, 10 tweets, 4 min read
**SCIENCE OF HARRY POTTER**
I was listening to Harry Potter and the Goblet of Fire, specifically the 2nd task, and I HAVE SOME QUESTIONS

Namely, how did Fleur Delacour and Cedric Diggory breathe inside their bubble head charm??
In the movie, the charm is depicted like this, just a little bubble around the nose and mouth of the caster.
However, for the purposes of this argument, I'm going to go with the book's description which is more like an upside-down fishbowl. Like this poor human is demonstrating.
From looking at fishbowl sizes I'm guessing that a human head would fit in a 10L fishbowl. Maybe even a 5L, but let's go with 10L.
As we know, the air is roughly 21% oxygen, and humans begin to experience negative effects as soon as it falls below 19.5% oxygen, by 16% we're confused, by 10% we're almost catatonic, and by 6% we're dying.

(source:sciencing.com/minimum-oxygen… & anatomy textbooks)
We don't use all the oxygen contained in one breath, so an exhale has roughly 16% oxygen, so even if you only had the air contained in your lungs, you could breathe it in and out a couple of times before the %O2 fell too low.
The average lung capacity of an adult male is 6L btw
So...
If Fleur and Cedric had 10L of air containing 21% oxygen, they would inhale and exhale roughly twice before all the air in that bubble had been in their lungs, after which point the air would be roughly 16% O2.
Meaning, that even if they can breathe 16% O2 for a couple more breaths (after which it would fall to roughly 11% O2), they have *maybe* 5-7 breaths of air contained in there.
5-7 breaths. For one hour, underwater.

Now to be fair Fleur gets attacked and turns around after only about 15 minutes (if I remember right), but even that time is too long for her O2 supply. Humans at rest breathe 12-20 times per minute btw.

Source: my.clevelandclinic.org/health/article…
and Fleur and Cedric were *NOT* at rest...

So basically, either this charm magically creates oxygen, or diffuses it into the bubble, or Fleur and Cedric are actually dead and HP 5-7 are fever dreams.

Thanks for coming to my @TEDTalks

#HarryPotter
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