Is the number 8 special in turning a sphere inside out?

general-topology soft-question differential-topology

No, 8 isn't special beyond it being the choice they made for that specific video.

The software the group wrote to make that video allowed you to choose that parameter arbitrarily. I bet if you spent some time digging you could find that software somewhere on the internet, and create your own eversion videos with a different choice of the number of corrugations.

You can find a (modified) version of the source code here: http://profs.etsmtl.ca/mmcguffin/eversion/

as well as commentary from Silvio Levy on the choice of number of strips.

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