Sciencey Wiencey: The Day of the Doctor

Guest contributor Caleb Howells investigates more Doctor Who science, this time from the 50th.

When the titles started rolling for the amazing 50th anniversary special, I bet none of you were thinking “You know, I hope this is scientifically accurate, otherwise I’m going to be really annoyed!” I doubt anyone ever thinks like that when they’re watching Doctor Who. Not even I do, despite what these articles might suggest about me.

So, therefore, in this article I shall be answering the question no one’s asking. How scientifically plausible was The Day of the Doctor? Well, this is the 50th anniversary special of Doctor Who, so it should be the epitome of the show, with all its ridiculous, whimsical madness. We can’t expect it to be very realistic. And this episode did indeed have many fantastical elements. But what basis did they have in reality, if any at all?

The Moment

The first one that crops up in the episode is the Moment, using the form of Bad Wolf. The Moment somehow projects an image of itself, which you might think would just be a simple hologram. But that evidently isn’t the case, since at various points in the episode we find that only the War Doctor can see the projection. And most of these scenes take place far away from the Moment itself.

In the recent development of virtual reality, some systems have taken a different approach to that of the conventional concept. Rather than having two screens in front of your eyes, special devices are used which shine the image directly into your eyes. Apparently it works very well, though it has the problem of not working if the light is even slightly out of line. As far as I’m aware, this has only been done with the devices right in front of your face, like a traditional VR headset, but presumably it could work from a distance. In which case, only you would be able to see it, yet you wouldn’t have to have anything strapped to your face.

However, the problems with this idea are obvious. You wouldn’t be able to turn your head away from the source of the light, and you certainly wouldn’t be able to face away from it, like the War Doctor repeatedly does.

So it can’t be a regular hologram, and it can’t be working by shining the image directly at the War Doctor’s eyes. Therefore, it must be transmitting the image – or rather, the thought of the image – directly into his brain. Is that possible?

Everything you see and hear is really just the result of many electrical signals through the neurons in your brain. If you want someone to see something that isn’t really there, then you would need to get those signals going by externally stimulating the specific neurons involved. This is actually easier than it sounds. There are already gadgets (some of which you can make at home, I believe) which you hold against your head near your ear, and it messes up your balance. You can program it in such a way that you feel like you’re falling over, even though you’re standing still. The same principle could be applied to your vision and hearing, though of course on a much more advanced level.

However, there’s still the problem of range. As I said, you have to have the device held against your head. But that wasn’t the case for the War Doctor. The Moment was transmitting the electrical signals from across the room (and in some cases from another part of time and space entirely, but I’ll get to that in a minute).

Transmitting electricity through the air is definitely possible. The brilliant scientist Nikola Tesla managed to do it on a large scale back in the early 1900s. Today, scientists can’t do it anywhere near that well, but they’re getting there… slowly.

However, even with that being possible, how precisely can you do it? Would you be able to do it so precisely that you could accurately control what someone sees and hears from the other side of a room, and even from the other side of a time/space tunnel? Could you get around the problem of not stimulating any neurons apart from the ones you want to stimulate, even if they’re on the other side of the brain?

I doubt it, but I don’t know. As far as I’m aware, this isn’t something that anyone’s actually tried before, so it’s hard to find things that have a bearing on it. So I’m going to have to leave this with a ‘maybe.’

Frozen in Time

The next sciencey plot device in the episode is the Time Lord art. There are two parts to this, which I’ll deal with separately. The first part is the idea of something being frozen in time. Is that feasible? Surprisingly, it may well be. You see, there are two ways to affect your rate of travel through time. Speed and gravity.

The faster you go, the faster you travel through time. For example, you could be travelling so fast that one second from your perspective is ten seconds from the perspective of everyone else. Or you could even be travelling so fast that after one minute in this ‘time machine’, a whole year has passed for everyone else. Incredible, yes, but theoretically possible.

Because time slows down for you as you approach the speed of light, it is theorised that if you were travelling at the speed of light, time would stop for you completely. Between the time you starting travelling at that speed and when you stopped, regardless of how long it actually was, you would feel no time passing at all. So to everyone else, it would be as if you were frozen it time (except, of course, they wouldn’t be able to tell because you’d be travelling at the speed of light).

However, this idea still has problems in terms of practicality. How, exactly, are you supposed to suddenly get a planet moving at the speed of light? And how do you avoid killing everyone in the process? Feel free to contradict me in the comments, but for now, I’m going to have to say that it’s not possible.

To save space, I’m not going to elaborate on the time-stopping concept that uses gravity, but I can inform you that it also presents the same problem – it would kill everyone.

So, in practice, it would be impossible to freeze a planet in a moment of time (at least the way it’s presented in the show).

Pocket universes

But what about the second part of this plot device? The things in the paintings are said to be hidden away in a “pocket universe.” Do such things exist? And if so, how would you get there?

This is the point where we start getting further and further into the depths of what’s essentially philosophical babble with virtually no scientific basis to confirm or deny it. Everything about parallel universes and pocket universes, etc. is pure speculation, so I’m not going to go into that.

Next, we have the time/space tunnels. Wormholes, basically. Good old classics in the realm of science fiction. Because of that, what I’m going to say here probably isn’t anything you haven’t heard before. But to put it simply, wormholes are theoretical structures in the fabric of space/time. Imagine that the fabric of space/time is in your hands, and there are two points on the fabric which are quite far away. Now suppose you bent the fabric so that the two points were next to each other, and then you made a short tunnel between them. So now you could get from one point to another really quickly, even though the two points are actually really far away from each other.

Hopefully you can see how that’s supposed to work regarding the physical space. I haven’t been able to find anything that properly explains how it’s supposed to work with time, but apparently it can, so let’s just go with it. In which case, the time/space tunnels, are theoretically possible. But apparently, it would require the energy of an exploding star.

Also, bear in mind that there’s a distinct difference between something being theoretically possible, and a small clockwork box being able to suddenly make it happen.

The Disintegrating Door

Now, let us consider something that didn’t actually end up happening, but is too cool to not talk about. The disintegrating door. While locked in the prison (or not, as it turned out), the War Doctor starts scanning the door. When asked what he’s doing, he says that if he can “activate an isolated sonic shift among the molecules, the door should disintegrate.” The Tenth Doctor then says that he’d have to calculate the exact harmonic resonance down to a subatomic level.

However, that’s unnecessary. You could do it in a way that wouldn’t require such advanced, precise scanning and calculations. All you need to do is find the frequency of the door itself. Knowing that, you could then send a vibration (using the sound waves from the Sonic) through the door, which would bounce back once it reached the other side. Then, when the vibration had reached the Doctor’s side of the door again, he would send another vibration through it, thereby combining the two vibrations. If you keep on repeating this, the door would eventually be shaking so much that it would fall apart.

Nikola Tesla used this same principle to achieve the (still remaining) world record of longest man-made lightning arcs (about 130 feet, if you were wondering). He pulsed electricity through the entire planet, and then sent another pulse when the previous one had returned. He again used this same principle – though using physical vibrations this time – to make a pocket sized earthquake machine (though, with some exceptions, it was only used on single structures rather than whole streets).

For his earthquake machine, Tesla used a small device with a rod that rapidly moves up and down (striking the structure to cause the vibrations), the speed of which was controllable. Presumably this would also work using sound waves to cause the vibrations. It probably would have taken a few minutes for the vibrations to build up significantly, but that certainly beats the centuries it took doing it their way.

So, in conclusion, most of the sciencey wiencey parts of this episode do actually have some basis in scientific reality, even though they’re quite exaggerated and none of them (apart from the prison door) are completely possible. But that’s perfectly fine, for a soft science fiction series.