Friday, June 07, 2013

A Post of Ice and Fire, but Mostly Fire

Daenerys and her dragon.  (Photo: HBO)
Sunday's Game of Thrones episode, "The Rains of Castamere," sent everyone who hadn't read the books into a tailspin.  There won't be any spoilers from Sunday in this post because if the great wide internet can keep a secret for 13 years, its not going to be spoiled here.  Since no one can seem to get this recent episode out of their minds, might as well add some physics.  There have already been great  articles about the "ice" part of A Song of Ice and Fire, but not many about the fire. Particularly the mythical Dragonfire.  We learned this season that "dragon glass" can kill White Walkers.  In previous seasons it was revealed that Harrenhal is in ruins because of dragonfire.  How hot does dragon fire have to be?  What makes dragon glass so special?  Could Daenerys's dragons attack the Red Keep of Kings Landing now even though they are small?




In the book "A Song of Ice and Fire" by George R.R. Martin and the associated HBO series "A Game of Thrones," the land of Westeros was conquered by Aegon the Conquerer and his dragons long before the story starts.  In one pivitol battle Aegon's dragon, Balerion the Black Dread, melted the walls of the castle of Harrenhal.  Is melting stone even possible?  Well, yes, it is.  Pretty much anything will melt if it is exposed to enough heat.  Lava is really melted stone.  Though it is said that Balerion's fire was so intense it burned black, really the hottest of flames is white.  Assuming his flame was in fact white hot, as all available art seems to indicate, it burns with a minimum temperature of around 2800 degrees Fahrenheit.  Most castles in the UK were built with granite so assume the walls of Harrenhal in Westeros are also made of granite.  The melting temperature is around 2300 degrees Fahrenheit so the walls of the castle, if exposed to continuous white flame, could actually melt.  Not just crack and crumble; become liquid.  Daenerys Targaryen hopes to cross the sea and again conquer the Seven Kingdoms and has her own trio of baby dragons with which she hopes to accomplish this lofty goal.  Her dragons are considered very young and not yet enough of a threat to try and take the city.  Frankly, they seem pretty dangerous to me.  They can fly and shoot flame roughly 50 yards.  But is their fire hot enough to melt the walls of the Red Keep of King's Landing?  In a word, no.  The flame these babies produce is only orange, not white.  Deadly enough for a man, but only about 2000 degrees Fahrenheit, 800 degrees short of what would be needed for an assault on the walls.  It seems that as they grow, dragons don't just develop in size, they develop in heat intensity.  Cool!  Or, I guess, well, deadly hot.

Dragonfire can be used to make more than just castle ruins, it can also turn sand to glass.  Dragonglass seems to be obsidian made with dragonfire instead of a volcano.   When lava rich in feldspar and quarts is cooled very quickly, there isn't enough time for the molecules to align neatly and form a crystal.  Instead, the molecules harden in a disordered fashion and become glass.  The resulting "volcano glass" is more commonly known as obsidian.  This is a distinct two step process.  First the rock is melted and becomes liquid and is then cooled quickly.  However, in certain cases this two step process happens very quickly and it seems the glass is produced in one step.  At the Trinity test site, it is not unusual to find what is called Trinitite or Trinity Glass.  During the bomb test the desert sand, composed mainly of quartz and feldspare with hints of other elements, was sucked up into the bomb blasts fireball, melted and cooled rapidly as it rained down.  It can be found in several colors depending on what trace elements are present, some types are even red when copper from near by electrical cables was brought into the mix.  It is mildly radio active.  This whole process can also happen when sand is struck by lightning.  The sand melts with the heat of the lightning then solidifies into glass very quickly.  It seems that there is no reason this shouldn't happen with dragonfire.  Interestingly, the temperature needed to melt rock and form obsidian is very close to the temperature needed to melt granite.  Seems like these dragons were made to conquer Westeros and create the weapons needed to rule Beyond the Wall.  If any one of the great dragons blew fire on sand or other glass-forming compounds, the sand would melt then harden quickly into the Walker-killing glass.

Obviously there is some magic in the dragon glass that makes it deadly to White Walkers, but would it be possible for obsidian to maintain its slicing and stabbing power at temperatures low enough to crack steel?  In the only scene of a White Walker being killed, he grabs a steel blade and shatters it and is then stabbed with obsidian.  Is this possible?  Steel is very good in normal temperatures, but becomes brittle below around -120 degrees Fahrenheit.  Apparently White Walkers have an extremely low core temperature.  But the Dragon Glass was unaffected by this creature's frozen body.  Obsidian has often been prized for its ability to make a very sharp edge.  It breaks in a regular way and when broken can create edges sharper than steel.  It is even sometimes used in surgeon's scalpels.  So even if it did crack on contact with the White Walker the way steel does, it would crack in a way that would make it more dangerous.  The trade off is that it breaks very easily.  An obsidian spear head can handle a lot of force hitting the tip, but not much force if hit from the side.  Good thing Samwell stabbed the Walker straight on!   If I were a Brother of the Night's Watch, I think I would have a steel sword with a back up obsidian dagger.

Personally, I swear my sword to House Targaryen.  Dragons that are perfectly evolved to conquer this world and a warrior queen, how could they lose? Though knowing George R.R. Martin, now that I've said that she's gonna get it in the next episode.

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