The news reported recently that perhaps we needn’t throw out the notion of time travel due to the problem of the grandfather paradox and various other related conundrums. As Desmond on LOST told Charlie after hearing it from Eloise Hawking, the universe has a way of course-correcting. In other words, if you go back in time and try to kill your grandfather, something will prevent it. In some ways, that’s more disturbing than the original paradox. As Daniel said on LOST, “whatever happened, happened.” He and others famously tried to prevent the incident that would lead to the creation of the Dharma Initiative Swan station where Desmond would push the button but would be late in doing so one fateful day that crashed Oceanic flight 815. Daniel was shot by Eloise, his mother, in the process of trying to accomplish this, and she later groomed him to become the physicist she knew he must, despite being an accomplished pianist and having the potential and desire to play.
The whole thing may have seemed like just a tangled puzzle when we first watched it. Looking back and focusing more on the characters and their story, it is heartbreaking. And it seems worse somehow if, simply because it happened, in a sense it “had to happen.”
Perhaps, of course, until it happens it genuinely could potentially not have, and it is only from the perspective of subsequent time that an event becomes immutable. We need not subscribe to determinism to view the past as fixed once it happens. But time travel inherently entails something worse, when it comes to free will, than determinism.
There is a direct connection between the view that time travel is possible, and the view of God as outside of time. Both posit that time not only exists as a fourth dimension akin to the three more familiar spatial ones, but that every moment in time exists, and from a perspective outside of spacetime, exists simultaneously with every other. Without that, time travel is not possible, and without that, God cannot omnisciently view every moment from a perspective outside. This means more than that events are predetermined and unalterable. It means that there is not only no free will but no actual choice, only the illusion thereof. Every moment in history is there, and is always there.
It is a very odd view, both scientifically and theologically, but also narratively and experientially. I object on all those grounds.
This does not mean that I will enjoy Doctor Who and other time-travel stories any less. Indeed, I just wrote a very short piece of flash fiction of my own that features time travel, and the short story I’ve published that I like best is “Certainty” which is also a time travel story. (It appears in my book Theology and Science Fiction, for those who want to read it). Time travel, transporters, and mind-transfers between bodies are all features of science fiction that allow us to engage in very useful thought experiments. But not everything that we can and should imagine is in fact real or possible.