Fire, Ice, and Physics: The Science of Game of Thrones

Fire, Ice, and Physics

Fire, Ice, and Physics

The Science of Game of Thrones

Rebecca C. Thompson

Foreword by Sean Carroll

The MIT Press

Cambridge, Massachusetts

London, England

© 2019 Rebecca C. Thompson

All rights reserved. No part of this book may be reproduced in any form by any electronic or mechanical means (including photocopying, recording, or information storage and retrieval) without permission in writing from the publisher.

Library of Congress Cataloging-in-Publication Data

Names: Thompson, Rebecca C., author.

Title: Fire, ice, and physics : the science of Game of Thrones / Rebecca C. Thompson ; foreword by Sean Carroll.

Description: Cambridge, MA : The MIT Press, [2019] | Includes bibliographical references and index.

Identifiers: LCCN 2019001209 | ISBN 9780262043076 (hardcover : alk. paper)

Subjects: LCSH: Science--Popular works. | Science in popular culture. | Game of Thrones (Television program)

Classification: LCC Q162 .T42945 2019 | DDC 500--dc23

LC record available at https://lccn.loc.gov/2019001209

10 9 8 7 6 5 4 3 2 1

ISBN: 978-0-262-04282-6

Retail e-ISBN: 978-0-262-35449-3

Library e-ISBN: 978-0-262-35448-6

MITP e-ISBN: 978-0-262-35447-9

d_r0

To

P.W.H., E.J.E., and R.I.M.

Next time I have an idea like that, punch me in the face.

—Tyrion Lannister

Contents

Acknowledgments

Foreword by Sean Carroll

Introduction

1 Winter Is Coming—Or Is It? Seasons in Westeros

What Exactly Are Seasons?

Why Does Earth Have Seasons?

Very Elliptical Orbit

Moving Axis

Milankovitch Cycles

Two Suns?

So, What about Westeros?

2 And Now My Watch Begins: The Science of an Ice Wall

What Is Ice and How Does It Work?

The Amazing Pykrete

Ice on a Large Scale Is Basically Ketchup

The Great Wall of Westeros versus The Westernport Wall

3 North of the Wall: How to Survive in the Cold

Body Temperature Regulation

When Your Body Just Can’t Take It

Animal Fur (Evolution Is Amazing)

Keeping Humans Warm

Does Jon Snow Need a Hat?

4 White Walkers, Zombies, Parasites, and Statistics

What Is a Zombie, and Do Wights and White Walkers Count?

Neurology and Biology of Zombies

Zombie/Wight Rot

Zombie Neurology: What’s Going on in Their Heads?

Zombie Statistics and a Survival Plan: Can Westeros Get Out Alive?

Bonus: Zombie Dragons

5 Regular Steel, Made in Pittsburgh

Hard, Soft, Brittle, and Bendy: Why Steel?

Isolating Metals: Smelting and the Dawn of the Bronze Age

The Bronze and Iron Ages

From Steel to Swords

How Does It Do in the Cold?

Sam versus a White Walker, Take One

6 Valyrian Steel, Made in Damascus

Raw Materials: Crucible Steel and Wootz

Working Ingot: Not Europe’s Sharpest Moment

Really Ancient Technology Meets Really New Science

Damascus Steel on eBay

Valyrian Steel and White Walkers

7 Dragon Biology: Bats, but with Fire

Warm-Blooded or Cold-Blooded?

Airplane Flight

Birds and Bats and All That

Dinosaurs

Finally, Dragons

8 How to Kill a White Walker: The Physics of Dragonglass

Solid, Liquid, or Both? What Is Glass?

The Sad Case of the Pitch of John Mainstone

Obsidian

Sam versus a White Walker, Take Two

9 Harrenhal: Can Fire Melt Stone? Take Down a Wall?

What Is Fire?

How Might Dragons Make Fire?

Different Colors, Different Sizes

What Is Melting, and Can It Happen to Stone?

What about Harrenhal and Balerion the Black Dread?

Viserion’s Magic Fire

10 The Battle of the Blackwater: The Science of Wildfire

Water Doesn’t Always Beat Fire

The Dangers of Pollution

Modern Fire Weapons Perfected

Colored Fire

Greek Fire

11 Houses Targaryen and Lannister: The Genetics of a Family Tree with Few Branches

How Genes Work

How Traits Are Passed On

23 and You

Identifying Genetic Diseases with the Help of Incest

The Importance of Variety and the Problems Caused by the Lack of It

Finding the Balance between Alike and Different

Diagnosing a Mad King

12 We Do Not Sow: The Science of the Sea

Quick and Light versus Slow and Deadly

Picking Up Speed

Getting There

Drink Your OJ!

13 The King’s Justice: The Biology of a Gruesome Death

Beheading

A Golden Crown

Hanging

Poison

Crushing the Skull

Burning at the Stake

Drowning

So, What Type of Justice Would You Pick?

Epilogue

Notes

Index

Acknowledgments

First and foremost, I’d like to thank my parents, Faye H. Daniel and Dr. Steven D. Thompson. Neither of you are here to see this completed, but your love and support throughout my life got me here, and I know you were looking down on me through the process. I absolutely would not have gotten through this on my own. Thank you, Amy Stern, for helping me figure out how this all works. Molly Kleinman, thanks for being an amazing research assistant and finding even the gory papers. Who knew you’d get to learn about hanging! Carolyn Kuranz, thank you so much for all your help with physics and graph production. Ted Beyer, my military historian friend, thank you for always having the answers and always making me think hard about mine. Thanks, James Roche and Stephen Skolnik, for making everything run smoothly and helping me keep a positive attitude. Thanks, too, for listening to an endless number of BecX Talks about everything from incest to Damascus steel. Many thanks to my copy editor, Elizabeth Agresta, for doing an amazing job and adding some fabulous jokes. A big thanks to NCIS for being my escapist show while writing about my escapist show. It has a slightly lower body count and at least Ziva and Tony weren’t related—though I think I’d rather face Jon with a sword than Ziva with a paper clip. And of course, thanks to Bo, who has put up with more than any partner should.

Foreword

Sean Carroll

As I’m sitting down to write this foreword—somewhat after the book itself has been finished—a study was just published in the journal Injury Epidemiology, with the title "‘Death Is Certain, the Time Is Not’: Mortality and Survival in Game of Thrones." The authors, Reidar Lystad and Benjamin Brown, address the pressing question of what kind of survival strategies were most effective among the major players in Westeros. (It’s a violent world; 14% of characters on screen died within an hour of their first appearance.) Their paper includes paragraphs such as this:

Important characters appearing in Seasons 1 to 7 of Game of Thrones were included, and data on sociodemographic factors, time to death, and circumstances of death were recorded. Kaplan-Meier survival analysis with Cox proportional hazard regression modelling were used to quantify survival times and probabilities and to identify independent predictors of mortality, respectively.

Serious stuff! Or is it?

Scientists pride themselves on studying the real world. The world of George R. R. Martin’s A Song of Ice and Fire books, and the TV show on which they are based, is not the real one. Martin made it up. Admittedly, certain situations and events were inspired by real-world history, but the Game of Thrones milieu features entirely fabricated climatology, astronomy, metallurgy, chemistry, and biology, not to mention zombies and dragons. What can science say about that?

Quite a bit, as you are about to discover.

The conversation between science and literature (science fiction, fantasy, or any other genre, for that matter) is a dialogue. Literature can learn from science in obvious ways. If your story is set in outer space, you’re going to want to know how rockets and closed ecologies work. Even if your story is set in a feudal society suffused with magic, all sorts of science might be relevant, from weather patterns to the chemistry of various poisons.

But information and inspiration also flow in the other direction. Scientists collect data by doing experiments and observations, and use that information to gain knowledge of how the world works. Reading a work of fiction is data collecting of a sort. If the world of the story is well constructed, it will obey rules, whether or not those rules are explicitly laid out. If anything goes, the story isn’t interesting; for the protagonists to be challenged and the audience to be engaged, characters have to operating within a logical milieu. Without physics, there can be no drama. A good scientist can examine a well-told story and figure out what the rules of the world are, whether or not they’re the same of our world. That’s what scientists do.

Here in Fire, Ice, and Physics, you’ll encounter a masterful exploration of both sides of the dialogue between science and fantasy. Rebecca Thompson takes the world of Game of Thrones and examines it through the eyes of a trained scientist. If there’s one thing that everyone who watches Game of Thrones knows, it’s that winter is coming—but on a somewhat unpredictable schedule. Unlike Earth, where we can predict well in advance when the leaves will start turning and the temperature start dropping, seasons in Westeros are much sneakier. It would be okay to think to yourself, Well, GRRM just made that up for dramatic effect; there’s nothing scientific about it. And you might be right. But when faced with that kind of unusual phenomenon, a scientist can’t help but think, "But how would that work . . . ?"

Examining questions like that—and not necessarily answering them—is what makes this book so delightful. Answers can be hard to come by, and since we can’t visit Westeros to collect additional data, we may never know for sure. But science is a process, not just a set of established results. And here you will see that process at work. Once we apply our brains to the problem, rather than just dismissing it as a fictional conceit, we quickly realize the incredibly rich set of scientific concepts that can usefully be brought to bear.

Happily, Martin’s world has given us an enormous amount of raw material to work with. The books, as well as the TV series based on them, are famously detailed, from what the smallfolk tend to eat for typical meals to what the mottos are for a dizzying number of noble houses. The scientific questions are similarly numerous and rewarding.

Of course, most of the questions seem just as fantastical and hopelessly unscientific at first glance. The Wall in the North is held up by magic, we are told explicitly. Nobody even tries to explain Valyrian steel, or how dragons can breathe fire. And wildfire is simply presented as an incredibly dangerous substance, not the careful product of diligent lab work by Westerosi chemists.

But here’s the thing about science: it’s always there, lurking beneath the surface. Game of Thrones is fantasy, but it’s not surrealism; everything that happens is either based on or inspired by features of our actual world. Take the example of the Strangler, the poison used to kill King Joffrey at the Purple Wedding. There’s no reason why it has to be an actual poison we have here on Earth, but it has properties we know and can analyze: it has to be something we can disguise as a gem on a necklace; it dissolves in wine; it doesn’t have a strong taste; it constricts the throat and renders the victim incapable of breathing. Scientifically speaking, we’re given a lot of data to work with.

As Thompson shows, there’s no known poison that matches precisely what we’re told about the Strangler, but we can come pretty close. Strychnine, in particular, can be made into the form of a crystal, and it kills by causing muscle contractions. But it’s not a perfect fit, since it affects muscles all over the body, not just in the throat.

That’s okay. The point is not to find a perfect fit; Game of Thrones is fantasy, not a documentary. What matters is that by investigating the question, we end up learning something along the way. If all you did was watch the TV show, you’d be left with a feeling of satisfaction at seeing a vicious, immature monarch brought down. But you wouldn’t necessarily appreciate that a strychnine-like poison does its damage by blocking the neurotransmitter glycine, therefore causing electrical signals in the brain to go haywire and resulting in a rapid death. That’s probably something that not even the Maesters of the Citadel really understand, but this book is here to fill you in.

What makes a book like this so much fun is just how many examples there are of fantastical events or objects that can teach us something about science. Even if the Wall is held up by magic, what do we know about the structural properties of ice that can tell us exactly what kind of magical assistance would be required? Dragons don’t exist, but dinosaurs did, and their biology and evolution can tell us something about what dragons might be like. (Interestingly, Martin’s dragons have two legs and two wings, which differs from the traditional four-legged dragon of mythology, but is biologically more realistic.) White Walkers are make-believe, but the natural world has some species that have more in common with zombies than you might think.

Like all good fiction, what happens in Game of Thrones is driven by the goal of telling a good story, not by being scientifically accurate. But the spirit of science is useful in any situation, and that spirit comes vividly to life in Fire, Ice, and Physics. As much fun as it is to kick back and lose ourselves in an alternative fictional reality, there’s an extra dimension of enjoyment we get from thinking about what we’re watching in a scientific way.

And who knows? We might learn something useful. After all, winter is coming.

Introduction

Because I’m a scientist, that’s why. As a trained scientist, I ask lots and lots of questions, and I want to know why things happen the way they do. I want explanations and reasons for what I observe. I wish I could turn this need on and off, but unfortunately, I can’t. What this means is that watching TV and reading fiction can be an interesting endeavor that often leads to me hit pause and yell to my fiancé about the questionable science presented. We then have the joy of a 20-minute back-and-forth on science, as we used to do in grad school. I hope that my obsession with asking so many questions and needing the answers will not ruin your fantasy fun but rather enhance it. I’m not out to nitpick every small detail in every scene in Game of Thrones. I don’t want to look at every sword swing or arrow trajectory and tell you why that couldn’t happen. So much of what’s done in Hollywood is done for drama, and I don’t want to spend too many pages telling you why it’s wrong. What I want to do is use Game of Thrones as a gateway to learning some really interesting science, and then use this knowledge to add a new dimension of appreciation to a really great show.

My day job, when not writing about the science of Hollywood, is getting nonscientists to appreciate science. My standard joke is that when I meet a guy in a bar and he asks me what I do, my answer is highly dependent on how attractive he is. If I want to continue the conversation, I say I write science-based comic books. If I’d prefer he leave, I say I’m a physicist. Both are technically true, though one is much less intimidating. My goal in life is to change that interaction.

This book began as a talk I gave at Biosphere 2 in Arizona. No, not Biodome (a horrible movie starring Pauly Shore)—rather, the experiment in which people were sealed in a glass dome to see if they could survive for three years. (They could not.) It’s now a research facility and an institute for training science teachers. I would highly recommend a visit, but make sure you go off the path and see the ruins. The organizers invited me to teach some classes and give a casual physics lecture during dinner. I asked what they wanted me to talk about, and they replied, Anything you want. I had written blog posts on the physics of various things, but I had never been able to give a full talk on anything, and I was not about to waste it. Game of Thrones had just become the number one pirated show in the world, and I was hooked. I saw so much interesting science in the show, and it seemed like a good anything to try. What I didn’t expect was that I’d be walking into a room with a talk full of blood and gore and death and graphic video clips—and that I’d be the only person who had seen the show. In spite of this, two things happened. Lots of people learned a lot of science, and more than a few new fans were converted. I’m not entirely sure the person who invited me to give this talk fully understood what I would interpret as anything, but here we are, many iterations of that talk—and now, a book—later.

Because this began as a talk, and because I am most comfortable explaining things as if I’m talking directly to a real person, my style is very conversational. In grad school, my advisor would push us to explain our research as if you were explaining it to your mother. I pointed out this was more than a little sexist, and that my officemate’s mother had a degree in engineering and could probably handle the big words. He rephrased, asking us instead to explain it to a 12-year-old. It forced us to find the core ideas of our work and explain those only. I can’t thank him enough for making us do that. It made us better scientists, better teachers, and better at applying for grants. I don’t know if my narrative choices will be good or bad, but I felt like it was how I do things, so why not?

I firmly believe everyone should have an understanding of at least a little science and be comfortable using common terminology and thinking the way a scientist would in order to understand the natural world (and occasionally the unnatural ones). So often you hear people say, I’m not really a science person, or I’m not really good at science, yet it’s not socially acceptable to not really be a reading person or good at politics. These are all skills that people need to learn to navigate society, and I don’t think science should be any different. There are different methods to get people interested in and comfortable with science, and through my job I’ve had the opportunity to try several, ranging from blog posts to comic books. I am hoping that this foray into a piece of Hollywood science will reach people in a way I haven’t yet tried. I hope you enjoy it, but more than anything, my goal is for you to look at things in a different light by the end of the book. There will be spoilers. (So, so many spoilers.) If you haven’t watched through season 7, know that you will learn what happens to key characters. You have been warned.

What I don’t want to do is take away your enjoyment of the show. Season 7 was airing when I began this project, and I was so worried I would only be able to watch the show as a scientist and that I would lose what I so loved about it: the characters and the interplay between them, their relationships, the unexpected deaths, and the dragons. I realized my fears were unfounded when I teared up as Daenerys rode in for the first time on Drogon with sweeping wings and flame-torch breath. I sobbed when Viserion was killed and cheered when Jon and Dany finally got together. My emotional involvement with the show actually increased rather than decreased, and I hope the same will be true for you. I hope this book will give you a deeper understanding of how rich and deep the world of Westeros really is.

I had a lot of fun picking topics I wanted to focus on and identifying specific pieces of the show that had fun scientific explanations. Because so much of the show involves death, I knew that would be a key chapter. I figured I’d watched so much death on the show that it couldn’t be too hard to write about the science of dying. I was very, very wrong. It was emotionally difficult, and despite my best efforts, I was not able to separate myself as a scientist as much as I’d have liked to. Know that it might be harder to read than you may have expected. But in writing that chapter, I learned two things. The first is that being a blonde woman at a cocktail party coherently discussing the science of the guillotine gives some people a shock and causes them to dash off for another drink. The second is that there is no easy way to go from alive to dead. It’s a hard transition no matter what, but I guess we’ll all find that out eventually. I chose not to go into the science of various methods of torture because that seemed like a bridge (or rat in a bucket) too far.

I know there are more than a few internet forums and pop science articles devoted to many aspects of both the show and the world within. Dragon fire and wildfire stand out as particular topics people like to discuss. In as many cases as possible, I have tried to address these elements of the show or use them as a starting point for discussions about real-world science. If you find yourself getting agitated and disagreeing with me, please give me a chance and read the full argument. I have used primary source references and a lot of scientific reasoning to back up my work. In some cases, I may very well have missed an argument or a potential scientific explanation, but I am certainly excited to learn about them. Publisher willing, perhaps there will be a second edition that can address these issues and potentially answer all of the interesting science questions you still have. HBO is already casting for a new prequel series, so who knows what will happen!

I hope I was able to make the science of these really complicated topics easy to understand. What I talk about here is what I thought was the most relevant to the topic at hand, not the sum total of the information out there. I’ve had the interesting experience of finding myself talking intelligently about the myth of saltpeter being used to suppress sex drives of soldiers or the efficiency of the German guillotine, but I didn’t include either in the book since they have little relevance to Westeros. Thanks to modern social media, however, I am more than happy to have lengthy discussions about all of these things.

More than anything, read and have fun. Learn something and become your own cocktail party buzzkill or the center of attention, depending on the crowd. Enjoy the show. Enjoy the science. Have fun, get emotional, get involved, and let science add to your fun. I hope you like this book as much as I liked writing it. I learned a lot and I hope you do, too.

All this being said, let me paraphrase Sansa Stark and Jon Snow: Science is coming. I have been promising.

1

Winter Is Coming—Or Is It?

Seasons in Westeros

Oh, my sweet summer child, Old Nan said quietly, what do you know of fear? Fear is for the winter, my little lord, when the snows fall a hundred feet deep and the ice wind comes howling out of the North.

—A Game of Thrones

Winter Is Coming—these are both the words of House Stark and George R. R. Martin’s ominous refrain throughout A Song of Ice and Fire. Behind the fighting of kings and the birth of dragons is that promise: winter is coming. Well, of course it is. It’s usually the season that follows fall and precedes spring. Why are the Starks making such a big deal of this? Because this isn’t taking place on Earth, that’s why. The continent of Westeros is on a planet that, for the most part, operates the same way as Earth. There’s land and sea, the surface temperature seems about the same as Earth, and there are, well, humans. But as much as Westeros seems like Earth, it’s clear from the early on in the series that something is amiss, and that something bigger than the fighting of kings is driving the plot. After all, political leaders fighting while dragons breathe fire isn’t anything new. Doing it with the imminent threat of a years-long winter so cold it can kill while also unleashing an army of the undead makes the whole story that much more ominously interesting.

Before I go into what causes seasons and whether or not a planet like the one in Game of Thrones could exist, it’s important to note that the biggest factors in Earth’s average temperature are its atmosphere and the amount of the planet that is covered by water. It takes a lot more energy to heat and cool water than it does to heat and cool land. Because 71% of Earth is covered by water, the average temperature of the planet doesn’t swing that wildly from night to day and from season to season. Water simply cannot change temperature that quickly. Our atmosphere also protects us from temperature swings. Most of the energy from the sun that reaches Earth is trapped as heat in our atmosphere due to the greenhouse effect. Yes, the greenhouse effect is responsible for global warming, but it is also the reason our planet can sustain life. I’m going to assume that the planet in Game of Thrones has the same general properties as Earth, a similar atmosphere, and a similar percentage of ocean. It’s possible that this is a bad assumption to make and that the unpredictable seasons are caused by swings in greenhouse gases or a lower percentage of water, but it seems safe to assume, based on the mythology, that this is not the case. That means there has to be some astronomical explanation—that is, an explanation having to do with the relationship between the planet and other massive bodies in its vicinity, such as moons and stars, for the seasons that drive the narrative of Westeros’s foreboding onslaught of winter.

What Exactly Are Seasons?

It seems silly to answer this question at the start, since everyone pretty much knows what a season is. If flowers are blooming, it’s spring; if it’s hot and steamy, it’s probably summer; and if the leaves are changing color, it’s probably fall. Days off work and a snow shovel mean winter is finally here. In the world of Westeros, it’s the white raven of the Citadel, not the French Toast Index,¹ that tells us when winter is here; however, it isn’t quite that simple. Even scientists don’t have one specific, fail-safe way to say what season we are in. There are actually two working definitions of seasons, meteorological and astronomical. As you would expect, the meteorological definition is based on what the weather is like, and the astronomical definition is based on where we are in our orbit around the sun. In the Known World of Westeros, the maesters seem concerned primarily with the meteorological definition, but an interesting book in the restricted section of the Citadel’s library seen in the season 7 premiere suggests they knew a bit more about astronomy than previously discussed. The two don’t differ that much in terms of start and end dates, but for most of this chapter I’m going to be using the astronomical definition because I care more about how the planet is moving and less about rain next Tuesday.

Meteorologists divide the calendar into four sections called seasons. Given that I’m writing this book in the Northern Hemisphere, the show is filmed in the Northern Hemisphere, and GRRM lives in the Northern Hemisphere, I’m going to talk about seasons from that perspective. In the Southern Hemisphere, the seasons are reversed. In the North, meteorological winter is December, January, and February; spring is March, April, and May; summer is June, July, and August; and fall is September, October, and November. This isn’t really surprising and generally aligns with our view of the seasons. These divisions were decided upon to make weather forecasting easier and to simplify the calculation of climate averages and trends, and they’re definitely biased toward the mid-latitudes, where the seasonal differences are most noticeable. When you hear phrases like hottest summer on record, it is referring to this definition of seasons. Figure 1.1 shows the average temperature by month for Washington, DC. If you look at the graph you can see that spring and fall really do represent the transition points. The average temperature is changing much faster during these six months than during summer and winter. The more math-y way to say this is that the derivative of the curve in spring and fall is greater than that in summer and winter. The derivative is a way to show how fast something is changing, so it makes sense to define seasons like this; however, this definition relates more to how humans have constructed months than how Earth is rotating around its axis and orbiting the sun. That’s where astronomical seasons enter the picture.

Figure 1.1

Average monthly high and low temperatures in Washington, DC. Data provided by the National Renewable Energy Laboratory.

Astronomical seasons lag approximately 20 days behind meteorological seasons. Instead of being based on what the weather feels like here on Earth, it’s based on where Earth is in its orbit around the sun. There are four important points that mark the change from one season to another: the winter solstice, the vernal equinox, the summer solstice, and the autumnal equinox. You can probably guess by their names which point is associated with each season, but just in case, here’s the official astronomical definition of seasons: Winter begins at the winter solstice, which is around December 21, and ends at the vernal equinox, around March 20, when spring begins. Spring lasts until the summer solstice, usually around June 21. Summer ends with the autumnal equinox, on or around September 22, and the cycle repeats itself. This definition of the seasons is based on two astronomical phenomena—the equinox and the solstice—so what exactly are those?

Both the solstice and the equinox were observed and named before Nicolaus Copernicus saw the publication of his heliocentric model of the universe on his deathbed in 1543. This means that the equinox and solstice were named for what people on Earth saw happening to the sun’s position in the sky. In the next section, I’ll talk about what this means in a heliocentric model, but for now, this is all based on observations of the sun from Earth.

The word solstice comes from the Latin sol, which means sun, and sistere, which means to stand still. As the sun moves across the sky throughout the year, it appears higher in the sky as the days get longer and lower in the sky as the days get shorter. If something is going from a high point to a low point and back again, it needs to turn around at two different points. These two points are called the solstices. The summer