Scientists Have a Few Problems with Harry Potter's Gillyweed and Skele-Gro

Friday, 03 June 2016 - 10:16AM
Friday, 03 June 2016 - 10:16AM
Scientists Have a Few Problems with Harry Potter's Gillyweed and Skele-Gro
Could Harry Potter really survive underwater if he grew gills? And is it possible that a chemical potion could re-grow a full arm of bones in real life? Scientists and HP enthusiasts set out to answer these very important questions, and found a few problems with Harry's magical substances.

First, a team of scientists investigated the potion Skele-Gro, which regrew all of the bones in Harry's arm after Professor Lockhart accidentally removed them.



Writing in the Journal of Interdisciplinary Science Topics, they calculated that regrowing 30 bones in a 12-year-old boy about Harry's size (and in only one night, no less) would require an astronomical amount of energy. Since there's no mention in the novel of Harry eating while Skele-Gro is working its magic, that means the Skele-Gro itself must provide all of the energy, which comes to about 133,050 kcal. To put that number in perspective, it's about 2.5 times greater than the maximum power output of Usain Bolt during his 100-meter world record. 

But Harry Potter is, of course, magical, so one could argue that it's a little bit futile to apply strictly scientific rules. Instead, it's more productive to examine whether it's internally consistent, which is where the Gillyweed study comes in. Although magic can function as a sort of catch-all explanation, Gillyweed is relatively primitive magic, as it seems to function simply by giving Harry gills. According to the study, his gills as portrayed in David Yates' film adaptation of Harry Potter and the Goblet of Fire were too small to provide the necessary oxygen requirements to survive. He would have needed to breathe twice as fast as a normal human for the entire time he was underwater to get sufficient oxygen to his brain, which isn't feasible. It would have worked if he had simply swum with his mouth open like fish do, as the water would have passed through his gills more quickly, but in the film he's seen swimming with his mouth closed.

Luckily for Harry Potter fans, we can argue that this is a problem with the movie adaptation rather than the novel, which doesn't specify the size of Harry's gills. Or, we could just argue that it's magic. That works, too.
Science of Sci-Fi

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