How To Slice A Bagel Along A Mobius Strip : The Salt Bagels are getting too big and puffy, throwing off proper ratios to cream cheese and lox. Something must be done.

# Cut Your Bagel The Mathematically Correct Way

Courtesy of Amy Pearl
Courtesy of Amy Pearl

When I interviewed mathematician Eugenia Cheng for an upcoming episode of The Sporkful podcast, she sliced a bagel along a Mobius strip.

A Mobius strip, in case you're not familiar, is a surface with only one side. You can make one by taking a strip of paper, twisting one end halfway around, and taping it to the other end. Like this:

MÃ¶bius strip Wikimedia hide caption

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If you were to start drawing a line down the middle of the strip and just keep going, you'd cover all the paper and end up right back where you started, without ever flipping it over.

So Dr. Cheng sliced a bagel that way, and it was cool. But how did it make the bagel more delicious?

"Well, it's basically completely ridiculous," Cheng says. "And isn't that delicious?"

Perhaps. But it occurred to me that the doctor may have stumbled upon a cure to the terrible trend plaguing bageldom. (You haven't heard?!) Bagels are getting too big and puffy, throwing off proper ratios to cream cheese and lox. Something must be done.

So like any great academic, I built on the work of my esteemed predecessors, Dr. Cheng and Dr. George Hart, who gave us the Mathematically Correct Breakfast.

I began by drawing a Mobius strip on a bagel:

Courtesy of Amy Pearl
Courtesy of Amy Pearl

The line needs to wrap around the outside and inside of the bagel, and end up connecting to the beginning. Then slice along the line using a small, nimble knife.

Courtesy of Amy Pearl

When you're done, the inside should look like an M.C. Escher staircase.

Courtesy of Amy Pearl

Now ready to get crazy? Slice a second Mobius strip, about a half-inch away from the first.

Courtesy of Amy Pearl