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I was thinking in a character who has a...kind of Steam powered Chainsaw, and a sword, what make them special is because the blades of the chainsaw are one-dimensional, same with the sword, they are made of iron.

I was actually curious what could they cut and what not, or anything with that level of edge can cut everything ? and, if that is the case, Could a one-dimensional paper cut with "ease" a Steel spoon ? Or my Iron Chainsaw could cut a armor made of Nuclear pasta ? ((just assuming that somehow someone manage to "deactivate" the gravity that thing should apply over everything, also assuming that material is solid, this is just a crazy totally hypothetical scenario, i actually don't want that kind of armor in my story))

Or be one-dimensional actually would made these thing very fragile ? if that is the case, just the edge part is one-dimensional (With one dimensional i am referring to something with thickness of one atom, only less if is scientifically possible)
I would really appreciate it if someone clarify my doubts, thank you

No.
First off, there are no truly one dimensional structures, but if you assume there are:
Cutting requires getting into the material and separating it. You need some sort of wedge for that, the tip digs into the material, and the flanks move the material apart.

Sharpness only helps to some degree, it makes it easier to get some indent for the wedge to move in, but beyond that a sharp edge mostly ensures a cleaner, less jagged cut.

To separate a chunk of metal, you need to provide enough force to drive in the wedge, and move the material out of the way.

A one dimensional thing would be a row of atoms. Think of it like a very thin rope. it could only work to transmit tension, any other load would make it nonfunctional:

• compression: any tip load would buckle the line, ruining it


• shear: same here, the line would simply bend and be useless

Ok, assume you have wire that's a single atom wide. You have each atom bonded with only two atoms left and right of it. If these bonds are weaker than the bonds of the material you want to cut, well, there goes your wire. As such, no cutting steel with a 1D paper "blade".

Next point is force. You need to supply forward force strong enough to move your "blade" through the material. When you cut something with a wire, all that forward force comes from the wire tension times the curvature of the wire. A straight wire simply cannot have any forward force to cut. The tension of the mono-atomic wire is limited by the strength of its chemical bonds, again. This puts a strict limit on the width of the material you can cut. If the material to be cut is to wide, you either cannot apply enough force to push the wire through, or your wire snaps. You may get away with cutting some soft stuff in the range of millimeters, but you won't be able to cut anything macroscopic.

Finally, if you try to cut wet stuff, well that's difficult. Since your "blade" is only separating stuff by the width of a single atom, the wet stuff will just rejoin after the "blade". Thus, you'll be able to pull your "blade" right through most living cells, and the cell will live on just like nothing happened. This does not apply to muscle cells where severing the structural proteins would cut the muscle, but your muscle cutting ability is already heavily limited by my second point above. Same story for bones. Anything else should survive your "cut" just fine.

So, bottom line: While a 1D blade sounds very dangerous, it's actually not dangerous at all.