How does Time work in Doctor Who?

Question

Does anyone have a succinct explanation about the physical laws governing time in Doctor Who? As events unfold in the series (I guess I'm mainly talking about the post-2005 incarnations) the Doctor and his companion move around at will in the mundane human 4D universe, but seem to be following some linear 'timeline' that threads their lives, as if there was an extra time-like dimension that the Doctor exists in that operates in the same way as 'our' time does for us, namely that it can only be moved along in one direction.

For example, 'The Time War' with the Daleks occurred in the Doctor's past. When he meets other time travellers, for instance Jack Harkness, they both believed that the Daleks 'had been destroyed', which implies a finality that goes beyond their ability to move around in our 4D universe at will. The same applies to Harkness's past.

Are there some canonical rules or explanation about how time operates in Doctor Who, or is it always mysterious and disjoint to the viewer?

Answer 1

The answer depends on the author. Currently...

“People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint - it's more like a big ball of wibbly wobbly... time-y wimey... stuff.” - Moffat

In fact with Moffat we see a fixed point in time, Rory's death, become undone despite the prior quote in episode 5.9.

“There are fixed points throughout time where things must stay exactly the way they are. This is not one of them, this is an opportunity. Whatever happens here will create its own timeline, its own reality, a temporal tipping point. The future revolves around you, here, now, so do good!”

The time lord is continually stating things like, "But that's impossible!" So I'm leaning more towards mysterious but always learning and exploring and thus revealing new information to the viewer.

Answer 2

as if there was an extra timelike dimension that the Dr exists in that operates in the same way as 'our' time does for us, namely that it can only be moved along in one direction.

Yes, exactly -- more or less.

In the whoverse, there is "time", being the ordinary 4th dimension along which you see an increase in entropy and a linear transition of cause to effect. This "time" is not precisely straight, however, because it is possible through various means for a subset of reality to disconnect from the temporal continuity and re-connect at a different point in "time".

Such subsets, who are often but not always sentient people, in effect come to have their own "timestream", within which you have always-increasing enthropy and a transition from cause to effect. You cannot go back in time to yesterday to convince yourself not to go back in time today.

Of course, such subsets DON'T have their own disconnected time dimension. They interact with the rest of the universe, contributing to both cause and effect, and in certain circumstance can even have subjectively latter causes that trigger subjectively earlier effects. And it gets even more confusing when you allow for multiple time travellers with distinct motives.

However, it IS apparent that the entire multiverse does have some persistent causality, wherein changes done at one part of the time-space continuum have both a "before" and "after", such as the case of the great Time War.

So, it may be most precise to say that the Whoverse has at LEAST two time dimensions -- "common" time, "eternal" time, and possibly some additional number of "subjective" times. (That whovian eternal time corresponds to actual time in reality is an aspect of fiction, and can be happily ignored for entertainment purposes.)