Stranger Things: 15 Stupid Mistakes You Completely Missed
13. The Acrobat And The Flea
Mr. Clarke's 'Acrobat and the Flea' analogy is a pivotal moment in the first season as it goes a long way in helping the boys (and the viewers) understand the physics of the Upside Down and how the alternate dimension even exists in the first place. But it turns out that isn't not actually the most logical analogy.
The science teacher uses a paper plate to explain that if an acrobat was walking on a rope, he can either go forwards or backwards, but that a flea could go forwards, backwards, along the side of the rope or even underneath it - suggesting that it could move between dimensions.
According to cosmologist Ranga-Ram Chary, the theory doesn't hold up as well as it sounds like it does because "Upside-down is the same as walking on top of the tightrope" and "Negative X is the same as positive X."