Occasionally in Doctor Who, we witness scenarios that suggest that perhaps all events in history are predetermined, that everything that happens is destined to happen. In this episode of the podcast, we look at the question of free will. Does the Doctor live in a deterministic universe, or do time travelers have free will to choose their own futures?

 

Transcript

Time is Not a River

In the common view, time is divided up into three parts: past, present, and future. It’s the grammar of our language and is based on our experience. For us, of those three, only the present is real. The past has slipped out of existence. The future is some possibility that has not yet come to be. So the “now” has special significance. It truly exists, and for us it is in motion. The present moves forward, adding more to the past and subtracting from the future. This process we call the flow of time.

Yet this understanding of time, though it seems to make sense, is at odds with modern physics. Einstein’s special theory of relativity has tossed the traditional conception of time out the window. As he once famously expressed to a friend, “The past, present and future are only illusions, even if stubborn ones.”

This reminds us of an exchange that occurs between Ian and the Doctor in “The Cave of Skulls,” the second-ever episode of Doctor Who. Ian says, “Time doesn’t go round and round in circles. You can’t get on and off whenever you like in the past or the future.” “Really?” replies the Doctor. “Where does time go, then?” And Ian expresses the common understanding: “It doesn’t go anywhere. It just happens and then it’s finished.” The Doctor laughs.

He laughs because the traditional notion of the passage of time is nonsensical. It doesn’t happen and then is finished. That’s a misconception. The present moment for someone here on earth would not be the present moment for someone on Mars or another planet. It’s all relative. If you and I were in different places in the galaxy, something for me might be considered the past, but for you the future. Since we cannot single out any moment as special or real, because every moment considers itself to be special, we must therefore conclude that past, present, and future all are equally and objectively real. Physicists prefer to think of time as a landscape, laid out in its entirety, all events existing together, and nothing in it is to be considered privileged or special. In other words, time is not like a river. It doesn’t flow. The Doctor and the Time Lords recognize this, and although they may use expressions that suggest a flow or movement of time, they do so in much the same way as we speak of the sun rising and setting. We know it doesn’t actually work that way, but it has become part of language.

Well, how can we say that time does not flow when we perceive it as flowing? It seems to move to us. The answer is to be found in psychology and neurophysiology. It has something to do with how our brains function. The formation of our memories is unidirectional—we might perceive this as the flowing of time. It may be even that we have some kind of time organ in our brain. The jury is still out on this.

The important thing is that time travel can occur because all events are real and exist, and the TARDIS can enter into the time landscape at any point.

But does this conception of time mean that everything is written in stone, that nothing in the time landscape can be changed? Some time travel stories are presented this way: anything that will happen has happened. Everything is fated to be. A time traveler cannot go back and right the wrongs of history; they cannot even move a speck of dust on a certain day in the past if it is established that the speck of dust remained unmoved. They can participate in the past, but they simply make the past as it was. Whatever they do is destined to be.