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The Breakfasts of Superheroes
One of the most obvious but overlooked questions that surrounds the science of being a superhero concerns the nutritional needs that would be required to have the capacity of superhuman powers. After all, a handful of oat cakes for Peter Parker (AKA Spider-Man), as he dashes off on a day of acrobatic crime fighting across Metropolis, just aren't going to cut the mustard. There has to be something else going on. And Peter Parker knows it. He must know that his daring deeds are only possible if he is fuelled by a proper diet. The oat cake breakfast may just be part of his cover story, but Spider-Man's breakfast is just the tip of the iceberg. After all, if Olympic athletes need a support team inspecting every morsel that passes their lips, then there must be an army of nutritionists monitoring the dietary requirements of the great crime fighting squads. It may not crop up in the comics and movies, but I bet there's a course entitled 'Nutrition for the Gifted – 101' on the curriculum at hero schools. Education about healthy eating can't start early enough.
1.2 FOOD FOR ALL
Before we get stuck into the nutritional needs of the superpowered, let's remind ourselves of what mere mortals in this reality tuck into. Mrs Average and Mr Ordinary need about 2000–2500 Calories per day. Now, compare that to the most athletic amongst us (Table 1.1). Many professional athletes feed on 3000–4000 Calories per day. Whilst some Olympic swimmers, at the height of their training regimes, claim to increase their diet from an already hefty 5000–6000 Calories to a stomach stretching 10 000 Calories each day!
The difference between the athletes' diet and those of the average Jo and Joe is subtler than just energy intakes; there's also a significant change in nutritional balance. The calories fuel an athlete's daily activities, but the machinery that powers their achievements is muscle, which is made of protein. Consequently, the athletes must increase their protein intake by as much as four times over that of Mr Ordinary. In short, they change their diet to take into account their activities, providing them with the nutrients to build a body prepared for the task ahead.
Just as athletes tweak their diets to feed the demands of their sport, superheroes must take into account their body's needs. Of course, many of our superheroes act in ways akin to real world athletes and their diets might well be very similar to Olympians. But there are some unusual cases who will have extraordinary nutritional needs to go along with their strange powers. This may be the result of the massive amount of energy they expel, but in other cases heroes need to remember that, with great powers come great side-effects.
1.3 A SUPER SIDE-EFFECT
Consider poor old Ben Grimm, also known as The Thing, a man trapped inside a craggy orange hide. His powers and stone exoskeleton might afford him fabulous stamina, strength and resistance to injury, but at the cost of a monstrous form. There is also something else to take into account ... His stony exterior makes him impervious to ultraviolet radiation. There's no tanning or sunburn for The Thing. Well, that's not such a terrible side-effect, you might think. After all, if you're a big orange stony hulk (with a small H) the least of your worries will be an inability to soak up the rays whilst sunning yourself on a Caribbean vacation. However, without exposure to UV, Ben will suffer from a vitamin deficiency that results in fatigue and muscle weakness and he will even have trouble thinking – all things a superhero really should do his best to avoid.
Most vitamins are synthesized biologically through a series of enzyme-controlled reactions that start with basic building blocks and, by stitching them together here and nicking a bond there, the final vitamin is formed. Sometimes an organism might be missing enzymes that allows it to make a vitamin, but that's generally OK because some other beast, bug or plant that we consume will have made it, transferring it into us when we eat. A perfect example of super-failing in humans (along with guinea pigs, capybaras and bats) is vitamin C, which we really need, but can't generate. So instead we need to get it from our food.
However, vitamin D is rather unusual. Nowhere on the planet is there an organism that can make it without external help; they all require energy from the sun to smash open a ring in a molecule called 7-dehydrocholesterol (Figure 1.1). This process frees up the new compound to twist (in a process called isomerization) into the shape of vitamin D, and this all goes on in your skin when you are out in the sun. So, if you have the misfortune of being covered in orange stone, then there is no way the sunlight will reach the 7-dehydrocholesterol. Instead you would need to ensure your diet includes plenty of the required vitamin.
Spend plenty of time outside and you'll probably manufacture all the vitamin D you need (assuming you don't cover yourself up). However, the recommended daily allowance assumes you generally lock yourself away in a dark room (reading comic books?), live in northern latitudes (where the sun isn't so strong), and cover yourself in factor 50 sun cream. So, the suggestion is that you should eat 15 micrograms of vitamin D each day. Ben probably needs to take in this amount as well, which means that a breakfast of oily fish (kippers maybe?) and he will be just fine.
1.4 FAST FOOD AND FLASH DIETS
Beyond simple strength and energy, superheroes who are super speedy also have unique nutritional needs in the morning. Let's take Marvel's Quicksilver as a start. In his original incarnation he maxed out at the speed of sound, although since then his powers have grown. From recent footage some clever clogs has calculated Quicksilver can whiz along at well over ten times the speed of sound (12 000 kph) over short distances. But, let's keep things realistic and work out what he might consume at breakfast to power a 30 minute Mach 1 run? Luckily, sport scientists have a handy equation for calculating energy usage for runners, so what happens if we apply it to our supersonic hero?
First, we need to work out how much oxygen our heroic athlete uses. By hooking up regular athletes to monitors whilst they are resting, we know that they generally use 3.5 mL of oxygen per minute per kg of body mass. As we all know, once we start running we need more oxygen and start breathing harder, so we need take this into account as well. The volume of oxygen used in a minute is known as VO and is calculated as follows:
V2 = 3.5 + (0.2 × speed in meters per minute) when running on the flat
So, our runner speeding along at the speed of sound (20 400 meters per minute) uses:
V2 = 3.5 + (0.2 × 20 400) = 4083.5 mL kg-1 min1
According to Marvel Directories, Quicksilver weighs 80 kg (175 lb). So, on his (quick) morning jog, he'd need 327 litres of oxygen per minute (80 kg × 4083.5 mL kg-1 min-1 = 327 L min-1). Because air is about 20% oxygen, that means he's breathing in 1633 litres of air every 60 seconds!
To utilize the oxygen he needs some chemical energy, which comes from food, and we know that works out at 5 kcal per litre of oxygen used. So we have another bit of maths:
5 kcal × 327 L min-1 = 1635 kcal min-1
This gives Quicksilver needing 49 050 kcal for his half-hour morning run. If you look back at Table 1.1, you may notice that this is much more than you'd eat in a day, but how much more?
Peanut butter and jelly (jam) sandwiches are a favourite in the US (the land of our hero) so maybe he's partial to them for breakfast? They come in at about 500 kcal per round, so before taking off on his run Quicksilver might want to tuck into about 100 of them!
1.5 FEEDING THE FLAMES
Super speed isn't the only power that's going to require a calorie-packed diet. In fact, compared to some of the superpowers that are out there, it may even be one of the more modestly energy-needy powers. In comparison, pyrokinetic superheroes, like Johnny Storm, who bursts into flames at will, generate huge amounts of heat, which certainly requires loads of energy. How Johnny ignites himself isn't entirely clear. On the one hand, he seems to need oxygen to maintain his flames, which suggests they are the result of combustion. However, comic book lore consistently states that The Human Torch's hot plumes are actually plasma. Now, plasma is a gas-like matter created by stripping electrons from their nuclei, like you get in stars. But there's no good reason why generating plasma needs oxygen. Actually, the mechanism by which he 'flames-on' doesn't really matter. Either way, he needs to heat up and then maintain the desired temperature, so how does he do it?
Johnny's energy requirements can be broken into two steps. First, how much energy is required to heat him from a normal 37 °C to his minimum 'flame-on' temperature of 416 °C? And then, what's required to maintain that temperature? The energy, in calories (small 'c' calories this time) needed (E) to heat up is simple enough and is given by the equation:
E = c × m × ΔT
where m is Johnny's mass (77 kg) and ΔT is the change in temperature (379 °C, in this case, the difference between the target of 416 °C and normal body temperature). C is something called 'heat capacity', which is how much energy is needed to increase a kilogram of a given type of matter by 1 °C. (I'll use water's heat capacity since humans are basically bags of the stuff.) Conveniently this is 1 kcal kg1 K(because that's how a calorie is defined). Plugging all these values into the equation we get a figure of 29 183 kcal. That's just to heat him up.
Next up, how to stay hot. As anyone who pays a heating bill knows you've got to pump in energy to keep something warm. Flaming superheroes will have to deal with this same cooling issue. The rate of heat loss through cooling was worked our centuries ago by a real superhero scientist, Sir Isaac Newton. His equation for energy lost by convection in 1 second is:
E = h × A × (Thot - Tcold)
E is the heat lost in joules (4.2 joules = 1 calorie), A is the surface area of the object and h is its thermal conductivity. Sticking all the numbers in and you end up with 135.2 joules or 0.032 kcal needed per second to maintain 416 °C. That isn't actually very much at all, certainly compared to the energy lost via radiating photons. A flaming Johnny is basically acting like an infrared heater, and that loses him 3227 kcal per second.
So in total, 10 minutes of flame time costs 29 183 kcal getting to temperature then another 1 936 277 kcal to maintain a toasty 416 °C. This means that, if Johnny Storm dropped in on Quicksilver for breakfast, the speedster would need to whip up another 3930 peanut butter sandwiches. Good job he can spread and slice at supersonic speeds!
1.6 SPIDER-MAN'S BREAKFAST
With all his leaping from building to building and wall climbing, Spider-Man will certainly need a nice high-calorie diet, but his energy intake is likely to be closer to an Olympic gymnast than a pyrokinetic or speedster. However, his silk-spinning power does have some very particular nutritional needs. Whether it is produced by fleas or flies, bees or beetles, crabs or spiders, silk is always made of protein. So, if Spider-Man spins copious amounts of web, then he must also consume huge amounts of protein. What, then, does Peter Parker have for breakfast to sustain his villain-beating lifestyle? To work this out, we need a bit of school-level physics, Maths and some basic biochemistry. First, we need to work out the strength of Spider-Man's silk, then calculate how much force Spider-Man would exert on the silk and, finally, figure out how much and what kind of protein will be needed to enable Spider-Man to do his stunts.
Let's assume Spider-Man produces threads that have the same characteristics as dragline silk produced by the European garden spider Araneus diadematus. That means it ought to have a tensile strength – which is the largest stress that a material can withstand before breaking – similar to that of a piano wire. A piano wire has a tensile strength of 1.1 billion pascals, which is a unit of measure for pressure, or the force per unit area.
According to Marvel's directory, Spider-Man weighs 75 kg. Applying Newton's second law, we can figure out the downward force that Spider-Man exerts, which is calculated by multiplying his mass by the Earth's gravitational acceleration (9.8 m s). This works out to be about 735 newtons.
Now we just need to take the downward force exerted and divide it by the tensile strength of the silk. Without going into the tiny calculations, it turns out that Spider-Man could hang from the ceiling on silk that is less than 1 mm thick. (Of course, being a scientist and not an engineer, I've factored in exactly zero margin for error.)
Next, we need to establish what mass of silk fibre this would represent, assuming Spider-Man's pre-lunch heroics requires 100 m of it. Silk is slightly denser than water (1.3 g mL-1 compared to 1 g mL-1 for water), which means that 100 m of the silk would weigh about 87 g. There is about 6 g of protein in an egg. So, could it be that Spidey only needs about 15 eggs (87 g divided by 6) for breakfast if he plans to use 100 m of silk? That doesn't seem too bad. However, all proteins are not created equal, so the equation is not quite this simple.
All proteins are made from the same building blocks, amino acids. There are around 20 natural varieties of amino acids, with different sizes, shapes and chemical properties (Figure 1.2). These amino acids link together into chains, and the order and length of the chain is unique to a particular protein.
Spider silk is made, predominantly, of a protein called fibroin, which is mostly made up of amino acids in the sequence glycine, serine, glycine, alanine, glycine, alanine repeated over and over again, forming long chains. These chains line up with each other and stick to their neighbours via masses of weak bonds, forming a structure known as a beta-sheet.
Other proteins are different. For instance, egg white is composed of a mixture of proteins, the main one being ovalbumin. Ovalbumin is made of 385 amino acids and all 20 different amino acids feature multiple times. Overall, it has a very different structure – composed of beta-sheets, plus corkscrew shapes called alpha-helices (Figure 1.3).
So, converting eggs to spider silk presents a bit of a problem, as the building blocks don't match up – their amino acid compositions are different. It's like having two model toy sets, a plane and a house, then trying to build the plane from the house kit. However, the body can do something with amino acids that can't be done with toy blocks. It has the ability to interconvert some amino acids. Another class of protein (with their own distinct shapes) called enzymes can whip bits off serine changing it to glycine or whack something onto serine and convert it to threonine (and vice versa, see Figure 1.4). We can take this interconversion of amino acids into account when figuring out how many eggs Spider-Man needs to make his silk.
In total, fibroin is 50% glycine, serine and threonine whilst only 15% of the protein in hen eggs is made from these amino acids. So, really, Spidey needs to consume over three times more egg protein than the silk protein he plans to use. This means he actually needs 50 eggs for his 100 m of silk. But that's not really the end of it either. After all, what happens if he leaps from a building to save a falling Mary-Jane and deploys his webslingers to save the day (as he does about halfway through the 2002 movie with Tobey Maguire as Spider-Man). Now, I'm guessing he's still using his drag silk (which stretches by 27%). He could go for the flag silk; it's not as strong (tensile strength = 0.5 GPa) but it's got amazing elastic properties as it can stretch to 2.7 times its original length! But that might be a bit too bouncy.
Excerpted from "The Secret Science of Superheroes"
Copyright © 2017 The Royal Society of Chemistry.
Excerpted by permission of The Royal Society of Chemistry.
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Table of Contents
Chapter 1 The Breakfasts of Superheroes Mark Lorch,
Chapter 2 The Evolution of Superpowers Louise K. Gentle,
Chapter 3 The Hallmarks of Hulk Isabel Pires,
Chapter 4 Supervillainy 101: Choosing Between a Zombie, Vampire or Werewolf Apocalypse J. Verran and M. Crossley,
Chapter 5 How to Build a Super Soldier Akshat Rathi,
Chapter 6 The Real World Super Metal Paul R. Coxon,
Chapter 7 Is It a Ceramic? Is It Graphene? No It's Vibranium! Mark J. Whiting,
Chapter 8 The Science of Super Suits Suze Kundu,
Chapter 9 Why Doesn't the Invisible Woman Bump Into Things? Kat Day,
Chapter 10 The Flash: The Fastest Man on Fire Brian Mackenwells,
Chapter 11 You've Got to Learn to Be More Flexible: The Mechanics of Marvellous David Jesson,
Chapter 12 Big Data, Big Heroes and Bad Computers Rob Miles,
Chapter 13 The Wonder-ous Truth: The Workings of Wonder Woman's Lasso Felicity Heathcote-Márcz,
Chapter 14 Super Frequently Asked Questions Karl Byrne,