Hobbit Smaug Poster Associate Professor of Physics at Southeastern Louisiana University, Alain Rhett, tries to use phsics in this interesting piece on Wired to estimate exactly how much energy would have been required to melt all that gold in that cool scene in The Desolation of Smaug — you know the one we mean.


After watching The Hobbit: The Desolation of Smaug I quickly realized my initial estimation for the amount of gold under the mountain was WAY too low. There are some other things I noticed, but perhaps I should give a SPOILER ALERT.

I don’t consider these to be REAL spoilers since the story essentially follows the book which published in 1937. But it’s better to be safe and I don’t want any ranting emails from angry parents saying I ruined their kids movie experience. Here is a random picture of trees [Editor’s note: I’ve put in some random Thranduil cheesecake instead.] in order to give you an opportunity to bolt out of here before seeing the spoilers.


Ok, now it’s just us. We are free to say whatever we like about The Hobbit: The Desolation of Smaug. First, let me make a few comments about the movie.

Of course there is a lot of material added to the movie that wasn’t in the book. How else could you make a 300 page book into three movies that are each about three hours long?

* In this movie, we finally get to see Gandalf use magic. Sure, he used magic in The Lord of the Rings movies, but that was just simple stuff. He made his staff glow and he blinded some orcs. Oh, that’s right; he also made an impressive and threatening voice when talking to Bilbo. Of course he still isn’t quite at the same magic level as Albus Dumbledore or even Harry Potter, but he is a wizard. Personally, I kind of like that Gandalf doesn’t use a ton of magic.
* The barrels down the river wasn’t so much a stealthy escape as it was an epic battle. Oh well, I have already looked at dwarves in floating barrels.
* The dwarves fight Smaug. Yes, in the book the dwarves just kind of avoid the dragon. Well, this fight is what I want to talk about in this post.
* You could consider this the spoiler part of the post. In an attempt to defeat Smaug, the dwarves try to drown him in liquid gold. Yup, that’s right. Apparently, there was a whole bunch of gold just waiting to be melted down and then poured into a GIANT cast of a dwarf statue.

The physics of melting gold

How much gold was melted? I don’t exactly know. How long did it take to melt this gold? It was just a few minutes at most, but I don’t have an exact time. How much energy would this take and what about the power? This is exactly what I want to estimate.

To start, I need to know some things about gold. If I want to take room temperature gold and make melted gold I have to do two things. First, I have to increase the temperature. Second, I have to make the gold phase change from a solid to a liquid. The specific heat (we use the symbol c) tells me how much energy it takes to raise a mass of gold a certain temperature. The latent heat of fusion (we use the symbol lf) tell me how much energy per mass I need to make the gold go from solid to liquid. Actually, it seems that the common name for this is the specific heat of fusion.

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