What if you wanted to cut a bagel in half not for toasting or sandwich purposes, but to explore its topology and mildly astonish your friends?

If you cut a bagel along a möbius strip pattern, you end up with two separate halves that form interlocking rings, as shown below.

Geoge Hart, who cut this bagel and made this video, is an engineering professor at SUNY-Stony Brook and “mathematical sculptor. On his web site, he offers two bagel-derived math problems: *What is the ratio of the surface area of this linked cut to the surface area of the usual planar bagel slice?* and *Modify the cut so the cutting surface is a one-twist Mobius strip. *

Via @mark_e_evans and The Onion A/V Club.