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Comment by ubasu | Hacker News Reader

You can always roll up the slice into a cylinder with the crust on the straight edge, and that also is an example of the theorem. It says nothing about the mechanics of the problem, i.e. how much will the pizza deform. It is quite possible to fold up the pizza as recommended and still have the tip sag - this depends on the material of the pizza and the self-weight, i.e. the mechanics rather than only the geometry.

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Tomato tomaato. You formulate equations of motion s = ut + gt^2/2 by essentially ignoring air friction. You formulate kirchoff's voltage law L(di/dt)+1/C(integral(i)dt) + iR = V, by ignoring voltage losses across the rest of the circuit. You formulate the heat equation du/dt = laplacian(u) by assuming no lateral heat loss across the rod. Almost all equations in stochastic calculus in finance make the assumption that trading fees are zero & there's an unlimited pool of equity derivatives so you won't move the market when you buy & sell. Including real-life considerations like weight of the pizza & the specific toppings it has & so forth only leads us away from the beautiful math that underlies this problem. As you know, Gauss was so thoroughly impressed by the theorem he called it "Theorema Egregium" - the Remarkable Theorem! It is consistently voted one of the ten most beautiful theorems in geometry[1].

[1]http://www.reddit.com/r/math/comments/1eoo1p/q_what_are_the_...

It's perfectly possible for it to be a Remarkable Theorem which does not actually explain what is going on with the way people hold slices of pizza. And this can be true even if people are fond of saying it does provide such an explanation; it's not uncommon for this sort of thing to be frequently repeated without critical examination.

(I don't know anything about physics, but I felt like making the above comment nonetheless)

Except the beautiful math of the theorum only holds if distances between points on the pizza remain constant, which is manifestly not true for real pizza in particular and real materials in general. Force applied to a pizza curved width-wise will cause it to curve length-wise, changing the value of K. The remarkable theorum predicts that the pizza will not bend regardless of the radius of curvature and length of the slice, however, in practice, insufficient curvature relative to length will result in failure. Thus, the remarkable theorum hypothesis of pizza strength is falsified.

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