if you had a thin enough material, could you pass it through you without causing damage?
like, if you "cut off your head" with a length of piano wire, you would certainly die. what if you had a single molecule of a very long linear hydrocarbon, and "cut off your head" with that? assuming a magical thread that wouldn't snap instantly.
the "severing of the head" is a result of splitting tissues at a cellular level, and potentially splitting individual cells.
would it be hypothetically possible to ever move a "rigid material" through the neck without resulting in death?
if not on the molecular level, what about a beam of protons, or electrons? you could pass xrays through your head, if you had a sufficient density of photons, could you form a "light knife" and cut material through physical processes alone?