Sciencey Wiencey: Deep Breath

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Guest contributor Caleb Howells investigates more Doctor Who science and plausibilities.

As I watched this episode, I was not constantly thinking of things to write about in my Sciencey Wiencey article for it. However, one thing immediately stood out as being inaccurate. The T.rex. The episode shows it as being half the size of the Elizabeth Tower – and its head even becomes more or less level with the top of the tower in some shots. This is a seriously huge exaggeration of that dinosaur’s size. In reality, it was about 4 metres (13ft) tall at the hips (they stood horizontally, remember). The Elizabeth Tower is 96 metres (315ft) tall. The Tyrannosaurus should have been thoroughly dwarfed by that tower. Also, Vastra mentions that most dinosaurs were that big. No, Vastra. No they were not.

A Difference in Atmosphere


But regardless of the size issue, how plausible is the concept of a T.rex roaming through London? And by that, I don’t mean how plausible is it to take a T.rex from the Cretaceous period to the present day, but what would actually be the consequence of such an action? You see, this planet’s environment 100 million years ago was considerably different to how it is now. It was much hotter, for example, and the oxygen levels were likely a lot different. So, if a T.rex was taken from the Cretaceous era to the present day, what would happen to it? Would it be able to survive, and if so, how well would it manage?

The problem with this question is the issue of what the oxygen content of the atmosphere was like back then. Of course, no one knows for sure, but there are ways of getting a reasonably good idea. Sometimes amber (which we all know from Jurassic Park) contains tiny bubbles inside. These, of course, contain the air from the time period in which the amber was formed – provided that the air hasn’t leaked out somehow. Using this method, one would think it would be quite easy to find out what the atmosphere was like in the past. But evidently it isn’t.

You see, it has been commonly believed that the oxygen content of the Earth’s atmosphere in the period of the dinosaurs was much higher than it is now – up to 30%, as opposed to the current 21%. This was backed up by evidence, using the method I described above (and it was welcomed as the explanation for how pterosaurs were able to actually get off the ground; the extra oxygen enabled them to perform with greater vigour). There are numerous articles over the years since the turn of the millennium that refer to this ‘fact’.

However, a recent study from just last year, which has apparently developed a 220 million year history of the Earth’s atmosphere using hundreds of amber samples, has concluded just the opposite. It states that for much of the Earth’s history dating back to the Triassic (beyond, therefore including, the Cretaceous) the oxygen levels have hovered between 10 and 15 percent. And that, of course, is lower than the 21% we have today.

Series-8-TV-launch-trailer-(24)So who’s right? Well, no one can know for sure. Maybe time will tell, but there’s always going to be a high level of uncertainty when dealing with things this far in the past. Playing detective is hard enough, but playing detective when your evidence is millions of years old is another matter entirely. There could be numerous factors about these amber samples that aren’t taken into account, yet would completely change the conclusions. No one knows what exactly was happening around the tree at the time the sap was developing bubbles. Maybe there had been a volcanic eruption nearby, which could have changed the gas content of the air in the vicinity, or even a limnic eruption (a very rare type of natural event involving massive amounts of carbon dioxide suddenly erupting from a deep lake). Or perhaps the dating methods employed were completely off, for one reason or another (for example, potassium-argon dating has the potential to be out by millions of years). The fact is, no one knows what the atmosphere was like back in the time of the dinosaurs. So, let’s look at both scenarios.

What if the atmosphere had contained less oxygen than at present? In that case, the increased oxygen percentage that the T.rex experiences might increase its activity levels. Birds and crocodiles have a higher concentration of haemoglobin (the protein in the blood stream that carry oxygen) than mammals do. If the same applied for dinosaurs, then that would mean that they had a capacity for carrying a greater amount of oxygen than we do. This being the case, it logically follows that increasing the oxygen levels would have more of an effect on dinosaurs than it would on mammals.

Taking in an excessive amount of oxygen does have harmful effects, but it’s unlikely that any of these would act quickly enough to be noticeable during the short period of time that the T.rex was in London.

Regarding the beneficial consequences: Put simply, more oxygen equals more energy. Of course, this only works so much, but a third more oxygen would probably result in relatively significant energy increases. Not that anything very dramatic would happen. The T.rex would simply become somewhat more energetic and wouldn’t get tired as quickly as it normally does. In other words, it would, in theory, be more dangerous in the present day than in the Cretaceous. Of course, the T.rex didn’t really do anything in the episode for this potential effect to become manifest.

But that’s presuming that the Cretaceous had less oxygen than now. If the reverse is true – if the atmosphere of the Cretaceous period actually had a higher percentage of oxygen than the atmosphere today – then the opposite would happen. The T.rex would probably not just get worn out more easily, but may even find it difficult to breathe. It’s extremely difficult to be specific, but the possibility exists that the oxygen demand for the T.rex would be sufficiently high in comparison to the oxygen it’s taking in that the creature would lose consciousness and eventually die. But such things are difficult to confirm, due to an inconvenient lack of Tyrannosauruses still around.

Spontaneous Human Combustion

dino-dies-deep-breathNow this is an interesting subject. The question of whether or not SHC is a real occurrence has been a heated topic for well over a century. However, most scientists now believe that there is no such thing – each supposed incident is simply a case of death by an external, but unknown, ignition source. The ignition source is usually presumed to be something as simple as a cigarette. The vast majority of SHC cases involve people with low mobility, usually with poor health. Commonly, the person who ‘spontaneously combusted’ could quite easily have died of natural causes, such as a heart attack, or simply wasn’t able to move and save themselves once their clothes caught fire from the cigarette they were smoking.

The reason for the odd way in which the fire completely destroys most of the body – though often not including the extremities – yet leaves the rest of the room mostly undamaged seems to be explained by the wick effect. This is an observed effect and produces pretty much exactly the same results as spontaneous human combustion cases. This is how it works:

The fire is fuelled by the fat inside the human body. Fairly soon into the burning process, the fat gets soaked into the clothes wrapped around the person, essentially creating a wick (which, since the fat is inside the wick, means the human body has basically been turned into an inside-out candle). The burning process takes a long time, but that’s the thing. The flames are quite small, and as fire goes straight up much more than it goes out, it’s no wonder the rest of the room doesn’t burn down.

A common objection to this explanation is that it takes an exceptional amount of heat to reduce bones to ashes. And how could that heat be produced simply by regular burning of the human body? Well, regardless of how amazing it may seem, it does happen. It has been demonstrated in the experiments done to test the wick effect theory. For one thing, the fire created by the peculiar wick effect is very hot, though admittedly not as hot as a crematory. In fact, it seems that the reason it’s able to reduce bones to ashes is due to continual fluctuations in the heat of the fire, causing the bone to become more brittle than it would be if it was burning at a continuous temperature.

It’s also been noted that many of the victims probably had osteoporosis, which makes the bones even more brittle. In any case, it’s been shown that the wick effect can cause bones to turn to ashes, so that’s no longer an issue.

The fact is, there is no known scientific explanation for how anyone could spontaneously combust. There are plenty of theories, but none of them are based on hard scientific evidence. The wick effect seems sufficient to explain the majority of cases (there are other cases that it doesn’t explain, but those are of a completely different nature to the majority and therefore justifiably have a completely different explanation).

Of course, the ‘spontaneous combustion’ in Deep Breath was brought about by alien intervention. The simplest explanation for how that was supposed to be done would just be that the robot placed several devices over the T.rex, which would create high-powered flames (probably including thermite in the mix to thoroughly destroy all the evidence). In this instance, Vastra is correct in calling out the scientific unlikelihood of naturally occurring spontaneous combustion.

Clockwork Droids

doctor-who-half-face-sideThe plausibility of the clockwork droids is fundamentally linked with two issues:

  1. Is it possible in any way for biological organs to work with clockwork machinery?
  2. Would the organic parts still be able to function?

The answer to the first question is both yes and no; it depends on what organ you’re talking about. For example, the heart acts as a pump. It produces relatively large scale movements, which could in theory be linked up to some mechanical device (though what it could be used for is anyone’s guess, since the clockwork droid surely wouldn’t need blood pumped around its body). In contrast, the eyes are a means of receiving information from the outside world, and they transmit that information to the brain via electrical and chemical signals. Clockworks, by their nature, cannot receive and be controlled by electrical signals. It wouldn’t be clockwork if it did.

Of course, you could always add some electrical components that would mediate between those organs and the clockwork parts. But you certainly couldn’t just stick them on and expect them to work.

There’s also the issue of what benefit many of the organs could actually have for the droids. For example, when scanning the Doctor, his liver is mentioned (evidently as a good organ to remove from him). But what good would a liver do for a clockwork droid? Even if there was some liquid, such as oil, that the droid needed to be cleaned, the liver is specifically designed to perform the function it has in our bodies. The droid would have to modify it to such an extent that it might as well build something from scratch. The practicality of the whole concept just doesn’t work.

Now on to the second point. How well would the organs be able to function outside the human body? You’re probably aware of the principle that if someone’s air supply or blood flow gets cut off… they die. The blood transports the oxygen collected by the lungs to the cells in the human body. Without this supply of oxygen, the cells will eventually die. Whole organs certainly aren’t still functional hours after death at room temperature.

Again, you could perhaps keep these things running if you had special equipment designed for it; you would need some means of continuously distributing nutrients and oxygen to the cells (like, you know, a circulatory system). Admittedly, that could be one reason for the droids having a heart – except no blood vessels were shown in the exposed part of the face. The whole concept of taking an organ and attaching it to a piece of clockwork machinery simply doesn’t work.

Do bear in mind that these aren’t necessarily criticisms of the episode. I am simply assessing the scientific plausibility of the show purely for entertainment reasons. I’ve always considered Doctor Who to be soft sci-fi, especially in the Moffat era, so there are no hard feelings when it includes something that is completely and utterly absurd and contrary to all reason and logic. It’s all good fun.

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