10 Important Doctor Who Questions NOBODY Can Answer
7. How Does Everything Stay Relative?
With at least 17 incarnations of the Doctor flying around the time vortex, why don't they bump into each other more often? Not only that, but why does each incarnation of the Doctor and the Master meet in roughly chronological order?
One potential answer for this comes in Flux, when the physical embodiment of Time warns the Thirteenth Doctor about her upcoming battle with the Master. Flux built on Steven Moffat's idea that time was somehow a sentient force, witnessing events and ensuring that they occurred in the correct order.
It's why River not shooting the Doctor at Lake Silencio caused the fabric of time and space to completely break down. So is this the answer? A being more powerful than even the Time Lords keeps everyone and everything on the correct path?
Or is it the TARDIS itself? We know from The Doctor's Wife that the TARDIS is self-aware, so perhaps it knows to keep the Doctor from crossing their own time streams. Like a car's parking assistance system, but instead of bollards, it warns about past or future incarnations in the same space and time.
The TARDIS could also be synced to local Gallifreyan time, ensuring that Time Lords always meet each other in order.
It's one of those aspects of Doctor Who that becomes more and more headache-inducing as you think about it. Just pop an aspirin and move on.