to make other choices then this could be so. But to my advantage this would only increase the inadmissibility of the Terror of the Vervoids venture from the Doctor's future as this would only be one outcome of an infinite number of possible outcomes of every single action the Doctor takes. Surely a court-room in admitting the adventure as evidence would need something a little more definite than the possibility that this adventure may happen assuming that the Doctor does several million other actions in a set manner first.

I cannot see that Terror of the Vervoids could be anything other than a predetermined future. Further if the Free Will argument can exist in the Doctor Who universe than it must mean that there are points where the Doctor cannot have acted in anything other than a pre-set manner. As mentioned above in order for him to have created the universe in Slipback or the Master to have caused the fall of Atlantis they must have acted in a predetermined manner for the entirety of their lives up to that point in order to cause those events to happen. In other words for the Free Will argument to exist the Doctor cannot have any Free Will.