Scientists tested whether the spells in Harry Potter could work in real life

Could Gillyweed and Skele-Gro be used without magic?


University of Leicester students have been dissecting some very important matters: do the spells Harry Potter and his fellow wizards use really need magic in order to work?


Two scientific papers, Gillyweed – Drowning with Gills? and Revealing the Magic of Skele-Gro, have been published in the Journal for Interdisciplinary Science Topics, analysing two spells that only exist thanks to author JK Rowling’s imagination.

Firstly, Gillyweed, which fans of the novels will recall Harry uses in the fourth book, the Goblet of Fire, during the Triwizard Tournament. Challenged with swimming to the bottom of a lake to retrieve his best friend Ron, Harry ingests the plant and grows webbed hands and feet and – crucially – gills which enable him to breathe under water.

The process was examined by natural science students Rowan Reynolds and Chris Ringrose who found that, based on the size of Harry’s gills and the maximum oxygen use of swimming for a boy his age, he would need to process 443 litres of water at 100% efficiency per minute for every minute he was underwater – meaning water would need to flow at 2.46 metres per second.

“This is extremely fast if Harry is to bring water into his gills through respiratory power alone,” they write. “The velocity of normal breathing has been recorded as 1.30 metres per second; 2.46 metres per second is almost twice the velocity of normal airflow, which makes Harry’s gills unfeasible.”

But they did concede that were Harry to open his mouth during swimming – which he doesn’t do in the film – allowing water into his throat and out through his gills, “it may be plausible that he could breathe underwater. However, without doing this, it is simply not plausible that he could extract sufficient oxygen for survival.”

What about Skele-Gro, which is used after Harry breaks his arm during a Quidditch match in the Chamber of Secrets? In the second paper, Ringrose, and fellow students Leah Ashley and Robbie Roe, examine the drug Madam Pomfrey feeds Harry after Gilderoy Lockhart inadvisedly removes the bone’s from his injured joint. He heals within 24 hours, meaning his bones regrew at a rate “at least 90 times quicker than is seen in the natural way of regenerating bone.”

Their calculations show Skele-Gro regrows bones using energy that amounts to “at least 113,050kcal, giving a power output of 6,443W”. This means that “Skele-Gro therefore must contain unexplained magical properties that allow it to hold such a vast amount of energy and indeed be able to apply it in a short period of time.”


Suffice to say, the magic of Harry Potter firmly belongs in the Wizarding World.