Visualizing quaternions (4d numbers) with stereographic projection

How to think about this 4d number system in our 3d space.
Brought to you by you: http://3b1b.co/quaternion-thanks
Part 2: https://youtu.be/zjMuIxRvygQ
Interactive version of these visuals: http://3imaginary1real.com

Quanta article on quaternions:

The math of Alice in Wonderland:


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Music by Vincent Rubinetti:


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