The Boy Who Lived Students put the science of Harry Potters universe to the test

In the world of Harry Potter the young wizard undergoes two magical biological transformations: eating Gillyweed to grow gills in order to breathe underwater and drinking Skele-Gro to repair broken bones.

Natural Sciences students have put these arcane medical practices to the test - and have concluded that a little magic might indeed be required in both situations to make them scientifically feasible.

The research is revealed just before Harry Potter and the Cursed Child opens as a West End stage play in London and Fantastic Beasts and Where to Find Them is released in cinemas worldwide.

Gillyweed – Drowning with Gills?

In Harry Potter and the Goblet of Fire, Harry passes the second Triwizard task by consuming Gillyweed, which allows him to breathe underwater by causing gills to grow on his neck. 

Calculating the feasibility of Harry surviving with home-grown gills, in a paper for the Journal for Interdisciplinary Science Topics, students Rowan Reynolds and Chris Ringrose found that the water in the Black Lake would have to flow at 2.46 metres per second – twice the velocity of normal airflow and therefore far faster than he could inhale and exhale, causing him to suffocate.  

Interestingly, Harry is seen swimming with his mouth closed, which is not how gills work – the students suggest that if Harry were to open his mouth to allow water into his throat and out through the gills, it may be plausible he could breathe underwater. By keeping his mouth shut, however, he would not be able to extract sufficient oxygen for survival, and as a result would lose his title as ‘The Boy Who Lived’.

Revealing the Magic of Skele-Gro

While Harry’s underwater success may be questionable, the bone-producing panacea Skele-Gro would be equally as farfetched.  

In Harry Potter and the Chamber of Secrets, Harry’s tense Quidditch match against Slytherin results in one of his arms being broken by a rogue bludger. After his broken bones are removed, the matron Madam Pomfrey then prescribes Harry a dose of Skele-Gro, used for growing bones that are missing. 

In a separate paper, students Leah Ashley, Chris Ringrose and Robbie Roe aimed to find how the rate of normal bone growth compares to this accelerated growth, and how much energy Skele-Gro would need to provide in order to rebuild Harry’s broken arm.

They found that Skele-Gro must have the capacity to supply an enormous amount of energy required by the body to regenerate bones beyond Harry's standard dietary requirements without causing any negative side effects - a power output of 6443 W. As a result, the students deduced that Skele-Gro must contain unexplained magical properties that allow it to hold such a vast amount of energy and be able to apply it in a short period of time.

The students presented their findings in a paper for the Journal of Interdisciplinary Science Topics, a peer-reviewed student journal run by the University’s Centre for Interdisciplinary Science. Students from the University of Leicester (UK) and McMaster University (Canada) have contributed to this year’s journal. The student-run journal is designed to give students practical experience of writing, editing, publishing and reviewing scientific papers.